The Stovebolt Site Forums The Shop Area Engine Shop Pulling to one side when braking

On my 53 GMC half ton, when I press the brakes the truck wants to pull, (and would pull if I didn't firmly hold the wheel), to the drivers side. What will cause this? It has all new brakes(shoes, cylinders, lines....) but has not been regularly driven (couple times a month +/-) for about 2 years. Thanks very much.

ArticCat I would check the adjustment then look to see if your new lines didnt get a kink on istallation. It happend to me and I made the mistake of assuming since all the parts were new it had to be another reason. Took for ever to find and more wasted money before I got it.

One of two things. Either a brake is grabbing on the side it pulls toward, or a brake is not working on the side it's pulling away from. One way to check is to stop on loose gravel with someone watching. If one grabs, it's easy to see. If one isn't grabbing, try a harder stop to see if one isn't working.

Adjustment problems alone do not cause hydraulic brakes to pull. Look for a collapsed flex line on the side opposite the pull. If it's pulling toward the driver's side, check out the flex line to the passenger-side wheel. Something is keeping the pressure from applying the brake opposite the direction of pull. A sticky wheel cylinder on the passenger's side brake will cause a pull to the other side, or you might have oil grease, or brake fluid on the side that's doing the pulling, resulting in a grab. Were the drums machined or replaced during the brake job? The rust-preventive coating on a new brake drum will penetrate the shoes and cause a grab unless it was washed off with a solvent like brake cleaner or alcohol before the drum was installed.
Jerry

Hotrod Lincoln I think I am reading part of your post wrong. Are you saying that I can't be an adjustment problem or are you saying it could be something other then an adjustment problem? Thanks

Thanks for all the great info. It was just painted today, but I will crawl below in the next day or two and check the lines. Jerry, the PO installed the new brakes when it was down to the frame do i'm not sure if they are installed properly though my mechanic checked them when they were in the shop and said they all looked new and fine. I will check the flex line on the passenger side carefully. I will also try the gravel thing if I can't see anything out of the ordinary. Thanks so much!!

Brian, the last time I expressed this opinion I got laughed out of the place, but I'm sticking to it. Out-of-adjustment hydraulic brakes DO NOT cause a vehicle to pull to one side or another. It's a physical impossibility for any brake to produce any stopping effect until all the brake shoes (or disc pads) are in contact with the drums/rotors. If 3 sets of shoes are in contact with the drums, and one set is out of adjustment, the pedal continues to go down, displacing fluid, until the last set of shoes contacts the drum. Then, and ONLY then, will any stopping effect happen, because that's when pressure begins to rise in the lines. Poorly-adjusted brakes cause a low pedal, not a pull. If a wheel cylinder sticks, or a flex line clogs, or there is any other way for pressure to rise before all the brakes are touching the drums/rotors, all bets are off!

OK, I've got my steel pot and flak jacket on- - - -somebody disagree, but you'd better have your physics right!
Jerry

I thought pulling to one side or another was just a design feature of drum brakes on the front. Brian

It might pull to one side if one of the front brakes is adjusted way too tight, but then it would pull whether or not the brakes were applied, and that brake certainly wouldn't last long.

I would agree with HRL except for the self-energizing nature of drum brakes (I not familiar with Huck, but Bendix are). Once the leading shoe makes contact, the rotation of the drum helps engage both shoes, thus one wheel can brake sooner than another, despite the uniform hydraulic pressure HRL mentions.

http://web.bryant.edu/~history/h364proj/sprg_97/dirksen/brakes.html

Now for adjusting - With the drum installed and working through the access hole, adjust the shoes while rotating the drum until the drum is locked up. This is the most important step since it seats and centers the shoes. Back the adjustment off a few notches until a light uniform drag is felt (a little more drag with new shoes). Since I learned this method, our drum brake vehicles stop straight.

I almost agree with Hot Rod. One small exception,unequal adjustment will cause one brake to apply sooner because of the small amount of pressure generated to expand the springs. When all shoes but one wheel are touching the drums, the pressure in the system should be equal to the amount of pressure needed to extend the springs in the last wheel. So, if the loose one was a front wheel you should feel a slight tug on the steering wheel toward the tight side, but as soon as the looser one touches the drum the difference should disappear. So if you apply the brakes gently you could well feel a slight pull for a short time due to the adjustment. But never a continuous pull.

I would look for contaminated shoes, drums that weren't turned equal amounts or shoes that don't match the drum diameter. We used to arc grind shoes to match turned drums. Don't think anyone does that anymore. Sometimes just a few hard stops will fit the drum and shoe more closely and even out a new brake job.

The correct adjustment method for Bendix brakes is:

Tighten the starwheel adjuster until a firm drag is felt when the wheel is turned. Do NOT tighten the adjuster until the wheel locks. Back off one full turn, 10 clicks on the old style adjuster with the coarse teeth, 20 clicks, (after releasing the self-adjuster) on the newer models with the fine teeth. Once the drag is relieved, there's no telling whether the shoes are touching or not, because of the self-centering effect of the Bendix shoes. When the brakes are applied the shoes self-center, so a light drag any other time is meaningless.
Jerry

Here is another possible cause for pulling to one side when braking:

I had that same problem, before I replaced the Oakie bushing of the torque tube to U-joint connection.
Trans oil ran down the torque tube and found its way into my left rear drum.

Although I thought the front brakes do most of the work, breaking power was almost reduced by half and the truck was pulling to the right when breaking.

Brake pads are useless once they have been soaked in any kind of grease, oil or lube and MUST be replaced. Soaking in cleaning solution is no good.

Major parts suppliers give life-time warranty on brake pads and you can replace them as often as you like for free.


Brakes ARE the MOST important element of any moving vehicle ...

When my students want to do go-fast stuff to their cars, I insist on a complete checkout and/or overhaul of the steering and brakes first. They're going to be able to steer, and stop, before they do anything to the engine!
Jerry

The main reason auto cos. went to hydraulic brakes is for the eveness. Adjustment has little effect on pulling to one side. I only back the adjustment up 3-4 notches. I like the pedal to barely move. I just apply pressure to it.

On the more modern stuff, brake pull and torque steer is caused by an alignment issue. I'm not sure how a straight axle could be out that far unless there has been recent modifications to it. I agree with HRL, brake adjustment only affect pedal free play with the exception of a gearlube saturated shoe and drum. Then, after a while, they just lock on until you come to a complete stop. Keep us updated as to what you find,
Scott

Hotrod Lincoln: With all due respect, I disagree. You have much more mechanical knowledge than I BUT. My brakes on my 62, 3/4 ton pulled to one side. I jacked that sucker up and readjusted them so that both front wheels are the same. No more problem.

When adjusting the brakes, you need to go back into the cab and hit the brake peddle a few times in between adjustments to get the pads to set properly.

Last time I had this problem it turned out to be a failed seal that had allowed grease to contaminate the shoes on just one side. It pulled hard to the other side.

It's going to be hard to tell if a brake flex line is good or bad just by looking. It sounds like they need the adjustment checked(it's not that hard to adjust unless there is a star wheel froze up) My opinion would be that if the vehicle pulls hard to one side when the brake pedal is depressed, you have a bad flex line. GM had a lot of trouble with them in the 70's and 80's models. I would not spend a lot of time monkeying with the adjustment before I replace both the flex lines. Make sure the wheel cylinder and seals are not leaking before anything(fluid on the the backing plate).

Hotrod Lincoln:

In a perfect world, your hydraulic scenario works. In the Stovebolt world however, those big goofy brake shoes, stick, bind and complain, every time the brake peddle is pushed. Because there is so much binding in each of the four wheels it IS possible to engage the pads of one wheel while not fully engaging them on the other side IF they are not adjusted properly.

Well, here it goes again! If you're content to make excuses for poor brake performance, so be it. Properly-maintained brakes do not pull, even when the adjustment is off. If you're willing to bet your life on unpredictable brakes, let's play some poker. You'll probably draw to an inside straight, too!
Jerry

My brakes work very well, thanks.

My point is that the pressure in the lines might be the same at all four wheel cylinders but the pressure of the shoes on the drums can vary.

When my brakes pulled to one side, they only did so initially. That's because the pressure in the lines pushed all the shoes the same amount. The shoes that were adjusted properly made contact with the drum first, THEN as I continued to brake, the "loose" shoes caught up and the braking became even. Another variable is that one side may take more pressure to push the shoes than the other because of friction variables within the mechanical framework. If the shoes are adjusted equally, and properly, the friction factor plays less of a part.

Again, what you say is technically correct but due to the variables in an imperfect, Stovebolt world, brakes WILL pull to one side if not adjusted properly.

Thank you, and good night....

The brake anchor bolt on the top of the backing plate is adjustable for position on these trucks.Loosen the anchor bolt nut slightly,have someone depress the brake pedal,tighten the nut.It's all in the repair manual,may or may not help,but it's worth a try.

Looks like I have lots to check, thanks for all the help! I'll get right on it!

I didn't see anybody suggest bleeding them. Might have a little air in one of the lines (which causes hydraulic pressure differences since air compresses and brake fluid doesn't, but I digress).

Now that's a good idea...forest through the trees!

mine pulled to one side because i had adjusted the bearing nut too tight on the same side that it was pulling towards.
tony

My '54 did the same thing, but pulled to the passenger's side. A wheel cylinder rebuild (and fresh shoes) took care of the problem for us. Good luck.

Period.

Sabrina

I'd say either one brake ain't biting for whatever reason (as previously mentioned by others) or you have a worn kingpin or tie-rod end on one side. As the brakes grab the drum on the bad side, the slop in the kingpin or tie-rod allows that
wheel to go in a direction different than the good side causing the pull.