Steering wobble

[79vette]

I have an 86 K5 on an 82 10 bolt front axle. 33" Wrangler MTRs.
Ball joints, tie rod/rod ends, wheel bearings, steering box brace all new about 10k miles ago, and the truck has driven fine for about a year and a half since I did all that work

There's a huge bump in the road on my way to work that I hit at 35mph and usually produces a minor oscillation in the steering that damps itself out after a second or two (5-6 minor oscillations)

Yesterday I checked the tires and noticed they were all badly under inflated (26 psi) so I aired them up to 35. When I hit that bump this morning I nearly wrecked the truck. It was instantly the worst death wobble I've ever experienced, and despite immediately applying gentle braking and maintaining as much steering control as I could the truck almost went off the road into a parked semi trailer. I went around the block and hit the bump again mich slower at 25 mph and got the same thing, but it was easier to regain control due to the lower speed.

When I get home tonight I'm going to jack up the front end and check for slop in the wheel bearings, ball joints and tie rods, check the toe in, check for loose/worn suspension bushings, loose steering box bolts/frame cracks, loose U bolts, visible tire damage/broken belts, and anything else I can think of. I think whatever the problem is has been there for awhile and was masked by the low tire pressure, but I don't know how to identify it.

I'd appreciate any suggestions on what to look for.

[mongocanfly]

Does it have a steering stabilizer on it?
Assuming you had the front alignment done when you did all the work before

[kwmech]

Check the frame for cracks around the steering box. How do you check the toe in by yourself

[mongocanfly]

Yep.kw,. I forgot to add the cracked frame

[79vette]

Turns out the toe in is ~1", which is WAY too much, and probably what was causing the problem. I did get an alignment when I did all the front end work a couple years ago, but there is no way the alignment shop did that. I must have bashed the tie rod on a rock or something recently and not noticed it, because if the toe had been that far in for a long period of time I'd expect to have really noticeable tire wear.
I reset it to ~1/8" and I'm hoping that fixes the death wobble.

Now I have a new problem though. I noticed the front brake calipers were dragging when I was checking out all the steering parts, and I assumed the old calipers had corrosion in the bores and we're sticking. So I had the rotors turned and replaced the calipers/pads

With the new calipers and pads installed before I bled the system the hubs spun free, but after bleeding and pumping the pedal a couple times now they drag again. Loosening the bleeder screw at the caliper allows fluid to weep out, but the caliper does not release. With the bleeder open it seems like any residual pressure should escape and the caliper should release, but they do not. Loosing the bolts between the master cylinder and brake booster also does not cause them to release. It seems like something is restricting fluid flow enough that the return spring in the caliper cannot retract the piston all the way, but I have no idea what it could be. Calipers are new, flex hoses are new, master cylinder was new ~1 year and 7000 miles ago.

Originally Posted by mongocanfly

Does it have a steering stabilizer on it?
Assuming you had the front alignment done when you did all the work before

Yes it has a steering stabilizer, but its old. This was really bad oscillation on a paved road though. I always though steering stabilizers were for rough roads/off road to keep the wheel from getting wrenched out of your hand. On the highway it might help mask a problem, but I don't think it would be needed for regular driving?

I did have an alignment done, but I didn't review the printout. I just drove off the lot and assumed it was good (mistake).

Originally Posted by kwmech

Check the frame for cracks around the steering box. How do you check the toe in by yourself

I use a set of tape measures and an aluminum fixture that bolts to each rim. See pictures below. You can take the difference between the 2 tape measure readings and with a bit of trigonometry determine the toe angle. See pictures.

The aluminum arms are 33.25" long and I can measure accurately to at least 1/16", so it should get 0.1 degree precision or better.

Frame seems free of cracks around the box

[RodnRudy]

It's normal for the brake pads to drag on the rotors. I'd replace that steering stabilizer too. I had one on my 79 K10 go bad at about 35000 miles, the wobble scared me to death. bought one from NAPA and it solved the problem.

[79vette]

Originally Posted by RodnRudy

It's normal for the brake pads to drag on the rotors. I'd replace that steering stabilizer too. I had one on my 79 K10 go bad at about 35000 miles, the wobble scared me to death. bought one from NAPA and it solved the problem.

It requires significant force to turn the hub. It's possible to turn it without a pry bar, but I'm a pretty strong 6'3" dude and I have to really try to do it. The hub will not coast at all when spun.

The pads might "drag" a tiny bit, but I don't think they should be clamped down hard enough to prevent the rotor fom spinning like this.

I'm hoping the alignment fix will correct the wobble. If not I'll get a new steering stabilizer, but I think that might just mask the real problem.

[mongocanfly]

On the dragging brakes, check and make sure the pads move freely on the mounting bracket
I had dragging brakes on my C30 and that's what the problem was..little rust and dust buildup...I used a roloc pad on the bracket and it solved the issue
I dont know of a return spring in the caliper piston, opening the bleed screw should release any brake tension you have,

[franken]

Wheel balance on the fronts? When was the last time you rotated the tires? Straight axle 4x4s need to be rotated often to help not eat front tires.
It doesn't sound like it's the the death wobble, but it's good practice.