Night Hawk

Ok today I was working on the rear brakes of my buddies 88 GTA. First I jacked up the rearend of the car, took off the wheels and told him to put the car into drive. To my surprise when he held down the brake the rotors were still turning no matter how much pressure he applied on the brake pedal. There was some scraping of the rear drivers side brake pad and the rotor really heated up. He told me once that his brake pad actually lit on fire from the heat a week ago.
I though it may have been his rear brake hose and replaced it, bled the brakes and still the rotors kept on spinning with the brakes applied. Could it be BOTH calipers seized? Both rotors are spinning just as freely as the other when brakes are applied. applied.

I know that when I lifted up the rear end of my car and put the brakes on, the wheels would slow down but not really come to a stop. Also my other buddies GTA's rear brakes never worked at all either. What the hell is causing this?

wm_sorg

What happens when you try the parking break under the same condition?

Night Hawk

no parking brake at all, why would this have any bearing on the situation, you've got me interested

Biochem

The parking brake will adjust the travel of the pads. I am assuming you have a 9-bolt... I think pre-87 was a screw type (like the one I put in my car) that actually screws the piston a little every time you pull the brake. I am not too familiar with post-87s... but I think Madmax is.

My wheels don't slow down either. I swapped from a drum 10-bolt to the 9-bolt disk and I was like WTF do I need a proportioning valve for to lower the pressure to my brakes if they don't even stop anyways! For whatever reason, even though the wheels will spin at idle with the car jacked, if you drop it and pull the e-brake, that car isn't going anywhere.

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1984 z28 w/ a 357 cu in. monster engine which is looking like the posterchild for Edelbrock... all the suspension stuff... 9-bolt posi disk is in... K&N filter... 93 octane...

-=ICON Motorsports=-

ws6transam

We've all experienced it. The rolling of the tires on the jackstands. There *is* a reason, and it came to me on the corners of Gingerman raceway, after making an unscheduled detour into the inner paddock.

When you nail your brakes, a huge weight transfer occurs from the rear to the front of the car. If you have enough brake bias to lock the rear calipers in drive, then chances are you have enough bias to lock the rear tires in a hard braking maneuver at the track. With locked rear tires, with any twitch of the steering wheel at all, you'll soon oversteer and go shooting into the land of toro riding lawn-mowers with grass all over your windshield. Worse, if you happen to catch a retaining wall!

Thus, I realize that GM has designed in a low-brake bias for a reason. One thing's for sure, these things slow my car down fast enough to make my passenger's heads spin!


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Daniel Burk
http://www.isthq.com/~dan/fcar.html
'84 Trans Am WS6/L69
KB SFC, Moser axles, Torsen Diff. PST suspension, Braided stainless brake lines,
5-point racing harness, Koni struts, 11-inch rear disks,Spohn Adj. torque arm,
Ported 305 heads w/1.94"intake valves, Comp Cams XE262H, Griffen alum. radiator,
Speed-sensitive steering conversion, underdrive pulleys, Crane Hi-6 & more. 1.05g skidpad verified.
New best E/T! 14.400 at 98.6 MPH in 88 degree air at Stanton, Michigan.