VipZ28

iTrader: (4)

Ok so about a month ago I broke the stock torque arm, folded in half. I got an edelbrock one as a replacement, put it in finally, and went out for a test drive... everything is great, until i'm on my way home and decide to do a brake test, nothing crazy, just 50-0. Well right after I nailed them, the low trac light came on and the rear ened started hopping!! WTC? I have never had a brake hope problem before...

I can only think the stock t/a was flexing enough to prevent this? And how do I fix it? My current suspension mods are: Bilstiens HD's, prokit up front, 1LE springs w/ no spacer in the back, BadZ's LCA's and PHR, 17X9.5 front, 17X11 rear....

HELP!

trackbird

iTrader: (4)

I have not personally used the Edelbrock arm (though friends have). My hunch is (since I've handled one, but not run it personally) that it's not rigid enough. It's stiff enough to eliminate some of the flex of the stock arm, but not rigid enough to prevent it from hopping. Brake hop is common on these cars. Having 11's in the rear will not help the situation (even a street tire in a 315 can make lots of grip, usually we only have problem on race tires, but those may make enough grip to cause problems as well). So, I'm guessing it's a combination of lots of rear grip, and an "almost rigid" torque arm. The only other thing is that the pinion angle could have been changed by the new arm (and maybe not in a good way).

That's my best guess. The problem is, I'm not sure how to fix it. (Weld a plate on the side and try to make it extremely rigid? If that's the real issue).

The other thought is, you have had the problem all along, but didn't usually nail the brakes like you did this time and never had it happen before. Does it happen in normal/aggressive braking/driving? Or only when you really pound on it?

Anyone else?

VipZ28

iTrader: (4)

It hasn't been happening all along, and it hasn't happened in the 2 years of autoX'ing the car... this arm is extremely rigid compared to the stock piece... Pinion angle could be an issue.... I'll measure that on friday. It really could have been that particular piece of pavement when I just hammered the brakes... so I'll check it more tonight when I take it out... under normal to hard braking it doesn't have a problem, just when the brakes were absolutley hammered. I'll see how it goes today...

I was wondering if stiffer front springs would be an option...

trackbird

iTrader: (4)

I guess the other option is that the arm is more rigid and acting like a proper torque arm. If the stock arm allows the axle some rotation, it could act like a decoupled torque arm (though a very poor one) to help reduce brake hop and this one is rigid enough that it is now an issue. Do some more testing and let us know.

VipZ28

iTrader: (4)

Ok after examining pinion angle, mounting points, LCA length, and everything else I could think of while under the car I decided to do some more testing. After a weekend of beating on the car, and a damn fine AutoX outting(considering it's been a year since I've run a course, and 6 weeks since I've even driven the car), I've determined that it must have just been the patch of road I was, because I have not been able to repeat the problem... WOOHOO Concern over nothing!