Brake problems, driving me CRAZY

[CumminsPower98]

I have brake questions on a customer truck and hope it's OK to post it here. I need more exposure.



I'm working on a '96 Ford F-350 and am having trouble with the front calipers sticking and causing brake drag. I did a complete brake job on this truck last Aug. and at the time I put rebuilt calipers on it. At first they worked great with no drag at all even after heating them up on a few test drives. I measured rotor temps after driving and they were equal. Well I now have it back in the shop again with front brake drag. The rotors are in perfect condition and not warped or cracked as far as I can tell. I decided to try another set of rebuilt calipers yesterday. The driver side worked fine out of the box but the passenger side hung up right away. Next I decided to try a brand new caliper from Ford and guess what, it hung up too but maybe a tad bit less. Well I decided to take it for a test drive and see what the temp gun said. After stopping back into the shop the passenger side was 20º hotter. I jacked it up and spun the wheels and now the driver side is hanging up just as bad even though it started out free before the drive.



The slide pins are fully free with new rubber boots and all other slides are smooth and lubed up. There is no fluid pressure in the caliper when the brakes are at rest as verified by cracking the bleed screw and of course the pistons are still not retracting fully. I took one of the calipers apart and lubed the pistons and seals with Syl-glide, which did nothing for the problem. A Ford tech told me they were having some trouble with the higher grade brake pads causing some drag and said they had better luck with lower grade ones. I have tried both and I see no difference.



I have been through the same thing on another '91 F-350 and also an '81 E-350 van. I have not been able to solve any of them all of which got rebuilt calipers and the works. I am starting to get really sick of these Ford brakes. The pistons look glassy smooth so I don't see any need to polish them further. They are Bakelite material it looks like. Does anyone know if there are different materials used for the sealing ring where one might slide better then another?



Well I think I covered everything I have tried and thought of. Is there anyone out there that has been through a similar experience and know what is going on??



Thanks so much - Mark -

 

[lschultz]

I think the person that can help you is



Sam Peterson

360 357-4958 8:30-5:30

-- email address removed --



makes his living working on brakes.

 

[RHogge]

Have you check the brake HOSE (rubber) going to the calipers, what they will do is close up on the inside and the pressure will not come all the way off.

 

[Joe G.]

Mark,



Dodge used those bakelite pistons in the '77 van I had. The brakes were a mess. When I finally decided to replace the pistons the replacments were metal. No problems after that.

 

[CumminsPower98]

Joe, steel pistons is something I have tried in the past to get and had no luck. I will have to try again and see where I get.



RHogge, it can't be the hoses because they still hang up even with the bleed screw wide open so there is no way it can be any sort of pressure problem.



Thanks guys for the input.

 

[RustyJC]

Mark,



If you've flushed and replaced the brake fluid before installing the new calipers, please ignore the following question. Does the brake fluid show any signs of water? Bakelite absorbs water and swells, so if the fluid starts getting too contaminated, the pistons swell and the caliper won't release... .



Rusty

 

[RHogge]

If the hose is bad it could be slow draining off, you should have some drag anyway, the only other thing is the o-ring in the caliper, when the piston moves only . 010 to . 020 the rubber o-ring will spring the piston back, if the piston moves more than . 020 then the o-ring lets the piston move in some, you have put more than one caliper on the truck, I don't think you have a box of bad ones, 20 degree's isn't any thing when you brake hard, if this truck has high mileage it could be the hoses.

 

[CumminsPower98]

I did flush the system with new fluid the first time I did this job and again this time from all the caliper changing. I tried 3 calipers this last time, one from Napa, one from Carquest, and one new one from Ford and all of them hung up on the passenger side and the driver side one hung up after just one drive even though it worked fine in the shop. It is impossible for the hose to be the problem as far as my understanding goes because they will stay hung up even with the bleed screw wide open and dripping fluid. I just keep coming back to that rubber o-ring and the piston.



Just today I did front brakes on an old '86 Chevy 4x4 along with a new rotor. One side worked great but the side with the new rotor hung up bad. I know there will be some extra drag on a new rotor until it shines up but this was excessive. I changed the caliper and all is well.



Thanks for all the comments, keep them coming.



P. S. I will check on the hoses just to be sure there isn't something going on there.