Confused over M030 Spec for S2 Rear Brakes

[beamishnz]

I'm converting my S2 to M030 spec and always thought that the rear Brembo calipers specs were common to the S2, S2 M030 and 951 Turbo/951S.

PET seems to confirm this but is listing a different brake pad for the calipers for the Turbo and S2 M030 cars.

I'm wondering if this is anything to do with matching up with the bigger front Brembo's on these cars.

... or am I reading the PET wrong???

[guru944]

beamishnz:

S2 and Turbo are same rotors but calipers slightly different. Remember 86 turbo has different offset 23mm not 52mm on later vehicles.

Hope this helps. Later...

[beamishnz]

Sorry .. still confused. Are you saying the rear offset was 30mm different .... what was that about? Also not quite sure what you mean by offset i the context of the rear. Apologies if I'm being slow on the uptake

[Techno Duck]

I would guess it is just a different pad compound to account for the larger front caliper. Its an easy way to adjust brake bias.

The rear calipers otherwise are exactly the same between the Turbo, Turbo S, M030 S2 and M030 968. Well technically you may get differences in the type of seal used depending on when the caliper was made, but the calipers and pistons are all the same size.

[beamishnz]

Originally Posted by Techno Duck

I would guess it is just a different pad compound to account for the larger front caliper. Its an easy way to adjust brake bias.

The rear calipers otherwise are exactly the same between the Turbo, Turbo S, M030 S2 and M030 968. Well technically you may get differences in the type of seal used depending on when the caliper was made, but the calipers and pistons are all the same size.

Those were my thoughts too. I've always beleived the calipers and rotors were the same on 951, S2 and S2 M030. The only 2 caliper options were with/without scraper ring the later cars had a slightly different piston seal design. Interestingly the later S2's and 951's - 90 onwards had the 5/33 brake bias valve (previously 5/18) which gave a greater rear bias.

Quote Kevin Gross 944 FAQ: "With the 944S, Porsche introduced a 33/5 proportioning valve. For the 944 Turbo and 944S2, Porsche originally used an 18/5 proportioning valve, then later superseded it to the same 33/5 valve used on the 944S and some 928-series models."

Another good trivia point is that the M030 pads are cheaper than the stock S2 pads ... go figure that ... 965 pre fi vs 951 prefix part #

[flash968]

more interestingly, they went back to the 5/18 on the 968. many of us have swapped that out for the 5/33, and gained much more balanced braking. that's where the cars need it, not in the front.

[beamishnz]

Woke up during the NZ night thinking ... if it was just a change in friction pad material why would it be a completely different number ..... Still curious??

965.352.939.04 = M030
951.351.939.08 = Stock S2

[beamishnz]

Originally Posted by flash968

more interestingly, they went back to the 5/18 on the 968. many of us have swapped that out for the 5/33, and gained much more balanced braking. that's where the cars need it, not in the front.

Interesting re 968 ... that is strange. My understanding was that they went to 5/18 spec for a couple of years after lawsuit re tail happy 911's ... then realised it was an over reaction. Same time that they went from 18mm rear swaybars on the 944S to 16mm swaybars on the S2