1990 740 turbo wagon -

I geta bad up and down wobble/hop when I hit the brake to decelerate.When I let go of the brake while I'm slowing down, it continues until I come to a complete stop. A "wug wug wug" kinda thing.

I've got no bubbles in any of my tires, there isn't any noticeable uneven tread wear on them, and just eye balling them, my rotors don't look or feel warped. I'm thinking it may be a bad master cylinder? Maybe one of my front wheel's brake caliper is not being actuated and it's putting more strain on the side that does work, thus causing the wobble/hop. That's my initial theory, anyway. Any thoughts?

Regardless, I'm going to replace the master cylinder. Does anyone have any pointers, tips ortricks? Anything I should be leery of, or is it a pretty straight forward replacement?


Thanks!

 

Never seen or heard of a master cylinder causing that kind of problem. It sounds like a bad tire or something in the steering/suspension to me. Jack up the front end so you can spin the tires, get in front of the car and watch the tread as you spin it. The groves in the tire should be fairly straight. If a belt slips inside the tire, usually you will see a wavy section in the tread. If it were something with the brakes it should stop when you let off.

 

I wouldn't look at the master yet.

Start with the rear calipers and see if one is hanging up.
If it were the fronts when you hit the brakes the car would dive to one side.

Make sure the brake lines are all good.