GT3 control arms on a 996

I was getting ready to order GT3 adjustable control arms for my 996. To get all the part numbers, I have copies of the 996 and GT3 parts catalogs. Looking at them, I discovered that the ball joint on the GT3 uses a 2mm larger end that the regular Carrera by comparing the lock nut sizes. This makes me know wonder if anyone has really done this conversion since it appears you have to drill the hole in the wheel carrier to install them. I have never heard of a problem before. Anyone have an insight on this? FYI, in my research I discovered that the front wheel carriers and hubs are unique to the GT3 from other 996 models. The rear wheel carriers, hubs and control arms are all common between the the 99-01' GT3 and the 02'+ 996 (non-C4S), but the 04-05 GT3's have also unique parts (including a unique adjustable toe arm).

I have an interest in this as well. Curious about the rear control arms.

I sure they will fit. On the stock control arms the shaft tapers down so that the threaded area is considerably smaller than the area that seats in the upright. Does that make sense? I'm sure the cup car and GT3 versions have a larger threaded area but the same size main shaft. I believe the rear toe arms (tie rods) are interchangeable between 996, GT3 and cup cars. Hope this helps. Jim

The GT3 rear toe arms suck. This is a much better solution (it's what I have on my car now): http://www.tarett.com/Browse_Item_De...ontrol_Arm_(pr )

i fit the gt3 front control arms to my 996 and they work and fit fine. i ordered the arms and nuts to make sure that they fit and secondly i just wanted new hardware.

I don't disagree that the stock tie rods suck but these seem to use the weak link from Porsche. It's the outer piece with the ball joint that fails. I went through four of them in one season before replacing them with the ones from Motorsports. They replaced the wrong end.

Not at all. The problem on the GT3's is with the eccentric. This design eliminates that. And I think the stock part flexes under load and this doesn't do that. For me, it's been a great upgrade.

if you are referring to the ball joint at the end of the control arm, then you should upgrade to the fabcar control arms. beafy and supposedly more robust than gt3 control arm but pricey and heavy

Carlos, I was reffering to the ball joint on the rear tie rod. They were a weak point for all 996s including cup cars. If you looked at the inventory of the big race teams they would have a dozen spares along. As I mentioned, I went through 4 in a season. My point with Holger is that the ones he has still use the weak Porsche ball joints so I'm not sure I would get too excited about them. Porsche Motorsports now makes a much beefier version although we had to have the wedges that go into the heim joints on the end remade in stainless. The alum ones that come with them wear out. Thanks for the tip on the Fabcar control arms. I broke two of the stock ones. Both broke right where the shaft narrows to the threads. I now use beefier ones but the Fabcar ones look better. Obviously my car deals with some stresses that most don't but I still think it's a good indicator of potential problems. Jim

Good GT3/996 Rear adjustable control arms http://www.vividracing.com/catalog/p...oducts_id/8370

These control arms are different than the lower control arm and different than the rear tie rod that Carrera originally asked about but it's always good to slip in a little advertising I suppose. Maybe we need a thread on the various 996 control arms, their function, their weaknesses and alternatives. Jim

and price

Hate to resurrect an old thread but can't find the answer yet despite my searches. I have a significant toe problem in my 996 C2 w/ x74 installed. Despite their best efforts, there is still too much toe in the rear for street use. It is so bad that it is killing my rear tires with both inside wear and moderate cupping. I know that I need to buy adjustable control arms but which will be better for a 'vigorous' street application with many highway miles? Lower or upper? Recommended brands?

This is the first I've heard of this problem. So at their shortest setting your rear tie rods are too long? How much camber do you have in back?

So JimB, I'd love to get an explanation of the different control arms! TRG sells rear toe links, start with what they do please.

http://www.vividracing.com/catalog/p...oducts_id/8370 v. http://www.paragon-products.com/prod...ap-996-200.htm v. http://www.theracersgroup.com/shop/trgracing.php v. http://www.tarett.com/items/996-prod...lnk-detail.htm ?????

I guess I can try. I wish I had some pictures but I don't have any handy. On the back of a stock 996 you have three primary parts that hold things in place. 1) The first is usually refered to as the "lower control arm. It is the large arm that runs from the chassis to the bottom of the hub. On the car side it is held in place with an excentric (sp?) bolt that allows you to adjust camber. On the hub side, it connects with a bolt that comes out of a ball joint. This is the bolt that I've had break a couple of times. Not a good deal. This is the part that many replace with GT3 or cup car parts. The GT3 part splits in the middle which allows you to make it longer with shims. Longer means more camber. 2) The top of the hub is connected to the chassis by two "upper control arms". These are not adjustable although they can be replaced by aftermarket adjustable versions. 3) Toe is controled by a "rear tie rod". This is another weak link. It has an excentric on the chassis side and a ball joint on the hub side. The ball joint tends to go bad. Other rear suspension parts include the coilover, drop links and sway bars. The front is actually is similar. 1) It has the same lower control arm and can be replaced by the same GT3 or cup parts. 2) Rather than upper control arms, the front hub is held in place by the coilover which bolts through the fender. The coilover bolts into slots in the fender which allow some camber adjustment. 3) Obviously the front also has tie rods which allow the car to steer. The stock versions actually keep you from adding too much camber although they can easily be replaced with longer motorsport parts. Like the back you have a coilover, a drop link and a swaybar. Oh and a diagonal arm that contols caster. I think that's pretty much everything. I'm doing this from memory. I hope this helps. Jim

The first two links here show the rear upper contol arms. Personally I'd look at the ones from ERP or Motorsports rather than Agency. The second two links are the rear tie rods I refered to.

+1 on ERP. things may have changed but the AP parts i got were sub par. cheap heim joints that rusted and binded and steel bolts that also rusted... all within a few months. one thing about the tie rods. be sure to lock out the eccentrics with the locking plates offered by tarett otherwise they are still susceptible toe changes.

I agree although many race series make you keep the eccentrics so the next best option it to "center" or "zero" them which is really nothing more than setting them to the middle position and not using them. Make sure to mark all your settings so you can correct them in case they move.

So I can fix the toe using just the adjustable rear tie rods? Is that the best solution?

first make sure that you are at the bare minimum toe. it's just very odd that you have a factory sport suspension which produces excessive toe in. the toe arms control the majority of toe adjustment. if you are at minimum then you should try out the tie rods before the upper control arms. one thing though. you never mentioned what your alignment specs are. maybe you have too much camber and your toe is fine. it's just hard for me to believe that x74 caused excessive toe in.

I was surprised to see this come back. Were you using GT3 control arms in back? I only used them in front as we NEVER had an issue getting enough camber out back. Only the fronts on these cars are really limited. We could get only -1.0 in front before the control arms, we could get almost -2.5 on my car out back with my ROW M030 which is no where as low as an X74 can go (the lower, the greater the maximum camber). After trying a few different alignments at the track, I settled on -1.9 out back. At this setting with 295/30 MPSCs on 11.0" wheels with 34-35 psi hot pressures, I get only a variance of 3 degrees across my rear tires hot (inner, center and outer). I am getting dead even wear out back with absolutlely no toe issues (I run minimal toe-in). Any more or less camber out back would result in less grip. My front is still camber limited, so I will be adding more shims on the next alignment; but the rear will be left untouched. If you are using GT3 control arms out back, why? What was the camber limit with your car? Most likely if you are using them, you don't need them. If so, how much of a shim pack are you using? If you were to try to run a rediculous amount of camber and run a big shim pack then you would have the problem you are describing and would have to elongate the toe links to correct it. On the front on my car with a 7mm shim pack, we had to take 5 full turns out of the tie rod ends to correct the toe when we put the GT3 control arms on. The only reason why we would ever need more would be to run some of the soft sidewall road racing slick (not DOT tires) that require -3+ in camber for optimal grip. There is no point going to these without going to a very stiff full race suspension that can use them. I have nothing against Vivid as a sponsor, but be weary of Agency Power links. They do work fine on the street. I highly advise against them for track use. The spherical ends are not up to track standards and fail commonly. I would look at TRG or Fabcar for race worthy pieces for track use.

Thanks JimB et al., excellent info. Now I have to run out and jack up the car to look :-) I still don't get the toe link for the rear. The lower and upper control arms should "fix" the toe as well. How is the toe link connected? (I guess we need pictures, I'll try to take some tomorrow morning)

OK it's 5:30 in the morning here and I'm taking suspension pictures. What's wrong with that picture. Anyway, here's a pretty good picture of what is probably about as good as 996 suspensions get. In the picture the two smaller upper contol arms are pretty clear connecting the top of the hub to the chassis. The stock parts are not adjustable. These are ERP parts and allow you to push the top of the tire out or pull it in. The large contol arm on the bottom (with the part number marked on it) is the lower control arm. It's a little hard to see where the lower control arm splits but it's near the chassis. The eccentric bolt is pretty clear. You can see the rear tie rod (closest to you) running from the hub to the chassis. It's eccentric is somewhat covered by the swaybar. This part is the Porsche Motorsport version but yours look similar. The tie rod is what you use to adjust toe. Changing camber changes toe but you then use the tie rod to correct it. If you are happy with the amount of camber you have and can't get enough toe then your tie-rods are not long enough. Like others, I'm a little preplexed by that. We had problems with the front tie rods not being long enough but the only problem we had with the rears was the very weak ball joints. Does that help?

The toe arm does just that, changes toe. Here is a pic of the TRG toe arm installed on my GT3. The control arms are NOT your toe adjustment places.

Jim, looks like we just tried to post the same info at the same time. You're right....wtf are we doing talking suspension bits at this time of the morning?

Carrera, There are several very good reasons to use upgraded rear control arms. First, the stock ones break and when they do it gets real ugly in a hurry. Second, you can control camber without using the eccentric. Third, I don't agree with your assessment of rear camber. 2.5 degrees may be enough for most but many track junkies will want more. BTW, you can't use tire temps to determine optimal grip. Optimal grip will result in excessive wear and excessive heat on the inside edge. Why? Because when the camber is optimal for corners it's overheating the inside edges going down the straights. If you have even temps and even wear you are leaving lots of corner grip on the table. Jim

You better get used to getting up at strange hours.

You ain't kidding! My wife's ob/gyn was telling us that the getting up several times a night to use the bathroom is GREAT practice for when the baby comes. But, I don't want to practice

Great info guys!!! Much appreciated!

damn jim, that's one beefy toe arm. is that an ERP piece? it looks twice as thick as the tarett/TRP toe arm.

Partially correct and incorrect. You are very right that you can't use pressures to track or determine grip. The only way is to use a probe-type pyrometer that will read temp at the cord. Anything else is worthless. Getting optimal temperature across the entire tire means you have reached optimal contact patch. If you are overheating the inside tread on straights (you are running severely on the inside tread, not the edges) then the inside of the contact patch won't be as grippy in a corner. In addition, it you have reduced the contact patch by over cambering then you will have less turn-in into the corner and less traction coming out. This is espeically true with MPSCs where they go away extremely quick once they exceed peak operating temperature. Keep in mind that each different type of tire has a different optimal operating temperature and the tire contstruction severly influences the optimal suspension settings. The cars suspension (spring rates, bushing rates and caster) are also major factors that effect optimal settings. Caster is the camber gain while turning. Stiffer suspensions need more static camber since they can't gain it in a corner. If you want to learn a lot more on this I highly recommmend the Evolution Dial-In Course . http://autocross.com/evolution/modules/news/ This is taught by national autocrossing champions. They will teach everything you will ever need to know about spring rates, shock rates, sway cars, alignments, tire pressures, contact patch and turn-in. You also get to see it first hand on the skidpad, slaloms and sweepers.

Partially correct and incorrect. You are very right that you can't use pressures to track or determine grip. The only way is to use a probe-type pyrometer that will read temp at the cord. Anything else is worthless. Getting optimal temperature across the entire tire means you have reached optimal contact patch. If you are overheating the inside tread on straights (you are running severely on the inside tread, not the edges) then the inside of the contact patch won't be as grippy in a corner. In addition, it you have reduced the contact patch by over cambering then you will have less turn-in into the corner and less traction coming out. This is espeically true with MPSCs where they go away extremely quick once they exceed peak operating temperature. Keep in mind that each different type of tire has a different optimal operating temperature and the tire contstruction severly influences the optimal suspension settings. The cars suspension (spring rates, bushing rates and caster) are also major factors that effect optimal settings. Caster is the camber gain while turning. Stiffer suspensions need more static camber since they can't gain it in a corner. If you want to learn a lot more on this I highly recommmend the Evolution Dial-In Course . http://autocross.com/evolution This is taught by national autocrossing champions. They will teach everything you will ever need to know about spring rates, shock rates, sway cars, alignments, tire pressures, contact patch and turn-in. You also get to see it first hand on the skidpad, slaloms and sweepers.

I have never been so informed on here in my life you guys ROCK Keep em coming. i am going to try some track time in August when I get back home so I will try to put some of this to good use.

Excellent info! So the only reason to change the rear toe links would be if there is a need to adjust toe more than the standard parts allow (which should be rare)? Or perhaps if they are too weak for racing. This is what it says on the TRG web page: "Rear Toe Arms These toe links feature a heim joint that eliminates the rubber bushing at the eccentric and usage of the eccentric for adjustment. Improves control of toe changes under acceleration, braking and cornering. Includes bushings for subframe attachment." Would the heim joint help keeping the toe more constant during acceleration, breaking and cornering??

the toe eccentrics have been known to easily go out of alignment from track use. the reason for using the locking plates is to eliminate the eccentric. then to adjust toe, use the toe links that are offered by tarett/TRG/porsche motorsport. the spherical bearings/solid bushings prevent any deflection, i.e., toe change. this mod is pretty much overkill for street use.

Carlos, The toe arm (aka rear tie rod) is the beefier version that Porsche Motorsports came out with a couple of years ago. They are pretty spendy. Around $800 I think but I haven't had any issues since I put them in. Before that I would go through several sets a year. Carrera, Where do I start? First I don't think I said anything about using tire pressures to determine grip. I said even tire temps don't indicate a setup with optimal grip. The article you referenced is about autocross. In autocross you are constantly turning with very few straights so using tire temps is a valid way of finding grip. It�s not as easy on the track because any amount of camber will cause the inside of your tires to heat on the straights. Therefore, if your tires are optimal in the corners, they will be heating the insides on the straights. That�s why fast track cars will never have even tire wear. At a track where there are a series of corners before the pits you will see more even temps. At a track where there is a straight before the pits they will be pretty far off. BTW, I don�t recommend the running enough camber to achieve optimal grip unless you are going to really stay on top of your tires. And, have a big budget. Jim

Carlos makes a good point. Spherical bearing/solid bushings/monoballs remove play which is good but also remove the insulation of vibration between your suspension and the chassis. You have to decide if that's something you want to do.

Thanks for the info guys. I'm going to another friend of mine today and have him look at it to see if he can fix the toe without changing the arm. I too was a little surprised that there was a toe issue, or any alignment issue, using the factory X74 suspension. Granted it lowed the car about 30 mm in the back but you'd think that Porsche would have considered that. In the event that I do decided to upgrade the upper control arms, where can I get the ERP version?

go with the toe arm first. it will adjust toe more than the upper control arms. try http://smartracingproducts.com/ for ERP parts. they have some ERP parts in their catalog.

Not really. The two HUGE benefits of having upgraded TOE ARMS is (1) the ability to keep the toe constant and not have to keep re-aligning your car all the time b/c the factory toe arms fall out of spec VERY easily; and (2) more importantly (for us track guys) is the removal (or serious decrease) in bump steer. Having toe changes at speed especially on a sweeper is ground for some serious trouble.

Do they fall out of spec because of the eccentric scheme in the standard part?

The eccentric is what is used on the stock arms to adjust the toe but on the TRG (etc.) arms you eliminate that and adjust at the turnbuckle. Because of the design of the stock arms they are VERY susceptible to eccentric movement under stress and thus changing toe settings.

like i said

oops. I didn't realize you said that already. wrljet asked, I answered.

just kiddin dude

Sorry, I (lazily) didn't read the entire thread before asking...

I know, just having a little fun today

Could going airborn and landing hard knock those out of kilter?

Going airborn and landing hard could knock a lot of stuff out of kilter. What altitude do you intend to reach?

The stock or the TRG/etc. ones? Stock? Most definitely TRG/etc.? Nope

going airborne won't knock anything out of kilter. it's the landing that will do the damage

Stock. Well, I've gotta get it adjusted after putting the M030 on anyway...

hehehe.....sounds like we are all drinking the funny juice today!

It wasn't funny when it happened. PSM over-corrected after braking one front wheel while the back end was still in the air.

I am *very* happy to report that my friend, a very good Volvo tech, got the alignment back into spec without me resorting to the adjustable toe arm. I am *very* pleased as my new son's stay at NICU has gobbled up my discretionary car funds...