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jly535 jly535 is offline
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Join Date: Jan 2008
Location: Spokane
Posts: 361
That is a good write up on brake upgrades, answered alot of my questions. I think I will just plan on saving up for the 78 turbo setup with floating rotors or go for the 993/S4 setup. Thanx, Jamie
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Originally Posted by spuggy View Post
Jamie,

Ive been thinking about and researching brake upgrades for quite some time now. And I've never even lost the pedal.

I see I wasn't clear. I don't own a shop, or work at a shop. I meant the shop I use to work on my cars since 2003. Owned and run by this guy (props to Craig 930 RS for posting the scan):



He knows a thing or two about Porsches. He's brought up the topic of brakes. Like when he PPI'd my car...

Bill Verburg over on the 911 forum is the resident brake expert. He considers the VCI upgrade "interesting", notes that it's mid-way in heat capacity between the 3.2 and the 930 brakes. When using the 951 rotor, please note. You were thinking of using the 951 28mm rotor, right?

Bill V has also said that hogging out the mounting holes on 964/951 calipers is not a good practice.

I think I'd prefer the machining and billet adapters, if you think about the forces involved when standing a 2500 pound car on it's nose from high speeds. But if you go that route, it's not cheap, and the 944T calipers don't then save you much over better (and bigger) solutions.

The VCI solution also has you modifying the pads on the rear to prevent overhang.

I haven't done the math, but you should check the bias ratio front/rear if mixing & matching random calipers...

If you've not seen it, take a look at this http://home.nycap.rr.com/wmv/generalbrmd.htm - and there's also lots of 911 brake upgrade threads already on the 911 forum.

3.2 brakes are a definate upgrade to SC/S brakes.

They're dirt cheap, parts are readily available (and also very cheap), bolt straight on, and I think they work fine on a light car. Certainly handle heat better than the smaller SC/S calipers over 20mm rotors would.

FYI, I also seem to recall that the aluminum S calipers overheat faster than the cast iron SC calipers. Ho hum.

After 3.2 brakes, it gets spendy pretty fast to do it right. Boxster calipers are light, stiff and look nice (TRE do a nice adapter kit) - but the weak link in 3.2 brakes is actually the thermal capacity of the rotors and the Boxster calipers just generate more heat. Somewhere around here you need to factor in a master cylinder upgrade as well.

930 calipers are not getting any easier to obtain, and 911 folks have been fitting them as upgrades for years, which doesn't make them any cheaper or easier to find.

The big issue with a narrow-body car is the '78-79 style hats and the scarce (or custom) rotors, because you can't use the late 930 rotors with the built-in spacer. If you can use stock late 930 front rotors (with the built-in spacer) in conjunction with your hubs/flares, that would be a lot cheaper.

But I'd suggest that stock 993 calipers are easy to find used (probably for much less than 930 calipers) and get adapters for to use over the stock 930 rotors. No machining.

Beyond a certain size, you need to start factoring wheel size/caliper clearance into the equation as well. Not to mention you're kidding yourself if you don't increase tire size.

Bang for the buck? Stock 84-89 3.2 brakes over 3.2 24mm rotors gets my vote, for >95% street use. Especially in a car that's lighter than a 3.2.

You might have all the same overheating problems at DE's that Brakezilla 3.2 owners have, but rotors, pads fluid etc. are cheap, you get to keep your stock M/C, and you don't have to change the wheels/tires. And learning not to over-rely on the brakes makes you faster anyway, (or so I'm told).

If you can use late-style (81-up) 930 rotors up front, I'd fit 993 calipers front and rear over factory 930 rotors in a heartbeat.


Good luck!
Old 06-26-2008, 10:45 AM
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