Installing GT3 Front Lower Control Arms

I know there are many existing camber & alignment threads, some of which have tangentially discussed this modification, but I am hoping for a specific and complete answer so I started a new thread. This will also make it easier for those looking for this information in the future. For those that have installed the GT3 control arms as a means of increasing negative camber, please let me know what you did and what you paid for the parts. If you are uncomfortable posting this to the thread, then please send me a PM. I am looking for all the required part numbers . This important, because I need to know whether you installed the 996 or 997 arms and whether the arms were the "street" part or the "cup" part. The Porsche Owners Club classification system allows only the "street" arms (rubber bushings) for a specific class and does not allow the "cup" arms with the solid bushings, etc. Thank you in advance for your response. Cheers,

Bump. I am hoping someone has done this successfully and can point out the critical issues (e.g. headlight angle sensor strut connection).

I had this site bookmarked. Schatz Motorsport Hot New GT-3 Products Check with BBI AutoSport - 15631 Graham St, Unit D, Huntington Beach, CA 92649 for installation.

CCC4321, Thank you for the link. I am not as concerned about locating the parts as about understanding whether the 996 arms fit perfectly (from someone who has done the install) or whether there are other modifications/changes necessary. Remember the wheel housings and bumper cut outs on the radiator install? So, has anyone done this that can help? Cheers,

Jeff at AASE installed these on Bill B's car. Did you check with him?

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I was asked to post my info on LCA installation on this thread. For the lower control arms: K996 341 121 90 K996 341 122 90 K996 341 441 90 (2) 900 076 025 02 (4) 999 025 269 02 (4) Shims (buy in pairs): K996 341 543 90 K996 341 543 91 K996 341 543 92 Front sway bar: K997 343 701 91 996 343 792 16 (2) Keep in mind: 1. Use your original diagonal control arm that attaches to the lower control arm, but shim it with cheap washers equally on top and bottom to make up for the difference in the thickness of the mounting point on the new LCA. 2. You may need to get more or less LCA shims, depending on what you are after. 3. The sway bar requires adjustable links to fit our cars- I made my stock pair into adjustables, but you may want to find aftermarket units. 4. LCA parts: $640, Sway bar parts: $150 5. You will need an alignment after this! The car will be unpleasant and dangerous to drive without it. My current alignment is front: -2.2 camber,1/16" total toe out rear: -1.5 camber, 1/16" total toe in This will be modified soon. The stock diagonal brace works fine and avoids $2-300 in costs. There is no sensor attached to the lower control arm. Hope that helps!

I have GT3cup lower control arms. I have no idea how they are different except like you say the bushings. I hope they are also beefier - I bent a front wheel on the track after i had these installs and they didn't crack or bend. Part #: 997-341-041-9M The shop also informed me i need new trailing arms for this the part number is: Part #: 996-341-043-06 I was charged $600 for the LCA (EACH!) and $228 for the trailing arms. I don't even kniw what a trailing arm is (is it like a tie-rod at the rear for adjusting toe??). But the shop is a reputable one, albeit i do add a fair amount to their profits i'm sure.

Does anyone have any pictures of the gt3 control arm? Please post them if you do. Thanks, Ricardo

The trailing arm is the diagonal arm I wrote about- do not spend the $228 each for this- shim the original with washers. 997 GT3 LCAs are a ton of money- go for 996 GT3 LCAs which accomplish the same thing. Like I said, I spent $640 TOTAL. Don't bother with this mod if you aren't going beyond -.9 front camber, of course. My front is -2.6 degrees after my last tweak. Here is a pic: It amounted to the following actions: 1. Disconnect tie rod and sway bar from wheel carrier. 2. Disconnect trailing arm (diagonal arm) from LCA. 3. Disconnect ball joint connection between carrier and LCA. (use prescribed Porsche tool- this came off with a lot of force and a BANG! I borrowed one from my dealership). 4. Disconnect LCA at cross member. The 996 GT3 LCA is the same length as ours without shims. Put initial shim pack you think is what you want. You get about 1 degree for every .350" you move it out at the botttom or in at the top. 5. Tighten the twin bolts that connect the two halves of the new LCA, with the shims in between. This takes a 13mm socket with a 1/4" drive u-joint to get into the cramped area between the ribs that are cast into the outboard half of the LCA. Porsche tech tells me the torque is 20 ft lbs. 6. Measure trailing arm mount on old and new LCA's with calipers. Go to the hardware store and get six thick washers to make the difference, and use 3 on bottom and 3 on top. 7. Reinstall as you removed the original. Tie rod torque: 56 ft lbs, trailing arm torque: 118 ft lbs, sway bar to link torque: 37ft lbs 1st stage/loosen 90 degrees/48 ft lbs second stage, ball joint toque <I'll post later>, LCA to cross member torque <I'll post later>. Note: the new LCA has two positions for the trailing arm bolt, so close together the holes overlap forming an "8". I guess this would change caster if you wanted. I chose the hole more rearward, which is along the center line of the arm and corresponds to our LCA mounting point. To get the trailing arm bolt to go through you will have to apply a little force flexing the LCA forward. 8. ALIGN IT! You've got a ton of toe-in now!

Krokodil and wpmjr, Great job guys! Tomorrow I'm getting GT3 LCA installed on my Cayman . Running BFG g-Foprce R1s (GREAT TIRES ) which like more negative camber in the front. I have PSS9s so can do more negative on teh rear. Currently the rear camber is set at -2.6 degrees, but only -1.0 up front and the car understeers too much. With GT3 LCAs I can get much more camber up front, but worry about drivability on the street. I think Krokodil you now have - 2.6 on the front, up from the original -2.2. How does it drive with street tires ? My thought would be - 2.0 front and -2.6 rear to start with but that may be too much up front for street driving and I may back off some from the rear to make it more neutral. Any comments or recommendations?

I just finished a conversation with the BFG tract guy about the set up for BFG g-Force R1 tires which do like a lot of negative camber up front. He seemed to think that removing (or adding) a shim on the GT3 LCA would not require a new alignment. If this is true we could set the front at a -1.0 - 1.5 degree camber for street use, and when I put on my track wheels add a shim to bring the camber up to about -2.6 or so for track use. I have a 2-post lift so this may be feasible as long as it doesn't screw up the alignment too much and not require any specialized tools. I will check out how easy this may be and how much it affects the alignment tomorrow when I have my GT3 LCA installed, and how easy it is to add/subract shims. Hope this works, if so it will be just one more step is preparing for the track! Does Krokodil, wpmjr or anyone else have any suggestions, thoughts or comments??

My car is running -2.5 up front and -2.1 in the rear (stock was -0.5 and -1.8 respectively) and have not noticed any adverse wear on my street tires over the last 3 months and ~ 5000 miles. I swap tires and brake pads for track/street, but I do not think it is necessary to remove/replace the alignment shims as well. Adding or removing shims will absolutely change the alignment. The trailing arm and strut top mount points are fixed and adding shims will push the wheel outboard, so without adjusting the track rod the change will alter the toe (create toe in). From my experience (others may differ), I do not think that running -2.5 degrees up front will cause too much of a problem, and certainly not enough to warrant camber adjustment and realignment. Heck, my wife’s E-class has -1.8 degrees stock and her tires wear fine. Remember, if you have Xenon lights you need the special shim that includes an arm on which to mount the leveling sensor strut. Cheers,

You can buy the camber gauge to check and adjust the camber yourself but I've never found an accurate method the measure toe-in. You can do it with toe plates and a tape measurer front & back of plate but you are talking about differences front to back of 1/16". Very hard to get that very well without professional equipment. There are also some rod measurer with a pointer but in my mind there are too many variables to feel good about what I'm measuring.

You all have been very helpful. I have a few questions that I need clarification on: Can the original sway bar still be used with the GT3 LCA 's, or do I need a GT3 sway bar? What brand of adjustable side arms for the sway bar do you recommend? There was a reference to shims being needed if you have Xenon lights. Can you be more specific on where to get these and how to install? What size of LCA shims do I need for -2.5 front camber? Can I get -2.1 camber on the back with stock components? Thanks!

Spec84, I just installed GT3 lower arms on my car with Xenons. My Porsche dealer did this for me with a 20% PCA discount. It is good to see Porsche helping out with after market mods! I now have -2.6 degrees up front and -2.1 degrees at the rear (stock suspension arms except PSS9s and about 1 1/4 inches lower, which also lets me have me get more negative camber at the rear). You do not need GT3 sway bars, standard ones work just fine, though I may add some after market sway bars once I get the feel on the track. You need the 2-piece GT3 lower arm only, not the diagonal arm if you make some spacers (some use a bunch of washers, but I prefer one piece). I made one-piece spacers from aluminum, 38 mm diameter, 14 mm holes and 8.5 mm thick, two per arm (one on each side since the GT3 lower arm has a 17 mm wider "Y"). I gave an extra set to Parktown Porsche for the next customer. For Xenons you need to buy the GT3 Xenon leveling shim (the 987 won't fit). It attached the leveling sensor to the lower control arm and is about $45. Make sure you get enough shims for the camber you need. I think I needed one 7 mm and two 3 mm shims per side for -2.6 degrees of camber. My Cayman drives great on the street with -2.6 degrees up front and no longer understeers. I will try it on the track this weekend.

Sorry to resurrect an old thread but I'm considering these arms and wondering about install... Has anyone done DIY on install with new diagonal arms? How does it rate on the 1-10 DIY scale? I've previously done a coil-over install on 996. I do NOT have a lift and I don't currently own a tool to break ball joints but would buy a tool if I DIY this project. Even If I were to complete this install myself, I would still take it to a local tuner for an alignment. I saw the earlier messages where washers were used to shim the original diagonal arms but I think I would want to use new diagonal arms as in the Suncoast kit. At 140mph on track, I don't want my life do be dependent upon a stack of 25 cent fender washers. Maybe I'm overly paranoid. Anyway, in the description of the install with the original diagonal arms and washers, I didn't get a good feel for complexity of the install so I'm not sure if I would be in over my head or if it's as simple as it sounds. For those of you who used a shop for install, how many hours with/without alignment? Thanks.

What are the chances Parktown still has these custom spacers? Would you mind letting me know who I might talk to? I'll be in StL in a couple of weeks (I live in Springfield MO), and could pick them up if they are available. I'd also owe you a favor...

I'm taking my CS in to get 996 LCAs installed next week. The race shop doing the job has recommended that instead of using flat washers or aluminum shims between the LCA and the diagonal arms, that they would instead press the bushings out of the original Cayman LCAs and press them into the 996 LCAs such that the diagonal arms would fit without washers or shims. What do you think of this approach? Is it any better or worse than using washers/shims? Doug

Did you ever get an answer to the question on trailing arm bushings for the GT3 LCA upgrade? I have a 2005 987S and need to get more negative camber too. I am going through tires at the track by wearing the front outside edge. I know we can order the Suncoast kit with control arms, but I have seen people do it with spacers as mentioned above and use the stock trailing arms. This idea of swapping LCA bushings seems like a better solution if it is true. Has anyone done this?

SteveK, Chris Cervelli at Spline Technologies in Aurora (Denver) pressed the original bushing out and into the GT3 LCAs on my Cayman S and also a friends. I've since had 4 days at High Plains Raceway with excellent results (new new personal best times - twice). I've checked the bushings for centering every time I change wheels and there has been zero movement. The force angles are such that I would not expect any problems. So I'm very satisfied with this approach. Chris used a hydraulic press and proper sized tools to push the bushings out and back in using a very slow and gentle process, ensuring that everything was straight and properly aligned. Doug

IF you do track days you know you cannot get enough adjustability nor enough negative camber. Inquire as to pricing / freight...you will be happy ;-) These are a must:

Probably not the right place to ask, but how about these for autox? PCA and SCCA, will they move you up into a different class?

Yes, altering the suspension geometry by any means other than alignment changes within the tolerance of the factory adjustments will move you out of SCCA stock class, AS for a Cayman S , and if I recall correctly BS for a Cayman . I believe you end up in BSP independent of whether you have a Cayman or Cayman S . In PCA it also moves you out of the showroom stock classes. There are several different "compressions" of the full PCA Parade Competition Rule autocross classes. Regions are free to use one of the shorter "compressed" class lists based upon size of the entry list. Worst of all, you are not only bumped out of stock class, but moved OVER the "production" classes and into "improved". I've recently conversed with Mike Lommatzsch, PCR head-honcho, and it is highly unlikely that PCA would change this. If you intend to be competitive, I highly recommend a very thorough reading of the competition rules for any organization you run with before making mods to you car. It's very dry, boring reading though! Better yet, engage a pro race shop that is familiar with the rules, your car and the available options.

Hi, I am considering adding front LCA to help save my new Nitto on the track. 996 GT3 are about $760. The new RSS LCA are sold at the same price and seems more compatible. Questions: 1) Which one of the two options is better ? 2) Do I need a rear LCA? (Sorry for my ignorance.. ) for rear negative chamber of -2.1 Thanks

Since I have no experience with the RSS LCA's, I can't comment about the relative benefits of the RSS vs. Porsche GT3 arms. The key is the ability to dial in more negative camber than the stock suspension allows. I suspect either solution is perfectly adequate for this. You can get -2 degrees of negative camber in the rear using the stock suspension components. So new control arms are not necessary in the rear. Normally you'll want a little less camber in the rear vs. the front. Too much rear camber can cause reduced tire contact patch area, a loss of traction and inability to put the power down on corner exit.

More adjustment options with the RSS units we have - more shims available and it contains EVERYTHING you need - incl the headlight leveling brackets! No reason to cob together a GT3 OEM thing.

One thing I haven't since mentioned is that the lower control arms go on the opposite to there marking. That is the right goes on the left etc. It will fit the other way but your caster will be off; thus the use of the 2 figure 8 holes. Do them as I noted and you end up in the correct hole with the correct caster. I had the original install done by a Porsche tech who didn't know this and naturally installed them the way they are mark. A year later I had the car to a race shop that built the Cayman and Boxster Spec car. They fix it and advised me that people who don't do this work regularly for a living (meaning race prep; not Porsche repair work) don't know this stuff and do it wrong. He knew it wasn't right just looking at the way the wheel fit in my wheel well and when I showed him the alignment spec's it proved it. You can still use the original sway bars but I upgraded to the GT3 Cup bar and solid drop links when the correction install was done. Don't do the drop links unless you can live with the noise of metal on metal and lots of clanking. Hope this helps everyone.

I finished my suspension last month and I'm very happy with the results. Bilstein PSS9s 996 GT3 LCAs Tarrett Camber Plates TPC Sway Bars Tarrett front adj. Drop Links w/rubber boots Adj rear Toe Links Lowered 1 - 1.5" Alignment -2.5f -2.1r My car is a DD and I'm very sensitive to squeeks and other noises. I can say I don't feel the ride quality has suffered at all and pleased with the results. My track tires were getting eaten up on the outside and was lucky to get 2 - 3 DEs from them, now I have even wear. The effect on my street tires has been mixed. 18" PS2s wore an extra 2/32s on the inside of the tires , my 19" Hankooks have even wear in the front so far and about 1/32 in the rear. There is no drop link noise at all! The car is more neutral handling, so I'm able to be more agressive in the corners. maybe I can slow down on the mods. now. Well maybe after I get some seats. :hilarious:

DMN - I'm curious about the camber plates and the LCAs. I know either can be used to increase camber. What is the advantage to having both? thanks, Dave

Who did the alignment for you ? The dealer ?Race shop ? any difference in price... I was quoted $299 by the dealer. Is it a good price? Also if anyone has recommendation in Ohio (near Cleveland) pls pm me. If you are uncomfortable to post $$ please pm me. Thanks

I've had race shops and/or Porsche tuner do my alignments. Usually around $199. The Gulf Station I deal with is $125 and does a fine job also.

Guys: Watching this thread progress has been fun. I think some of the guys new to this stuff need to know a couple things. 1. Adding a shim to the GT3 Lower Control Arm will definitely affect the toe-in on the front. You need to get toe re-set if you change the negative camber with a shim. 2. If you drive your car to the track with a lot of camber on either front or rear (or obviously both), you need to set your toe-in at near zero to avoid extreme wear on the insides of your tires while you're driving to/from the track. Tell the man at the alignment machine to set toe at zero front and rear. He'll come close enough. The car will drive pretty well although it can feel a little different than stock. It's not the ultimate setting for track use, but you'll still be quicker than not increasing the negative camber. I've used near zero toe for about 20,000 miles on summer, winter and track tires . Wear is very good and it works. I have about 1.8 negative in front, about -1.6 in back. Stock PASM . TRACK SUSPENSION FOR DUMMIES: Thought maybe some basics ought to be covered for everyone. Camber: Negative Camber is when the bottom part of the tire is more outboard of the car than the top. Car sort of digs in to corners better and has less tendency to roll it's tread over. This is a good thing....However.... More is not always better. At some point, excess negative camber hurts straight line braking because the wheels are not sitting flat when you are driving straight. Similarly, acceleration is affected because the rears aren't sitting flat either. It becomes easier to burn rubber, but harder to actually accelerate. Like a lot of things in life, camber is a trade-off. Getting the right balance for how and where you like to drive is where the magic is. Positive Caster - This is where the axis of the steering part of the front wheels is tilted back at the top. At zero caster, the axis is straight up and down. Wheels are flat on the ground as you turn the steering wheel. As you put more positive caster in, the wheels tilt inward at the top as you turn the steering wheel. Positive caster is very cool because when the steering wheel is straight, the front tires are flat on the ground (assuming zero camber). When the steering wheel is turned, the farther it is turned, the more effective negative camber is created and the more the front tires dig in to the turn. How cool! A way to progressively increase the tilt of the tire as you turn the car harder! Let's put A LOT of that on! And, if you look at the front wheels of almost any German high-end car when it's parked with the wheels turned sharply. Others are catching up, but I really am amazed at how much caster is dialed in to some of these suspensions. But the benefit doesn't stop there. Positive caster also makes the steering wheel more self-centering and everyone likes that, right? Well, like everything else, there's a limit. You don't get a corresponding camber change at the back, so you can really create some wicked oversteer situations on a rear drive car, especially one with a solid axle. The use of semi-trailing arms or multi-link suspension in back can create variable geometry situations to provide some tilt and even wheel steer in back that sort of matches what's going on in front as the car enters a turn. As you stiffen up the rear suspension, however, there is less of that going on, so you have to take care to balance what's happening in front with what's going on in back. It's tricky to make a car using these all these interactive things and make it feel really balanced. That's why a lot of car makers don't like us messing with their suspensions. Get it wrong and you can end up with a lot less money in your pocket and a truly evil handling car. At this point, I'll again plug the TPC sway bar kit. The rates are phenomenal on it. They really are the first change anyone should make for the track followed by negative camber improvement. Very little street ride sacrifice and not that much money spent for a massive improvement in fun. The RSS LCAs for the front should work just as well as the Porsche GT3 units and are likely a bit cheaper. (You have to email Craig to find out). I think you can put pretty much negative camber into the stock rear suspension without changing anything. When you lower the car, though, it won't adjust the toe properly in back, so you need aftermarket adjustable toe-links to prevent a lot of bump-steer and tire wear. I'm running stock suspension height, so stock works fine for me in back. I know I can go faster if I spend a bit more or tow my car to the track, but I'm trying to create a well balanced car for street and track.

One more question... in the for sale threads of people who bought their LCAs from Tarret, the LCAs have part numbers 996 341 341 90. Why is it different vs. the quoted PNs above, plus what are shown in part catalogs? (996 341 12x 90)