Having trouble with brakes on my 72 Malibu. Disc on front, drums on rear. Replaced old rotors with slotted rotors and kevlar pads last year. Worked great for a while then eventually started wheel hopping when braking. Then replaced calipers and pins and used high heat grease. Again after a while the car started wheel hopping. Changed to ceramic pads this again last a while then car started wheel hopping. Anyone have any ideas what could be causing this?

Did the car originally come with disc brakes? If not, what parts did you use for the conversion?

Are they single or dual piston calipers?

The car originally came with disc brakes and the calipers are single piston.

Okay, I took a good hard look at your first post.

Just to get things all "up and up," you're having wheel hop on the front wheels, correct?
This started AFTER you put on slotted rotors, correct?
A change of pads did not help, correct?
The only non-stock items are the pads and the rotors, right?
The other items, even if replaced, are factory-style pieces?

If I understand you correctly, it sounds like the rotors are causing the problem. I do know that some slotted rotors don't always function great because they are meant for hard use and not regular street use.

What sort of rotors did you put on? Were they recommended as direct replacements for stock rotors?

Its not the rotors because I had to replace the rotors several times with original replacement rotors. They would be fine for a while then they would warp and the wheel hopping would start. So I search for a rotor that was guaranteed to resist warping and would fit without modification. Thats when I found and put on the slotted rotors.

Okay, so you were having trouble with the rotors warping and wheel hopping. Now you've got some that will resist warping, but I guess they're probably not totally completely resistant to it, and so you're having a similar problem again.

Unless you ride the brakes while you drive, or you use them pretty severely, I'd say there's a chance that there's a problem with the pressure going to the calipers. You've somehow got too much while your foot isn't on the pedal, and it's causing the calipers to hold the rotors too tightly when not engaged.

I can't recall if there is a residual pressure valve for discs or not. I don't think that there is, but I'm not an expert on '72s. I also can'r remember what the deal is with the distribution block and if it involves any kind of particular proportioning valve.

Have you replaced or modified anything relating to the vacuum booster or the master cylinder? Are those parts original spec for a '72 Malibu? How about the distribution block? Are you sure it is correct for your car? How about the routing of the hard lines to your front brakes? Have you checked them to make sure they are okay? Are the hoses in good shape and free to move about appropriately when making turns? Do you have a line loc or anything like that installed in the braking system?

Have you checked your brake pedal pushrod? The rod has two mounting points, one is for manual brakes, the other for power. Someone else here can tell you what hole the rod should be in. I'm out of the loop on that one at the moment. If it's installed in the wrong hole it could be that it's creating residual pressure even when your foot is off the pedal.

Have you done any mods under the dash that could *somehow* affect the proper travel of the brake pedal? Is it at rest in the proper position when your foot isn't on it? Crawl under and have a look. Sometimes stuff hangs down that you don't see while your driving.

All good questions. One that seems very interesting is the line question. The line on the one side has been replaced but not the other side. I will replace the other side and see if that is the problem. Will let you know how it goes. Thanks for all the tips!

The rod from the booster is supposed to go in the lower hole for dosc's & upper for drums.

s57575s,

Thanks for clarifying. I'm actually going to need that info here in the next week! (Swapping from all drum to all disc at the moment.)