333pg333

If anyone is interested I have a brand new pair of Cayenne rotors that I'm not using. They are in the US and are available for sale. I'll sell them for 15% off what I paid for them...just don't have that price to hand as I write.

Voith

How do you set proportion valves with 6 pot calipers?

333pg333

With Gloves.

Duke

Yes. Silk gloves only for 6 piston calipers.

DVC

marc a- thanks for your post on setting the drive shaft and notching the coupler.

Voith

Gloves are for pussies. Serbians have a great saying for people that use gloves while working on car: Jebao bi, a da ne uđe.

I wanted to know how is the proportion of force managed with upgraded calipers, since they obviously change front/rear force distribution. Is it enough to just use GT3 proportion valve for front calipers (assuming you leave rear stock), or is it necessary to change anything else?

Olli Snellman

With GT3/GT2 front & GT3 rear calipers original 951 master cylinder & p-valve works just fine. We did these conversions for 951's first time about 5-6 years ago. Lot's of info with pictures can be found here.

333pg333

We have a saying down here. "Ubber n'tang wibber fist". It means people who laugh at others wearing gloves while working on cars are probably secret glove wearers when the Sun goes down.

As for proportioning valves etc...well there are plenty of people who think you should increase m/c size when going up in Caliper size...but some actually suggest decreasing...take your pick. I wouldn't be trying a GT3 valve unless you put the same rear calipers in....and install 9 bags of cement in the rear to simulate an engine back there.

Voith

Jebao bi, a da ne uđe. means something like: one would like to swim but without getting wet.

Voith

Thanks. I would maybe use just the front ones, since I don't want to mess around with handbrake.

Olli Snellman

We developed about 6 years a go a kit which allows to use GT3 rear caliper & rotor and still have a working handbrake.

marc a

Hey Olli,

I first looked at the Cayenne 6 pots, but the pad selection did not include race compounds so that is what turned me to the GT3 calipers.


_____________________
'00 Audi TT
'99 996 (Wife's ride)
'86 951 LS1 (C-2)
'77 911 3.2 (C-1) Gone but not forgotten.
3.2 Conversion and 915 Rebuild Home Page
The 958 Conversion
958 Track Video
PCA National Registry of Instructors

marc a

You are very welcome. I am glad someone was able to benefit from my unfortunate experience. Very nice conversion on your part btw. Have you gotten out on the track yet?

_____________________
'00 Audi TT
'99 996 (Wife's ride)
'86 951 LS1 (C-2)
'77 911 3.2 (C-1) Gone but not forgotten.
3.2 Conversion and 915 Rebuild Home Page
The 958 Conversion
958 Track Video
PCA National Registry of Instructors

marc a

Here are the piston area numbers and why the OE 951 M/C works with the GT3 front and rear calipers.

Non S piston size: 36/38 front, 28/30 rear. Front/Rear ratio 62/38. Total piston area: 13898.44 sq/mm
GT3 size: 28/32/38 front, 28/30 rear. Front/Rear ratio 66/34. Total piston area:15506.92 sq/mm.
S calipers: 36/44, 28/30, 66/34, 15444.12

The S master and the non S master are the same size, but have a different P/V on the master. So the capacity of the 951 M/C is just fine for the GT3 upgrade, but as pointed out above, there would be a bias problem (although slight) due to the rear end weight of the GT3.

I have a dash mounted P/V so a few adjustments after the brakes warm up and I'll be good to go.

Marc
_____________________
'00 Audi TT
'99 996 (Wife's ride)
'86 951 LS1 (C-2)
'77 911 3.2 (C-1) Gone but not forgotten.
3.2 Conversion and 915 Rebuild Home Page
The 958 Conversion
958 Track Video
PCA National Registry of Instructors

Olli Snellman

Yes, that's one of the problems. Found out it is possible to have a custom made pads with race compound locally. They have both Ferodo & Pagid compounds available.