So i have a 1973 ford f250 camper special it has dual pistion caliper disc brakes on the front and drums on the rear...
My problem is the brakes on the right front keep locking up! Now so far I have installed a new brake booster, and master cylinder, a new set of brake pads on both front wheels a new caliper on the passenger side and a new hard brake line from the proportioning valve over to the passenger side along with a new brake hose.. I put new wheel bearings and race on both sides and it was all working fine for a few miles than all of the sudden the front end started shaking like crazy and the caliper was locked up on the passenger side as if I had the brakes pressed on.. I have bled the crap out of the system, the brake fluid is crystal clear the brake pedal is not spoungy at all it's actually really stiff.. What could this be?? I'm a pretty good mechanic and this has me just stumped! I'm sick of throwing money at the brake system! I can't figure out the problem anyone have this problem?

 

Did you lube the tracks the caliper rides on? They make caliper grease for this purpose. Take a wire brush and clean the track on both the top and bottom where the caliper rides. You seem to have replaced all of the parts that can cause your problem. I will add this though, when you pull the caliper, use a O'ring puller\scribe and pull back the seal around the pistons and spray your favorite lubricant around the piston. The bottom line, the caliper needs to retract after brake application. if the caliper body sticks, a caliper piston sticks, or the brake fluid cannot return to the MC, this will cause your problem. A defective rubber brake hose can cause this problem, but I read you replaced that.

 

Yeah I guess I will try lubing everything... But shouldn't the caliper be fine since it's new? Could I possibly have bad wheel bearings?

 

your master cyl push rod may be out of adjustment,( adjusted to long ) not allowing the brake fluid to return fast enough to the master cyl. MC piston covering the port, remove the master cyl. put some grease on the tip of the push rod where it goes into the master cyl, install the master cyl , then remove it, if the grease transfered to the master cyl piston, the rod is to long, and needs to be adjusted shorter, sometimes you can tell by just putting the master cyl. on and pushing it back against the brake booster, and see if the grease transfered, Hope that helps, Chellie

 

Chellie! Hey I think I have seem u on another forum! The R/C forum...

 

Hi, Yes your correct, Wattflyer.com Hi Dan i bought a used truck, and am having smog emission issues I will get it figured out sooner or later , Take care, Chellie

 

Oh yeah? What's going on with your truck?? Possibly I could offer some advice?

 

Hi, I was checking the emissions vacuum flow chart lable, and noticed that this truck was missing a 3 port vacuume valve, the vacuume goes from the intake manifold to the 3 port valve, the vacuume is tee d off the single manifold vacume port, goes to a V REST what ever that is ? and the divided 2 vacume hoses with the V REST goes to the 3 ported valve, the 3rd hose goes to the dist. vacuum advance.off the 3 port valve. also, there is a large hole in my air cleaner on the pass side, i belive a vacume valve should go there, that may even be the V Rest area, the hole is taped off, so i am trying to put back all of the emmision devices so i can get this truck smogged, I know this is old school but it sure would have helped if the smog stuff was still there Take Care, Chellie

 

That hole in the side of the air cleaner is for you your breather/ oil filler cap on your valve cover... I'm not really sure why your vacume advance is plugged into that block on your intake manifold... That vacume andvance should be plugged into your carb on the left hand side there should be a vacume inlet on the carb that your hose plugs into. It's possible that the previous owner took that out for some reason... Do you need to get emissions done on your truck?

 

Hi Dan I have the breather in the air cleaner, its on the driver side of the air cleaner, on this thread i have been getting some info to fix it with, starting from post #22 Take care and have fun, Chellie

https://www.ford-trucks.com/forums/8...ia-smog-2.html

 

how thick is the rotor? has it been turned? is it new? I wonder if your rotor is too thin and its drawing the pistons too far out of their bores.

 

Well guys! Problem solved! And you will never guess what it was! Was the damn brake light switch was too far out pushing on the brakes slightly! I re adjusted it, and took it for a spin and it works like a champ!
So I was taking chellies advice and going to adjust the push rod on my brake booster and I was inspecting everything and wash watching how it moves to make sure everything looked ok and when I did I noticed the switch was out to far... So I adjusted it and now everything is a ok!
Thanks chellie!

 

Kewl, Glad you found the problem, i had a push rod that was to long and caused the same problems, that drove me crazy for a while too and that brake light switch was causing the same problem, the master cyl piston was not returning enough, Take care and have fun, Chellie

 

So i have a 1973 ford f250 camper special it has dual pistion caliper disc brakes on the front and drums on the rear...


"My problem is the brakes on the right front keep locking up!"

Gatta love the internet, your diagnosis is only as good as the description of the problem.

This is not a slam to the original poster,,but ya got to admit, on disk brakes, how can this happen? Drum brakes, one can understand it would be the adjustment to tight on the right, to loose on the left, but disk brakes? After the solution given, I'm confused.

When the brake pedal is pushed down with all parts working correctly, the pressure to both front calipers are equal. The front\rear presure is a diferent story. These hillbilly remidies given here are kicking my ****

I gatta know, with the parts the OP replaced and everthing working as the OP stated in the original post, how can a mis-adjusted flippin brake switch or Master Cylinder push rod cause only one side to lock up? You push to far on the pedal, for any reason, both front brakes drag, not just one, unless you have another problem. (yes, there is constant fluid presure to the calipers to cause a slight drag, but not enought to cause lock up as described) Sorry folks. I guess I have been doing this crap for to long and the older stuff is kicking my ****.

 

Idk, but it happened... I have been working on cars for about 12+ years and this has never happend... I think it's crazy however it seriously happend... And god damn, I must say I was ready to drop my truck off a cliff or light it on fire!