what rotor with 951 calipers on late ali arms

[zen]

these are 944S arms. i believe a 944S ran NA calipers though didn't it? bolt spacing is the same for the 951 calipers (94mm) though. i am trying to determine which rotors i should run and if i will need to do any caliper spacing.

thought the '87 and up 951s ran the same arms and therefore 951 rotors for the late arms are probably the right answer, but i am out of time for more mistakes and hoping someone here can confirm.

any ideas?

[zen]

anyone? someone has to know this. my PET isn't working and haven't found a definitive answer on the web yet. talked with a a$$hole at vertex auto that was useless. it is a shame because the last guy i talked to there was great.

[boygenius]

You can borrow my rotors if you need them, I can also send you up the rear rebuilt calipers.

[zen]

here is what i have gotten out of the shop manual so far:

944S used 289x20 discs
951/944S2 used 299x24
(these are both early year numbers)

what i can't get out of it is which year had the big pot/hat that these 87 944S arms use due to the hub size (to accomidate ABS).

question...if i have the arms that normally use the small discs, but still have the correct caliper bolt spacing of 94mm, is the caliper going to be sitting too low to allow the larger 951 discs on? should i use the NA discs with 951 calipers? it is substantially thinner. the wear limit on the 299x24mm disc is 22.6mm. not sure how well the caliper pots can push down to a 20mm disc especially after wear. perhaps i should have gotten late turbo arms and not 944S.

seems like this should be a common upgrade path for the 944S guys though.

[boygenius]

My trailing arms have the 951 prefix on their part number so I would assume that they are the same as the turbo. But there is also a 302 prefix number on the trailing arms. I think though that the N/A and turbo arms are the same and that the onlly difference is the caliper and the rotor. I'm not really sure though. Let me know if you need my N/A parts to get you to dyno day.

[zen]

you are correct that the arm is the same and the brakes are different. still don't know about the diameter clearance for the larger rotor, but did find out that the swap is straight forward and caliper spacing is required (great , more custom work on a short schedule). info is here .

[boygenius]

Looks like you only need the rotors + calipers + the spacers. I wonder if the spacers are factory???

[boygenius]

I think the spacers are nothing more than washers. Does anybody have a 1987 and later 951 that could take a look under their car. See what the caliper spacers look like. :idea:

[zen]

looks that way. he is looking up part number and dimensions for me. didn't realize they ever did that from the factory.

[boygenius]

If it's just some washers you could just go to your local hardware store, Or shell out the money for the factory ones. I always like using factory parts, I even ordered the porsche lock washers and bolts for my sway bar.

...if you use 951 calipers then you want to have 951 rotors
...if you use 944 calipers then you want to have 944 rotors

[zen]

thanks guys. got some 951 rotors and used 3mm spacer on all bolts and rear brakes are in. just have to get my right front on when i get a bearing seal and brakes will be done sans the e-brake. have to get dave up to do some welding and we are going to take care of that.