steering wheel wobble while braking

[cheap 40]

First off, 96FZJ80, 196,000 miles, OME medium, 285/75 BFG AT's. Began to develop a wobble in the steering wheel while on the brakes. My first thought was something in the tires - I've had belts slip before and cause something similar, so I rotated the tires. The first one or two times that i hit the brakes, I thought that I figured it out, then it started wobbling again. Changed wheels and tires with my '97, same thing. So, it's not wheels or tires.

Checked the wheel bearing by grabbing the wheels at 12 and 6 - could not feel any looseness, but when it was on the ground, I could feel a slight clunk while rocking it sideways. Jacked it up, removed the drive flange, and with a prybar in the fins of the rotor and my finger at the ID of the hub, could feel a slight bit of movement on both sides. So, I tore everything apart and found some slight wear at the bottom of the spindles. I did the prick punch trick, repacked the bearings, and adjusted the bearings as per the FSM. The wobble was better for a short time, but returned. I found that the clunk had returned when I shook the truck sideways.

I then readjusted the bearings as per Landtank's method with the same results. It was better for longer, but the wobble still returned, so I thought it was time for new spindles. I figured I was fighting a losing battle with bad spindles. Friday night I buttoned everything up with new spindles and bearings and took it for a test drive. It still wobbles when braking.

So, this is what I've done/checked so far.........

• rotors are not warped. Both check at .001" runout, well within the .006" allowed per the FSM.
• all of the TRE feel tight. I cannot find any looseness in any of them.
• control arm bushings feel tight. With a prybar, I cannot get any movement beyond normal bushing flex.
• calipers seem OK. All pads are worn even with the exception of the passenger side outside pad. It is about 1.5mm difference top to bottom, but I could not find anything binding on either of those pistons.
• I checked the steering system for slop. Found no slop in the input shaft. Rag joint and U-joints seem tight. I did, however, notice some slop in the steering gearbox. This translated to about 15mm at the steering wheel as per the FSM method. Of course, this is well within the 40mm allowed, but the 15mm is representative of the wobble that I see under braking. My '97 feels similar, yet I have no wobble in it.

My first thought is that I need to take up the slop in the gearbox, but I'm afraid that something else is causing the wobble and the slop is allowing it to happen. I want to fix the issue, not put a band-aid on it, but I'm about out of ideas. Help?!? Thanks in advance.

Tony

 

[cheap 40]

I should add that my wife did mention to me that she felt like the steering was not very responsive at times, like it didn't react to input as fast as she thought it should.

Tony

 

[ScottyDog]

Your rotors might not be warped.. however you can get build up of break dust on the rotors that causes pulsating. Either take the rotors off and have them cut or get new rotors.

I had the same thing. At first I only noticed it during braking on steep down hills.. but it got worse over time and started every time I would break. I replaced the rotors and added new 100 series pads, repacked the bearings and hubs and it all went away. I just did this 2 weeks ago and it brakes so much better now. Absolutely no more shaking steering wheel and pulsating brakes.

Good luck.
Scott

 

[cheap 40]

Sorry, I neglected to add in the original post - I have zero pulsation in the brake pedal. Early on in this mess, I rebedded the brake pads because it was easy and I know it can cause some issues.

Now, one interesting thing that you reminded me of is that when I did that and got on the brakes hard, the wobble virtually disappeared. I did not check that the other night. I'll have to check that out on the next test drive.

Tony

 

[cheap 40]

Test drove it again tonight - the steering wheel wobbles whether I brake normally or hard. The interesting thing is that it wasn't too bad the first time I hit the brakes. A little worse the second time, fully bad by the third time.

I checked for trunnion bearing play as per Landtank's method - all was tight. I checked the rear rotor runout to see if they were warped. They both checked under .002", well within spec again. Both rear calipers appeared to be in good working order.

I had my wife turn the steering wheel back and forth within the range of slop to see if anything else was moving and it was not. I had her turn it enough to move the pitman arm while I checked all TRE's again for looseness. All four were tight. What is notable, IMO, is that we did the same thing on the '97 and found about the same amount of slop in the steering gearbox. It stops smooth as glass.....

I'm beginning to think more and more that about the last thing I want to do is adjust the gearbox. It seems like something else is causing the wobble and that the normal steering slop is letting it happen. By tightening the preload in the gearbox I think I'd just be masking the problem. Band-aid on a gunshot wound, so to speak.

Thoughts??

Tony

 

[cheap 40]

What about caster? I just remembered that the OME bushings were laying in the box of parts that came with the Cruiser....

 

[cheap 40]

Bump for opinions....

 

[BlueCruiser84]

If you have a lift and have done nothing with the caster then it will be off. I have no idea if it would be off enough to cause wobble but it would definitely exacerbate any wobble that was there. If the bushings that came with the truck are caster correction bushings I would put them in and see what happens.

Have you adjusted the caster on the 97?

 

[cheap 40]

The caster correction bushings are going in soon. I ran the 97 for a short time without and very much liked the difference with them installed. I'm just not very hopeful that the caster correction bushings are going to stop the wobble.....

Tony

 

[cheap 40]

is this right??

So, I'm working on swapping the control arm bushings for OME yellow caster correction and I noticed that the FSM specifies the small holes in the bushings should be 90 degrees from where they are. Obviously, the front bushings are not a problem because I am going to swap them out anyway, but is the rear (axle end) bushing a problem? Will the bushing flex different because of the orientation of the holes? Thanks for any input.

Tony

 

[psfpilot]

Test drove it again tonight - the steering wheel wobbles whether I brake normally or hard. The interesting thing is that it wasn't too bad the first time I hit the brakes. A little worse the second time, fully bad by the third time.

What brand of rotors are currently on it?
Was the same brake pressure used each of these three times?

 

[Kernal]

cheap40: a bit off your main topic but in your original post when talking about wheel bearings and the spindle you said "I did the prick punch trick---"; what is that??

 

[Cube Dweller]

Rotors. Mine was doing the same for a while, although the rotors weren't warped, I could see 10-12 evenly spaced "hot spots" in the rotors (OEM) when I removed them. No play in any of the bearings either. New rotors, 100 series pads and a repack (since I was there) eliminated the issue and the truck brakes much better.

 

[cheap 40]

What brand of rotors are currently on it?
Was the same brake pressure used each of these three times?

OEM rotors to the best of my knowledge. I would say yes, roughly the same pressure. Weird thing is, tonight I tried it again after installing caster correction bushings, and when I stand on the brakes, it is perfectly smooth.

cheap40: a bit off your main topic but in your original post when talking about wheel bearings and the spindle you said "I did the prick punch trick---"; what is that??

When the spindle is a little worn, you can deform the area that the bearing sits with a sharp punch to take up some of the slop. The preferred method is to knurl it, but that usually requires chucking the part in a lathe.

Tony

 

[cheap 40]

Rotors. Mine was doing the same for a while, although the rotors weren't warped, I could see 10-12 evenly spaced "hot spots" in the rotors (OEM) when I removed them. No play in any of the bearings either. New rotors, 100 series pads and a repack (since I was there) eliminated the issue and the truck brakes much better.

Did it change behavior when driven for a while? I've noticed that when the brakes are cold, it doesn't seem as bad. But after the brakes are good and warm, the slightest amount of braking induces severe shaking. But even then, if I stand on the brakes, it is nice and smooth.

Tony

 

[Cube Dweller]

Did it change behavior when driven for a while? I've noticed that when the brakes are cold, it doesn't seem as bad. But after the brakes are good and warm, the slightest amount of braking induces severe shaking. But even then, if I stand on the brakes, it is nice and smooth.

Tony

It was not consistent, more noticeable on slight turns to the left when braking, sometimes it would wobble, sometimes not. Not sure on the cold vs. warm part, at least I never noticed any correlation. I was sure it was a wheel bearing issue, and had checked them several times.

 

[cheap 40]

I think you're right, I realized that my bed-in procedure may not be sufficient. I found Stoptech's method and am going to try that. If 20 aggressive stops from 60 to 10 mph won't clean the rotors up, nothing will and it'll be time for new rotors....

It's snowing right now and will be for another day, so it'll be Wednesday or so before I try it again. I'll update when I do. Thanks again for the help.

Tony

 

[cheap 40]

It worked!! I actually did 12 stops on the second round just because I could still feel it shake a little bit. Once the brakes cooled off, they work fine, just like the 97. Thanks for the help!!

Tony