Thread: Need diagnostic help on SEVERE steering wheel shake

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Originally Posted by Lord Antagonism

Is this power or manual rack & pinion steering? Had a buddy in the army way back when that had an old Honda car with power rack & pinion, some internal seal or O-rings gave out and because of the internal leak from the high pressure to return side inside the rack assembly, the steering wheel on his car would do a weird toggling wobble without actually affecting the direction the wheels were pointed.

Manual, but a good thought

OK

while you have the wheels off---look at the rotors very closely---I have had split ones that you could squeese with a set of channel-lock pliers and see the movement /cracked area---

also toward some comments----a loose steering column will not cause front end shimmy/wobble---something is not in the correct specs/geometry---

Are your front wheels / hubs giving you the correct scrub radius???

Originally Posted by jerry clayton

OK

while you have the wheels off---look at the rotors very closely---I have had split ones that you could squeese with a set of channel-lock pliers and see the movement /cracked area---

also toward some comments----a loose steering column will not cause front end shimmy/wobble---something is not in the correct specs/geometry---

Are your front wheels / hubs giving you the correct scrub radius???

Will do,... how would I find out what the correct "scrub radius" for my set up should be?

One thing to remember is that you probably can’t use the alignment specs from the original car the front end items came from. Your car is now heaver and the weight distribution is different.

I am thinking that your caster and camber is probably too close to “O” or the combination of the two does not match what your car needs.

Take your car to an alignment shop that specializes in hot rods or custom cars. Your local tire shop and part houses only know one thing anymore (check the book and/or do what the computer says to do).

Good luck and hope you get it fixed soon.

Bug

Originally Posted by Bug

One thing to remember is that you probably can’t use the alignment specs from the original car the front end items came from. Your car is now heaver and the weight distribution is different.

I am thinking that your caster and camber is probably too close to “O” or the combination of the two does not match what your car needs.

Take your car to an alignment shop that specializes in hot rods or custom cars. Your local tire shop and part houses only know one thing anymore (check the book and/or do what the computer says to so).

Good luck and hope you get it fixed soon.

Bug

Good advice! Thanks!

I'm almost certain you need more caster and possibly more toe in.
If you have the strut rods you wil probably find there is a bit of bind at the "up" travel limit. My car is pretty low in front and I get just a little bind at the "up" travel limit.

I run about 7 deg caster and 1/8 toe in measured at the tire center line. About 1 deg neg camber (top of tire is closer to the center of the car.) Other than the car is a bit heavy on the steering for a light weight car it tracks very well and is rock steady in the cross winds. It actually handles pretty well for a big tires, little tires car. I did a funny car high speed back up just to relive the old days and it does ok there too. Often lots of caster would cause death wobble backing up.

Death wobble usually occurs when the alignments are very close to "0".

I have an adjustable strut rod with spherical bearings for my MII based front end suspension. No binding through the whole travel range.

Bug

if I may....
I not have as much experience with hotrod engines and old cars as you guys.
But the "death wobble" I am very familiar with.

this was very common with F350's with the Dana 60 front axle (I've owned 4 of them, and only one didn't have the problem).
The first time we had the problem we changed out EVERYTHING on the front end.
We discovered and subsequently proved that you needed a good trac bar, with good bushings to keep the axle from wobbling (which starts the movement at 45-50mph).
Also installing a good power steering dampner was essential.

I don't know if this will apply to you, but I figured I'd mention it as we've spent many a night scratching our heads to figure out the problem.

Drew

A guy I worked with bought something like an 08 Jeep and it had DW. He took it to a 4 x 4 shop and it turned out the dampener was worn out. Replaced it and it went away. So you are right about the importance of one. Don't know if one can be added to a MMII front end, but they sure don't hurt.

Don

Take and put the wheels and tires off of something different and drive it and see if it goes away. I bet that the steel belt in one of the tires is seperating as the wheel spins. When you stop, it returns to normal and then starts up again after a touch. It will be a violent shake. A seperated belt doesn't always stay as a swollen up knot on the tread. I beleive you have a bad tire. I even had it on a balancer and it spun good. It would only do it on the car with the weight on it. ( Went thru this crap on my wifes car ) I learned something on that one.

Originally Posted by Weasel Diesel

Take and put the wheels and tires off of something different and drive it and see if it goes away. I bet that the steel belt in one of the tires is seperating as the wheel spins. When you stop, it returns to normal and then starts up again after a touch. It will be a violent shake. A seperated belt doesn't always stay as a swollen up knot on the tread. I beleive you have a bad tire. I even had it on a balancer and it spun good. It would only do it on the car with the weight on it. ( Went thru this crap on my wifes car ) I learned something on that one.

Changed tires now to 3 different combinations, same symptoms, though slightly better (less violent) the larger the tire I used. Two of the sets were 2010 dated tires (the larger ones) the small sets were a real miss-match (2007 & 2009 dated).

BT---

scrub radius-----take a line thru the upper and lower ball joint and it should pass thru the center of the tire/pavement contact patch--

I once had a car that the wheels/balance weights hit the brake components.

Did you measure/examine the brake rotors???

It seems you are wondering around in circles and not eliminating possible causes--

does the wobble worsen/lessen with more /less brake pressure???

What are the results of the alignment??? actuall numbers for toe, caster, camber left and right---

How much did you lower the car???
I am assuming the car in your gallery is yours?

Originally Posted by jerry clayton

BT---

scrub radius-----take a line thru the upper and lower ball joint and it should pass thru the center of the tire/pavement contact patch--

Thanks!

Originally Posted by jerry clayton

once had a car that the wheels/balance weights hit the brake components.

Checked, not happening

Originally Posted by jerry clayton

you measure/examine the brake rotors???

on my list to do next

Originally Posted by jerry clayton

the wobble worsen/lessen with more /less brake pressure???

lessens with more brake pressure

Originally Posted by jerry clayton

are the results of the alignment??? actuall numbers for toe, caster, camber left and right---

Front Left / Right
Camber -1.4/ -0.7
Caster 1.6 / 2.5
Toe 0.12 /0.11
SAI (?) 9.3 / 10.1
Included Angle 7.9 /9.4
Cross camber -0.7
Cross castor -0.9
Cross SAI -0.7
Total Toe 0.23

Rear Left/Right
Camber 0.1 /0.0
Toe -0.01/ -0.15
Cross Camber 0.1
Total Toe -0.16
thrust angle 0.07

Originally Posted by jerry clayton

much did you lower the car???

4" front, 2" rear (not certain what stock levels were, this is from "pre-change" numbers)

Originally Posted by jerry clayton

am assuming the car in your gallery is yours?

yes...

Originally Posted by jerry clayton

seems you are wondering around in circles and not eliminating possible causes--

Completed many of the the suggestions, but have compiled quite of list of where else to look which will wait until next weekend (work days) wheels off today to be rebalanced at a specialty alignment shop today. Will check the rotors with a borrowed cal tonight.

The "55 mph" and "Goes straight" part sorta sounds like a driveshaft out of phase or out of balance.

Death wobble is a common demon on Jeeps with 33" and larger tires running on the highway. While it can be a real bear to solve, it almost always involves some combination of caster and/or toe in out of spec plus one or more worn components in the front end, either tie rod ends, drag link ends, pitman arm, ball joints or panhard bar. One of the biggest causes is the panhard bar mount being loose, or having worn ends allowing the differential to oscilate side to side on up and down suspension motion. I understand that the panhard bar is not a possibility here on a MII IFS - just pointing out that it is a common demon on 4WD's.
The steering dampner by itself is not going to solve death wobble - it is indeed an important component, especially with big, aggressive off-road tires, but if you have things out of spec the steering dampner is a temporary band-aid at best. IMO you need to be looking for a worn front end component, plus being sure your caster and toe are set on the money.