Wobbly at high speed (1 Viewer)

[Mackeath]

Greetings wise cruiser people,

my 99 LX470 with a retrofitted to a 100 series suspension has developed a wobble at high speed. Above 55 or 60 or so. Especially when a wind or a truck comes along. I think it might be what you call on the forum body roll. Regardless, I don’t think it is safe on the highway.

the steering stabilizer seems OK. And the shocks are only about 20 months old. What else should I be looking at?

thank you for your thoughts and ideas.

 

[highonpottery]

My understanding is the conversion is pretty much only springs, torsion bars and shocks - those won't really develop a speed wobble. When was it done - 20months ago? Is the speed wobble a new event? Where do you 'feel' said wobble in the vehicle? Through the steering wheel, the body of the rig, etc

Wobbles can be caused by all sorts of things but to start I'd check basic things like the lug nuts, wheel bearings, maybe look for bad bushings and get your tires checked for balance. Those are simple things you can do.

I'm sure others will have more suggestions

 

[trdcorolla]

I'm assuming your running LC shocks/LC torsion bars and LC rear springs. If you cranked the front to level it out, you may have to lower it to get your wobble to go away. If your at stock heights maybe have your tires/alignment checked, a real alignment that checks/adjusts caster, not the quick toe and go alignment.

 

[JunkCrzr89]

Unbalanced tires, worn inner tie rod ends, etc...

 

[Mike NXP]

General advice on body roll would be to check Sway Bar Links which are a main component in controlling roll.

If you have more of a wobble or shake then you are into steering and suspension parts.

 

[utflowerman]

Understanding it is worse in wind/semi wash...

Is it constant at those speeds? Only on a curve? Only after a bump? Present in a straight line?

 

[Mackeath]

Hi, thank you for the fast responses!

1. It has steadily gotten worse over the last 3 months. It was not like this after the conversion. The springs used in the conversion were slightly used but I don’t think that is it.

2. I am consistently not the sharpest tool on these. How do I check for a bad bushing?

3. I did level it out. So lower the front again?

4. How do I check for worn inner tie rods?

5. It seems to be the same on curves as it is on straights and seems to only get funky when a wind kicks up or a truck passes hard. Bumps don’t seem to affect it.

6. And by sway bar links you mean where it actually connects? Make sure it isn’t loose?

thank you!

 

[Mike NXP]

Hi, thank you for the fast responses!

1. It has steadily gotten worse over the last 3 months. It was not like this after the conversion. The springs used in the conversion were slightly used but I don’t think that is it.

2. I am consistently not the sharpest tool on these. How do I check for a bad bushing?

3. I did level it out. So lower the front again?

4. How do I check for worn inner tie rods?

5. It seems to be the same on curves as it is on straights and seems to only get funky when a wind kicks up or a truck passes hard. Bumps don’t seem to affect it.

6. And by sway bar links you mean where it actually connects? Make sure it isn’t loose?

thank you!

I think we need to focus in more on the symptoms. If your cruising down the highway what do you feel? Does it shake or do you only feel the issue when trying to maneuver the truck and counter passing vehicle?

Generally speaking If your vehicle is feeling more of a roll and boat like feeling you can consider sway bar links and bushings ( the big bar that runs under the vehicle and connects both sides) OR worn out shocks as the top two culprits.

If you are getting more of a wobble , pulsing, shaking then you need to look at wheel balance, tires, suspension, steering components, etc.


Just need to narrow down the symptoms a bit more . Anything just look visually worn down there? maybe some pictures of suspension and other components would help.

 

[Mackeath]

Thank you for the comments and advice. After work we are going under the car to look and will take photos if anything looks weird. Thank you for the tips

 

[Mackeath]

Ok, underneath the stabilizer looks ok. I don’t know how to tell the links but they seem solid and nothing has play. Nothing particularly obvious on connections (obviously not and expert) except I have a tiny axle leak and this damn rust spot

so I’m thinking next to do is check alignment and balance it is there something else I can do?
Thank you all again.

 

[kevin2i]

“Wobble” at speed could be a tire out of round/out of balance. Swap the tires front to rear and see if that changes the problem.

Suspension check:

Jack up each side (at the lower control arm, next to the tire) - and when the tire is off the ground grab it at top /bottom (12/6pm) and pull in and out (helps to have someone else to do this, so you can look underneath). If there is play, look at the upper, then lower control arms. Grab the tire at each side (3/9) and tug in out. Look at tie rods, and steering rack for play. (Note: hard to tell the difference between inter tie rod slop and loose steering rack, but any movement and you can pull the boots back and take a better look). Next put a crow bar or piece of wood under the tire and lift the tire up and down. Check for ‘slop’ at the upper and lower ball joints.

If there is slop in the wheel, but no suspension parts move - check your wheel bearings.

Edit: a loose suspension part or parts you will notice at lower speeds too, and on curvy roads. If the problem only occurs at higher speeds (and wobbles in a straight line) I would check wheel balance and tires first. I have had a bad tire that looked fine, but tread was separating on the inside.

Hope that helps,
Kevin.

 

[Mauser]

If you want another set of eyes on it come by sometime.

 

[mdcoa]

so I’m thinking next to do is check alignment and balance it is there something else I can do?
Thank you all again.

Already mentioned above by @trdcorolla , but since you didn't mention it, I'll throw it out there. In addition to doing what you list here, you should "un-crank" your front torsion bars so the front hub-fender measurement is 1" less than at the rear. You could wait to see if getting caster adjusted fixes the problem, but these aren't designed to sit level. . .

 

[ramangain]

I'm not convinced you have a wheel balance/tire/etc issue. The issue only happens when there is a weight transfer of the body (from side to side) at speed correct? This manifests itself during cross-winds on the highway, or equivalent circumstances when a semi rolls by on the highway?

My initial guess is you have a damping issue, which (again in my mind) signifies shocks/springs/roll bars either being worn or loose.

I do think setting the correct rake is the free-est and easiest way to proceed. If you are familiar with underdamped vs. overdamped (control) systems, can you say if it feels underdamped or overdamped? Google can show some great graphs to help visually describe the two systems.

 

[Mackeath]

Ok, to start as it is free I will lower the rake of the front. So one inch lower than the rear? Just attach a racket and move it counter clockwise? Silly question I know but I have not done it.

 

[Mauser]

Does it feel like the rear end is shifting sideways when you hit a bump in a slight turn while driving? If so I would look at rear sway bar bushings and end links.

 

[Mackeath]

Ok. I will try that out and see if it does. I seem to think it kind of does.

 

[Mackeath]

My wife says no. It only shifts in winds and stuff. Hmm. I will experiment!

 

[ramangain]

Just keep in mind these rigs don't have 2Klbs/in of spring rate and shocks to match. In general, they are not "taught"

 

[kevin2i]

Ok, to start as it is free I will lower the rake of the front. So one inch lower than the rear? Just attach a racket and move it counter clockwise? Silly question I know but I have not done it.

Yes, but you need to get weight off of the wheel - lift it up from the frame so wheel droops and is suspended. 32mm socket if I remember . . .
And definitely check the shocks as ramangain suggests.
Kevin.