944T calipers on my 911

[Bill Verburg]

Just to keep things in balance here are a couple of a Brembo candidates
280x25.4

280x28

[absinthe]

perfect

[Bill Verburg]

The hats are also very simple as they need to be flat w/no o/s
here is a pic of a non-floating hat the inner bolts connect to the hub, the small outer bolts connect the rotor to the hat


The 964/944t calipers would be good matches for the 28mm versions of the above rotors.

[Colby]

If you use 944t calipers with the above rotors, would you have to mount them using axial/radial adaptors?

Colby

[jwetering]

I'm not 100% sure what you mean - but I'll go ahead and answer no. My wrench had the calipers modified. He filled the old holes, and milled new holes so the calipers mounted up to the 911 strut. I don't think he had to shim them to bring them out or in, and he used 944T rotors and there was no need to move the caliper closer to or furher away from the centre.


Funny you should ressurect my 100 year old post just now. I ended up solving my spongy brake pedal (the original reason for my post) problem today. It turns out that I'd lowered my brake pedal too far so many years ago. I just raised the pedal back up and now it feels hard like rock.

Cheerio

Porsche (just in case this is the 500Kth post).

[Bill Verburg]

Here's a link to VCI's page for the 964/944t to 911 mod. They want $550 for the caliper mods and adaptors at the front. Chris Streit is using this kit and at last report was very pleased w/ it.

VCI link

The AP or Brembo rotors shown above would be used w/o machining in the 280x28mm size. The 290 or larger sizes would require machining and adaptors.

The beauty of radial mounts is that rotors of different diameters can be swapped in/out by swapping adaptors.

VCI also likes to machine radial mounts into the rear calipers. I don't think that this is necessary but do understand their perspective.

[Randy Webb]

"It's not the calipers that are heavy it's the rotors"

And, in fact, the rotors are the heaviest component of all re unsprung wt. I posted a spreadsheet analysis of that on one of these threads a while ago.

We really need a lighter rotor material. The Al matrix stuff apparently did not work, PAG doesn't seem to have the bugs out of itws ceramic technology etiher. I heard a rumor about Ti matrix rotors, but that all -- just a rumor. BTW, tires are heavy too...

[Kahuna]

Heavy rotors are good heat sinks, Bill's description above is perfect

The benefit of bigger brakes is almost entirely in the larger rotors. The design goal should be to have the smallest rotors/pads that last for the entire duration of an event but no longer!

[ChrisBennet]

Originally posted by Colby
Most ppl will say nothing is too be gained by upgrading to 944T calipers if you don't also upgrade to 930 rotors. However, this was my rationale (even if incorrect): 1) the 944t calipers are much lighter resulting in less unsprung weight, 2) the 944t calipers have more clamping power, 3) the 944t brake pads have greater surface area allowing more dissipation of heat.

I don't think that last part sounds right. Does the pad actually dissapates heat? I think that's the rotors job. The pad doesn't really have much exposed surface area. I would think that if you increased the pad area you would decrease the rotor area exposed to cooling air.
-Chris

[Bill Verburg]

The pads only dissapate heat in the sense that the larger area a pad has, the more the heat energy is spread out. This alleviates the thermal load per in²

[Randy Webb]

"Heavy rotors are good heat sinks,..."

- Yes -- that's why we need a new material -- the best would be for the rotor to _transfer_ heat not to act as a heat sink.

[Bill Verburg]

the best would be for the rotor to _transfer_ heat

Where do you suggest it be transfered to?

Just for you Randy, a liquid cooled caliper for use on a nice light 28x315mm 6kg rotor

[Randy Webb]

Well, golly gee! Now how about a heat pump??
BTW, I note you used the term "liquid" not "water" -- what is the owrking fluid?

And I suggest it be transferred to the air. As you prob'ly know a hheat sink only works long enough to absorb a thermal transient -- after that it will necessarily function as to transfer heat.

[CHP-POR]

Bill,

What reference points are used for determining the size of the adaptors so that they will position the calipers properly for the diameter of rotor chosen?

Similarly, for the "axial" (?) positioning of the caliper so it is positioned over the center of the rotor?

Maybe I missed it in earlier threads, but isn't a larger diameter rotor a significant contributor to more effective braking because of a longer moment arm?

I acquired some Brembo 944 caliipers some time back that I was told were turbo, but after measuring (what's sticking out past the the dust boots) I think I got something else based on the varieties you have listed.

The part numbers are 20.4691.01/20.4692.00; I'm getting 33/36 mm. Are these possibly rears?

Thanks for posting the pics btw, they really are a big help.

Is the small or the large piston supposed to lead?

[MotoSook]

Originally posted by Bill Verburg
VCI also likes to machine radial mounts into the rear calipers. I don't think that this is necessary but do understand their perspective.

I hope Bill isn't on vacation or ignoring this thread because it's old...

Bill,

Can you elaborate on the 944T rears in back...I don't have one in hand (yet). Is the mounting hole spacing 3 inches? And will the unmodified 944T rear caliper bolt onto a 911 (say 76) while using a 930 rear rotor to retain e-brakes? (It's too cold to head over it to Streit's garage for measurement!)



Thanks,

[MotoSook]

Originally posted by Colby
The rear caliper also won't fit over the thick 930 rotor, and a few places need to be ground down just a little. Not a big deal.

Colby, can you elaborate on the above?

Thanks,

[MotoSook]

OK...it's starting to come together..the 944T rear calipers are not wide enough for the 930 rotor, so one has to ground or maching them a bit wider.... (read Bill's "5-path to Braking Wisdom", good reading Bill!).

Yet! I'm still foggy on the attachment of the 944 rear caliper to the rear of our cars... oh man I wish the UPS truck was in the driveway now!!!!

[MotoSook]

Originally posted by jwetering
My wrench had the calipers modified. He filled the old holes, and milled new holes so the calipers mounted up to the 911 strut. I don't think he had to shim them to bring them out or in, and he used 944T rotors and there was no need to move the caliper closer to or furher away from the centre.

Jasper ( or Bill):

By not using a spacer like that provide by VCI, is the rotor centered in the caliper?

Or did VCI create a necessary widget by making their adapter such that their spacer is required?

(Talk about a one-man thread! ...four post in a row!)

[SprintStar]

Originally posted by Bill Verburg



There are 2 different front kits manufactured by Race Technology, Wayne sells them here as do most other retail outlets in North America. They are very nice kits.

2 different front kits? What difference is there?

Also I've been doing some research on Turbo brakes. But I can't find any answers as to whether they will fit a SWB 911?

I think the fronts should be a bolt on if I can find the early rotor that takes a 911 hub? How about the rears? A Turbo arm is shorter? Will it fit a SWB car?

Thanks.

Sprint.

[MotoSook]

Still looking for answers....

Anyone use a 3.2 Carrera rear rotor (290x24 mm) with a 944T caliper in the rear of a pre-Carrera car to retain e-brakes (as oppose to the 930 rear caliper)?