Help me break the guess and replace dealer strategy

[stevegriffin]

I have a 1999 Chevrolet suburban 2500 with the big 7.4 L gas engine.

I also have on this car a brand-new pair of front brake calipers and rear drum pads, pistons and turned drums.

And, the brake fluid has been cleaned and there are no air bubbles in it.
This is after 1000 thousand dollars and four trips to the dealership.


And, drumroll, I still have the same problem.

I took the car in because when I break sometimes it will pull to the left it seems to be variable but once it starts the more I break the worse it gets to a point.

I bought this car to pull a flying cloud at 8800 pounds.

I just bought this car and there was clearly some problems with the brakes so I don't count the money a total waste. However, from a safety perspective I am still concerned about how Squirrley this car stops at speed with the thought of having nearly 10,000 pounds behind me. Of course I have electric trailer brakes and that will help damp this out some

When I break and this is without the trailer, it just seems like the wheels are not breaking evenly almost like a crab scooting sideways with the front end going to the left

Before I take this back to the dealership or find somebody else who has a little more ability to diagnose brake problems and probably come to the conclusion that they only part left to replace is the brake master cylinder, I thought I would ask the real experts who have driven thousands of miles in these kind of cars.
Hoping some of you out there have experienced this and can get me out of this cycle of guess and replace with the dealership many thanks in advance.

[dznf0g]

I would replace the front left brake hose. Over time, they can delaminate and cause a delayed engagement of the caliper (or reduced pressure). This commonly happens when a tech allows the caliper to hang (or drop) by its hose during a pad replacement, but can happen of it's own accord.

This, too, is a long distance "guess" (albeit, educated), but it does exhibit exactly how you describe and you have eliminated the other possibilities with the prior repairs.

[Rich W]

If it's pulling to the left, then that side is working. The right side has the problem. But dznf0g has a good thought, there may be a problem with the hose. If you've replaced the calipers then it's got to be in the line somewhere.

Master cylinders have 2 paths. The brake lines are typically paired; right front and left rear, left front and right rear. This is a safety feature so if one pair go bad you still have even braking on the other, albeit weaker. If the right front isn't working so well, how about the left rear? Does it show less than normal wear? If so, it could be the master cylinder.

Is the right front hot after you've been driving? The brake might be dragging and boiling the brake fluid, glazing the pads.

How is the emergency brake? Some vehicles have the emergency brake as a set of smaller brake shoes/pads inside the rear wheel hub. One of those might be seizing up on the right side/rear. It's a consideration

Finally, the vacuum booster should be checked out. I've never had one of those fail so it may just work as a single unit on the master cylinder and not apply pressure on the lines separately. The booster is a gray area for me. I've done a lot of brakes but never had to work on the booster.

[dznf0g]

OOPs, it's what I mean, not what I say...thanks for the catch.

[r carl]

If you replaced the front calipers and pads and turned or replaced the front rotors then the next step would be to replace the front rubber brake lines. I would also check the front suspension for worn parts.

[Rich W]

Originally Posted by dznf0g

OOPs, it's what I mean, not what I say...thanks for the catch.

Yeah, I thought you did Sounds like you've replaced a few brake sets yourself . Probably a good idea to replace both anyway, just to keep everything even-Steven.

[Zil]

I have the same problem in my dodge 2500. I know it is the drag link end causing toe-in alignment problems. Will fix mine soon.

[dznf0g]

A drag link should be inconsistent in the pull, right and left, dependent upon road surface undulations, etc. I suppose an out of alignment condition could produce a consistent brake pull with a worn drag link, but it would still be somewhat inconsistent, IME.

[nipperguy]

I had a similar problem with a 1993 C1500 many years ago. After much troubleshooting and trips back to dealer, it turned out to be the hose.
Get the hoses replaced before you spend any more time or money.

[TomKirk]

Mileage?? Two or four wheel drive?? Rear drum brakes; not disc?? In the past, has the truck been wrecked?? Is the frame or some suspension component bent??

Does problem occur when brakes are cold or when thoroughly warmed up?? Sometimes your truck hasta be driven several blocks before brakes can work normally. My '83 Suburban is like that, especially when it's cold or wet.

Sounds like the right front caliper piston is hanging up for some reason. You could have a defective caliper. It happens. Also, make absolutely certain that front brake pads are an exact match. Different friction materials can make a difference in brake performance.

Get a tread depth gauge and check for abnormal tire wear. If you've got new tires, this could be a problem. Find a tire technician that knows his stuff. Get your truck on a rack and let him do a thorough "shake-down."

Get your truck on an alignment rack for a thorough inspection. Idler arm and lower ball joints are problematic on these trucks. This is the moment of truth. This is where you find out if something is bent or abnormally worn.

Softened brake hoses are a possibility, but unlikely.

Tom

[tevake]

Replace the flexie hoses to all the wheels gets my vote as a next step.

Then the list above to follow on with.

Please let us know the out come, as we are all learning as we go along.

Cheers Richard

[Gnorts]

How many miles on this 16-year-old beast? Before spending any more $$ with the dealer, take it to a front end - alignment specialist for a thorough checkup. Some taking-apart time may be necessary to tell what's worn out.

[perryg114]

You have to watch on rebuilt calipers. Some of them are junk. I had a truck with replacement calipers that had been sand blasted on the inside of the piston bores. The metal was rough and pitted. This caused the piston to not move freely in the bore. The only rebuilds I would trust are ones you do yourself or Bendix. There are also some that have phenolic pistons that are reused. The best ones have new pistons in them.

Sometimes the hose can collapse so those should be replaced as well. Pistons should move freely in the bores. The proper way to rebuild them is to hone them to remove small pits and scratches. If the pits are really big they should be honed to the next size and a bigger piston should be installed. Bores should be smooth with a cross hatch pattern on them. The $25 Autozone specials are probably going to be junk especially on something that is old and there are half a dozen rebuilds on them.

The slider pins/rails or what ever allows the caliper to float back and forth need to be lubed and not frozen. You can apply air at low pressure to force pistons out. Many times one piston will stick in a two piston caliper. Pop out the old pistons and see what the bores look like. You can always put them back together to turn them in as cores.

Perry

[stevegriffin]

Thank you all who posted replies to my inquiry re braking problems.

Answers are:

1. Brake lines on front were replaced when new calipers were put on
2. Ball joints were just replaced
3. Car is in alignment
4. Best of my knowledge and previous owner and background check, it was not wrecked.
5. Shocks are heavy duty and just replaced
6. Initially the front left wheel was warmer and had more dust. The replacement of the front right had little or no affect on that. The front left had sticking calipers and when front left caliper and hose was replaced, noticeable heat difference went away.
7. Tires are basically new.

Additional info:
The emergency brake light does not work. Before all this work, but unclear whether before this braking behavior started, I ended up driving the car a couple of miles with the emergency brake on. The car started to shake and I pulled over. Discovered the brake on and released it. The car was fine after that and I did not notice the pulling, although I was not looking for it either at that time.

Due to the bad ball joints the front tires got cupped a bit. They are now on the back.

[stevegriffin]

And I forgot a few anwsers
- 170k miles
- 4WD
- all parts were from the dealer - hence no rebuilts
- I am assuming the emergency brake is fine given they had to replace the rear back pads, pistons, and turned the drums.

Thanks
Steve

[jcl]

Did I miss it, or are these the original rotors that were on there when you had a caliper sticking? Didn't see mention of replacing them, or turning them to ensure a consistent surface finish.

[Rich W]

Any chance the right rotor is oil/grease soaked?

Brakes are just a hydraulic system. Master cylinder applies pressure to the calipers. If there is unequal pressure the steering will pull to one side. You've eliminated all the other possibilities, just keep trekking up the lines. So maybe the line between the right-front caliper and the master cylinder is clogged or pinched (did you follow the metal line up to the master?). Maybe the master cylinder is clogged, possibly rust if there was any water in the fluid. Have you opened up the master cylinder and checked for any visible problems?

You say the caliper is new. If it was me, I'd disconnect that new flexible line from the right caliper, put a bucket under it and step on the brake pedal to see how much fluid came out. Then I'd inspect the fluid for rust and debris. If there's any indication of rust, I'd replace the master cylinder and totally bleed all 4 wheels, replacing it with new fluid.

[Flht2k]

Burnish the brakes I work for freightliner , this is a common issue it could solve the problem

[Al and Missy]

Is there any "steering" with engine acceleration and deceleration? Find a nice straight stretch of highway with little or no crown. Starting at about 45 mph or so, floor it while holding lightly to the steering wheel. Does it pull one way or the other? Then let off of the accelerator completely. Does it pull in the opposite direction? If the answer to either question is yes, suspect bushings in the rear suspension.

Even though the front end was recently aligned, any "slop" in suspension components can result in steering when braking. In a vehicle of this age, worn suspension bushings are a distinct possibility. Braking puts more load on suspension components than going down the road without braking and might not be noticed during an alignment unless the tech is specifically looking for it.

I had bad bushings on a vehicle once. The result was fast wear on the front tires and acceleration/deceleration steering on the rear.

Al

[ROBERTSUNRUS]

Originally Posted by Al and Missy

Is there any "steering" with engine acceleration and deceleration? Find a nice straight stretch of highway with little or no crown. Starting at about 45 mph or so, floor it while holding lightly to the steering wheel. Does it pull one way or the other? Then let off of the accelerator completely. Does it pull in the opposite direction? If the answer to either question is yes, suspect bushings in the rear suspension.

Even though the front end was recently aligned, any "slop" in suspension components can result in steering when braking. In a vehicle of this age, worn suspension bushings are a distinct possibility. Braking puts more load on suspension components than going down the road without braking and might not be noticed during an alignment unless the tech is specifically looking for it.

I had bad bushings on a vehicle once. The result was fast wear on the front tires and acceleration/deceleration steering on the rear.

Al

Hi, I think Al and Missy has your answer. Just because you get a reaction from braking doesn't mean that you have a brake problem. Any thing worn like tie rod ends, differential bushings, or even an alignment problem could cause pulling to one side or the other. Another test that I do is to find a straight and level road, Let go of the steering wheel, [or hold it with one finger] and see how long it takes to drift. If it tries to turn quite quickly, it could be an alignment problem. I have driven vehicles that drift badly and it was a bad tire; And when the brakes are applied that drift turns into a bad pull. Swap front tires and see if it pulls the other way.