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Estimating lift

Fresbone

Fresbone

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My CJ5 just developed death wobble. I previously rebuilt the front end and the tie rods aren’t loose. I think the problem is 1. Low power steering fluid level due to slow leak I have been ignoring and/or 2. Bad shocks. The shocks were beat up when I reinstalled them and I installed the front shocks upside down to get better clearance from the axle.

So, I’m definitely going to top off the power steering fluid and fix the leak, but I’m also going to replace the shocks with new shocks that can be mounted upside down. I’m trying to figure out how much lift I have.

I measured the diameter of my tires (31.25) and the height of the windshield (73.75). I have read that the original CJ was 67” tall with 16-6 tires that are 28.75 diameter.

If I calculate windshield height - 1/2 tire diameter (for center of axle), I get:

Original CJ 52.625
My CJ 57.875

So can I assume that I have a 4+” lift?
 
Fresbone said:
My CJ5 just developed death wobble. I previously rebuilt the front end and the tie rods aren’t loose. I think the problem is 1. Low power steering fluid level due to slow leak I have been ignoring and/or 2. Bad shocks. The shocks were beat up when I reinstalled them and I installed the front shocks upside down to get better clearance from the axle.
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Kinda doubt either of your theories.
Have you measured the caster?
More likely you have no caster, or the tires are badly out of balance.

Re the lift height, my tires are 32" and the top of the windshield is 72" with a nominal lift of 2.5".
This puts you at a 5" lift, though I think this rather arbitrary and the overall height is not relevant to the wobble.
Changing the springs will change the caster, and I'd imagine that's enough to wipe out the factory caster.
Lots of threads about this if you search.
 
As per Tim, I doubt the shocks, PS, and lift are directly responsible for the DW's. Did you check the shackle bushings, king pin bearings, and wheel bearings? Caster can contribute to the problem but usually isn't the cause. But tire imbalance certainly can.
 
Death Wobble can result from wear in any and all of the steering system components - including the ones you've never wanted to think about. Did your 'rebuild' include all of those, and have you checked adjustments and specifications since then?

Estimating lift seems like guesswork to me. Assuming their dimensions and range worked okay, can you remove an old shock and take it with you to your FLAPS?
 
Couple of things.

I don’t think the lift is causing the death wobble. When I was researching shocks for a 67 CJ5, sites list less than 2” lift and 2-4” lift. That’s why I was trying to estimate my lift.

My shocks were banged up, bad ride, and I want to flip the front ones upside down, so I was planning to replace them anyways. That was why I was going to start with shocks. I knew they shouldn’t be installed upside down when I did it, but thought I would roll with that for a while to postpone an expense.

Kind of the same thing with the power steering. Low fluid plus leaks is bad, and I read a few threads where people claimed it could contribute to death wobble. It needs to be fixed, so I might as well do that first.

For my rebuild, I went down to the frame. This was the first time I have done anything like this, so anything could have been done wrong, but I put new bearings in the steering knuckles, rebuilt the lockers, and cleaned and relived the tie rods. I didn’t see any signs of wear, but, again, I could be wrong. On and off the lift, nothings seems loose. I had the tires rebalanced about a month before the death wobble started. I took my jeep to my mechanic to make sure there wasn’t anything unsafe, poorly done before I started driving, and he did some work on the steering to get a better angle from the column and the Saginaw gear box. That was about 6 months ago.

So, I may be wrong about what is causing the death wobble, but it seemed like the first place to start.

I certainly can take the shocks to FLAPS, but they are aftermarket, and who knows if they were the correct shocks in the first place. I think they were part of a rugged ridge lift kit.
 
Fresbone said:
I certainly can take the shocks to FLAPS, but they are aftermarket,
Click to expand...

Well if they worked okay, you can ask for some with the same range of travel.

Getting a reliable professional alignment might be a good investment at this point.
 
Fresbone said:
had the tires rebalanced about a month before the death wobble started.
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IME, tires are the culprit 90% of the time.

Tires can be statically balanced (which will make the tire roll without a bounce in a straight plane), or dynamically balanced (which will also reduce or eliminate any wobble or sideways forces in its rotation). A statically balanced tire can still be horribly out of balance dynamically. If don’t have wheel weights on the inside AND outside of your wheels, I’d recommend getting a dynamic balance first.

Just to see if it makes a difference, first try swapping the tires front to rear. You might just have one tire up front that is the issue.
 
A few things to add.
I replaced the kingpin bearings and wheel bearings when I did my rebuild. I had my wheels dynamically balanced. I think the professional alignment is a good call. Thanks, everybody.
 
Get the printout from the machine.
They can only set toe and center the steering without a labor upcharge and installation of shims and such.
 
X2 on tire balance.

I have a side project with older 31 inch tires. It sat for a long time and when I got it back on the road it would enter a heavy death wobble right away. The steering and alignment are prefect and it even has a steering stabilizer. I took it over to the tire shop and he had a difficult time balancing them. It has mags so he had to use a dozen or more stick on weights.

My theory is tires that sit for a long time like this one develop flat spots and the rubber becomes less pliable and hard to balance. Even now, it will occasionally enter a death wobble but after the tires warm up it goes away.

I know, I should get new tires but this is a toy for buzzing around town, tread is still good and not my favorite for off-roading so it gets very little of the budget.
 
I would say you are right about the shocks they are probably doing absoluetly nothing upside down did you cycle them like that to test? Caster is important but it doesnt solve the problem all the time. Also I would remove the wheel weights entirely and try that. Just mark where they were so you can put them back on if you want. How old are the tires?
 
This sounds familiar.

I have a 48 CJ2A that has about a 3" lift. The Jeep came to me with some serious problems in the steering system which could have gotten me killed. It had a steering stabilizer I assume the previous owner installed in an attempt to resolve some of the problems. Might have helped some, but it didn't fix much. The driver side TRE was binding from being too deep into the steering arm, the oversized tie rod was hitting the shocks before reaching full stop on turns, and the steering stabilizer was bottoming out on left turns. This called for a rebuild.

I rebuilt the steering with a new tie rod, new drag link, all new TREs, and new manual steering box (Saginaw conversion with two hole knuckle and one piece flipped tie rod). I ditched the oversized tie rod and stabilizer.

I first set toe in at 1/4" because that is what the previous owner had recorded in his build log. On first test drive I encountered severe death wobble around 45MPH. This was my first time experiencing death wobble, and it was a bit discombobulating.

I adjusted toe in to 1/8" and that helped but still some shimmy above 40 MPH. I adjusted toe in to 1/16" and that did make it more stable at speed, but steering is still too light giving a loose feel, and it does not return to center well. I measured caster using a digital angle finder on top of the Kingpin bolts, and decided this is where the problem lies.

The previous owner had installed 4 degree caster shims, wedged to the rear, reducing positive caster by those 4 degrees. I think this was an attempt to get better pinion angle, but it sacrificed caster.

My next step will be to remove those shims to gain 4 degrees on positive caster. This should stabilize the steering and improve return to center.

I don't think this will present much of a problem with pinion angle, but I have a set of 2 degree shims if that looks to be a problem.

The springs used on this Jeep are Holbrook Longleaf springs, which were very popular a decade ago. Because the center pin of these longer springs is offset forward of center they will normally increase caster, which I think was an intentional part of the design. This design feature is circumvented by folks adding shims to level out the pinion angle. I prefer safer driving behavior over perfect pinion angle on a front axle with lock out hubs.



Below is the Jeep I am talking about.
 

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If I find an issue with pinion angle, something like that might be an option to consider, but I don't think the angle will be enough to be a problem.

I described what I am going through hoping it might be of help to Fresbone, who may be going through the same sort of thing I am, but I don't want to hijack his thread.
 
I have been goofing around at the beach and working on my Jeepster, so I put the CJ5 on the back burner. I put the CJ5 on a lift and the steering stabilizer was loose. I was hoping that the loose stabilizer was causing the problem by having shifted into a bad position, so I took off the steering stabilizer and there was no improvement. My suspicion is that the steering stabilizer was put on to mask a problem, and when it became loose, the problem was unmasked. Now to figure out what is causing the problem!
 
Alignment. On a simple leaf spring suspension, it is, well….simple. On our jeeps you can easily control caster and toe-in. You want around 1/8”-.1/4”toe-in and 6 degrees of positive caster. With a lift, caster is often the problem. You can check this with an angle finder on the knuckle on level ground. If you don’t understand caster, watch some videos on it and things will make sense.

Edit: this of course assumes that everything else is in good condition: suspension and steering components, TREs, tire balance/pressure, etc.
 
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I have woodworking tools, so measurements are a little janky. My toe in looked fine - just about 1/4” like you said. You can’t change camber, but it looks like there is just a degree or so. I think caster is the problem. I used my digital angle finder on top of the bolts for the upper king pin bearing vs the floor and it was neutral. I think I have about a 4” lift, so I wouldn’t mind dropping it a bit. It is a project car, not a rock climber for me. The wheels are also a little suspect the way they are weighted. I took my JEEP to my shop to have my buddy do some real measurements and give me suggestions.

Spring bushings looked ok to me.
 
I developed a wobble in Farm Jeep Willy. I put new spring bushings in and everything else was tight. I was previously running 1/8" of toe in. Every now and again, if I hit a bump just right, it would do it again. A friend suggested to try 0 to 1/8" toe out. Works perfectly now, no wobble. Heck, my ball joints nowadays have play even and still no wobble. Also, no irregular tire wear.
 
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