Help needed with Brake Problem

[DRV2FST]

I have an 85 930 that has recently (i think) developed a brake problem. When I press hard on the brakes I get a bad vibration in the steering wheel.

The faster you are going when you step on the brake the worse the vibration.

The harder you press on the brake the worse the vibration.

Brake pedal feel if firm and catches almost immediately with very little travel.

This may sound crazy but I would swear that I was not having this problem before I hit a peice of retread on the interstate. After that I noticed this problem right away.

Thanks,
Kirk

[DRV2FST]

By the way...I bought this car recently from a member on this board. So I owe a thanks to the Pelican Community for helping me find a nice car. Sure it need some work but any 20 year old car should.

Thanks
Kirk

[Rick Lee]

Sounds like a warped rotor upfront.

[Coral Red Syd]

Sounds like you could have a peice of debris between the disk and pad. I'd remove each front tire and inspect the pads, disks, and calipers. Little travel on the brake pedal suggests debris or the pad is not seated. Else the caliper could be out of alignment.

[sammyg2]

Jack up the front until the wheel just barely clears the ground, then roll the wheel. If the tire is out of round you should be able to tell by looking closely at the gap between the tire and the ground as you roll it.
Also, if you feel the brakes rubbing in one spot as you turn the wheel that make indicate a warped or bad rotor. They all do it a little, but if it drags hard that will point to the problem.
Rotors don't really warp very often but they do get hard spots that don't wear as much as the rest of the rotor. That makes them slightly bigger at the hard spot and smaller at the low spot. I just replaced a right front rotor because of this problem. My right front always locked up early. I had it turned but the problem remained. I replaced the rotor, no more problem.

Oh, and I'm sure you know this but I have to say it anyway, use jack stands

[SCOTITUDE]

Does the steering wheel shake without braking?Does the car pull to one side now? Considering you had no problem before the impact, you might want to have the front wheels rebalanced and the alignment checked. Maybe you just knocked the weights off causing a vibration or knocked out the toe. Check the wheels and tires for roundness while they are on the balancer. Maybe you knocked a tire out of round. If that doesn't solve the problem, I'd check the pads for seating issues. Lastly, check the rotors. You won't warp rotors by that minor impact.

[DRV2FST]

Thanks for all your suggestions. I'll try them this weekend.

Scotitude - no I do not have the vibration when I am not on the brakes. I;ll report back with the results of these tests.

Thanks
Kirk

[CliffBrown]

Kirk

Does the shake get worse after the brakes are hot? Is the shake less pronounced on the first application of the brakes on the first drive of the day (cold rotors)?

If so then I would agree with Rick Lee, warped rotors.

Even if there's no change between hot & cold, I would probably go with the rotors (measure them).

[DRV2FST]

I don't think the shake gets any worse as the brakes get warmer.

[Nine9six]

I would do as sammyg2 suggests. Until then, its all guess work. A certain amount of inspection may help with your next post