This raises a concern regarding this kit that I've been mulling over through the course of this discussion: 4-piston rigid calipers mated to 1 piece rotors. What would be the conseqence of such a setup during hard cornering? Obviously you would expect a drop off in braking force as the pad-rotor angle slews away from zero, but how bad would it be? There will be some compliance by virtue of the fact that the pads can take up some of that angular mismatch in the pistons/pads interface... but that two will lower the amount of force a piston will be able to apply to the pad.

Obviously the floating caliper is the optimum design, allowing you to have a truly rigid caliper design and take out any angular deflections in the rotor with little or no binding forces, but does using a 1 piece rotor cost you any of the potential gains a 4-piston rigid setup gets you? (on a suspension that I imagine is nowhere near as rigid as a Porsche's)

 

Dave,
It’s all a set of trade-offs and compromises. Even Brembo’s street and race floating rotor systems are set up differently. As I recall from a technical seminar I attended last year with Jim Kontje, Brembo’s Sportscar Program Manager in the U.S., they like .006-.008” play for their hat-to-rotor float for racing. That allows plenty of adjustment without bind. From a conversation with Brembo’s street division a few years ago, I recall they set street systems up with @ .003” slop. This avoids clunking rotor noises on street driving, and minimizes wear at the floating junction of the hat/rotor. But, that tollerance somewhat limits dynamic adjustment, per Brembo. And yes, the floating caliper helps with the dynamic centering, but mainly at the start of braking. Once a certain threshold has been reached, the guide pins will be under some (limited) bind and not easily allow further adjustment. If you are a serious trail braker, you will be braking deep and letting up slowly, after having steered your back end out appropriately with the brakes. It may be halfway through the turn before you are fully off the brakes. If during the corner you hit a bump, this puts additional side load on the suspension and more instantaneous deflection occurs. The floating rotor can adjust, if it is set up with adequate play. The floating caliper will have a harder time because the guide pins will be under some binding force until you let off the brakes sufficiently somewhere in the corner. The majority of the braking rotational force is resisted by the hard mounted pad abutment bracket, so the guide pins are not totally locked up.

I tried many times to buy the Brembo system. First from LG Motorsports (back in ’96 when it came with a 12.76” rotor, but it was discontinued when Baer switched to Alcon), then from Callaway, then from Stillen, and then from Brembo when they came out with their own adapter bracket. No one could get me the system with plain rotors. For an additional $100, Brembo said they could eliminate the cross drilling, but said I would have to accept slotted. There would also be an up charge every time I bought replacement rotors. I passed. Now I’m glad I did; what I have is completely adequate for my track driving. I really feel that Brembo should offer one of their mono block calipers for their $3000 asking price.

To respond to your question about the system you are considering, there are many other factors to consider besides floating rotor/caliper. Some of them are far more important. Some of them are less important, but you might never think of them, like the aggravation of trying to successfully bleed some Wilwood calipers. How many total miles of trail braking will you do on a set of pads anyway? I suggest talking with people who have made the change you are considering (and lived with it for a while), who also use their cars the way you plan to use yours. Unless you have money to burn, why blaze a new trail? The current market offers us lots of choices.

Jon, no harm done. A few have suggested a brake “shootout”. It may never happen that we can get a good sampling of the various systems at the same track on the same day, but I am game if others are. Have car, will travel.

Bob Bishop


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lateapex@charter.net
'94 Z28 with C5 front brakes and other road racing stuff

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WOW!!!!!! You guys have really gotten into the PRO'S and CON'S! I have The C5 set up with Bob's brackets, and all I can say is they work!..........now no jumping on me, I have nothing to gain from that statement other than the FACT that the brakes finally work ( now if I can only keep from breaking wheels ) great discussion, and THANKS to all, I have learned a lot about brakes and where not to spend your $$$ Gary

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GM01SS/ 2001 SS/ #5747 Rally Red/ mods! /RIP #3/GOD BLESS AMERICA 9-11-01 // FLFB of WNY // WNYFA//

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I personally think that this Porsche brake fanaticism is a bit esoteric. Porsches brake exceptionally well in part, due to weight distribution (engine in rear) and chassis rigidity.

I installed the BAER 13.15" (also massively thick rotor) GTP brake kit with the C5 calipers 2 months ago on my 1994 Z28 M6 and am VERY pleased. Even though the pad surface area could be greater (ala 6 piston calipers, etc), the larger diameter (& much thicker) rotors perform phenominally. Now I need tires stickier than Kumho Victoracer 700's to use all of the brakes!! Standard C5 Vettes don't have over 13" diameter rotors, so maybe that is why they replace them. I for one find the C5 calipers to be very strong. If I need more brakes than this, my car (& myself) will go on a diet.

Just my thoughts.
Rick R