Have alot more "drag" when they are hot (warm) ? I drove up in my car the other day and got out and put the front end up on jackstands. I happened to reach over to spin one of the front wheels and it had quite a bit of resistance,I could turn it but I couldnt make it just spin on its on at all! I checked the other side and it was the same way. No its not a bearing related drag ,its the brake pads resting against the rotors...firmly. So since I was leaving the car on the stands until the next day anyway, I decided to try to spin them again with them all the way cold,well you can really tell a big difference in how easy they turn ,and I can spin them and they will turn a few times after I let go before they stop. Has anyone else ever noticed this ,and is there anything that can be done to take the drag off of the front rotors when they are hot?
While they are a "floating" caliper they don't slide very well. I lube them with white lithium grease or Synthetic brake lube. You might also want to crack the bleeders while they are hot and see if it releases pressure if so........the master cylinder could be overfilled, or you have a brake hose that is collapsing. Another thought is check it cold and then pump the brakes a few times and recheck. If they stick, once again think collapsed hose.
remember,... the rotors get hot after using the brakes, and hot metal swells up a bit... and when they cool that contract... allowing free movements..... its sounds about right... and if you adjust them too much, then it will be harder to break when its cold...
I think pretty much all disc brakes have some drag. Lance mentioned lubing your caliper and that's a good idea. It's very easy to take the caliper apart and clean it on the slides and reassemble. I prefer to use a silicone grease as it doesn't break down under heat as much as regular grease. Another thing is the caliper pistons themselves...if your calipers haven't been rebuilt before you can bet there will be some sludge behind the pistons which can cause the pistons to stick somwhat and not release which will cause the excessive drag. Try sticking your finger in the bottom of your master cylinder and see if you get black sludge on your fingertip. If so, you'll find the same sludge behind your caliper piston. That sludge can eventually cause your piston to seize. Time for a rebuild. Better yet, it's so much easier to just pick up a pair of rebuilt calipers from the parts house and get it over with. They are generally $10-$15 each...not hardly worth the effort to rebuild after you buy the kit. Again, disc brakes are gonna have some drag so unless your trying to get all you got at the track, you may be worrying over nothing.
depends on how sticky. I've had them stick only when cold or only when hot... cars are fun beasts to work on...
Mike I Would Look At The Brake Lines And The Caliper Pistons,if They Are Old They A Probably Phenolic Pistons (composite Material) They Can Swell With Age And Cause The Very Sympton You Are Describing, You Can Get A Caliper Rebuild Kit And Get Steel Pistons, It Will Cure Your Problem. Jmo Wayne
Sorry to get off topic but is the proportioning valve any diffrent between power disc and manual disc cars?
Ok , the front brakes are discs from a `76 non power brake Maverick...when I installed them I used New rubber hoses, rebuilt calipers,rebuiltMaster cyl.(for a `76 non power disc Maverick ) The brakes NEVER pull left or right when stopping. Everything from the donor car was used on my car...hardlines,prop valve, and all. I have no problem with the brakes as far as performance. I just was wondering if it was normal for them to have so much "drag " when they are hot.( I took into consideration that heat causes expansion) . It seams that I remember someone talking about a "residual" valve used in some race cars that will allow the brakes to work like normal ,but keep the pads from contacting the rotors while driving. I want to say it was Steven Moore who talked about it.???? I`d like to get one if they are sold somewhere.
No, but my '76 donor vehical was originally power discs and they will be manual when I put them on my '74.
Exactly...I had a guy trade me a set of original Mustang disc for a drum setup for his race car a while back.
On a combination brake car....You can adjust (loosen) the rears so that only the front are holding so a burn-out can be done.......this eliminates the need for an adjustable proportioning valve....
