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Pulls the the right and a bandaid on the Death Wobble

joshthemule

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Clarksville, TN
LOTS OF DETAILS SO PAY ATTENTION

First. 91 Burban with custom Alcan lift springs and Kingpin D60 with cross over. Stock tie rod. 37" H1 radials on 16.5 wagon wheels. When I did the cross over, I put in new upper kingpin springs and bushings. I pulled the axle out of the original CUCV it came from so, it never had oversized tires on it but I'm sure it was abused.

Under normal driving conditions the truck pulls the the right on laterally level road. Its not a progressive pull. Its just that when steering is in a state of equilibrium, its turning slightly to the right. Enough so that I have to hold constant pressure against it. After the axle swap it also had a death wobble only when I hit a bump on the right side (the side it pulls to) and only at slow speeds. I put a big fender washer under the right king pin spring and the wobble went away. Now its starting to wobble again. I have not taken apart my knuckles to check the condition of bearings and such.

Here is a weird note to add. If I go around a right hand turn hard enough, when I straiten out, the truck drives strait with out pulling. But, after a few seconds of strait driving the truck starts pulling to the right again. Also, the truck leans more to the right when turning left than it does to the left when I turn to the right.

So here are all the things I thought of and why they might be true or untrue

1st, I wondered if the axle was square and if the center pins in my custom made leafs were miss aligned. I did measure from the hanger bolt to the axle and the axle seems to be squarely under the chassis. I haven't pulled the springs out and actually measured the pins though.

2nd, I wondered if the right side spring is sagging more than the left. Since the spring center moves more towards the rear of the truck when compressing, this would explain the axle being off center and pulling to the right. This would also explain the tendency to lean so much more to the right when turning. I'm not sure if the constant correction to the left would help cause DW or make it more susceptible to it. But, as I mentioned above, when the truck is sitting in my driveway, the axle is squarely under the chassis and it does not seem to be leaning. (I measured from the ground to the front hanger bolt on each side)

I think what I need to do to eliminate or prove the above possibilities is swap the left and right front springs around. Its just so F'ing cold out lately but I'm sure I'll end up doing it before long.

3rd possibility. My right side lower king pin bearing is worn out. This is my favorite possibility because I get to buy something and tear apart something I've never torn apart before. Also, it could be spindle bearings. The lower kingpin bearing could definitely explain the pull because it would affect camber and caster. It also explains the DW. That poor spring (even though it was new when I did the swap 3 months ago) just wouldn't have the strength to hold the lower kingpin center and even with the fender washer shim, its getting worn out. Now, this may be a stretch but if the right side knuckle is misaligned, it would cause more drag on the right side of the axle and thus pull the leaf spring to the rear some. This pulling could cause the leaf spring to compress a little and exaggerate the compression in a turn. Also, the knuckle would have a chance to recenter itself when its offloaded in the right turn so that could be why it drives strait for a few seconds then starts pulling again.

Here is my plan, I'm going to swap the front springs and if that solves it, the guy at Alcan springs is going to replace them free. I'm doubtful that this is the problem though.

Next, comes a kingpin rebuild kit for both sides. As much as i would like to do this (just because I like putting new **** on the truck) it cost money and there are other things I'd like to do when I get it apart (new locking hubs) and I really don't have the money for that.

So, I'm looking for your ideas and suggestions obviously. Is there something I'm not thinking of? Should I go about trouble shooting in a different order or is there another way to trouble shoot?
 
I think your #2 option is not what you think. The spring sagging on one side would only make a difference if it were a non-steerable axle. Any amount of slight difference is easily taken up by the steering knuckles being able to self-center.

I'd have to guess you have some bearing or kingpin issue since those were not replaced.
 
i got the same problem with my k5... for a quick fix i just stuck a few washers under the king pin caps. that fixed the death wobble but now it drives kinda weird.

the pulling could possibly be a bad wheel joint? sounds weird but i had a 10 bolt that would do that. after turning a corner it would stay pulling that way then would snap back after like 20 seconds of driving. so do what you say your going to do. rebuild the king pins and check out your wheel joints for the hell of it since you have it all tore apart
 
What about a sticking brake caliper, or some severe toe-in or toe-out?? :dunno:

You have two issues...the pull to the right, and the DW. Something is obviously wrong with the front-end if it's pulling like that. Even stock "push-pull" steering setup shouldn't do that.

Step 1 is to isolate the source of the pull and fix that, then re-assess if the DW is still an issue and to what extent.
 
after turning a corner it would stay pulling that way then would snap back after like 20 seconds of driving.

Might be going off on a tangent, but FWIW, I had this problem on both my 84 & 87..fixed both times by replacing the front springs & shackles - My guess was that the bushings where the shackles mounted to the body were shot, allowing the whole assembly to cock one way or the other when turning.
 
Might be going off on a tangent, but FWIW, I had this problem on both my 84 & 87..fixed both times by replacing the front springs & shackles - My guess was that the bushings where the shackles mounted to the body were shot, allowing the whole assembly to cock one way or the other when turning.

Good idea but the springs and bushings are all new
 
First, I appreciate all the ideas and help.

The weather was great today in Virginia so I was out in a tee-shirt wrenching away.

I swapped the front tires left to right and right to left and that didn't change anything. Then I preceded to pull out the leaf springs in order to swap them too. Once I had them out I did some measuring and I think I found the problem. I laid them next to each other and they seemed to be ached the same. Then I did some rough measuring from the front hanger bolt hole to the center pin. It seemed to be off a little so I figured a way to compare them.

First I put the hanger bolts through both sides in order to line them up.
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Then I used a speed square to measure the difference between the pins
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So as it turns out, the pin on the right side spring is 3/16" farther back than the left side. Since the pin is about half way out on the axle from center, the tire is probably more like 3/8" farther back than the left side.

The conclusion.
The axle is not square under the frame, even though I thought it was from my original measurements. This definitely causing a pull to the right. Also, because that side is always correcting to the left and compressing the king pin spring more, it may be more susceptible the DW.

Anyway, guy at Alcan Spring already told me that if I find something wrong with the springs, he would replace them at no charge to me. So the rig is on jack stands for a few weeks I guess. I'm just glad I figured it out.

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Sounds like you might have found the problem. Have you replaced the front shackles yet? Just a little insurance.
 
Good idea. I wanted to buy the ORD shackles but I haven't figured out what that would do to my lift and camber.
 
When you say "wheel joints" what are you talking about?

wheel joints as i thought they were called, are the ujoints in the front axle shafts. what are the proper names for those things are they just ujoints?
 
They are negligible. I put them on, even though mine looked okay. As soon as I took the stock ones off, I saw shiny spots on the frame where they were rubbing.
 
So after all that measruing and realigning, its still pulling. So, I'm going to swap the springs and see if it goes away.
 
So I swapped the leafs (left for right) and the problem is still there so I guess that totally eliminates the leaf springs.

Two other thoughts.

One, if my axle is shifted to the side would that cause a pull and would a panhard bar help?

Could my axle tube be bent? if so, how do I straiten it?
 
Rather than the axle being bent, it's more likely one of the original issues mentioned. Lower kingpin bearings or a stuck brake caliper. What's your toe-in set to?
 
I'd be totally lying if I told you I know the right way to set toe in. I've read about it a bit but I've never done it. I might take it to an alignment shop to do that. They can at least tell me what else is out of spec.
 
If you have a tape measure, you can do it.

1. Measure the distance between the inner sidewalls of the front tires as about halfway up the tire (near the tie rod ends).

2. Measure the distance at about the same height, except at the back of the tires on the other side of the axle.

You want the fronts of the tires to be a little closer than the backs of the tires. Somewhere between 1/8"-1/4".
 
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