Updated rear calipers

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May 5, 2003 | 05:57 PM

#16

Bill Verburg

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Jeff is giving you some good advice. You want the stock 964(30/28) C2(RSA) rear calipers to match the C2 front(40/36)

I disagree about the p/v(I wonder if Jeff got some 30/34 993 rears by mistake? that would account for the need for a stronger p/v which he used). The correct p/v for the 40/36 & 30/28 setup is the factory 55bar(replacing the existing 45bar) Some even like this setup w/o a p/v though it's a bit on the aggressive side.

If you do as TT did(front 44/36 993calipers) then you do need the matching rear 30/34 993 calipers.

May 5, 2003 | 08:03 PM

#17

Bill Gregory

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<blockquote>quote:<hr />I disagree about the p/v<hr /></blockquote>My experience lines up with Bill's comments. I found going from the 55 bar to the Turbo 60 bar provided more stability in braking at the track, using the stock 93 C2 brake setup. I know others who, when upgrading their 1990 rear brakes to the C4/92+ C2 rear brakes also went to the 60 bar bias valve, which worked for them.

May 5, 2003 | 09:36 PM

#18

MB965

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Bills,

Where can I get the proportioning valve pressure rating to Porsche part number listing?

Thanks,

Mike Behrman

May 6, 2003 | 06:15 AM

#19

Jeff Curtis

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From: Virginia Beach, Va.

Ya know, and I seem to remember this, amazing how my mind fades, but that does ring a bell or two...I believe I did acquire a pair of calipers with 30mm/34mm pistons and figured out later that they were bigger than the standard rear calipers on a '92 and above 964??

I'm going to double check that now, because that would make sense being that they were "too much" when I installed them and still had my factory 45bar bias valve for a '91.

Before I regurgitate my findings on the "art of valve biasing" again, I'd better double-check...thanks for the kind reminder.

FYI, I currently have a 60bar valve (thanks to Cupcar) with my Big Reds up front...works well...Cupcar suggested going with NONE, but if I do in fact have the larger calipers, that's why I'm content with a 60bar limiter!

Mike, I have the info. at home, and Cupcar showed me how to find it on the PET CD, it's in a section for the 928 or something??

I forget, so many bolts, clamps, hoses and fittings on these damned cars! <img border="0" alt="[hiha]" title="" src="graemlins/roflmao.gif" />

May 6, 2003 | 02:09 PM

#20

Dave R.

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So it appears the 993 rear calipers will bolt into the rear of a 964.

Will the 993 fronts bolt in as replacements for the 964 fronts if the 964 front rotor is swapped for a 993 front rotor?

May 6, 2003 | 05:28 PM

#21

Bill Gregory

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<blockquote>quote:<hr />Will the 993 fronts bolt in as replacements for the 964 fronts if the 964 front rotor is swapped for a 993 front rotor?<hr /></blockquote>In order to bolt a 993 caliper onto the stock 964 non-Turbo front, you need a set of adaptors which run around $150-$275. FVD, TRG, and most other sources offering Porsche brakes offer them (except possibly the dealer, unless you want to buy the Turbo hub).

If you put 993 calipers on the front, you need to use the 928 86-91 S4 rotor, which are also used on the 944T. You can also use the 968 M030 rotor, however they are pricey (cast-in hole rotors). 993 rotors are the wrong offset for use on a 964.

If you have 16" wheels, you may need a spacer for the wheel to clear the 993 caliper. 1/8" works on mine with the 92+ 16" cup wheels. Another friend also has to use a spacer with his Design 90's.

If you upgrade the front, you might consider upgrading the rear, to keep things in better balance. Also any brake upgrade, front or front and rear, may require a change to the factory bias valve.

May 6, 2003 | 06:15 PM

#22

Dave R.

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From: Seattle

Bill G.,

Thanks!

I assume that with only a 1/8" spacer, you did not find it necessary to install longer wheel studs.

-Dave

May 6, 2003 | 07:02 PM

#23

Bill Gregory

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<blockquote>quote:<hr />I assume that with only a 1/8" spacer, you did not find it necessary to install longer wheel studs.<hr /></blockquote>Dave,

I didn't install longer wheel studs. A 1/8" spacer is probably at the extreme of what you'd want to do without longer studs, however.