If anybody here has some 996 stock turbo front calipers or 6 piston 350mm calipers, here is what I am looking for. Measurements edge to edge distance between caliper mounting holes. A picture with a ruler for reference would be perfect. Can also be a picture of a front turbo spindle or GT3. Everybody posts mounting hole distances but does not mention if they are measuring edge to edge or center to center. The correct way would be center to center. But eyeballing center is not always precise.

 

146mm center to center if I recall correctly. I can confirm that on Friday as I have an extra hub at the shop.

 

Just a big picture of why I need this for those interested. I picked up two 997 C2S uprights that have the same steering geometry and shock mounting diameter as the 996GT2/3. The 997C2S version has had a few upgrades that in my research should allow for a way to use Gt3 and other RWD suspensions without a spacer sleeve, use standard 997 turbo brake rotors versus the more expensive less available GT2/3 rotor selection. The upright will also be more available. And also, the 997 C2S upright is lightened compared to the GT3. And seeing the 997 C2S uses the 996 turbo calipers the 997 turbo calipers will also bolt right up.

The spindles I received were pulled off a C2S, but when I measured the caliper holes they measure at 142mm to the outer hole edges and 130mm center to center. So I need to be sure they did not accidentally send a standard C2 spindle instead.

 

I'm not familiar with the C2S upright but I would venture a guess that the GT2/3 upright is designed with a lower pick up on the tie rod to correct for bump steer of the lower ride height on the GT3. I know the GT3 upright has a lower pickup that the stock TT upright. This is something I would not overlook... The GT3 uprights are not that expensive at around $500 each is I recall...

 

I think you may be mistaking the straight GT3/2 street uprights with the RSR uprights. The 997 C2s uprights locate the tie rod pickoff in the same height location relative to center of wheel rotation and the lower control arm as the 996 GT3 street, GT2 and cup. The RSR uses an upright that shifts the whole wheel bearing up something like an inch relative to the tierod attach point and lower control arm mount holes. They are basically drop arms. Below is a picture of the 997 C2S upright.

 

How are you going to solve the ABS sensor issue? 997 uses a completely different sensor and they are not interchangeable.

And the answer to your question is 142mm center to center.

 

I am working on that. Several options for that to solve the issue. I am currently researching if the sensors electrically put out the same signal. If so it is just a connector change. If not then I will have to modifiy the upright for the 996 sensor. Which neither is difficult.

On another note, their are numerous reasons to use the c2s upright over the gt2/3 upright for those not in the know. One is availability. The other is brake rotor and caliper options being more favorable for the 997 C2S upright. And the third being the steering geometry and attach points between the 997 C2S is the same as the 996 GT uprights. The two downsides is solving ABS compatibility difference as mentioned above and you still need an adapter sleeve for the skinnier cup and GT suspension solutions. Both of which are not that difficult.

 

VAG,
Please continue to post - I am in the same boat here. Very interested in seeing your results.

 

Well here are the two hiccups so far.

The shock diameter on the 997 c2s upright matches the turbo shock diameter. So for my sachs cup shocks I have to run a shim. Super easy to May though. I just ran a piece of .060 aluminum through a rolling tool to for it into a sleeve. Works like a charm.

The second challenge is the ABS sensor. The 996 turbo uses a magnetic passive hall type sensor. This sensor reads the little bumps in the hub tension bolt which creates an AC frequency equivalent to wheel speed. Super simple. The 997 switch of to an active type sensor that senses off of the wheel bearings for that AC signal. So now I am just looking to modify the upright to accept the 996 sensor. ABS systems can be one of those systems that people get iffy tampering with. But the sensors are very straight forward.

The million dollar question people ask is "why are you going through all this? Just get GT2/3 uprights and be done!!!"

While this is true, the uprights are not easy to get. They are easy to order. But then you get to wait for the part from Germany. And the salvage yards seem to not have them.

Also there is the benefit of brake options. Using a 997 upright means you can run the following factory brake setups without running rotor shims or non-factory caliper adapters: 996TT/ 997s, 380mm GT3(997), 997turbo 350mm and 997 turbo ceramic. The 380mm factory ceramics use a factory caliper adapter. This can be ordered from the dealership.

Basically the 996 GT3 street and the 997C2S run the same front spindle geometry but with the same 996 shock diameter and same brake offset as factory 996 turbo.

 

theres some gt3 uprights for sale on r/l

 

Link? I can't find them.

 

First post here!

Interesting subject, I was also looking into this when I did the RWD conversion but the ABS problem scared me away and eventually I found all the parts I needed from a GT3 instead.


What I am really interested in now is what you are going to do about the rear shocks and the twisting movement you will get from having the attachment of the drop links on the shock at the same time as you have spherical bearings in the lower eyelet.

I have the same setup but with Bilstein MDS and I had to fabricate some plastic spacers to stop the shock from twisting when loaded by the sway bar. It doesn't look good but it serves the purpose...

 

Well, the Cup and GT2/3 street rears have a threaded sway drop link bracket. So this means you can clock that to be lined with the drop link perfectly. This will mean any force on the link if the bracket is properly align should not induce any twist. Only linear force. However with stock 996tt shocks and some other coilovers have a fixed drop link bracket which if couples with a spherical lower mount point can cause twisting.

As for the front ABS, remounting the sensors is not a precision or sensitive thing. You have to be mindful of the clocking of the mounting tab relative to relict or notches and distance. The rest is simple.

 

http://rennlist.com/forums/parts-mar...ipers-etc.html

 

Those look like 996 Cup shocks. I assume you know this already but the rear shocks will not work on a 996TT. Even if they did, they are valved for 240/260 N/M springs which are not exact street rates.