Help me break the guess and replace dealer strategy

[stevegriffin]

I will test it again but on a straight interstate in a lane with no crown with no braking it goes straight as an arrow

The mechanic said that when he pulled the rear brake shoes really nasty brown fluid started pouring out which was from the Pistons, which is why I had the brake lines flushed.

However you comments about rust and possible damage to the master cylinder makes sense. That might be the next part to go.

More feedback after I do the straight line test

Thanks
Steve

[dwightdi]

Sounds like the only thing left to check is the master cylinder. The two chamber design could be causing the front left brake to engage more that the right one.

[Rich W]

Letting go of the steering wheel is not a valid test of alignment, ask any tire garage. Slipped belts, dragging brakes, failing bearings, road angle and many other things can impact steering. The OP says he's had an alignment and the brakes are still pulling. I would eliminate alignment.

The dual chambers in master cylinder are for safety and have been in use for more than half a century, maybe longer. If one side is getting more pressure, there's a blockage in the master or in the lines. The flex lines at the caliper have been replaced, I would eliminate them.

The OP has had the following work done at the dealership:
(please correct me if I'm wrong)
Replaced calipers and rear wheel cylinders?
Replaced the front wheel flex line hoses
(I believe the rear wheel cylinders are steel lines up to the cylinders, not hoses)
Replaced pads and brake shoes (confirmed they are not contaminated?)
Turned the rear drums
Turned the rotors
Replaced all brake fluid and bled the lines of air
Wheel alignment (2 wheel or 4 wheel?)

We can eliminate all these parts unless these new parts prove to be defective, which is possible but not likely.

Symptoms: (Please correct me if I'm wrong)
The vehicle travels true until the brakes are applied. The harder the brakes are applied the harder it pulls to the left. Most cars use the right front / left rear and left front/right rear connection for brake lines. If the car is pulling to the left when the brakes are applied, it has to be the right front, left rear, or both brakes that is causing this.

The only two original things (other than the steel lines) left are the vacuum booster and the master cylinder. I think the booster is not specific, it only assists in applying pressure. That leaves the master cylinder. Since the lines were professionally bled, and nothing unusual was noted, that leaves the master. (I'm assuming you replaced the rear wheel cylinders.) Each chamber of the master has its own set of gaskets, one chamber's gaskets may be weaker (or failed).

In for a penny, in for a pound; replace the master cylinder. After that, I don't have a clue. I'd look for Gremlins I guess.

[jcl]

I'd look for confirmation that the rotors have been replaced or turned before looking to the master cylinder.

The brakes aren't just a hydraulic system, they are a hydraulic and mechanical system. Let's eliminate friction differences.

[overlander63]

Most Suburbans have front/rear split brake systems. If it is in fact a right front/left rear system, there can be a proportioning valve at the master cylinder that may not have been replaced. If one allows more fluid through than the other, it will cause uneven braking noticeable in the front.

I know my Ford had a problem with the truck diving left when the brakes were applied, and it was a bent caliper bracket.

[stevegriffin]

I did a straight line test and it drives straight with no pull.

I do not think it is suspension because the pulling to the left will get worse to a limit as I brake multiple times. Ie brake and pulls a little brake again a little worse ditto ditto until the pulling does not increase with additional braking. This seems like either a partial blockage or something sticking.

I will check out lines And master cylinder as some have suggested.

[Rich W]

Originally Posted by jcl

I'd look for confirmation that the rotors have been replaced or turned before looking to the master cylinder.

Yes, SteveGriffin, were the rotors replaced or turned? This would be normal if the brakes are being professionally done, but please confirm.

[crispyboy]

Are the rear brakes working ok?
I helped a neighbor with his Expedition last month. Found the rear brakes were not working at all and the vehicle would pull hard to one side when stopping.

[xrvr]

Hope you find the problem. Be safe. As an aside, my mother in law had a late nineties Tahoe with the same symptoms as you have. Dealer did everything you have done, including tires. This car was unsafe to drive and they admitted they could not fix it so took on trade in. Yours is the only other vehicle I have heard of with this problem that can't seem to be fixed. Peace,jim

[spf1268]

I had this same issue on my '97 Silverado.

Take your front brake caliper bolts out, clean them, and lube them with disc brake slide grease.
The caliper or the pads will hang up on the dirty / ungreased bolt and cause the swerve left/right when you are braking. When the new brake calipers come out of the box, those caliper bolts are not lubed. Should be a 5 minute fix in your driveway.

Good Luck

[Jammer]

Hello steve

Good luck with your repair.

I have the a 1997 pickup with a nearly identical configuration. No easy answers although the suggestions upthread are good ones.

You should replace the rear wheel cylinders if you have not already done so. You should also replace the hardware kit and self-adjusting screws for the rear if this was not done. This vehicle has a parking brake that uses a cable setup to apply the rear brakes. It is common for the cable assemblies to corrode and stick, and they should be replaced if there are any signs of sticking.

There can be a slight pull to one side if one of the drums is worn almost to its service limit and the other is near new. If that is your situation or even if the drums are just badly worn it might be best to replace them.

You would also want to check visually for a kink, crimp, or other damage in the metal brake line that runs along the rear axle.

You may find the folks over at gmtruckclub.com to be more helpful since Chevrolet suburbans are one of the vehicles they focus on.