KW V3 997.2 C2 settings and advice - Page 4 - 911/Carrera GT - PistonHeads UK

I have just had a set of KW V3's fitted to my 997.2 C2 and await the information as to how to reduce the very hard rear suspension, RPM fitted but in 3 weeks have failed to send alignment details or offer any help as yet. I was really hoping to have better support after spending £12k on suspension and a few other things, maybe I'm still too smaller customer to be of any worth I will also see what they set the suspension to either their own recommended fast road and or the base recommended, If they ever get back to me, whilst they have promised to I have not received the promised call back or a copy of the 4 wheel alignment. I have done this a few times with various cars 2 way and 3 way a few questions : Do please share your front and rear settings for bump and rebound (as KW measure clicks backed off from full hard) Any recommendations and input to the setting up process and tips, Ive re-read all I can so far I am running new 235/305 continental Sport contact 7 and will start 30/36 PSI again any recommendations for pressures as well, these rise to 33.5 / 40.0 after a short run. I am reasonably happy with ride heights, measuring form ground to arch lip - 656 Front 670 Rear, but may raise a little to something like 660/675 (when they left RPM the back was very high 690mm which made no sense, Ive not moved the fronts and they have settled a bit) The challenge I am having is a jarring rear and moving around the recommend KW staring point changes and to a degree improves but this is currently more jarring than my 991 GT3 Any input appreciated

Sorry if you said it in your post. Did you get the KW setup pamphlet? And are the dampers actually set to the recommended values for your use case, street or performance?

I think if you look at the KW spring rates compared to Porsche and the other aftermarket options, their rear spring rates are way higher than anyone else. Damping isn't going to be able to fix that. That's what i remember reading on here over the years when people were discussing KWs. You will probably need to investigate whether you can get some custom rear springs with a lower spring rate.

Thanks, I’ll see what RPM say, they were chosen as they are the 997 experts and I discussed my needs and use. If this is the case they need to fix this

Yes I did set the dampers to the recommended settings and moved around from there

Harsh ride is the norm with KWV3 for 996/7s I am afraid. I could live with it on my 996.2 GT3 (standard settings) as it was tracked a lot, but not a road car.

I couldn't live with it on the road on my 997.1 GT3 and went back to standard Billies what a relief that was.

braddo said: I think if you look at the KW spring rates compared to Porsche and the other aftermarket options, their rear spring rates are way higher than anyone else. Damping isn't going to be able to fix that. That's what i remember reading on here over the years when people were discussing KWs. You will probably need to investigate whether you can get some custom rear springs with a lower spring rate. In theory, the damping is supposed to be matched to the spring rate that the damper has been valved for. If KW have iirc 120-130ish Nm/mm rear springs, putting on a softer rear spring (and you'll have to be sure there is sufficient travel to match) might not help either. Ohlins R&T are the other manufacturer I think that has ballpark similar spring rates fwiw...

You can usually download the KW documentation on the KW website. Might be worth looking at what they recommend and seeing if you can soften them at all initially. Hope you get a follow up from RPM though.

Hi all I’ve been doing a bit of reading about comparative spring rates looks like the KW V3 is close to 997.2 GT3 front but a little at the rear. Not super excessive but no idea why they chose to go more at the rear. I’m also going to experiment more with damping rates so far I’m up a little on rebound and bump at front and down by one click on both from recommended at the rear. Moving too far feels underdamped I’m also finding thinking of one axle independently is not helping me either I’m going to chase RPM yet again Edited by Adrian-9iafn on Wednesday 9th August 09:34

This is what I have collated so far on spring rates, note some do cover wheel rates which is much more helpful to understands the rear numbers for springs

Interesting. If you add a ratio of front to rear stiffness it looks like it will show the KWs as quite an outlier.

braddo said: Interesting. If you add a ratio of front to rear stiffness it looks like it will show the KWs as quite an outlier. Yep, was just looking at that myself.

Okay, I have for the moment dropped the rear pressure a little more, Now cold 30F 35.5 R and the recommended settings are F 7/9 R 5/9 Bump/Rebound At the moment I am 6/6 and 6/10 Rear, interestingly adding a little more rebound at the front has improved feel and also bizarrely has improved the hardness a bit at the rear. I will see if I can find out how stiff the Conti sidewalls are they are non N rated but are 102Y extra load at the back and 91Y extra load front. as it might be better to get closer to GT3 tyre recommend pressures (29/33 ?) If I add more bump or rebound at the rear it does become much more jarring and seems less integrated as a chassis. I was also thinking about offsets I am 50F (so 7mm more) and 58 rear so (9mm more than stock), so at least this will reduce the wheel rates a small amount So far I have tried : 7/9 5/9 7/7 5/9 6/7 5/9 6/7 5/8 6/7 5/10 6/8 5/10 6/7 5/9 6/7 6/9 6/7 6/10 6/8 6/10 6/6 6/10 And a few further afield 5/4 5/4 5/4 5/5 5/9 5/9 5/7 5/9 5/6 5/9 4/6 5/8 I bet my neighbour wonders where I go for 20 minutes twice a day !

Just a note that I'm pretty sure the GT3 tyre pressures are for Cup tyres. Those low settings are not for non-Cup tyres. Have you tried setting the dampers to full-soft and then edging up from there to find your optimum? I still think the problem is the rear spring rate and that the damping is comparatively trivial for your problem. Good luck.

I’ve had two very different experiences with KW V3, sublime on an E46 M3 and rock hard on a Monaro (later found to have been developed in America not Europe). My Last Exige came on 3 way Nitrons, the ride was a bit harsh on factory settings, backing the high speed compression off by a couple of clicks made a big difference to ride quality, as it did with the Tractive dampers on my recent CSR Caterham, give it a go if you haven’t already.

A little more progress. RPM are in holiday season but they have again promised to help and support when people return, so fingers crossed. I have found that more miles has allowed a little more bedding in and it's just hard as oppose to crazy hard. I spoke with KW and confirmed spring rates 228/742 seems they take the stock car and assess indepently (not looking at say GT3 rates), They can also supply lower rated rear springs if that ends up being the solution. I ended up going back up one notch on the rebound as I did find I was having a little less control over larger fluctuations and although 'stiffer' I felt it was marginally better one click up (back to stock) on rebound. I am now 6/7 front and 6/9 rear. Tyre pressures 'cold' today were 32/38, so potentially some room to reduce a tad as well. I'm not going to give up and am 'fussy' with everything which is a curse and blessing....

Adrian-9iafn said: I have just had a set of KW V3's fitted to my 997.2 C2 and await the information as to how to reduce the very hard rear suspension, RPM fitted but in 3 weeks have failed to send alignment details or offer any help as yet. I was really hoping to have better support after spending £12k on suspension and a few other things, maybe I'm still too smaller customer to be of any worth I will also see what they set the suspension to either their own recommended fast road and or the base recommended, If they ever get back to me, whilst they have promised to I have not received the promised call back or a copy of the 4 wheel alignment. I have done this a few times with various cars 2 way and 3 way a few questions : Do please share your front and rear settings for bump and rebound (as KW measure clicks backed off from full hard) Any recommendations and input to the setting up process and tips, Ive re-read all I can so far I am running new 235/305 continental Sport contact 7 and will start 30/36 PSI again any recommendations for pressures as well, these rise to 33.5 / 40.0 after a short run. I am reasonably happy with ride heights, measuring form ground to arch lip - 656 Front 670 Rear, but may raise a little to something like 660/675 (when they left RPM the back was very high 690mm which made no sense, Ive not moved the fronts and they have settled a bit) The challenge I am having is a jarring rear and moving around the recommend KW staring point changes and to a degree improves but this is currently more jarring than my 991 GT3 Any input appreciated I build competition cars, and have competed in the WRC, so have some experience of damper setup. Damper settings are a very personal preference for each driver. What suits one person will be considered awful for another. Firstly, the dampers will need a few hundred miles to bed in. From memory, a KW damper has 16 clicks of adjustment for both bump and rebound on their 2 way damper. Is that the case on yours..? Your cold tyre pressures at 30F / 36R are good. If I were you, I’d make a big step change; wind back both bump and rebound 5 clicks softer on both front and rear, and go for a drive on a piece of road you know well. You should notice a difference. Keep in mind the front and rear balance, and get an understanding of how the car reacts under braking and rapid direction changes. To me, the jarring at the rear you describe sounds like too much rebound. Softening off should sort this. It isn’t going to be a quick fix, but this is the appeal of adjustable dampers…!

Thanks, I’ll dial out some bump and rebound and see what I can learn

Well, I'm still learning.... First off the car is much less 'bouncy' and the suspension has bed in for the most I suspect. 4-500 miles now. Im running 31 cold F and 37 R (but a warm day so cold is not really cold. 24 degC I backed everything off to F 12/14, R 10/14. As a reminder the bump is 0-12 and rebound 0-16 o being full closed/hard. 'recommended' F 7/9 R5/9, s a good 5 clicks off The rear was less crashy and not as 'bouncy' as the last time I backed it off (settling springs ?) still showed traits of being hard. the front felt soft and compliant, very 'road' with slow response to changes in direction and notably more vague. But more 'comfortable'. The back does not feel soft So I went up and at the moment F 6/7 R 7/11 after a few trial and error adjustments. It's better than too backed off, not more comfortable at the back but not significantly worse and better feel at least it has better feel and is responsive to transition and feels taughter throughout. I'm definitely not there yet, but I haven't given up !!!

Adrian-9iafn said: Well, I'm still learning.... First off the car is much less 'bouncy' and the suspension has bed in for the most I suspect. 4-500 miles now. Im running 31 cold F and 37 R (but a warm day so cold is not really cold. 24 degC I backed everything off to F 12/14, R 10/14. As a reminder the bump is 0-12 and rebound 0-16 o being full closed/hard. 'recommended' F 7/9 R5/9, s a good 5 clicks off The rear was less crashy and not as 'bouncy' as the last time I backed it off (settling springs ?) still showed traits of being hard. the front felt soft and compliant, very 'road' with slow response to changes in direction and notably more vague. But more 'comfortable'. The back does not feel soft So I went up and at the moment F 6/7 R 7/11 after a few trial and error adjustments. It's better than too backed off, not more comfortable at the back but not significantly worse and better feel at least it has better feel and is responsive to transition and feels taughter throughout. I'm definitely not there yet, but I haven't given up !!! Glad you’re finding an improvement. The reason I suggested a big step change of 5 clicks is to exaggerate the change and make you notice what’s going on. To help reduce the vague direction change at the front, try stiffening the bump by a couple of clicks on the front axle only. Leave the front rebound alone. What would also achieve the same effect is to stiffen or close the rear rebound. The key thing to keep in mind with all these changes is weight transfer. Sounds like you’re making progress, and heading in the right direction.

I'd go to Center Gravity to get it setup. I had KW V3s in the late 00s on a 8P A3, set to pretty much fully soft front and rear....was more comfortable than stock.

Another journey and this time I experimented a bit at the front and was reasonably okay with F 6/6 and R 7/11 6/7 front felt a little loose and turn in was less responsive, I also found 6/7 seemed less controlled. F 6/6 feels tighter and sharper at the front and perhaps less of a chassis and more of a front and rear. I'll leave it here, get to know it a bit more then try a few variations. Still a bit jarring, but this does seem to be reducing (or I'm getting used to it) I'll see what the tyre pressures are as well in more normal UK summer temps

neverlifted, hi what's an 8P A3 ?!

neverlifted said: I'd go to Center Gravity to get it setup. I had KW V3s in the late 00s on a 8P A3, set to pretty much fully soft front and rear....was more comfortable than stock. A geometry specialist will be able to get the wheel geometries and corner weights right, but damper clicks which deviate from the standard default setup is very much a personal preference. It’s also extremely rewarding to learn and understand how the bump and rebound affects the car’s handling. Very few tuners will be able to give you individual damper click settings

I think I prefer R 7/12 over 7/11, a little bit less thud and very similar feel, perhaps a little more time to fold in at the rear. so at the moment 30F 36R Psi cold, F6/6 R 7/12 Edited by Adrian-9iafn on Sunday 13th August 18:55

Adrian-9iafn said: neverlifted, hi what's an 8P A3 ?! It was a 2003-2012 second generation Audi A3, which I had I post uni in late 00s.

Adrian-9iafn said: Another journey and this time I experimented a bit at the front and was reasonably okay with F 6/6 and R 7/11 6/7 front felt a little loose and turn in was less responsive, I also found 6/7 seemed less controlled. F 6/6 feels tighter and sharper at the front and perhaps less of a chassis and more of a front and rear. I'll leave it here, get to know it a bit more then try a few variations. Still a bit jarring, but this does seem to be reducing (or I'm getting used to it) I'll see what the tyre pressures are as well in more normal UK summer temps If you find the car is ‘jarring’ on bumps, then try softening the bump only front and rear. But as you’ve found, this does make the car a little less precise on turn in…chassis setup is always a compromise. To make turn in more responsive, and to encourage the rear to rotate, try opening the rear rebound. What you’re trying to achieve by increasing the rear rebound is encouraging the rear dampers to extend more quickly when you’re turning into a corner, this increases the load on front end. If you open the rear rebound too much, then you’ll begin to create oversteer… Another possibility could be to increase the ride height front and rear to give the spring more room to move…but this won’t be a simple driveway fix as you’ll mess up the corner weights and geo…

IREvans said: Adrian-9iafn said: Another journey and this time I experimented a bit at the front and was reasonably okay with F 6/6 and R 7/11 6/7 front felt a little loose and turn in was less responsive, I also found 6/7 seemed less controlled. F 6/6 feels tighter and sharper at the front and perhaps less of a chassis and more of a front and rear. I'll leave it here, get to know it a bit more then try a few variations. Still a bit jarring, but this does seem to be reducing (or I'm getting used to it) I'll see what the tyre pressures are as well in more normal UK summer temps If you find the car is ‘jarring’ on bumps, then try softening the bump only front and rear. But as you’ve found, this does make the car a little less precise on turn in…chassis setup is always a compromise. To make turn in more responsive, and to encourage the rear to rotate, try opening the rear rebound. What you’re trying to achieve by increasing the rear rebound is encouraging the rear dampers to extend more quickly when you’re turning into a corner, this increases the load on front end. If you open the rear rebound too much, then you’ll begin to create oversteer… Another possibility could be to increase the ride height front and rear to give the spring more room to move…but this won’t be a simple driveway fix as you’ll mess up the corner weights and geo… Question is how much time and effort you want to put into understanding all the details of chassis set-up vs. finding a KW-experienced professional who you can describe your intended use and your driving style to. As stated above, set-up comes with inherent compromises and only you can decide how you prefer them to be approached

Neverlifted, the A3 bears no comparison I'm afraid. I spoke to KW and they approach the V3 in the light of the car, a road car with V3 is not intended to be as focussed as a sports car with V3. I did have a KW V3 fitted to an F10 competition BMW M5 a few years ago and managed to dial that in very well. On this occasion the rear has thrown me a little. On the M5 I tweaked, checked and re tweaked many times, I could get my head around the chassis much more easily and I was up on all the suggested bump and rebound settings and it was still more comfortable than I necessarily wanted. I had a DINAN kit on that car before fitted by Centre of gravity and it was WAY, WAY too soft an the car was very erm, boring and blunted. The KW V3 was miles ahead on that occasion. My damping adjustments were more feel and experience based, but it was very good to the point that I could happily shuffle the car along on unknown welsh back roads on the way to Anglesey quicker than a more than competent friend in a McLaren 675LT, I'd assumed he had hung back to avoid stone chips. It was only after he said what the hell have you done to that, that I realised just how good the car was. I hope RPM will be in touch soon so I can learn more. Keep the advice coming I will experiment a bit more with rear rebound and handling. I have had cars where the rear has been a bit unpredictable from too much rebound and undulations on corners causing the grip to diminish, so I'll definitley avoid that !

I am still exploring settings and may now go elsewhere if necessary to resolve. RPM Technik after 5 weeks and over 10 calls and e-mails have failed to return my call to offer any advice and support. The invoice was £4k more than expected (I had quotes for the work and an expectation that it would be another £1k to replace the front coolant pipes) After specific instruction to not have excessive rake and be too nose down the car came with a 30mm delta between arch to ground clearance which I have manually adjusted. I have had ZERO information on any alignment settings or infromation on the geo and ride heights that I paid £475 for I have e-mailed RPM yet again this morning and will call to see if I can get any more information. Needless to say if I knew what I know now I would not have gone to RPM Technik as if they are KW and suspension experts they have not demonstrated this over the last 5 weeks

Sorry to read this. Sent you a PM.

Adrian-9iafn said: I am still exploring settings and may now go elsewhere if necessary to resolve. RPM Technik after 5 weeks and over 10 calls and e-mails have failed to return my call to offer any advice and support. The invoice was £4k more than expected (I had quotes for the work and an expectation that it would be another £1k to replace the front coolant pipes) After specific instruction to not have excessive rake and be too nose down the car came with a 30mm delta between arch to ground clearance which I have manually adjusted. I have had ZERO information on any alignment settings or infromation on the geo and ride heights that I paid £475 for I have e-mailed RPM yet again this morning and will call to see if I can get any more information. Needless to say if I knew what I know now I would not have gone to RPM Technik as if they are KW and suspension experts they have not demonstrated this over the last 5 weeks A 30mm difference in front to rear ride height is indeed puzzling. The lower ride height on the front will have messed up the weight balance significantly, explaining the stiff rear end. (Lowering the front axle ride height reduces the front axle weight, which thereby increases the rear axle weight) Now that you’ve raised the front ride height, you will have increased the front axle corner weights, thereby taking weight off the rear axle. This should help your ‘crashy’ rear end phenomenon you described, so you may need to now adjust your rear bump and rebound accordingly. (Incidentally, when you changed the front ride height, did you measure from the spring platform to the adjuster ring..? When we do ride heights, we make changes by measuring full rotations of the spring platform. Each full rotation of the platform is a change equal to the thread pitch on the damper body. I believe a KW is 1.25mm..?) Personally, I’d suggest as RPM don’t seem to be willing to engage with you, to take it to another geometry specialist (I’ve heard good things about Spires Tuning) and get the geometry and corner weights setup correctly, and then you can talk to them about setting the car up to suit your needs.

I finally managed to speak to RPM and have taken some advice and will continue to explore rear settings, tyre pressures and await the GEO settings to get some bearings. The kits is factory KW spec so the spring rates I have looked up are correct. One question which is a fair question is tyres and how stiff the rear side wall might be with Conti 7's which are not N rated. Having said that I doubt they are Cup2 stiff and my 991.1 GT3 is less jarring When I have explored more settings and tyre pressures I will book a day to head back over and they will work with me to assess and possibly try swapping wheels and tyres to eliminate tyres if that happens to be a problem, I hope it isn't

Adrian-9iafn said: I finally managed to speak to RPM and have taken some advice and will continue to explore rear settings, tyre pressures and await the GEO settings to get some bearings. What was their excuse for not responding to your ten emails and phone messages? And why can they not simply send you the settings from when they geo'ed you car?! Did you get to test drive the car after they installed and set everything and, crucially, before paying their bill? IMO, RPM is now too big an operation. Center Gravity is where I go when attention to detail and clear explanations as to what's been done and why is required.

churchie2856 said: IMO, RPM is now too big an operation. Center Gravity is where I go when attention to detail and clear explanations as to what's been done and why is required. Too big can indeed be off putting in terms of the service feeling a bit impersonal. I used Nine Excellence for the first time recently to fit some Bilstein B16 Damptronics. I didn't realise how big an operation it is. It's a bit unnerving dropping the car off and picking it up and only interacting with a receptionist if you're used to smaller outfits and actually talking through things with the technicians or the proprietor. The work was done well in broad terms, and the invoicing was reasonable and in line with expectations. Car probably has a tiny bit more rake than I wanted and I'm not sure I love the geo. These are not criticisms, there's huge bandwidth for preference and the setup was / is perfectly reasonable. But with the size of the outfit, it's less straight forward to have a conversation about the car's setup. With a smaller outfit a pre-job discussion might have covered the rake, for instance, and talked through the geo in a bit more detail. I'm sure it's different for some long standing customers and a relationship can be built up, but large versus small certainly has an impact. I used them rather than my usual outfit because they have lots of experience fitting B16s and I thought the odds of having significant post-fitting issues would be lower and so far that has worked out and I don't regret using them or question their competence in any way, as far as I can tell they are a very efficient and competent outfit. I just wouldn't rush back for more general stuff because I'd rather be able to have more detailed discussions about any work and while that may be possible in the long run, it's all pretty impersonal for a new customer and I'm not hugely comfortable with that. I'm actually going to be a bit embarrassed when the car next goes in to my usual guys. Hey, where did these shiny new B16s come from?!

I was hoping to do a longer trip this weekend and experiment further but I seem to have a darn coolant leak at the front so I have booked in to a local garage just to investigate what might be the the problem as it will need the under tray removing to see In the meantime I have moved a little more on tyre pressure and tried backing off bump a little more, but went back as the overall result was not more comfortable just a bit looser. Currently F30.5 R 34.5 PSI cold. F 6/7 R 7/13 for bump and rebound. I will raise the ride heights a little and get back to just over 370mm rear and just under 360mm front

My guess the leak is coming from the cross-over pipes.

I hope not as they were all replaced 1m ago

Adrian-9iafn said: I was hoping to do a longer trip this weekend and experiment further but I seem to have a darn coolant leak at the front so I have booked in to a local garage just to investigate what might be the the problem as it will need the under tray removing to see In the meantime I have moved a little more on tyre pressure and tried backing off bump a little more, but went back as the overall result was not more comfortable just a bit looser. Currently F30.5 R 34.5 PSI cold. F 6/7 R 7/13 for bump and rebound. I will raise the ride heights a little and get back to just over 370mm rear and just under 360mm front I’ve had a similar recent front coolant leak. Turned out to be a flattened o-ring on the hose into the LH radiator. You can source just the o-ring, but a complete hose isn’t expensive.

IREvans said: A 30mm difference in front to rear ride height is indeed puzzling. The lower ride height on the front will have messed up the weight balance significantly, explaining the stiff rear end. (Lowering the front axle ride height reduces the front axle weight, which thereby increases the rear axle weight) Now that you’ve raised the front ride height, you will have increased the front axle corner weights, thereby taking weight off the rear axle. This should help your ‘crashy’ rear end phenomenon you described, so you may need to now adjust your rear bump and rebound accordingly. (Incidentally, when you changed the front ride height, did you measure from the spring platform to the adjuster ring..? When we do ride heights, we make changes by measuring full rotations of the spring platform. Each full rotation of the platform is a change equal to the thread pitch on the damper body. I believe a KW is 1.25mm..?) Personally, I’d suggest as RPM don’t seem to be willing to engage with you, to take it to another geometry specialist (I’ve heard good things about Spires Tuning) and get the geometry and corner weights setup correctly, and then you can talk to them about setting the car up to suit your needs. I thought lowering the front axle (more rake - front low, rear higher - increased weight to the front, not reducing it? Hence the increased rake on track set up 911s to increase front end bite and reduce understeer?

MarkM3Evoplus said: I thought lowering the front axle (more rake - front low, rear higher - increased weight to the front, not reducing it? Hence the increased rake on track set up 911s to increase front end bite and reduce understeer? Corner weighting a car is counter intuitive. To increase the load on a wheel, you need to raise the ride height on that corner. It’s an iterative process, and takes a long time to get right. When you increase the ride height (and subsequent load) on one corner, you reduce it on the opposite corner. Also, changing the ride heights to get your corner weights right will often throw out your geometry which then needs re adjusting. This could then affect your corner weights again, which need further adjustment….its not a quick process…!

OK, I get lifting a corner will change the load diagonally, but am I right that lower the front of a 911 to increase rake down, will put more load on the front to reduce understeer (particularly if the front lower due to increasing the camber on a mcpherson strut type from)? Thanks.

MarkM3Evoplus said: OK, I get lifting a corner will change the load diagonally, but am I right that lower the front of a 911 to increase rake down, will put more load on the front to reduce understeer (particularly if the front lower due to increasing the camber on a mcpherson strut type from)? Thanks. IREvans would know much better but my understanding is that in overall terms, rake down (ie front ride height lower than rear) is to get more weight over the front wheels (as it moves the CoG further forward). the 997 gt3 rs for example is ~30mm front to rear differential, the 991 gt3 rs are ~150mm iirc per OEM recommendation. That's a slightly different thing to what's being discussed per above which is in terms of redistributing corner weights once ride height is largely set - in this case one would raise the ride height to increase weight over that corner by winding up the spring but that adjustment will be small relative to what the ride height differentials are so effectively whatever you do the 'rake down' position is still preserved.

isaldiri said: IREvans would know much better but my understanding is that in overall terms, rake down (ie front ride height lower than rear) is to get more weight over the front wheels (as it moves the CoG further forward). the 997 gt3 rs for example is ~30mm front to rear differential, the 991 gt3 rs are ~150mm iirc per OEM recommendation. That's a slightly different thing to what's being discussed per above which is in terms of redistributing corner weights once ride height is largely set - in this case one would raise the ride height to increase weight over that corner by winding up the spring but that adjustment will be small relative to what the ride height differentials are so effectively whatever you do the 'rake down' position is still preserved. Thankyou!

Not sure how much difference say 10mm will make of a difference in the actual weight distribution as do the maths on the effective pick up points and I suspect it would be less than 10kg per spring probably less Probably more to do with the geo and how forces are shared under dive and squat etc ?

isaldiri said: IREvans would know much better but my understanding is that in overall terms, rake down (ie front ride height lower than rear) is to get more weight over the front wheels (as it moves the CoG further forward). the 997 gt3 rs for example is ~30mm front to rear differential, the 991 gt3 rs are ~150mm iirc per OEM recommendation. That's a slightly different thing to what's being discussed per above which is in terms of redistributing corner weights once ride height is largely set - in this case one would raise the ride height to increase weight over that corner by winding up the spring but that adjustment will be small relative to what the ride height differentials are so effectively whatever you do the 'rake down' position is still preserved. Correct. The issue here is static and dynamic loading. You’d set your ride heights to get the desired corner weights correct. By adding more positive rake (front pointing down) you’d actually reduce the static load on the front axle, but you’ll increase the dynamic load on the front under braking, as you’ll have more weight over the front axle due to the CoG having moved forward.

Adrian-9iafn said: Not sure how much difference say 10mm will make of a difference in the actual weight distribution as do the maths on the effective pick up points and I suspect it would be less than 10kg per spring probably less Probably more to do with the geo and how forces are shared under dive and squat etc ? Exactly that. Positive rake shifts the CoG forwards, so your dynamic loads will change. You’ll have more weight on the front during braking, and less weight on the front during acceleration.

Seems that most run something like 10-15mm difference between front and rear arch to ground difference so whilst this in some ways is arbitrary as the actual chassis rake might be very different I’m guessing this is still a useful guide if I am unable to measure chassis pick up points ? I suppose part will be to avoid too much front lift at speed as well ?

isaldiri said: IREvans would know much better but my understanding is that in overall terms, rake down (ie front ride height lower than rear) is to get more weight over the front wheels (as it moves the CoG further forward). the 997 gt3 rs for example is ~30mm front to rear differential, the 991 gt3 rs are ~150mm iirc per OEM recommendation. That's a slightly different thing to what's being discussed per above which is in terms of redistributing corner weights once ride height is largely set - in this case one would raise the ride height to increase weight over that corner by winding up the spring but that adjustment will be small relative to what the ride height differentials are so effectively whatever you do the 'rake down' position is still preserved. Very succinct!

IREvans said: Correct. The issue here is static and dynamic loading. You’d set your ride heights to get the desired corner weights correct. By adding more positive rake (front pointing down) you’d actually reduce the static load on the front axle , but you’ll increase the dynamic load on the front under braking, as you’ll have more weight over the front axle due to the CoG having moved forward. Now this bit caused quite a bit of discussion with some friends earlier this week Isn't that because of the springs as used on a vehicle work though and not just a static/dynamic issue? Assume a purely fixed system say a table with extendable legs set at 2 different heights for each pair with or without a big weight fixed at the higher end - raising the lower legs will reduce the weight over those corners as the CoG shifts backwards.....

Thanks, I’ll dial out some bump and rebound and see what I can learn

I thought I'd drop and update note : I have experimented further with bump and rebound and find if I back off too much it does feel underdamped and adding more bump and rebound to the front tightens the car up, but ultimately I find it feels a bit too disjointed and the road surface starts to show NVH more than most would like. So I have ended up back at Bump/Rebound F 6/7 R 7/13 and moved the ride heights to 270R and 258F, by increasing the turns by 2F and 1R, I also found one rear was consitently higher so dropped that back a 1/2 turn. Feels stiff and damped, still a little hard, but slightly less jarring (or maybe I am getting used to it). Handles well and feels quite sharp. No 4 wheel print out, so I have no clue about toe or camber. Using a spirit level and 'measuring' camber I think I am 1.9 neg front and 2.3 neg rear, so probably add a small amount of additional front camber when the suspension is checked ? My plan now is to head back to RPM and try alternative wheels/tryres just to eliminate and hardness from non N tyres and see what the settings are and possibly drive another car (997 GT3) just to see and see what they think It's no longer terrible, just rather stiff and go over bumpy roads and your very aware how hard it is

You measured the camber yourself?! Why haven't RPM technik given you the printout of the geo once they set it up? Surely given the £1000's you spent with them they owe you that. Any garage that does geo work (whether good or bad) provides a printout. As for trying new wheels, tyres etc ... Pesonally, I'd spend £300 ish with Center Gravity and have them give you a full appraisal of how what you have is working (or not) against your requirements, and then dial in something that meets your needs (you even get to test drive the changes with them in your car). To date, from what I can glean, you're doing all the work when you shouldn't be. Hope you get it sorted.

I have been told the machine had some issues and I haven't got a print out, my plan is to go back establish if tyres are an issue, I am open minded but the Contact 7's are 102Y, the same as the N rated Michelins. The car has not been corner weighted, still confused why the rear was set so high, I've gone up at the front and down at the back to get a 12 mm differential on arch measurements (which seems about the norm). I am about 10mm up from the lowest settings at the back and similar, perhaps slightly more at the front, increasing ride height did add a little compliance but the higher C of G you noticed and I am quite happy with the approximate ride heights now, lower than PASM sport and around GT3 ride heights Given how much I have spent so far I want to see what RPM can do to resolve and see how another car drives before investing more money. Be interested to see what cambers others run for a fast road set up

Adrian-9iafn said: I thought I'd drop and update note : I have experimented further with bump and rebound and find if I back off too much it does feel underdamped and adding more bump and rebound to the front tightens the car up, but ultimately I find it feels a bit too disjointed and the road surface starts to show NVH more than most would like. So I have ended up back at Bump/Rebound F 6/7 R 7/13 and moved the ride heights to 270R and 258F, by increasing the turns by 2F and 1R, I also found one rear was consitently higher so dropped that back a 1/2 turn. Feels stiff and damped, still a little hard, but slightly less jarring (or maybe I am getting used to it). Handles well and feels quite sharp. No 4 wheel print out, so I have no clue about toe or camber. Using a spirit level and 'measuring' camber I think I am 1.9 neg front and 2.3 neg rear, so probably add a small amount of additional front camber when the suspension is checked ? My plan now is to head back to RPM and try alternative wheels/tryres just to eliminate and hardness from non N tyres and see what the settings are and possibly drive another car (997 GT3) just to see and see what they think It's no longer terrible, just rather stiff and go over bumpy roads and your very aware how hard it is You’ve done an impressive amount of setup work so far..! To my eyes, the car still looks low, and this appears to be reflected by your NVH comment. If you now have settled on a setup which you feel works well, you could try raising the car 5mm front and rear and see how it drives. Allowing the damper more movement will reduce the overly stiff or hard feeling you’ve noted on bumpy roads, as it’ll allow the spring and damper to work. One observation is that a correctly corner weighted car will not always have equal ride heights from side to side. Assuming the car was correctly corner weighted when you collected it, just do the same number of turns on each damper body spring platform. For fast road use, I’d suggest -1.9° negative camber is enough on the front axle.

Thanks for all the comments, much appreciated. I have done my 'best' with camber measurement by using a spirit level on the edge of the tyres (the widest part is the rim protector which is 545mm in diameter). I have used this by using a 1m spirit level up right get it vertical and measure how many mm the level is from the top point of the tyre that is not flush with the upright level, the fronts are 17mm and 19mm so I averaged and the rear 22mm and 23mm again I averaged. Easy to see how I mighty be out, but I did measure and remeasure and this was as accurate as I could be. KW recommend the height range as shown below, I will get under and recheck the 'A' measurements. Again doing my best to measure 'B' as the wheel centre is inset I use a small spirit level to allow a more accurate measurement of this height and I am circa 350mm at the rear and 343mm front This ties in with what my measurements show as I have the original arch measurements and I collated some threads where people have shown their car and this measurements. In essense I am in range with the dampers as the expected drop and measurements all tie up Edited by Adrian-9iafn on Tuesday 5th September 07:24

I tried 3 times to get the right pic in the right place, the image upload is clearly problematic the other pic below

Adrian-9iafn said: Thanks for all the comments, much appreciated. I have done my 'best' with camber measurement by using a spirit level on the edge of the tyres (the widest part is the rim protector which is 545mm in diameter). I have used this by using a 1m spirit level up right get it vertical and measure how many mm the level is from the top point of the tyre that is not flush with the upright level, the fronts are 17mm and 19mm so I averaged and the rear 22mm and 23mm again I averaged. Easy to see how I mighty be out, but I did measure and remeasure and this was as accurate as I could be. KW recommend the height range as shown below, I will get under and recheck the 'A' measurements. Again doing my best to measure 'B' as the wheel centre is inset I use a small spirit level to allow a more accurate measurement of this height and I am circa 350mm at the rear and 343mm front This ties in with what my measurements show as I have the original arch measurements and I collated some threads where people have shown their car and this measurements. In essense I am in range with the dampers as the expected drop and measurements all tie up Edited by Adrian-9iafn on Tuesday 5th September 07:24 For measuring wheel camber, download a free spirit level app to your iPhone, then zero it using a spirit level. Then hold it against the wheel using a flat object.

I did try the app, but could seem to locate straight enough 600mm edge and wasn't sure I was able to set verticle accurately enough, so no closer really !

Adrian-9iafn said: I did try the app, but could seem to locate straight enough 600mm edge and wasn't sure I was able to set verticle accurately enough, so no closer really ! Set a spirit level on a flat surface so it reads level. Then zero the app while resting on the level. Rotate the phone 180° (so away from you) to confirm it also reads zero in the other plane, and you’ll know it’s correct. Most apps then allow you to rotate the bubble 90° to read a vertical plane

A quick update A few more miles and the car now has warm pressures of 33F and 37R cold this is 30/34 depending on weather. I may still experiment here. I have experimented a little more with bump and rebound and find I am getting a balance between tight, sharper and more controlled but harder, more NVH and less forgiving of pot holes. I also ended up moving some of the rebound but have kept the bump so I am now 6/8 F and 7/12 R from 6/7 F and 7/13 R If I increase one and not drop the other it does seem to affect the overall balance, I am realising its one chassis and not two ends I am with RPM early October, the kit will have done >1,000 miles by then, the tyres similar, so I'll try alternative wheels just to see if the tyres are 'harsher' than N rated tyres and if this has an impact, probably re-balance the wheels as well and look at any geo alterations. Today the car feels better as a chassis but still aware of the rear stiffness. I'll probably live with it for a while and see how the car compares to say a 997.2 GT3 as that has 660 lb rear springs, so just over 10% less. Whether that is material is another question. Edited by Adrian-9iafn on Thursday 14th September 21:23 Edited by Adrian-9iafn on Thursday 14th September 21:24

An update I spent some time at RPM yesterday, the car now has 1,200 miles since the suspension and tyres were fitted. For some reason the miles, tyre pressures and revised damper settings have significantly reduced the sometime incredulous jarring at the rear. I was of the opinion that if the tyre test showed that the Conti 7's were for some reason part of the problem then it was now tolerable and I wouldn't buy another set of tyres straight away My only adjustments had been a few ride height tweaks to get the nose back up and avoid too much rake, this was simply 4 turns down at the rear and 2 up at the front and the car was and is just under 660F and 670R measured road to arch and ofcourse damper settings I am currently 6/8 F and 7/12 R seems also I had one damper between rather than on a setting when they checked The camber was approx 1.5 degrees F and 2 degrees, so my man maths spirit level measurements were clearly inaccurate. The geo was reset with 0 degrees toe at the F and 13' toe in rear. The car is now very different in terms of rear jarring, this has now essentially gone and the car feels well damped and sports car stiff. So I am delighted. I wonder if the inner side walls of the Conti 7's are less forgiving than say N rated tyres and perhaps the increase in camber was increasing the wheel rate by moving the contact patch further in and the camber was increasing the load on this inner side wall ? Just a wild guess ! Anyway the car now feels great. I may experiment a tiny bit more with damper setting before refitting the carpet at the rear. I did try increasing the rear rebound by one click, but preferred it as is. So perhaps for me with my wheels and Conti 7's the following settings are pretty good Tyre pressures 30/34 Dampers 6/8 7/12 and camber 1.5 degrees front and rear with 0 toe front and std toe in rear

Good that you're delighted after all this time, expense and radio silence. Enjoy!

An interesting read in this month EVO assessing the best high performance tyre, The Continental Contact 7 destroys the competition in actual performance and feel wet and dry. It stops way ahead of any other tyre in the dry and wet as well. And it’s the lowest rolling resistance - incredible really. BUT my experience with the suspension jarring until I reduced the rear camber and spent many hours with bump/rebound settings, tyre pressures and ultimately rear camber now makes sense as the only drawback of this tyre is comfort on bad surfaces where they say “The continental delivers the best steering with lovely connection, directness and linearity but its let down by a sharpness and audible report over sharper impacts". I have got it very good and happy now but I still think with 2 degrees of camber and the fat that the rear springs are very hard was really loading up the inner side wall and exacerbating this small drawback. Glad to say I am now super happy having resolved this but those with big camber or a very stiff suspension might have similar challenges with the 7. I think the wet grip is amazing as it actually feels grippy in the wet These are about 70% of the cost of my usual go to tyre the Michelin and reputedly good wear to boot

I thought I'd pop another update as it's now some 1,500-2,000 miles in and I have upgraded the engine mounts as well. The car is now riding very well indeed, it's very taught and stiff but no crashing at all. It feels much better with the new engine mounts (I has the FF mounts fitted) the mounts are 250 miles in and the engine resonance is coming down nicely and the tickover is also showing less chassis transmission - I like the visceral feel of the connection as it's no longer harsh, its not NVH, it's more NV if you get me ! The engine mounts have made a difference and improved the ride, as I suspect with the stiffer chassis there were times when the engine and chassis were working against each other and effectively allowed to be out of phase compounding the jarring on occasion. That was how it sometimes felt as if there was possibly something worn. So I do recommend new or slightly uprated engine mounts with the KW V3, now the car feels very honed, tight and well damped/controlled. It reminds me of an E30 M3 I spent ages getting the suspension how I wanted 20 years ago. I'm almost looking for those ridges and slightly raised central Islands, so I can cut them and feel the damping at the back. So it feels like taking the curb at Spa !

I enjoyed reading this thread some impressive nerdiness and obsessiveness, some of the concepts quite hard for me to grasp and likely even more difficult for me to perceive changes being made without a dedicated track. The only contribution I'd like to make is for reference my 997GT2 weighing in at 1463kg DIN with distrubution 37.6%F 62.4%R. I have Tractive DDA with DSC package as developed by TPC racing who have a lot of experience racing the 997. Because I like to use the car on the street and after lots of discussion I ended up going for 336lb front and 616lb rear springs, the car is amazingly comfy, even with full solid joints, but when the DSC fires out the, virtually instant, messages to the Tractives it handles very well, probably too soft for serious track work but certainly fully stable and predictable at Autobahn speeds. A recent set up by Suspension Secrets made the thing even more grippy no bouncing around on bumps and cambers like it used to with the old PASM B16s. I realise that the KWs are passive shocks but maybe the spring rate is too German road biased and dropping the rate whilst playing with the settings will hit the spot ?

Thanks for the contribution and feedback I do think that the car spring rates on the KW are relatively high and probably compounded the challenges getting it to be good on the road. I also think the ability to change damper settings electronically is very useful From what I understand you can think of a damper as part damping and part 'spring' in other words a softer spring and stronger damper can behave more like a stiffer spring and softer damper in certain conditions. But in other conditions much less so as the damper will I suspect be more spring like and stiff when asked to move quickly if purely mechanical and less spring like or not spring like if its moving more slowly. The only fag packs maths that makes me think that KW might have chosen stiffer than ideal rear springs (but now for me very tolerable), and this is ofcourse only 'armchair' expertise ! Is that if you look at the stiffness ratio of front to rear on all the 997 variants and aftermarket suspension the ratio is 2-2.5 or so (ie if the front spring is say 200lb the rear is between 400-500lb). With the more track oriented cars stiffening the front more so nearer 2:1 The KW is 3.2:1, interestingly the KW club sport is 2.4:1. I can only assume they decided on this outlier for a reason as I did ask them why so stiff at the back and they said KW only look at the chassis and application not comparables Personally I'd rather trust Porsche ! If you follow through the wheel rates (the stiff rear spring are further in so the wheel rate is reduced, so the wheel rates are nearer 1.2:1) they make sense as well for the weight of the chassis with a fag packet calculation I suspect, but I dont know, I'd prefer the KW V3 with say a 100lb less spring rate on the car and more bump and rebound damping. However very happy with it now so I won't fiddle just yet !! Edited by Adrian-9iafn on Tuesday 28th November 11:39

Adrian-9iafn said: Thanks for the contribution and feedback I do think that the car spring rates on the KW are relatively high and probably compounded the challenges getting it to be good on the road. I also think the ability to change damper settings electronically is very useful From what I understand you can think of a damper as part damping and part 'spring' in other words a softer spring and stronger damper can behave more like a stiffer spring and softer damper in certain conditions. But in other conditions much less so as the damper will I suspect be more spring like and stiff when asked to move quickly if purely mechanical and less spring like or not spring like if its moving more slowly. The only fag packs maths that makes me think that KW might have chosen stiffer than ideal rear springs (but now for me very tolerable), and this is ofcourse only 'armchair' expertise ! Is that if you look at the stiffness ratio of front to rear on all the 997 variants and aftermarket suspension the ratio is 2-2.5 or so (ie if the front spring is say 200lb the rear is between 400-500lb). With the more track oriented cars stiffening the front more so nearer 2:1 The KW is 3.2:1, interestingly the KW club sport is 2.4:1. I can only assume they decided on this outlier for a reason as I did ask them why so stiff at the back and they said KW only look at the chassis and application not comparables Personally I'd rather trust Porsche ! If you follow through the wheel rates (the stiff rear spring are further in so the wheel rate is reduced, so the wheel rates are nearer 1.2:1) they make sense as well for the weight of the chassis with a fag packet calculation I suspect, but I dont know, I'd prefer the KW V3 with say a 100lb less spring rate on the car and more bump and rebound damping. However very happy with it now so I won't fiddle just yet !! I'm going through this process currently with a set of Ohlins R&T's on a 996 C2. Just as KW have gained a reputation for running far stiffer spring rates than required (certainly for UK road use) so too have Ohlins with their R & T kits. I'm now running spring rates (on on my third set of springs) drastically softer than the original nonsense specified by Ohlins (and when they first released the kits 7-8 years ago, the rates were even higher !! So much so that after some years, they finally took on board what owners of those early kits were saying, and offered an alternative, softer spring option. You'd be right to trust Porsche over the majority of manufacturers of aftermarket coilovers when it comes to choosing spring rates in my experience. Though Porsche have the "luxury" of being able to use progressive springs on their production cars, which whilst the benefits can be replicated by using dual spring arrangements on coilovers, there seems to be a complex blend of art and science required to make them work properly/well. Edited by Slippydiff on Wednesday 29th November 07:08

Good commitment! After reading this journey I’m pleased for you that a set up that feels right has been achieved. I played this game for a few years with my 997, and not coming from 911’s found it a challenge! Perhaps at first I was a bit too hit and miss, in the end I had a notebook in glove box and a mat in the boot. To be fair I think I was slightly beaten as went back to oem springs dampers and alignment (ish), but only after 20,000 miles and plenty of iterations. Getting a sweet set up is a rewarding journey and you will no doubt enjoy the car more having honed it.