Manager Forum

I have a 1971 ford bronco with drum brakes all around, the cust brought me his truck saying that after he had brakes put on by another shop, it started pulling real bad to the right. we checked it out and found that the shoes , drums, all hardware has been replaced including wheel cyls. we did do alignment and did rotate the tires to see if it made any difference. but no luck. I evan put a pressure guage on the ft cyls to see if they are the same . And they were Is there anyone out there that has had a problem like this before and how did you fix it

Thanks for your time,
Dean

OK, is this "pulling" while braking or all of the time?

Did you LOOK at the w/c's, are the pistons the same size side to side??

Make sure the adjustment is right on.....both sides have to be the same. Diiference is friction surfaces could cause this too...make sure the drums finish is the same on both sides.

I have seen incorrect alignment readings cause this, but it is a rarity.

I like Rich's idea...maybe the cylinders are different in bore diameter. That'll definitely do it!

one more dum question.....are the shoes on correctly. Now i have no idea the differance between primary and secondary shoes, but if both secondarys are on one side will it cause this??

[quote="Rich"]OK, is this "pulling" while braking or all of the time?

Did you LOOK at the w/c's, are the pistons the same size side to side??[/quo It pulls real hard when brakes are applie but when brakes are released it drives straight. I checked the wheel cyls i even took them apart to ck the pistons for size and for movement.

ricmorin wrote:Make sure the adjustment is right on.....both sides have to be the same. Diiference is friction surfaces could cause this too...make sure the drums finish is the same on both sides.

I have seen incorrect alignment readings cause this, but it is a rarity.

I like Rich's idea...maybe the cylinders are different in bore diameter. Th
at'll definitely do it!

I have gone so far with the brakes i even switched the right side with the left including the drums and it still pulls when brakes applied today because I can't find anything else I have installed new frount radius arm bushings and insulators and it didn't help one bit

I would check the brake hoses. I have had many problems on older cars with this problem being one hose collapsing on the inside.

That happened to us twice (two different cars) last month. We never saw any sign of anything causing them to collapse.[/quote]

liljoe wrote:I would check the brake hoses. I have had many problems on older cars with this problem being one hose collapsing on the inside.

I two thought of that and since there was no way of checking for that I replaced the brake hoses on both sides and before that i flushed the metal lines just to make sure everything was clear. And it still pulls and I don't mean a little pull I mean a very hard pull that will put it right into a ditch if your not careful

You're back to wheel cylinders (one bigger than the other), loose steering components, loose track locator bar (if equipped), strange tire condition (cross the fronts), unusual brake line routing. By this, I'm questioning: do the front lines come from a Y, or come seperately from the proportioning valve? If so, that "might" be a culprit.

You stated that you did a pressure test in your first post. If you really did and they are equal didn't you then rid the question of bad hoses?? If you are still wondering I would think it would be the prop. valve. Could it be the master cylinder?

Another question about your "pressure test" did you also do a "volume" test?

I can put 200 psi in a garden hose and it will take a year to fill up a fire truck. But give me 100psi in a 6" hose and i'll be a happy fire fighter.

If you are getting good pressure but different VOLUME your gonna pull to one side. Right?

Rich wrote:You stated that you did a pressure test in your first post. If you really did and they are equal didn't you then rid the question of bad hoses?? If you are still wondering I would think it would be the prop. valve. Could it be the master cylinder?

Another question about your "pressure test" did you also do a "volume" test?

I can put 200 psi in a garden hose and it will take a year to fill up a fire truck. But give me 100psi in a 6" hose and i'll be a happy fire fighter.

If you are getting good pressure but different VOLUME your gonna pull to one side. Right?

I don't rule out the possiblility that i'm wrong about this and if I am please let me know.
In your example you are talking about a system that is open. since the brake system is closed it wouldn't matter if it is a 1/4" hose or a 1/2" hose. if you tap any where in the system it will still read the same presure.and volume would not be an issue. thats is if there is no air in the system. also the pressure I was refering to is the force of the wheel cyl pistons not the actual line pressure. and the reason i did the test that way is I needed to verify that the same force is applied to the drums.

Bent spindle?

i've had radius bar bushings cause this. the brakes may be fine and the other shop may have bent the radius arm or frame bracket.

another idea (i almost said thought) but that would have left me wide open. when a vehicle comes into my shop with a customer complaining that after it left another shop the work they did wasn't correct i always take what they did off and box it up, this could be an inferior part issue. i strongly suggest before you go any further tell the customer that for you to continue working on the truck everything that was installed must be removed. two reasons here, #1 the parts may be of a lesser quality and be the sole reason of the pull. #2, when you repair the pull the customer will bring truck back to you, not the original shop and you may become (in their eyes) responsible for their inferior work because after all you were the last shop to repair the brakes. i haven't seen any drum measurements mentioned here and are the shoes bonded or riveted? i've personally seen drums that have been re-boxed so many times that you really don't know what you're getting. you may have one bendix and one wing wah and the diameter may be different. bonded shoes are best used as a chok block. there are just way to many variables here for you not to replace all parts with KNOWN quality parts. i'm not sure here but if i remember correctly the front drums are removed from the hub and if aren't installed on the hub correctly will cause a problem. if the hubs were part of the drum make sure the bearing seats are installed correctly. basically to cover any issues it would be best if you removed all parts and check for damage during installation. i can't begin to recall how many times i've seen brake lines forced into ill fitting cylinders or lines. this era truck is right around the time when metric was being introduced and for those of us that lived through it should remember what a nightmare it was. sorry for the ramble but i put a lot of thought into this.......