Martin996rsr

Here is a link to Martin Hill's build thread of his 996 C4 that he's rebuilding into something that's basically going to be a GT3. He's using Cayenne calipers front and rear. The fronts are machined. Discs are, I think, 350x34 front and 330x28 rear.

TheChunkNorris

Depending on which caliper, the 350mm set up are 18z’s which I have on my Touareg. They were standard on the Hybrid and V10 diesel T2 models.

TheUnscented

Cayenne TT caliper is massive & really heavy. You lose the ability to quick change pads. The caliper & the 390mm rotor seem like overkill on a vehicle that weighs 2000lbs less.

ed750duc

Any new info on rear brake upgrade ?

Martin996rsr

Sorry, no new info. I'm dealing with a serious medical condition and am undergoing successive surgeries to correct it, so the brake work regularly has to be put on the back burner. I've pursued several different rear brake ideas and none of them have borne fruit in terms of something that I would be happy for someone to put on their car. I have however deveoped an Arduino based brake temperature monitoring and logging device which also displays the current and highest temperature from the current session. Something that was immediately revealed was that even on standard rear discs, a very hard driven car never gets the rears anywhere close to the temperatures experienced on the front. Although this was somewhat predictable, I'm an obbessive when it comes to empirical data, so it was great to get to find out exactly what was going on. This means that if you're after a brake upgrade for the rear for performance reasons then you needn't bother, the car doesn't need it. I know there will be a few people who want a larger rear rotor for aesthetic reasons, and I may produce a few. However, if you want a set in a hurry then I recommend Girodiscs, they really are very good.

hatchetf15

Get well soon, Martin.

work_truck

hope you come back out the other side in great health!

Martin996rsr

Thanks guys, you're very kind. The last surgery was a month ago and has yielded some good improvements, but I have two more major procedures to look forward to over the next 18 months which will really bloody hurt and I'm steeling myself in anticipation. I'm also working on a shifter design on my good days which I'll share on here and some of you guys might like.

hardtailer

I wish you all the best for your health, that the outcome shall be what you want it to be.

Interested what sort of temp. sensor you chose.
Can you measure the heat in the disk and little of the heat it radiates if you see what I mean?

TheChunkNorris

Best wishes Martin. Let us know if we can help in any way.

Martin996rsr

Thanks Hardtailer and ChunkNorris. I used infra red sensors (MLX90614, for the deeply technically minded) that are positioned to take an average of the swept area in the coolest part of the arc (shortly before the disc is swept by the pads). This is because the sensors I used had a maximum reading capability of 380C, and you can easily get the disc significantly hotter than that immediately after it's gone through the pads under very hard use. For my application though, the absolute temperatures reached by the disc were of far less importance than the relative temperatures between front and back, and front with stock discs vs front with my kit on, as well as the time taken for heat to dissipate. I'm hoping to put together a Youtube video when I'm well enough to run through this test rig to demostrate my development process.

uncle_sam

Hi @Martin996rsr : Have a friend who’s offering his pre-owned 330/330 (F/R) rotors from his 997.2 C2S. Can these rotors fit my 996 C2 calipers given that the 997S rotors are thicker than stock C2: Front 34mm vs 28 in 996, Rear 28mm vs 24 in 996? Are the stock 996 C2 calipers wide enough to fit the pads with rotors of 997S?

De Jeeper

Nope. U would need to somehow adapt the calipers too. Not worth the effort.

Martin996rsr

De Jeeper is correct.
The stock 996 C2 rotors are 28mm thick and so the calipers won't fit around the 330x34mm front 997 C2S rotors. It's similar on the rear in that the stock 996 rotors are 26mm and the 997 rotors are 28mm. However, you can use the rear 997 rotors on the front of the 996. I use 330mm 997 rear rotors on the front of my 996 as I have 17" wheels that mean I can't fit the 350mm rotors as used by the starter of this thread, but the kit to make it happen is essentially the same for both rotor sizes.

Atgani

I think the stock 996 C2 rear rotors are 24mm thick Martin, not 26mm. As ever, happy to be corrected though.