GT4 or modded Cayman R - Page 3 - Boxster/Cayman - PistonHeads UK

Tough call this. Spec of the CR is pretty much bang on what I'd ask for in a car (manual, NA, flat 6, mid engined, RWD, hydraulic steering, proper hand brake, buckets, PSE, sports suspension, etc etc) but I think it lacks a bit of poke and I'd like more feel. My name is down for the new GT4 and it should be pretty epic but it will cost the thick end of £75k with toys I'd have thought. Whereas I could keep the CR, spend £7k on a Stage 4 Cargraphics upgrade which would take the power up to 360-380BHP and then get a 3 way adjustable Exe TC suspension for £10k, which would hopefully get more feel. This would probably get me a car that is just about ideal for me but cost me a lot less (I'm not planning on selling if I upgrade so don't need to factor in the additional depreciation of a modded car). Thoughts?

GT4 spec unknown therefore difficult to gauge what route to take. Modding a Porsche will never see a financial return on investment (I find this rather strange as you will be improving the car but the wider market doesn't seem to appreciate this). I would wait until GT4 spec is officially released before making any decisions.

Richie200 said: GT4 spec unknown therefore difficult to gauge what route to take. Modding a Porsche will never see a financial return on investment (I find this rather strange as you will be improving the car but the wider market doesn't seem to appreciate this). I would wait until GT4 spec is officially released before making any decisions. True but I'm not bothered by the financial return on investment and some things for the GT4 are known; for example, it will have EPAS and it will have e-handbrake and I still need to find another £30-£35k to get into a GT4, so not exactly pocket change either.

anonymous said: [redacted] Yes - I'm thinking that it's massively unlikely that the GT4 will have suspension that is anywhere near as good as a top end after market outfit like EXE TC. The problem with the 996, is that I can't stand the interior, it'd be something that I'd put up with to have a 996 GT3RS but they're out of reach for me now sadly and a 964 or 993 is just too old for my liking as my one car to use for track days etc. so I'd rather keep mine and spec it up than get something else and spec that up.

Richie200 said: GT4 spec unknown therefore difficult to gauge what route to take. Modding a Porsche will never see a financial return on investment (I find this rather strange as you will be improving the car but the wider market doesn't seem to appreciate this). I would wait until GT4 spec is officially released before making any decisions. ^

J-P said: I still need to find another £30-£35k to get into a GT4, so not exactly pocket change either. I guess this is the million dollar question if the GT4 will be work the additional outlay!? The CR is already a very focused driving machine and more than enough for the public roads... I suspect you probably won't be able to drive the GT4 (when it comes out) any faster without taking serious risk... so the question perhaps is how often will you take it on track where I'm sure the performance advantage with become apparent? I'm sure the GT4 will be one heck of a machine when it arrives and probably hailed one of the greatest drivers cars currently available but subjectively, I wonder if it can provide more fun than the CR? I suspect it will be a close call and there maybe some arguement to say on this occasion "less" is perhaps "more"...

Tow bar on the M and get a Caterham

sootyvrs said: J-P said: I still need to find another £30-£35k to get into a GT4, so not exactly pocket change either. I guess this is the million dollar question if the GT4 will be work the additional outlay!? The CR is already a very focused driving machine and more than enough for the public roads... I suspect you probably won't be able to drive the GT4 (when it comes out) any faster without taking serious risk... so the question perhaps is how often will you take it on track where I'm sure the performance advantage with become apparent? I'm sure the GT4 will be one heck of a machine when it arrives and probably hailed one of the greatest drivers cars currently available but subjectively, I wonder if it can provide more fun than the CR? I suspect it will be a close call and there maybe some arguement to say on this occasion "less" is perhaps "more"... I'm convinced the GT4 will be utterly awesome. The high performance car division of Porsche don't really do clangers, so I'm sure it'll be brilliant. What I'm struggling with, is will it be worth £35k more than my CR? And if I'm prepared to spend £20k on mods to the CR, then which car would actually be better? Either car would be used almost exclusively for track days and weekend blatts, ironically, I could afford to do way more track days if I keep the CR as I'd have saved so much cash. The other issue is although I really like the CR, I don't love it and it's hard to put a finger on why, so I'd hope the mods would transform the way I feel about the car too!

juansolo said: Tow bar on the M and get a Caterham It's sooo tempting but it would hardly ever get used in reality. The thing with the CR or GT4 is that you can still use them for shopping, driving to the station, driving long distances etc. Mrs. Will still get in it, if we're going out. With a Caterham it'd be just me all the time and track days only.

As others have said wait to see the GT4 spec sheet then decide. The renderings I've seen of the GT4 look totally amazing. In terms of the Cayman R is it really in need of that sort of fettling? I understood the R to be sublime out of the box? Not sure i'd drop that sort of money modifying it and this is coming from someone who's spent not far of a Cayman R modifying one of my old bangers!

IMIA said: As others have said wait to see the GT4 spec sheet then decide. The renderings I've seen of the GT4 look totally amazing. In terms of the Cayman R is it really in need of that sort of fettling? I understood the R to be sublime out of the box? Not sure i'd drop that sort of money modifying it and this is coming from someone who's spent not far of a Cayman R modifying one of my old bangers! I'll definitely wait to see what the spec of the GT4 is like. The way it looks already has me thinking "want". If Porsche choose to equip it with double wishbones (as they did with the front end of the new Cayenne???), dry sump the NA engine, offer a manual and LSD, I don't think I'll be able to resist! CR is a great car and when I'm driving it, I really enjoy and I suspect that if I do sell it, I'll really miss it a lot. But for me, it could be quicker and I'd like it to have more feel. Also, I do like the convenience of some of the mod cons, like phone prep, nav and iPod music library (even if I don't use them much).

J-P If you are serious about weighing this up you need to talk to John at BGB Motorsports. They ran the caymans in Rolex and do a bunch of cool stuff with Caymans at all levels of mods, including 3.8 transplants. They will be able to make you aware of just what is possible and back it up with actual metrics on what effects etc are based on what they are doing, seeing and logging. This thread may suffice if you just want to talk it around but at the end of the day there's no one can give you any actual advice that's more substantial than anything pulled out of their a$$. Your time will be better served talking with them and letting you properly evaluate at least one side of the equation with respect to what you can do and how it will work for you to then enable the GT4 route to be compared. Edited by fioran0 on Sunday 4th January 00:54

Wow. Talk about dangling a carrot, Neil. What a shame they are US based. http://rennlist.com/forums/racing-and-drivers-educ...

fioran0 said: J-P If you are serious about weighing this up you need to talk to John at BGB Motorsports. They ran the caymans in Rolex and do a bunch of cool stuff with Caymans at all levels of mods, including 3.8 transplants. They will be able to make you aware of just what is possible and back it up with actual metrics on what effects etc are based on what they are doing, seeing and logging. This thread may suffice if you just want to talk it around but at the end of the day there's no one can give you any actual advice that's more substantial than anything pulled out of their a$$. Your time will be better served talking with them and letting you properly evaluate at least one side of the equation with respect to what you can do and how it will work for you to then enable the GT4 route to be compared. Edited by fioran0 on Sunday 4th January 00:54 Thanks, Neil. I am serious about this, keeping the R would mean a lot more track time. I'll give John a call in the week and find out what's possible and get a view on costs.

Sounds good. Obviously they aren't a practical option for doing the work given location but John is usually very helpful and should really be able to get you thinking. As I said, he will actually be able to tell you what an outcome will be for whatever is input based on what they are actually doing and have done. Just to add some extra fuel; It would be interesting to know just what can be achieved using a 981 as a base instead of a 987 taking a similar approach as another comparison. IF the R is at a premium just now then looking at the bigger picture one wonders whether swapping out the R for a 981 which will then be modded offers an approach as cost effective but with better outcomes. The work, particularly on the engine side may be cheaper using the 981 opening up some options. Reading your post about creature comforts. Keep in mind its perfectly possible to take the car where you like from a driving and mechanical perspective while leaving the interior pretty much stock. The track or race safety/practical stuff doesn't need to be included if its not something thats wanted. Not a BGB car but similar in scope to what they do and with a 3.8 etc..

Very nice...

OP - I'm following this with interest and would be grateful if you could post up your findings.

Trev450 said: OP - I'm following this with interest and would be grateful if you could post up your findings. Will do Trev.

fioran0 said: Sounds good. Obviously they aren't a practical option for doing the work given location but John is usually very helpful and should really be able to get you thinking. As I said, he will actually be able to tell you what an outcome will be for whatever is input based on what they are actually doing and have done. Just to add some extra fuel; It would be interesting to know just what can be achieved using a 981 as a base instead of a 987 taking a similar approach as another comparison. IF the R is at a premium just now then looking at the bigger picture one wonders whether swapping out the R for a 981 which will then be modded offers an approach as cost effective but with better outcomes. The work, particularly on the engine side may be cheaper using the 981 opening up some options. Reading your post about creature comforts. Keep in mind its perfectly possible to take the car where you like from a driving and mechanical perspective while leaving the interior pretty much stock. The track or race safety/practical stuff doesn't need to be included if its not something thats wanted. Not a BGB car but similar in scope to what they do and with a 3.8 etc.. Look awesome. I've contacted John by email already, so I'll see what he says. I'd probably get the car and chassis very close to track spec but yes I'd keep the interior more or less as is. Not too worried about carpets, sound deadening etc, but like convenience of Nav and phone module - Mrs always calls me on my way to and from track days and Nav looks tidy and enables me to get to and from tracks I've never been to before. I'll think on what you've said on 981 platform, although there are some things I don't like such as the EPAS and eHandbrake. I do like the gear positioning more though but getting a 981 to spec and then spending some cash on making it awesome is likely to be more expensive in my view. With the CR I'll keep the oily bits, so if it does ever become a sought after collector's item, then it can be reverted to stock and sold at any time if needs be. Likelihood is though, that if I mod, then I'll just keep it forever.

anonymous said: [redacted] Moose I'd seen that SVP car. I may even have contacted them around a year ago or so. Yes I think this is the kind of thing I'd like to do to the R but I really want the ExeTC suspension as I think that they would build dampers with the best balance for ride and handling, as builders of championship winning rally car dampers and if you're going to mod the car anyway, may as well go for it! I'd also seen that you can get a bigger oil pan for the CR, which I was considering too but it's £2k, which seemed like a lot!

anonymous said: [redacted] It's a good shout. I'll give them a buzz in the morning and see where we get to. Thanks Moose

I would also look into KW dampers too as they have a wealth of experience with Porsche, albeit the 996/7 platform. I can vouch for their effectiveness and quality having got a set fitted to my track Evo.

Two comments. It was my understanding that KW haven't offered custom valving on their V3 dampers for a while now. If you now want custom options you need to plump for the competition stuff which they will do in valving appropriate for a spring rate you like. The V3 type stuff can still be rebuilt by KW but nothing more. You are fixed with the spring rates they have allocated to the package. I have covered this before but the limiting factor with respect to modern Porsche suspension is that there is only a small amount of travel available. Run huge amounts of droop and you can start to do really clever things with suspension. Just look at the WRC stuff for an example of what can be done when you have a large travel range. Its incredible from an engineering perspective. Anyone coming at suspension options on modern Porsche sports cars are limited by the same lack of travel as everyone else. By bumping up the ride height there can be some opportunity to gain extra travel but thats not without significant compromise either. The other aspect of the suspension set up, and its particularly relevant to the Boxster and Cayman because it runs struts at the rear also, is that as soon as the lower control arm moves past horizontal you lose camber. You don't need to get that low in terms of ride height for this to happen, nor do you need much suspension compression for it to happen. So now you have limited suspension movement, plus for the box/cayman a compression limitation with respect to camber loss working to limit what you can do on the car. Its simple to work around if you want maximum performance. Once you require comfort and improvements in control it gets tricky very quickly since theres little in the way of scope for differing approaches. Your spring is what its all about after all. The damper just controls the spring.

fioran0 said: The V3 type stuff can still be rebuilt by KW but nothing more. You are fixed with the spring rates they have allocated to the package. Neil, I didn't have any problems in requesting 'non package' spring rates for my Clusports.

fioran0 said: Two comments. It was my understanding that KW haven't offered custom valving on their V3 dampers for a while now. If you now want custom options you need to plump for the competition stuff which they will do in valving appropriate for a spring rate you like. The V3 type stuff can still be rebuilt by KW but nothing more. You are fixed with the spring rates they have allocated to the package. I have covered this before but the limiting factor with respect to modern Porsche suspension is that there is only a small amount of travel available. Run huge amounts of droop and you can start to do really clever things with suspension. Just look at the WRC stuff for an example of what can be done when you have a large travel range. Its incredible from an engineering perspective. Anyone coming at suspension options on modern Porsche sports cars are limited by the same lack of travel as everyone else. By bumping up the ride height there can be some opportunity to gain extra travel but thats not without significant compromise either. The other aspect of the suspension set up, and its particularly relevant to the Boxster and Cayman because it runs struts at the rear also, is that as soon as the lower control arm moves past horizontal you lose camber. You don't need to get that low in terms of ride height for this to happen, nor do you need much suspension compression for it to happen. So now you have limited suspension movement, plus for the box/cayman a compression limitation with respect to camber loss working to limit what you can do on the car. Its simple to work around if you want maximum performance. Once you require comfort and improvements in control it gets tricky very quickly since theres little in the way of scope for differing approaches. Your spring is what its all about after all. The damper just controls the spring. Neil - the ExeTC system suggests using a softer spring with their dampers as the tyre remains in better contact with the road. I'd have thought that this would have the added benefit of improving the ride comfort as well as sharpening up the handling. Is this correct?

Trev450 said: fioran0 said: The V3 type stuff can still be rebuilt by KW but nothing more. You are fixed with the spring rates they have allocated to the package. Neil, I didn't have any problems in requesting 'non package' spring rates for my Clusports. In 2011 when I asked for custom spring rates on my KW CS kit the reply was no sorry... ?

Trev450 said: Neil, I didn't have any problems in requesting 'non package' spring rates for my Clusports. Did your non package spring rate require the damper to be revalved though? How long ago did you get them? You used to be able to get the V3 etc revalved to match any rate you liked but they stopped doing this. My info was that users could only get it done on the competition line of products from that point on. If they still offer this on the Clubsports then thats good for end users but surely the V3 has even less appeal if thats the case.

J-P said: juansolo said: Tow bar on the M and get a Caterham It's sooo tempting but it would hardly ever get used in reality. The thing with the CR or GT4 is that you can still use them for shopping, driving to the station, driving long distances etc. Mrs. Will still get in it, if we're going out. With a Caterham it'd be just me all the time and track days only. Not suggesting you sell the CR, just don't modify it Spend the money instead on a Caterham. I guarantee you'll never look back.

juansolo said: J-P said: juansolo said: Tow bar on the M and get a Caterham It's sooo tempting but it would hardly ever get used in reality. The thing with the CR or GT4 is that you can still use them for shopping, driving to the station, driving long distances etc. Mrs. Will still get in it, if we're going out. With a Caterham it'd be just me all the time and track days only. Not suggesting you sell the CR, just don't modify it Spend the money instead on a Caterham. I guarantee you'll never look back. Ah I see what you mean - don't think an extra car will get past the steering committee.

fioran0 said: Trev450 said: Neil, I didn't have any problems in requesting 'non package' spring rates for my Clusports. Did your non package spring rate require the damper to be revalved though? How long ago did you get them? You used to be able to get the V3 etc revalved to match any rate you liked but they stopped doing this. My info was that users could only get it done on the competition line of products from that point on. If they still offer this on the Clubsports then thats good for end users but surely the V3 has even less appeal if thats the case. I purchased them about 6 months ago. They didn't require revalving as the change in spring rates was relatively marginal and it was considered to be well within the valve's operating window. (This information came through conversation directly with Germany). We purchased the dampers and springs from KW UK and their only condition was that they supplied the dampers with the package springs fitted, and we then had to change them ourselves and return the original springs to them. This 'around the houses' way of doing things I can only put down to the UK arm being primarily a sales operation. You are probably already be aware of this, but you really need to speak directly with Germany for any degree of technical advice. Edited by Trev450 on Monday 5th January 09:50

J-P said: juansolo said: J-P said: juansolo said: Tow bar on the M and get a Caterham It's sooo tempting but it would hardly ever get used in reality. The thing with the CR or GT4 is that you can still use them for shopping, driving to the station, driving long distances etc. Mrs. Will still get in it, if we're going out. With a Caterham it'd be just me all the time and track days only. Not suggesting you sell the CR, just don't modify it Spend the money instead on a Caterham. I guarantee you'll never look back. Ah I see what you mean - don't think an extra car will get past the steering committee. They're very small, she'll never even notice it... and a good selling point is that you'll get your money back when you come to sell it, unlike the mods which will actually do the opposite to the value of the CR. You know it makes sense Here you go, here are two that are pretty much spot on for your needs. http://www.pistonheads.com/classifieds/used-cars/c... http://www.pistonheads.com/classifieds/used-cars/c... I wouldn't bother getting a road one if you're wanting to track. It'll compromise it for track use and you'll never use it on the road if you make it into a track car. As race cars these will be tough, well looked after mechanically (race cars tend not to be that pretty...) and have the bits on you want (dry sump, track suspension, quick rack, 6 speed, LSD, cage). Also potential there also for much more power and toys (sequential box) as the obsession kicks in. Again, modding a Caterham properly, unlike a road car, is not considered a bad thing. You will not drive a more capable or better suited track day car than a Caterham IMO. Initial outlay aside, the residuals are very strong, you look after it and you're not going to lose a lot. Nothing responds on a circuit like them. All road cars will seem soft and unresponsive in comparison. Running costs are pennies. They're so light on consumables it's untrue and anyone can look after them with a small amount of mechanical knowledge. Finally if you stack it, they're not that expensive to repair and you haven't just trashed a very nice Porsche. All it has against it is that it'll take up space in your garage (Brian James Minno or the like for a trailer and it can live on that in a single garage). Otherwise, no tax, no test, no MOT and it's an awesome toy to play with even when you're not driving it. Hook up, do trackday, bring it home, stick it in the garage. Honestly, before you blow knocking on £20k on upgrades, hire an R300 race car from Bookatrack for a day and at least try the alternative. EDIT: trying not to seem like an advert for Caterham. I've driven most of them, and owned/ran a few Westfields (not recommended unless you really know what you're doing with them so you don't get a clunker) and god I miss them. Nothing comes close. Nothing at all. Here is a more road focussed one, but he totally nails the appeal of them: https://www.youtube.com/watch?v=JAwNfgvF_Ww&sp... I'll have another at some point, but I won't sell the Cayman to do so That serves another role. Edited by juansolo on Monday 5th January 09:52

While you know I'm a great fan of Caterhams juansolo, I suspect you don't have to submit your choices to a higher authority as some of us do. That said, unless you are doing a lot of track days I wouldn't BUY a Caterham for the track - I'd hire them from Bookatrack as Juansolo suggests in the offseason when they are ridiculously good value. An R300 is an ideal track day weapon - fast enough to be interesting without being at all scary. That's what I'm doing - it's a far better track day car than a Cayman. The expression you WEAR a Caterham, but DRIVE other cars is spot on. I probably wouldn't mod a Cayman for the road either - but might have in my younger days, so I'm not going to knock it.

I'd love a Caterham, I really would but I can't justify one. I'd never use it enough. If Caterham track days are in my future, it will be rentals through bookatrack. Spoke with Dom at SVP this afternoon. I have a test drive of their car booked for 19th January, which I'm looking forward to. Dom is very confident that I'll find it pretty mind blowing.

anonymous said: [redacted] Sounds good to me!

J-P said: anonymous said: [redacted] Sounds good to me! If they can fix the ride and not ruin the handling in the process, I might join you! Though I don't think I'll be sticking £10k of suspension on a car worth £15k

J-P said: Neil - the ExeTC system suggests using a softer spring with their dampers as the tyre remains in better contact with the road. I'd have thought that this would have the added benefit of improving the ride comfort as well as sharpening up the handling. Is this correct? Sorry for not getting back to you on this before now. A softer spring does indeed help maintain better contact with the road. With a softer spring a wheel can move vertically in response to changes in surface with more ease and this is good for both traction and comfort. The softer a spring, the less the vertical load on a tire changes as the road surface changes or as a car corners. A tire pushed up by a bump does not have to lift as much of the chassis weight with a softer spring, while during cornering weight transfer is taken by the spring rather than passed to the tire as vertical force. This is generally good since grip and vertical load are related. While lateral grip increases with increasing vertical force, it does so with reducing effect as vertical load reduces the tires friction coefficient. For handling however.... With softer springs comes greater body roll and pitch. This creates problems maintaining optimal suspension alignment, introduces bump steer and camber loss etc as a result of the large amount of suspension travel required. One may also in certain situations run out of room to allow the required suspension travel. This will create a situation where the wheel becomes coupled to the chassis and all vertical force is now transferred to the tire (see above for why this is bad along with rate of weight transfer below). Having the chassis wallow around is also not good for handling since it allows forces to build up before being applied. In order to avoid all of these problems a harder spring is better. Suspension stiffness also dictates the rate of weight transfer. The faster it is transferred the more responsive the car feels. Stiffer suspension increases the rate of this transfer though as stiffness increases, the skill required to handle the rate of transfer increases. In the Cups, stuff happens FAST as a result of the hard suspension settings. Hopefully you can see the conflicts that are starting to arise here Theres also the issue of dynamic weight transfer to consider (and roll couple) and how it impacts grip. Spring rates dictate how much of the dynamic load changes are passed to the tire. Increasing a spring rate prevents excessive suspension movement during dynamic weight transfer (preventing loss of alignment or introduction of unwanted effects) but increases the amount of vertical load applied to that tire. The tire is increasingly less able to transfer this load to grip. This is why stiffening the front of a car creates understeer. One needs to then select spring rates while considering the over all balance available while also keeping in mind the points above. Tire temps are crucial to their performance and spring rates impact these (along with alignment which is also impacted by spring rate via travel). Increasing vertical load will increase the tire temp and thus the grip offered by the material but at some point the temp may become too high and grip from the tire is lost. But whats the relationship between tire temp and the rest of the factors above? You could increase temp by adjusting the spring giving more grip from the tire material but lose grip overall due to the changes to above factors. Likewise you could reduce temp by softening springs, losing tire grip itself but increase grip over all. Aero is also impacted by excessive body movement. The more it moves the more aero is changed so one needs hard springs if one wants to control ride height changes and aero impacts. Aero can mostly be ignored for road cars but its worth a mention. Once you think you have all of this sorted out, the real world decides to intervene and anything you do to solve one aspect changes everything else in some way. Welcome to the world of suspension Edited by fioran0 on Tuesday 6th January 15:52

Im going to get geeky for a moment. Theres an interesting thing happens with suspension when a wheel loses contact with the ground. When this happens the effective spring rate on the axle - being twice the actual spring rate when both wheels are on the ground - is cut in half. The effect of this is that the side that is under load suddenly sees increased suspension travel. Whatever the travel length has been immediately doubles and the car feels like it is falling over. When the wheel this is off the ground re-establishes contact this reverses and the car jumps up at the loaded corner. This is why race cars run dual springs though most people think its to prevent spring dislocation at full droop. The softer spring is set so that its blocked (i.e. fully compressed) at static ride height. It sits there, in effect waiting, for large negative travel. When it occurs the soft spring becomes active responding rapidly to changes in load and hopefully keeping the tire in contact with the ground. Theres no need to worry about dislocation at full droop because an appropriate spring length is selected for the required ride height. Aftermarket coilovers miss a trick in this regard. They simply run second springs purely to prevent dislocation. It lets a single spring length be used across a variety of settings, components and ride heights and nothing more. The rate is so low that its effectively zero. FWIW, i run a modified approach to the dual spring set up on my project 996 (as I do on my my other Cups for bumpy tracks). The second, softer spring is selected so that it is not blocked at static ride height but instead has a small amount of travel left. This lets the car ride on a soft spring to absorb small bumps etc and in slow speed corners apply power earlier. In high speed situations or in situations with large dynamics (i.e. braking) the main (hard) spring rate is used as the softer spring is either blocked or blocks instantly. Its highly effective at helping with some of the compromises identified in my post above but requires careful set up and design. I know a few big name GT class teams that adopt this same approach. (theres little new to be done with a shock and a spring after all, just simply things that are more or less common) This approach should not be confused with simply stacking two springs together as is more commonly seen. In this situation neither of the springs are designed to ever block transferring the combined rate to the single rate of the unblocked spring. They simply work together continuously as a single spring and create a new rate based on the equation: (rate 1 x rate 2) / (rate 1 + rate 2) Edited by fioran0 on Tuesday 6th January 15:53

oh yeah, have fun on your outing in the SVP car

Thanks for the above, Neil. All very interesting and leads me to the conclusion that I definitely need expert help in this area. On a separate note SVP is thinking about being able to have a brake bias box. What is brake bias? I won't be racing the car but wondered whether or not it would add to the experience? Does it mean changing the braking force applied to each axle? If so, does that mean you need to amend for every corner? Thanks

anonymous said: [redacted] That's exactly what I want to do with mine, Moose and is exactly what I feel is wrong with the current set-up. I'm also thinking about getting gyrodiscs over the std items.

Have you got the GT3 master cylinder fitted yet? This would be the first port of call on the cayman if it were me. The larger MC will reduce pedal travel and require more effort which is definitely a good thing in its case.

fioran0 said: Have you got the GT3 master cylinder fitted yet? This would be the first port of call on the cayman if it were me. The larger MC will reduce pedal travel and require more effort which is definitely a good thing in its case. No I've got, better pads, brake fluid, GT3 brake ducts, as well as braided hose. GT3 MC is definitely the next thing on the list from braking perspective, I'll prioritise it if it's going to improve brake pedal feel (which to be honest is one of the few things about the car that I really don't like).

J-P said: Thanks for the above, Neil. All very interesting and leads me to the conclusion that I definitely need expert help in this area. On a separate note SVP is thinking about being able to have a brake bias box. What is brake bias? I won't be racing the car but wondered whether or not it would add to the experience? Does it mean changing the braking force applied to each axle? If so, does that mean you need to amend for every corner? Thanks Like others have said, it's about changing distribution of braking between the front and rear. It's extremely desirable when racing - you need to bias braking to the rear in the wet and the front in the dry. BUT with ABS this is not needed, and so its value is much reduced. It is probably a waste of time (with ABS) UNLESS you need to use trail braking to get turn in AND you can't get the degree of turn in you are trying to get. I think it almost certain that you won't need it since you are asking the question - and if you do you won't be asking the question! Edited by bcr5784 on Tuesday 6th January 19:34 Edited by bcr5784 on Tuesday 6th January 19:39

bcr5784 said: J-P said: Thanks for the above, Neil. All very interesting and leads me to the conclusion that I definitely need expert help in this area. On a separate note SVP is thinking about being able to have a brake bias box. What is brake bias? I won't be racing the car but wondered whether or not it would add to the experience? Does it mean changing the braking force applied to each axle? If so, does that mean you need to amend for every corner? Thanks Like others have said, it's about changing distribution of braking between the front and rear. It's extremely desirable when racing - you need to bias braking to the rear in the wet and the front in the dry. BUT with ABS this is not needed, and so its value is much reduced. It is probably a waste of time (with ABS) UNLESS you need to use trail braking to get turn in AND you can't get the degree of turn in you are trying to get. I think it almost certain that you won't need it since you are asking the question - and if you do you won't be asking the question! Edited by bcr5784 on Tuesday 6th January 19:34 Edited by bcr5784 on Tuesday 6th January 19:39 That's interesting. At Snetterton a couple of years ago, the CR was great apart from the hairpin, where I did need to trail brake and the car still under steered. It really annoyed me actually, is this something that brake bias could have helped with?

J-P said: That's interesting. At Snetterton a couple of years ago, the CR was great apart from the hairpin, where I did need to trail brake and the car still under steered. It really annoyed me actually, is this something that brake bias could have helped with? In theory, possibly - but there may be other factors at work.

bcr5784 said: J-P said: That's interesting. At Snetterton a couple of years ago, the CR was great apart from the hairpin, where I did need to trail brake and the car still under steered. It really annoyed me actually, is this something that brake bias could have helped with? In theory, possibly - but there may be other factors at work. Might need to try a car with it and see if it makes any difference. Cheers

J-P If you have done all that work you need to get the GT3 mc on there. It's almost criminal you haven't. It will give you a proper brake pedal once you get it on. The one in there presently is long! Cmoose I've no idea on price, £300 or so most likely. TRW make the part however. I'm sure with an afternoons effort one could source it via an alternative channel for half the price. Its a fairly easy swap if you are handy, though I would probably pay someone as bleeding brakes is possibly the dullest car work around.

fioran0 said: J-P If you have done all that work you need to get the GT3 mc on there. It's almost criminal you haven't. It will give you a proper brake pedal once you get it on. The one in there presently is long! Cmoose I've no idea on price, £300 or so most likely. TRW make the part however. I'm sure with an afternoons effort one could source it via an alternative channel for half the price. Its a fairly easy swap if you are handy, though I would probably pay someone as bleeding brakes is possibly the dullest car work around. I'll get it done - sounds like a no-brainer and not too expensive either.

anonymous said: [redacted] When I had mine done in October 2013 it was £302.31 + VAT for the MC part number 997.355.910.30. It does make an incredible difference to the pedal feel. I also fitted GT2 brake ducts and titanium heat shields and used Mintex M1166 pads with Castrol SRF fluid. Brakes have never been a problem since To fit the GT2 ducts you need to cut a slot as shown in the picture

http://sharkwerks.com/porsche/987-cayman-and-boxst...

Interesting - like the look of that Tubi exhaust. I'm looking forward to trying the SVP car in a couple of weeks.

FWIW, the 997 GT3 MC is the same on both the 997.1 GT3 and the 997.2 GT3. Its also the MC used on the 997 Turbo/GT2. Its not particularly relevant if you are going to get from an OPC, but it may prove useful if you are going to source elsewhere.

J-P said: Thanks for the above, Neil. All very interesting and leads me to the conclusion that I definitely need expert help in this area. On a separate note SVP is thinking about being able to have a brake bias box. What is brake bias? I won't be racing the car but wondered whether or not it would add to the experience? Does it mean changing the braking force applied to each axle? If so, does that mean you need to amend for every corner? Thanks No problem. At least you can refer to it if you need help sleeping. As already mentioned by others, brake bias is the front/rear distribution of braking effort. I'm not following the brake bias box bit though. Do they mean they will give you adjustable bias control or just make a bias change to the car? With an adjustable bias control you can change how much braking effort is sent to the front and to the rear. Usually the control is in the cabin and you can do it on the fly. You could adjust it for each corner, like an F1 driver, or you could set it up for different conditions. In practice its as likely to see you heading down the road backwards as it is to give you an involved drive . If you tweak it and end up with the rear locking before the fronts its definitely "code brown". A single hit bias change would simply involve adjusting the system (usually by fitting some sort of proportioning valve) so that the current brake force split becomes something else. Its an interesting suggestion. The bias on your car, as with all the modern Porsches since 2005, uses an electronic bias adjustment as part of ABS. Its actually highly active and very proactive (as is ABS as well). While the driver doesn't feel anything at the pedal, under hard braking the electronic bias actually pretty rapidly reduces rear system pressure sending everything to the front after the initial pedal pressure is input. You can see it pretty clearly if you run data logging on the brake lines. As such, any physical adjustment to bias (either allowing adjustable bias or a one time bias change) would usually be overruled by the electronic bias control unless the ABS was removed completely or somehow reprogrammed.

fioran0 said: FWIW, the 997 GT3 MC is the same on both the 997.1 GT3 and the 997.2 GT3. Its also the MC used on the 997 Turbo/GT2. Its not particularly relevant if you are going to get from an OPC, but it may prove useful if you are going to source elsewhere. It's available as a std TRW part but I don't have the part number to hand, however I went for the Porsche part and was fitted by OPC to avoid any warranty issues

anonymous said: [redacted] Not sure which part you want me to comment on. All I can tell you is my brakes are perfect now. Take advice from others if need be but it wont affect the way my cars feels for me thanks

anonymous said: [redacted] It's not 'rock hard'.... you're reading "Americanisms" It's a lot firmer than before and doesn't travel so much when used hard for long sessions. Basically, you have a "Good" pedal I stopped reading the USA forums a while ago as they have very different/Strange ideas compared to us here in Europe. (They probably think the same about us)

cmoose, Force applied by your foot on the brake pedal creates a pressure in the master cylinder. For any given brake pedal force a larger master cylinder will create less pressure than a smaller master cylinder. Pressure = Force / Area so increasing area reduces pressure if force is fixed. Pressure created by the master cylinder then acts upon the brake pistons which (pressure acting on an area) apply force to the brakes. This force is directly related to pressure since piston area is fixed. Applying X pressure will generate Y Force. Since a larger master cylinder generates less pressure for a given pedal force, in order to generate Y force using X pressure, greater force must be applied at the pedal. In addition to generating pressure, the master cylinder must also move a volume of fluid. Volume = area x length. To achieve a given volume, a master cylinder with a larger area requires less length of travel than a smaller master cylinder. As a result, a larger master cylinder requires greater pedal pressure and less travel to achieve a required brake force in comparison with a smaller master cylinder. Edited by fioran0 on Wednesday 7th January 01:45

I have a ton of mods on my 987 CS inc the gt3 mc and steel lines. The spongy pedal feel is reduced and it's a good improvement. It also helps the feel if you change the stock pedal covers, I am using rennline pedals. My only brake mod left is to fit pagid rs yellows and I'm more than happy with this for the road.

While modding the R will be fun, and you could potentially end up with something better, it's a lot of dosh to lose. I've modded plenty of cars including Lambo's and you can kiss goodbye to most of the money you put into mods when it comes to selling on, it can also limit the market of people who are even interested in the car. If you can get a build slot on the GT4 I would definitely go that route, as you will end up with one hell of a car, and it might just appreciate over time rather than be throwing money in a drain.

cmoose, I ran quick calculations on the MC change out to give you an actual number on the change in pedal force. It may prove useful given your questions (and for others too of course). For a Cayman with steel brakes, changing the MC to a GT3 version will see you need to increase pedal force by 27.5% to achieve an equivalent pressure using the stock MC. For a Cayman with PCCB, changing the MC to a GT3 version will see you need to increase pedal force by 12.1% to achieve an equivalent pressure using the stock MC. For 40 bar pressure, a steel cayman needs 20 lbs force and a PCCB cayman needs 25.28 lbs force. After GT3 MC change out the required forces are 25.52 lbs and 28.35 lbs respectively. The difference is down the different booster assists between the PCCB and steel cars. As a side note. I was surprised at the amount of assist from the brake boosters on these cars. The steel cayman has an assist of 5, the PCCB cayman has an assist of 4.5. Thats much more than I was expecting to see. For reference, the 986/996 used 3.85 and the 996 GT3 used 3.15. A 986/996 would need 26 lbs force to achieve 40 bar pressure while the 996 GT3 would need 36 lbs force. Changing the booster at the same time would also be of benefit if one wanted to firm up the pedal further and could find one with less assist to physically fit in. For the steel cars, even using the PCCB booster (while still not great) assuming its probably an option would yield an improvement. Pedal force would increase to the same 28.35 lbs as the PCCB car post mod. Thats an increase of 41.5% pedal force over the original steel pedal/booster combo.