The Stovebolt Site Forums The Shop Area Engine Shop Brake problem Help!

I am working on a 46 1/2 ton. When I got it, the truck pulled hard to the left when you slam on the brakes. I have rebuilt the entire system, including brake cylinders, master cylinder, and new flex hoses. I rebuilt the front end also, with oversize kingpins, it is tight. I have adjusted the brakes loose, tight and in between and the truck still locks up the left front wheel if you nail the brakes. If you mash the pedal less fast, it stops straight as an arrow. I have even checked the hard line to make sure I have no obstructions to the other brakes. I have worked on cars and trucks for many years and never had this problem. Help would be appreciated!

These always sound easy to fix, as you have learned. If all the other brakes are working properly, first try backing off the adjustment on the wheel in question. Leave the others tight.

If that doesn't cure it check and make sure everything is assemble right. My nest step would be to swap the front drums and bearings. You didn't say, but I am assuming you had the drums turned.

Sounds like the left front is doing all the work. Did you have the drums turned? Did they turn the RH side more? Did they grind the lining to the same cruve of the drum? Look at the lining to see if the lining is making the same contact with drum on both sides. If all looks good swap linings or drums side to side and see if problem follows if it does then you know it not the fixed hardware.

The alignment will also cause brake steer,
Scott

One thing comes to mind when thinking about "everything was rebuilt". When I pulled my wheel cylinders off the front and took them apart, they both had rubber from the flex hoses buried inside the supply hole. Is there a possibility that this may be the case with the right wheel cylinder?

Did you replace the shoes? Mine were "new" when I bought my truck, but the beast had been in the barn and the shoes were saturated with grease. As I said, they looked great...but would not stop my truck. The shoes would not release after locking up the wheel. I had to back up at stop signs to unlock the brakes.

I also re-adjusted mine several times..

Adjustment and grease requiring new shoes were my problem.

Replace - do not rebuild - wheel cylinders. They are cheap enough you should just buy them. When you try to rebuild them, they can have a problem "catching" in the bore, which will result in the problem that you describe. The bore that has the "caught" piston will have less brake pressure - in this case the right wheel cylinder.

Also, if you have access to a brake pressure gauge - check the brake pressure at each wheel cylinder. This can tell you if there is a problem with the plumbing leading up to the wheel cylinder. It helps a lot in brake diagnosis.

Tudorman,

One thing I forgot to add..I can't tell if you replaced all of your steel lines..I see the flex hose. If you did not, I would do that. The lines rust from the inside out. The insides are filled with crud/rust and might rupture...

Since you have worked on cars/tks for a long time, you prob know that..I just add it for others that might look at their 60 year old lines and think they are good to go..they might not be.

By the way...you have pix of your 46 to share?

Also,most brake systems have a front and rear brake shoe per wheel-one has a longer lining than the other;could you possibly have the shoes in wrong on one side? I've made that mistake before,but it showed up as just less effective braking since I had both sides wrong. (helpful hint-don't do brake jobs at 3 AM with only a failing flashlight for light. Rather,leave it until daylight and catch a ride to work with a friend.)
Speed

Check for smooth wear pads on your backing plates. Make sure the shoes aren't hanging up. Both primary shoes in the right place?

Both tires match? Inflation? No separation?

Drums turned within .050 of each other? New shoes?