Crazy suicidal steering and braking.

[superburban]

My phony CUCV (85 3/4 ton Suburban w/6.2/TH400) has developed an unsafe condition. The steering pulls to the right during normal driving, but pulls hard to the left during braking!

Here's the deal, though, it's got new shocks, year old tires, new draglink thinger (the link from the gearbox to the left hub), rebuilt brakes in rear (with exception of cylinders), new rotor on passenger side, new front brake pads. Yet still this condition persists!

What possibly could be the problem? I'm starting to spend enough money on parts for this thing every month to make a payment on a newer truck!

 

[mangus580]

Sounds like you have a caliper that is hanging up to me...

 

[Recovry4x4]

and maybe a bad hose with a flap in it

 

[superburban]

Re: RE: Crazy suicidal steering and braking.

and maybe a bad hose with a flap in it

What does this mean? Like a rubber hose that has a portion of the inner tube that is acting like an expedient check valve?

 

[mangus580]

Re: RE: Crazy suicidal steering and braking.

and maybe a bad hose with a flap in it

What does this mean? Like a rubber hose that has a portion of the inner tube that is acting like an expedient check valve?

Exactly!!

 

[papercu]

brakes

Is either side hotter than the other after braking hard a few times? Could be a bad calipers, shocks, proportioning valve, brake fluid leak on the pads, air pressure but check your rear brakes. A simple check is how far you have to pull the parking brake lever. If it's easy to pull, the rears need to be tightened. when they are properly adjusted, there will be more tension on the parking brake.
Do you do any off-roading? Wayne

 

[superburban]

RE: brakes

I only off-road every once in a great while with this, because it's my daily driver and I cant afford to fix a big problem right now, especially if it's self-inflicted. The parking brake takes quite a bit of pressure to get it going...

...you know, now that I think about it, last time I had my Utah state safety inspection, the plate brake test showed one side on the rear axle as way light, and one side way heavy, but I figured that it was just due to a rusty adjusted, and I did the old "hit the e-brake while driving in reverse" trick to break it free. Maybe it didn't break free after all!

 

[CCATLETT1984]

RE: brakes

after driving for a few miles, are either of the front hubs hot?

I would suspect either a caliper or a brake line issue. both are pretty cheap to fix.

 

[sprucemt]

RE: brakes

I have been in the situation where not only were the inner brake pads frozen in place, the front axle u-joints were locking up when the lock out hubs were in the free position. The axle would rotate to a spot where the truck, heading in one direction would not want to come back to center. Throw in the frozen in place inner brake pads and it was quite a challenge to drive. It was constantly fighting which way to go.

 

[jwaller]

RE: brakes

hey don would you pls call me? I've tried both your numbers all day long and got nothing.

 

[CARNAC]

Had the exact same problem with a 1009 this past spring. If it's slewing to the left, it is your right brake cylinder and or caliper refusing to close in conjunction with your left one. If slewing to the right, it's the other way around.

If you keep slewing back and forth and back and forth as you are driving down the road, it was the pitman arm. Replaced both the short and long pitman arms and that fixed everything.

 

[Jake0147]

RE: brakes

The statements above are quite valid, I'll second all of the above, and of course throw in that any time brakes are in question it's a good excise to check all four, but a couple of things to keep in mind, the front brakes do a lot more work, you'll usually smell "burnt brakes" or end up with a fading pedal after a good bit of driving. Rear brakes do less work, don't smell burnt (at least not from the driver's seat) and have to be a A LOT hotter to boil the fluid. I usually find that a front brake will steer the truck a little and pull the steering wheel a lot, where a rear brake will steer the truck a lot and only pull the steering wheel a little.

If you have (or if you can borrow) an infared thermometer, a couple of firm stops will tell the tale. Compare the front brake temps to each other, and the rear brake temps to each other, but do expect the fronts and rears to be different. It's really an underused tool for brake diagnosis.

Even if you find the issue to be in the front brakes, I'd still consider knocking the rear drums off to investigate the issue there. Keeping both of the back drums working good won't make a miracle from the drivers seat (provided it's "good enough not to pull"), but it WILL assist in adverse conditions, and will make a surprisingly noticable difference on front brake component life, by keeping the temperatures down a bit.

And to throw in my best guess based on your description- I'd make sure that you don't have a "not quite frozen but really sticky" parking brake cable. If so, that'll also cause heavy wear that won't be compensated for by the self-adjuster on that side.

 

[littlebob]

RE: brakes

Something I've learned is spend time instead of money to diagnose the problem. I worked at a place that had a 3/4t chevy and was eating up brakes. we changed calipers and lines before we finally changed the propotioning valve and that finally fixed it. I'm not a mechanic by trade and don't know how to check one, but I'm sure someone here does. My only thought on diagnosing would be to get the brakes warm by driving and stopping multiple times aggressivly and then jacking the front and checking to see if the wheels rotated without any excess drag.
Good Luck,
littlebob

 

[superburban]

RE: brakes

All good suggestions. I think that I'll do the temperature checks first, then move on to more complicated test.

One more thing that I should note is that the ball joints on the driver's side are a bit sloppy. Would that cause all of the above, or just be a contributing factor?

 

[superburban]

Re: RE: brakes

hey don would you pls call me? I've tried both your numbers all day long and got nothing.

Who is this directed at?

 

[doghead]

RE: Re: RE: brakes

It looks like it was for Don Bagwell.
www.sprucemtsurplus.com

 

[superburban]

RE: Re: RE: brakes

Hey, I just had a thought. Perhaps the pulling to the left is a separate issue from the pulling to the right (while braking). I remember when I replaced the link thinger (between the steering gearbox and the left hub assy), I wasn't careful about ensuring that the new link was the same length as the old one. Could it be that I got it too long, so when the gearbox centers itselft, the front wheels are not actually centered, but to the right slightly?

 

[mdlbldrmatt135]

RE: Re: RE: brakes

Sounds like an Alignment is in order................

 

[Jake0147]

RE: Re: RE: brakes

The temperature gun will determine if there's one or two issues. If there's two issues (a chassis/suspension/tire pull in one direction, and a brake pull in the other direction, the tire treads (right in the middle) will tell you. Brake pulls don't heat tires, chassis/suspension/tire pulls will heat a tire. Better to check that after ten or twenty minutes on the highway however.

Ball joints on one side MAY cause a bit of an issue depending on the severity of the wear, but most likely just a crooked steering wheel and a bit of tire wear, maybe a drift but not a pull. The WILL however "stack" on top of just about anything else that can go wrong and make it act worse.