rbahr

Yep, on the 996, there is no difference between the cup part and the GT3 street part.

I would have no problem putting a 997 upright in the car as long as it was done to both sides.

Any changes made are likely for the better.

Ray

powdrhound

The 997 uprights have significantly lower pick up points which results in higher roll centers on the front of the car. If you simply upgrade the front end without changing out the rear components to 996GT3RS parts (about $10k worth), you will end up with significantly different roll centers front to rear which will effect handling, not necessarily for the better. Just stuff to think about as doing things half way does not always yield and improvement, in many cases quite the contrary.

T10Chris

There are subframe differences as well between the 996GT3, 996GT3RS, and 997GT3 as well, correct?

When I looked into uprights, the conclusion I came to after many hours of looking up part numbers and researching was the need to match your subframes to your uprights and don't play mix and match, particularly with the rears.

powdrhound

Correct. You need different rear subframes as well as the uprights. The 6GT3RS was the test mule for the 997 stuff. The nice thing with raising the roll centers closer to the CG is that the vehicle will roll less about its axis in the turns. This should allow one to run softer springs in exchange. Great in theory but if you look at the spring rates on a 996Cup vs. a 997Cup, the rates stayed the same or actually went up a bit on the 997Cup. The 996RSR which utilizes the fancy 997 style uprights with the low pick up points runs spring rates of 1970/2140 so go figure. With proper tuning you are not leaving that much on the table with the 996 parts in my opinion. Anything can be made to work but there is more to it than simply slapping on new parts and expecting a miracle.

rbahr

If you do a search on rbahr you will find a lot of information on upgrading the GT3 suspension.

The GT3RS was the homologation platform for the 996 GT3 RSR

The front and rear subframes are the same for the GT3 & GT3RS, they are different for the RSR

The cup car spring rates are as high as they are to prevent the suspension from moving

Rising the roll center (and it is not by much) will offset the issues from lowering these cars...

rodneyr

I called Auto Atlanta and they confirmed 996-341-157-91 was the correct part for my VIN #. However, they said the part is not available anywhere in the world, go figure. So, I got around 5-6 months to find a used part before the next track season starts unless something else changes.

Vanos13

Sorry to hear that. There are a few options that I was pursuing.

- Call Porsche corporate customer service for a delivery estimate. I had them providing me weekly updates. They'll either tell you there are no production plans (not the case for the passenger side) or provide a manufacturing run timing estimate. For the passenger side it was early/mid November.

- Try and source a new cup upright from a race shop. These parts time out for the race cars so shops sometimes keep spares that wouldn't show up in the standard Porsche system. I wasn't able to find one but I suspect they're out there. The best lead I had was that Wrightwood has some but I was never able to get them to confirm. They're not retail facing so you might have to go through a shop with an existing relationship.

black04

Famous last words

T10Chris

Yep, I've got your suspension (and transmission) build threads bookmarked. Great info and reading in there.

Interesting note about the subframes. I thought in your thread, you bought RS subframes and they were different? I'll have to go back and read again, but thought you took measurements that showed the difference. Or were those RSR subframes?

Looking at PET, the 03-05 GT3 rear subframes are 99633105590 and 99633105690; the GT3RS street version (option code M004) are 99633105192 and 99633105292. Option code M005 is RS Racing Version, which I assume is RSR.. I haven't looked for those PNs yet.

Front subframes are the same across GT2, GT3, TT, GT3RS.

DesmoSD

Whoa, this just happened to another person during this track day.

https://rennlist.com/forums/gt4/1030...n-learned.html

AudiOn19s

It's going to happen on any car with aluminum uprights that's had the caliper removed enough times. The aluminum threads just get weak. I was meticulous with fresh bolts and proper torque on my car and still had it happen.

The timesert kit isn't as cheap as you'd think it would be, but it's a well thought out solution and a fairly easy fix. You really want to pull the uprights, make some sort of jig and drill them in a press if at all possible, but other than that the process is rather easy.

AutoQuest Motorsports

Get Time Serts installed for the caliper bolts, this has happened before many times unfortunately. We do it on all our cars seeing track use.

rbahr

This is good advice - will be doing timecerts this winter...

Thanks

Ray

b8_rdc

Not sure if too late, but I have a set of 350mm six piston calipers for the 996 for sale.

Gadsby

Weld, drill and tap, and face boss, then use studs, machine shop should be able to handle this quickly