ANother brake caliper query

[Randy Webb]

I'm not ready to upgrade (or should it be "downgrade") my brakes yet, but being inspired by the plethora of brake threads right now...

Jim Calzia (of super light 911 fame) put 944T (i.e. 951) REAR calipers all the way around on his race car (to save wt.). He told me that the calipers worked great and that he had no F/R balance problems (he also did _not_ use the late model proportioning vlave on his car.

Bill V. or others -- what do you think of this idea? It would be lighter than the Carrera calipers currently on my (modified) '73 and look better to boot. Mine is a street car, so overheating shouldn't be any worse than on JC's race car. I realize that the total % change wouldn't be that great (because of the rotors, wheels and tires) but a lb. or two would be nice, as would the pretty red color....

[Bill Verburg]

Randy, I suspect that you misunderstood or misinterpreted what he did. having the exact same calipers at each wheel is a bad idea.

What he most likely did/said was that he used the same size caliper at all 4 wheels.

If you take a good look at my brake page you will see that there are only 3 sizes of the Brembo calipers used on all 944/951/964/993


Each comes in 3 flavors except the unique Big Red

What Jim most likely did was use the small 4 piston caliper at all 4 corners. The fronts use 40/36 and the rears 30/28. I have that setup as one of the configurations that I have been very happy with. And No ap/v wouldn't be used w/ that setup.

The small caliper weighs ~6.5# w/o pads, ~8# w/ pads this is what a 911 M w/ pads weighs but has 63% more pad area and more importantly utilizes a much bigger rotor.

[bell]

good info bill

[Randy Webb]

Hmmm, maybe so. I thought he told me that on the phone or inan Email but I don't have a saved Email from him stating exactly that. He does list the wts. of the calipers in his table differently -- 6 lbs. for one and 7 lbs. for the other one (at: http://early911sregistry.org/jcalziaweights-3.htm).

Does the 6 and 7 lb wt.s soud about right for R vs. F calipers? Jim is a petrologist and he confirmed my guess that he took most of the wts. on a highly accurate scale.

[lateapex911]

Bill, that is a staggering peice of work!

I tried to wade through it, but perhaps you can give me direction. I have a '73E that was originally a euro car. It is coming out of storage and needs some brake reworking. Why be simple and just rebuild when we can make it bettter!??

So, what is an appropriate step up for a 2300 lb car with about 200 horse. It will see DE events, but I have a dedicated race car for that kind of fun. I would love to keep the ability to run the original 15" Fuchs. Suggestions??

Thanks!

[Bill Verburg]

Randy, Please read my post. Yes, it does sound right. The 6.5# in my post above is the weight of a 965 rear which is as wide as the 964 front(Jims 7#) but has slightly smaller pistons and is wider than a 964 rear(Jims 6#) but has bigger pistons.

For small stuff like calipers/pads I use a postal scale. Its pretty darn accurate.

[Bill Verburg]

lateapex911, for a light car like that stock A or S and M rears should be good.

A cheap upgrade that would bump you to prepared(or up 1 class)
is a set of '84-'89 CArrera front calipers and rotors with no other changes.

After that it gets expensive.

The rule of thumb that I use is under ~2300 # and under 210hp(think 2.7RS) stock is ok, increase one of those and upgrades are desireable increase both and upgrades are necessary. What upgrade depends on the magnitude of the increase, but if you model after the factory race cars you won't go too far wrong.

[lateapex911]

Thanks, Bill. I agree...the Civics I see running around with 6 pot brembos crack me up!

I take it that the Carrera parts should bolt right up?? And fit in the 15" Fuchs?? Great news!

[Bill Verburg]

yes and yes

more selection info here

[lateapex911]

Excellent! Thanks much! My path is clear....

[Randy Webb]

Let me ask a slightly different question, Bill:

For street use on an early car that already has Carrera struts/calipers installed, what is the best F/R caliper combo to use -- esp. if one is mor concerned about weight?

[Bill Verburg]

For street use on an early car that already has Carrera struts/calipers installed, what is the best F/R caliper combo to use -- esp. if one is mor concerned about weight?

S front calipers, M rear calipers on drilled stock rotors, use Axxix metal master pads. You can save more/additional weight by being selective when choosing tires.

Don't worry about cracking because in street use it'll never happen.

[Randy Webb]

Thanks, Bill.