NJ-GT

Mike,

With the stock ride height and solid bushing toe links like the ones from TRG, bump steer at the rear will still be a small problem, but not as bad as with the stock toe links with rubber bushings.

The main benefit to switch to TRG toe links is to eliminate the use of the eccentric bolts to adjust toe when doing an alignment. The stock eccentric bolts don't offer too much precision, and they wear out with few alignments. When they wear out, they slip and the toe static setting changes. This condition is even worse because the car will have different toe settings left/right, creating an ill handling GT3, because the trust angle is off (left to right toes together ==> Trust angle).

Running a lot of static toe-in helps the car to not reach toe-out during a turn exit while on the gas (quite scary). 35 min total is a lot of toe-in. Your car is fine with that setting, the TRG toe links and the stock ride height.

I just set my rear toe-in at 15 minutes (0.125 degrees per side, 5/64" total, 2mm total), for the same reasons you mentioned: stiffer springs, metal bushings, and corrected bump steer.

By being able to reduce static toe-in at the rear, I was able to remove the toe-out I had before at the front (0.125 degrees per side). My front is now set to zero toe. This should balance the handling, but I won't know until next Monday, as I'm running a couple of track days at Streets of Willow with POC.

Rickard 993 Turbo

Thanks Hank, i must thank Nj-gt i have read all post he has writen on toe and suspenstion over all and he is very knowable so i have learnt alot from him

I will post a picture of my rear set up tomorrow, i have locked the ecentrics with special homemade waschers that fitt in the exenter hole and a regular bolt is used so the toe and lower arm is locked in there places, most invards that will say

Then i have the RS lower arm so i adjust camber with shims and i have ERP monobals so no rumber left here

Caster arm has a solid home made alu buch so no rubber here either

Toe link is ERP with home made spacer 15mm and monobal here also

Right now i have stock upper shock mount but a new one is orderd from Mike at AWE same with the ERP dogbones

I also have Öhlins suspention and running 910 front and 1260 rear in springs

Weight of the car is 3050lbs and 530hp@770nm

MetalSolid

Informative!

va122

In regards to Rad's comment about the RSR geometry, jsut get the RSR or ERP upper dog bones, it re-intruduces the kinematic toe from the 993's and effectively toes the car in under load. That's how i get away with very little toe in the rear.

Rad, what are you going to do with the uprights? Can I use them on mine?

Hank Cohn

Victor,

Not trying to be a contrarian but I don't want to spread misinformation. The dog bones alone can't correct for rear bump steer and you wouldn't want them to in this case. The geometry of the stock rear toe links is compromsed especailly on a lowered car. Additionally, if you change the length of those links relative to the stock pieces then you will need to work with a shop who understands and has the time and equipment to set them up. Keep the dog bones set at the factory length. Get the bump corrected rear toe links combined with locking plates to eliminate the rear toe eccentric adjuster. The next step is to replace the inner rubber bearing of the lower rear a-arm with a cartridge type bearing. If you're going that far you might as well get the split rear lower a-arm (same piece as the front). Next eliminate the rubber in the a-arm where the diagonal connects. At this point you are in good shape at the rear and the car will be much more comfortable to drive on the track.

Hank

va122

Sorry Hank, I wasn't clear, i was only talking about toe. i guess i digressed.

My toe links have bump adjust so i guess i dont' think about it anymore. Oh and i have all that other crap and set up by a pro, the car FINALLY does what it's supposed to every lap. Should have bought a cup in the first place.

NJ-GT

Vic, this is an old thread.

I sold the 996 GT3 RS uprights. The 996 GT3 has plenty of bump steer front and rear. The 996 GT3 RS uprights just lower the pick up points by 10mm, the Motorsport (RSR or R) lower the pick up points by 40mm. The street 996 GT3 RS uprights are 5 lbs lighter.

ERP Racing has rear toe links with bump steer adjustment for the back, and steering links with bump steer adjustment for the front. I bought another set from Ira @ Tarett for the RS (front and rear), it has yet to be installed.

If you lower the car 20mm or less, you shouldn't need new uprights. For aggressive low cars (40mm lower than stock or around that), the uprights should be changed, because you won't be able to re-index the rear axles and they will be more prone to break.

Running stiffer springs reduces suspension travel, this reduces bump steer, so your stiffer springs and the ERP parts will be enough to optimize your car.

va122

Hey Rad,

the car is optimized for track. but the bump problem in front is on the street. I believe it's my toe out in front. I'm at 100mm/120mm f/r,chassis height and 2mm in/out f/r toe.

What is that piece from Ira that will fix it? I can get a GMG bump kit for front easily (i have a balance at GMG i need to use, but is it necessary.

NJ-GT

Necessary? definitely.

I ran my 996GT3 higher than that and front bump steer was a problem. I lived with it most of the time, until 911Design fixed it.

Front stock ride height is 125mm for U.S cars and 115mm for ROW cars, both cars sharing all the suspension parts. You're running 15mm below stock ride height, so you should use a bump steer kit for the front steering links.

GMG parts are top quality. You don't need to replace the entire steering rod, just replace the ends.

va122

what did Loren do to fix it on yours?"