Performance Q&A Tech Section

Our Resident tech guru, Big Mac, tells all.

Kevin McClelland Apr 1, 2009 0 Comment(s)

As for gears, Richmond, Strange, and Zoom all offer high-quality ring-and-pinions. Your best support and technical advice is going to come by way of Randy's Ring & Pinion, which has a complete inventory of rearend components you'll need to set up the perfect diff, from posi's and gears to bearing and shim kits.

Source:ringpinion.com

Get Your Heat On
Q
My '87 Camaro IROC-Z came from the factory with four-wheel disk brakes. I recently added a Baer Sport Brake Kit up front, which is basically a 1-inch-larger, drilled and slotted rotors and dual-piston calipers. I'm told it's the same as an '88 Corvette would have used. In the rear I upgraded my differential to a Strange S60, which allows the use of my '93-97 Camaro rear disk brake system. Do I need to add an adjustable prop valve on the rear main brake line? I was told no because my car had a factory four-wheel disk prop valve already. Could you explain any differences between the factory '87 rear brake setup and the '93-97 rear brakes I'm using? The rear is new, so I haven't been beating on it yet. After a leisurely 10-mile drive, I used a temp gun and I'm seeing 220- to 240-degree temps in the rear and 180-200 degrees in the front. That seemed backward to me, but I didn't want to condemn it yet, with all the changes made and the addition of an extra piston in the front calipers. I was expecting to see higher temps in the fronts over the rears. Thank you for any insight.
Dave Mosler
Via email

A Nice brake system, but make sure you don't have any loose fillings in your mouth when you go out to test your brakes. Those Baer brakes really slam the nose to the ground when you jump on them. We did some digging to spec out your brake conversion and ran into many roadblocks.

Ken Casey at Burt Chevy spent half a day trying to spec out rotor and caliper piston sizes for us on both third- and fourth-generation Camaros. Unfortunately, GM has dropped many of the dimensions from its computer catalogue. Since most of these parts covered five or six years of application with one part number, GM didn't see the need to give out the technical specifications.

Here is what we've come up with. Your '87 Camaro with the J65 rear disc brake option came with 10.5-inch rear rotors. The '93-97 Camaros came with 11 17/32-inch rear rotors, which are slightly larger than 11 1/2 inches. We were unable to spec out the caliper piston size difference between the '87 and the '93-97 calipers.

Now let's talk about your brake heat for a moment. The Baer front system uses 13-inch rotors that are drilled and slotted for cooling. The four-piston calipers they utilize are from a fourth-gen Corvette. The brake pads they come with are for street/sport driving, and those take a bit of heat to bring into operating range. We assume the rear brake system you are using is factory pads and components (not drilled or slotted rotors). The factory pad must give great stopping friction from stone-cold brakes so little old ladies don't hit you in parking lots. They will build heat faster than the performance-style pads on the front. Also, the front brakes receive much more cooling air than the rear brakes do. The rear wheels and brakes are stuffed up into the rear wheelhouse, reducing cooling air to them.

Finally, the bottom line for brake bias is going to come from testing. After you're comfortable with all your new components, you need to go out to a safe place and do some 60-mph panic stops, just below the threshold of locking the brakes. You should be able to stand on the brakes and stop very quickly, and possibly just begin to lock the right rear brake in about the last 10 mph before coming to a stop. If the rear brakes lock before this, you need to add an adjustable rear prop valve and back off the rear brakes until you reach this point. This will give you the best stopping performance for your car.

Technical questions for Kevin McClelland can be sent to him at chevyhi@sourceinterlink.com.

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