996 TT/GT3 4 Pot Calipers

[Error404]

Seems a bit ghetto if you ask me. I could understand it if they were cheap but they are not far off the price of a pair of AP rotors

[twoqu]

Seems a bit ghetto if you ask me. I could understand it if they were cheap but they are not far off the price of a pair of AP rotors

Certaintly OE ones are expensive but the decent quality aftermarket ones are reasonable.
I think this pic shows how it is done!

[Mcstiff]

Here are my 322 x 32mm rotors:



They stop quite well (even with fewer pistons)!

The hats and brackets were made a long time ago by "BillZCat1" http://www.audiworld.com/forums/audi.../#post18478018

[jade]

This is the only pic I could find of those disc without the bells:

There no recess, I have a few sets here, 996,993,RS2 bells and 330 x 34mm and 322 x 32mm discs

[twoqu]

The companies that use the 996/7 Porsche 1 piece discs as a basis for their 2 piece conversions machine the recess so that the bell/hat sits within the centre of the disc rather than on top of the annulus. Hopefully this picture makes it clearer.
What we don't know is if this is only possible with OE discs.

[Rusty]

Surely the machining costs mean that you might as well get some 2 piece read discs off the shelf, if that's the route you want to take?

AP do 332 & 343x32 discs.

[jade]

The companies that use the 996/7 Porsche 1 piece discs as a basis for their 2 piece conversions machine the recess so that the bell/hat sits within the centre of the disc rather than on top of the annulus. Hopefully this picture makes it clearer.
What we don't know is if this is only possible with OE discs.

on the 993 dics this done but not on the 996 ones there is nothing to center the hat

[twoqu]

Surely the machining costs mean that you might as well get some 2 piece read discs off the shelf, if that's the route you want to take?

AP do 332 & 343x32 discs.

There isn't any right or wrong way. I am just pointing out what other companies have used with these calipers and the matching discs is not a bad idea subject of course to the cost!
Most aftermarket 2 piece discs do not have a large enough annulus for the GT3 pad. It looks as though Alex has found one as mentioned in a previous thread although I fear they may be too large and have the same pad issues that others had had when trying to cram the largest discs possible.
From the cost/benefit perspective the choice is obvious.
Ideally it would have been nice to be able to get replacements of the shelf without any machining but that would mean sticking to an OE disc. Its the same issue with 2 piece as its not unknown for manufacturers to discontinue products or have long lead times and you are sat there with your bespoke bells and brackets!

[twoqu]

Some more useless data stolen from other sources, which may be useful (or not).
The folowing are comparsion between the 429/430 (996T/GT3) and the 425/426 (996/Boxster S).
Weight: 3090gms vs 2660gms.
Dimensions: 262x157x91mm vs 247X155x92mm (LXWXH)
Piston size: 44/36 vs 40/36
Mounting spacing: 142mm vs 130mm (C to C)
Pads: 136x61mm vs 118.5x61mm (WxD)

[Gazmitchell]

So further to my earlier posts I've fitted caliper and bracket onto the hub and pic show 996t with standard size discs . 276mm . If there was a disc with same hat height but larger disc it would do the job and measuring from centre to edge of pads in caliper it's around 30mm so that would total a disc of around 330..

[Gazmitchell]

So was going to use PCD adapters but this will push the face out to around 70mm from face of rear pad. Whereas it is around 48mm as is , so just trying to suss out so I know which PCD 17" to fit.

[montyrs2]

Alex would you be prepared to share the CAD for the front hub? I've got some bigger brakes going on but not Porsche based.

[twoqu]

I don't understand why you keep mentioning PCD adaptors. Basically you just want the disc to sit on the hub.
If those brackets are for 334mm discs then its no surprise that your measurements stack up to that dimension.
Its going to be a lot easier to make a bracket to suit a disc than find a disc to suit those brackets on our vehicles. Which is why you need to sort the disc out first. Unfortunately there are no ideal solutions. It's either OE ones which some consider either too thin in 30mm width or too large in diameter and need machining. The Merc discs sort of sits between those two variables but also need the centre machined out slightly.
The OE discs also position the disc further inboard whereas the Merc disc is further outboard!

[Gazmitchell]

I don't understand why you keep mentioning PCD adaptors. Basically you just want the disc to sit on the hub.
If those brackets are for 334mm discs then its no surprise that your measurements stack up to that dimension.
Its going to be a lot easier to make a bracket to suit a disc than find a disc to suit those brackets on our vehicles. Which is why you need to sort the disc out first. Unfortunately there are no ideal solutions. It's either OE ones which some consider either too thin in 30mm width or too large in diameter and need machining. The Merc discs sort of sits between those two variables but also need the centre machined out slightly.
The OE discs also position the disc further inboard whereas the Merc disc is further outboard!

Was considering PCD change as everything with correct dia seems 5 x100 , and the thickness of the adapter would replace the 15mm spacers already on my 16" wheels but agree as you say better on the hub . I have found a set of 334 x 32 5 x112 from Germany which have same dimensions heights and bore as discs on the car so hopefully sorted.

[Gazmitchell]

So I've now fitted the 996 TT calipers under 17 " with the 334 x 32 discs. Had to have the centre bore milled out slightly as said above and a minor adjustment on the bracket needed. But all bolted on and bled . Fit nice under 17 s with spacers and longer bolts. Bought a set of 225 cross contact so will see how these tyres fair. Next up rear brakes to B7 s4 spec as understand this is a bolt on upgrade with the 300 discs .