cause of a shimmy?

[Scorpio-jw]

if the knuckles were leaking and worn, would this cause a shimmy?

i have new ome-low height heavy springs, bilstein shocks, pan rod bushings, caster correction, steering damper, wheel bearings, alignment, sway bars, tire and wheel balance. i'm running out of ideas for the cause and solution.

any help or suggestions would be appreciated.

thanks,
jw

 

[-Spike-]

If the trunion bearings were shot it might. Rebuild the knuckles and see what happens, sounds like they need it anyway.

-Spike

 

[Hants]

You don't identify when the shimmy is occuring -- could be brake-related.

 

[landtank]

low height springs shouldn't have the caster bushings installed. I'd take them out and see how it does before anything else.

 

[Scorpio-jw]

it seems to occur when i hit a bump or depression on side of the vehicle. almost like an undamped side to side oscillation.

 

[Scorpio-jw]

it was out about .8 degrees, so the caster correction reduced it to .4. it seemed to help a little

 

[-Spike-]

Feels like you're gonna die? Otherwise known as 'death wobble'? If so, that's not a shimmie, that's a whole 'nother animal!

-Spike

 

[Scorpio-jw]

man a fre looked at it and their suggestion was to replace the shocks and the pan rod bushing. Both were replaced.

 

[-Spike-]

How about the steering stabilizer? Both panhard rod bushings? Again, if you haven't rebuilt your knuckles with new trunion bearings, they may very well be the cause.

-Spike

 

[Scorpio-jw]

thanks for the suggestions. changed the steering damper and both bushings. i took it to a local mechanic and he's leaning towards rebuilding the knuckles.

 

[sleeoffroad]

it was out about .8 degrees, so the caster correction reduced it to .4. it seemed to help a little

Huh? This does not make sense at all? Caster is 3 degrees, plus/minus one. So it should be 2-4 degrees. So you have a prinout of the alignment?

 

[Scorpio-jw]

hi slee,

no i don't, but i meant to say it was outside of the normal range and now it is .4 away. i have bfg all terrain 275-60-16 load range d and the mechanic thinks that the side wall combined with the ome springs and the worn knuckles is causing the shimmy. once the tire pressure was dropped most of the sudden side to side shake was minimized.

what do you think?

jw

 

[sleeoffroad]

I would still like to see the alignment readings. You can get a caster sweep done for pretty cheap. Describe suddden side to side shake?

 

[Scorpio-jw]

this may be a simple question, but what is a caster sweep?

the side to side is triggered by an unevenly distributed bump between the left and right side. the shake seems to be an undampened oscillation of 4 little jolts; right-left-right-left.

the mechanic reduced the tire pressure and this shake was reduced. that was when he mentioned that the load range d of the tire might be too firm for the weight.

 

[-Spike-]

the side to side is triggered by an unevenly distributed bump between the left and right side. the shake seems to be an undampened oscillation of 4 little jolts; right-left-right-left.

the mechanic reduced the tire pressure and this shake was reduced. that was when he mentioned that the load range d of the tire might be too firm for the weight.

Sounds like a load of crap to me. When you lower the tire pressure, you're just giving the occilation a place to go- the softer tire absorbs it. You still have the problem.

-Spike