99 Z34 Brake Issues
 

Hello All,

I re-signed up after finding that my old account was deleted (years ago). Anyhow, I have quite a few brake quirks that I'm not quite sure where the problem lies.

99 Z34, purchased 03 with 25k miles, currently 160k)

My rotors were warped or the hubs are bad and my car was violently shaking braking at high speeds. Brake pulsation has been nominal previously but recently has gotten real bad so I purchased PowerSlots Drilled rotors all around and new pads to go with.

I've already replaced the rear rotors and pads and noticed several things. On the rear right, the inner pad was worn twice as much as the outer pad. Piston went in fine, hub seemed ok. On the rear left, I had to hammer on the caliper housing to get it to release from the rotor (bad piston?) Once freed, spun the old rotor, way out of whack. While checking the hub, it made a grinding sound when rotated backwards, seemed mostly fine moving forwards. It also felt tighter than it should, bad hub? Cleaned the hub face so the new rotor spun perfectly, replaced everything.

At the start, braking was smooth, pulsation nominal (probably front rotors little warped). After running around about ten miles, I could hear the constant rubbing of pad on rotor in the rear left. As they heated up toward the end of my errand, it almost sounded like it was slapping the pad (as if it were warped). Rear right also made a couple funky/clunky noises. These are all brand new rotors and pads and the only thing I can think is that the hubs are messed up or the calipers are somehow failing.

Also, I haven't bled the brake lines ever, could that not be helping quite a bit?

Any suggestions?

Thanks

gotta '98 Z34: i had the same problem as you regarding braking at high speed. the problem starting with a slight "pulse" feel in the brake pedal and turned into a violent shuddering after awhile. felt like I was landing the space shuttle on a cobblestone street. I changed all my rotors and pads (which also wore down funny) all the way around. the back brakes were a pain in the @$$. the piston on the back calipers couldn't be turned or pressed back in so I replaced them. the dude at Autozone said those particular calipers are known for "dragging" or otherwise being problematic. he said he sells alot of them. the front calipers were easy to work with. long story short: try changing out the back calipers. even if they seem OK, they may not be.

Replaced all rotors and pads, the cars brakes smoothly for the first time I've had it... Rear left caliper is dragging and is the only thing left that appears as an issue. Thanks for the suggestion vincenti, I will be replacing the caliper.

I also noticed there was no spring on the left side parking break cable, but the right side had it. I read a post earlier about this, but is it a big deal? Perhaps it has something to do with the causation of the dragging caliper?