Any difference between RSA and "regular" 964 calipers?

[Bill Verburg]

Originally Posted by jhynesrockmtn

Sorry for the delay in getting this measurement, the calipers went to the rebuilder and I just got them back and mounted them tonight.

Here is the measurement, looks like .444 inches or roughly 11.3 mm's if I'm reading the caliper correctly.

Thanks!

[Noel]

Sorry to resurrect a old post, but I have a question for Bill related to using the 964 calipers and want to add to this thread for archiving purposes.

Bill, I have a set of front 964 rotors in my garage and was considering going with the 28mm 86944 turbo rotor route (Since they are much cheaper) with VCI machining plus using Carrera calipers and 24mm rotors in the rear. If I did go with the 930 rotor in front, does the machining of the caliper change or will the same VCI machined caliper work with both the 86 944 turbo rotor and the 930 floating?

[Noel]

Also, why is the 930 floating rotor so expensive? Is there another source to get these, other than Porsche?

[KTL]

VCI's adapter is machined differently for the 944 Turbo rotor. The OE 930 rotor is located differently (has a different offset) than the 944 Turbo rotor. So i'd venture to guess that the caliper adapters Bill used to have for his 964 calipers are dimensioned differently than the VCI adapters.

http://www.vehiclecraft.com/Brakes/vciweb4.htm

I believe VCI does machine calipers for the use of 930-like floaters, but they use the bigger 993/S4 calipers and not the 964 calipers. Reason being, the S4 caliper is originally designed to accept the 32mm thick rotor that is used in this upgrade, vs. the 964 being sized for a 28mm thick rotor. I'm not sure if you're aware of this, but the 86 944T rotor not only requires the calipers to be modified for adapters- you must also use some wheel bearing spacers which are installed onto the strut spindle. These spacers push the rotor another 4mm-5mm (depending on which spacer you request from VCI) away from the a-arm to make the rotor face clear the end of the a-arm. I use the 5mm spacers and still had some rubbing, even after grinding down the a-arm.

There are other sources for the rotors besides the OE floaters. Wilwood, Coleman (VCI uses these -floating or non- and some people have had poor results with them), Brembo racing, AP Racing, Alcon. These need custom sized hats/annulus to mount them to the wheel hub. I used a Wilwood HD 309x32mm rotor with my 993 front brakes. I got the adapters (both the caliper adapters and the rotor hat/adapter) from Dave Walsh at ProBraking.

[jhynesrockmtn]

This doesn't address the most recent question but is an update to what I ended up doing.

The PO for my car had mounted 964 calipers in front, carreras in rear with 24mm rotors all around and no update to the MC. He elongated the mounting holes on the calipers to fit them.

I had a mushy pedal, felt very uncomfortable on the track.

I ended up installing rebuilt carrera calipers and the carrera stock proportioning valve from a friendly Pelican donor. Installed PF97's all around and had much better braking at the track yesterday. I also have cooling ducts in the front.

This seems to be a good compromise for me now. Had good consistent brakes all day yesterday, very predictable.

Could I reuse those 964 calipers later with the elongated holes???

[KTL]

Originally Posted by jhynesrockmtn

This doesn't address the most recent question but is an update to what I ended up doing.

The PO for my car had mounted 964 calipers in front, carreras in rear with 24mm rotors all around and no update to the MC. He elongated the mounting holes on the calipers to fit them.

I had a mushy pedal, felt very uncomfortable on the track.

I ended up installing rebuilt carrera calipers and the carrera stock proportioning valve from a friendly Pelican donor. Installed PF97's all around and had much better braking at the track yesterday. I also have cooling ducts in the front.

This seems to be a good compromise for me now. Had good consistent brakes all day yesterday, very predictable.

Could I reuse those 964 calipers later with the elongated holes???

The folks with Carreras that only put the 964 calipers on the front do contend that it works well for them. If I recall correctly, Bill Verburg says this setup with VCI fronts (964 40/36 calipers and '86 951 turbo rotors) and stock Carrera rears, with pressure limiting valve in place and stock master, is more front biased but still can function well.

You can certainly reuse the calipers if they are properly fitted with radial-to-axial adapters. To fit them for adapters, the existing mounting ears with the elongated holes are cut off completely to mill the caliper flat and tap the caliper body to accept the adapter mounting screws.

[Bill Verburg]

Originally Posted by jhynesrockmtn

Could I reuse those 964 calipers later with the elongated holes???

I wouldn't.

They are a good candidate to be converted to radial mount
like this



Then you can use them w/ 304x32 930 size rotors

[Porsche-O-Phile]

Link - text of RSA owner's manual says they're the same as 911 C2:

http://www.rsamerica.net/OEMinfo/Tech%20Service%20Info/index.htm#brakes