Violent wheel wobble - need some help

Violent wheel wobble - need some help

Hi all, we were about to leave on another outback adventure but we recently been beset with violent wheel wobble when the left wheel touches anything uneven on the road, at any speed, even 40-50 kph.

Sounds simple to find and fix but I have been spectacularly unsuccessful and I’d appreciate some suggestions. Here’s what I’ve already done/checked:

Had the wheels balanced (and swapped them around).
Replaced the shock absorbers.
Replaced the steering damper with a previous one which was of a similar strength and not worn out.
Adjusted the alignment twice (was slightly toeing out, now 3-4mm toe in).
Checked all the tie rod ends for play, (wheels on the ground, engine on and Janet waggling the steering wheel). Only one (steering arm top from steering box) had a some small play but no clonking from any of them.
Checked the wheel bearings (no movement although it’s slightly less tight than the RH bearing)

None of these have made any real difference in fact is seems to be getting worse. So what other areas should I be checking?

Loose U bolts, broken spring leaf, problem with the king pin swivel mechanism, cracked chassis? I’ve had loose tie rods and springs shackles before and they didn’t cause wheel wobble.

My feeling/hope is that it’s the steering damper but why only when the left wheel hits a bump?

Any and all suggestions appreciated.

Caster wedges, S I R scrub radius
? New tyres.
Spring bush slop

Sounds like a Caster wobble to me. Has the Caster angle changed for any reason?

Dave, I had the same problem with a forward control Land Rover. It felt like the hole front end was jumping up down and it was hard to hole the steering wheel and you would have to come to all most a complete stop before it would stop . The Land Rove had been modified and the front end was heavier the normal. We ended up fitting two steering dampers and that fixed the problem. I can't explain it but it worked.
Cheers Peter.

Broken spring centre bolt, FWH engaged.

David,Have a look at the plastic bush on top of the king pin,wear will change caster and camber,when you take the bush out clean and look at the shiny/wear marks on the cone.
Cheers,Joe

Hi
Joe, I agree somewhat with you but my guess would be that the bearing at the bottom will be had it. The top plastic bit alters the caster and camber but the bearing at the bottom can make it shake sideways. I have seen it many times on old Land cruisers. The first being in the mid 60's as we had 2 of the first L/C they had 3 on the tree, along time ago and they had trouble with the bearing failure and it always gave wheel wobble. I had similar experience with Franks old OKA and it had bad wear marks in the cone and had rust as well from not being greased as much as it should of had, due to the creeks and other water areas he drove in. I have heard of the actually loosing the cage and that makes them impossible to drive but that would be the extreme case. I replaced the cup and cone and had no more trouble. Frank always thought it was wheel balance. Just another thought.

Regards
ABE Tony

Hello David,we had that exact same problem in 96 a few years ago. We checked everything that you have but it turned out to be loose shackle pin nuts,rear of the springs,both sides but the left side were the worst.Tightened right up,problem gone. Chris.

Many thanks for all your replies.

My plan is:

Change all the tie rod ends. They probably need changing after 10 years anyway and I'll have a couple of spares. Also they might be causing dynamic problems which are not evident in static testing.

There have never been caster wedges under my front springs and since caster angle has cropped up a few times (and in my research ), I'll fit some while I'm checking the springs/centre bolt/U bolts/shckles etc.

I have fitted camber correction shims to fix the wheel leaning-in problem, which does affect camber, toe-in and caster settings but they've been OK for over a year.

I did change the bottom swivel bearings and top cones a few years back but last years GSD crossing placed a heavy strain on the steering and front suspension so I'll have a look at those too while the tie rods are out. The more I think about it the more possible a worn/broken swivel bearing seems (only on one side, rough travel history, hard to check statically).

A second steering damper would be nice (since I have one) but there's no obvious fixing location on the RH spring mount without a lot of modification and the bulge in the diff cover would get in the way anyway. Hal fitted dual dampers but the fixing arrangements are not clear.



Does any of this ring any other bells?

Regards

I fitted the same dampers as on HOOKA. Easy installation and all fixings are via bolted clamps. Bought them from the US.

I drove 123 for a couple of hundred km without any damper at all and it behaved normally. Only fitted the dual damper because it was cheaper than buying one locally - and no particular reason to renew the OEM damper anyway.

Think mine came from www.summitracing.com/int/search/product-...steering-stabilizers

David,

A little late, but here goes.....
I have had trouble with wheel shimmy in 191 too, it was "on the edge" where mostly it would die away but sometimes build up quite violently. The shimmy usually followed a disturbance, for example a bump.
I found that quite small changes affected it - for example changing the front airbag pressure (which affects caster angle slightly) made a noticeable difference. Slightly more toe-in improved things too. I have had no trouble since changing tyres (to Michelin XZTs).
From this, I agree that something affecting caster / camber is the most likely, and my experience is that it may take only a small change to go from "no real problem" to "big problem".

Good luck!

John

Hi David, I did a trip from Broome to Brisbane and as I got into Brisbane I had a violent wheel wobble. I didn't have any wheel wobble on the trip back from Broome but all I did was to get the front wheels balanced while they were still on the vehicle and also replaced the steering damper. I do remember I was quite shocked at the amount of weights they used at the time, however, that was about 8 years ago and since then I have changed the tyres and I have not had any problems. I have in the past had wheel wobble on other 4WDs and a good steering damper seemed to solve the problem, however, I feel that the steering damper would probably only be masking the problem but since I have not had any wheel wobble, I have not looked into it any further. I do realise this may not be of much help but I just thought I would mention it as it helped me. Paul.

Thanks John, I've found nothing wrong in today's investigations but I'm changing the tie rod ends anyway.

The swivels seems OK, the nylon cone in the top has no wear and the lower bearings were replaced a couple of years ago, but I'll look at them later if all else fails since it's a bigger job.

The U bolts and spring centre bolts are all OK so tomorrow I'll look at caster correction wedges.

But I'm a bit confused, the manual shows 2 wedges on top of both springs plus another one below the drivers side spring. I wonder what gives, do I really need 3?





Either way I assume the manual is correct and the thicker edge goes to the rear??

the two wedges on the RHS are needed.
the one on top allows the spring clamp bracket with tailshaft safety hoop to line up with the tailshaft.

David,do you know what the actual caster angle is at the moment? over the past couple of year I had three different diff housings on the stand with different angles machined for the spring perch,it is a fine line ,was the feel of the steering really light before the wobble,look at all the parts affected by wear before adding any wedges,too much caster will alter the angle of parallelism between the pinion centre line and the transfer case output shaft centre line causing vibration +- 1.5 degrees is acceptable.
Cheers,Joe

Voice of reason, thanks Joe.

No I don't know the current caster angle and the steering has always been quite light. I've changed nothing on the front suspension/steering area in the past year so I guess something has worn or broken.
So far I've found nothing amiss except slight wear on one tie rod end.

Both swivels turn smoothly with around the same torque (not conclusive of course since they're not under load), no wear on the top cone, nylon bush or broken springs:



Wheel wobble seems to be a very common 4WD problem with a lot of inconclusive causes. The search continues...

David
Some observations

1. The vibration developed suddenly, not developed over time. - points to something broken or failed
2. You've looked at all the obvious things and can't see anything broken
3. You've tried the swivel housings with wheel off and up on jacks - this takes the weight off the lower bearing

I'd be looking at a collapse of one of the lower cone bearings in the swivel housings or a split in the cup as this is one of the things you can't see until you pull it apart. Another possibility is a broken/weak spring above the nylon bush. Is the spring putting load on the cap as you replace it?
Pete

Joe,

Thank you! You have given me a place to look.
191 has always had light steering, although not having driven another Oka I had nothing to compare it with.
I had suspicions previously that its sensitivity to shimmy was probably related to caster angle being not quite right.
I also get vibration from the front driveshaft.
It all adds up.....

Thanks, John

Thanks Pete, yes, I'll have to dismantle the swivel system next to check the bearings, messy job but I might even find a cracked knuckle.

It's always possible I installed the new bearing cup incorrectly 2 years (25,000km) ago, the cup was tricky to install, but I figured the weight of the vehicle would quickly seat the cup anyway.

The king pin top cap is a quite highly loaded, I had to clamp it down a fair bit yesterday after I checked the nylon bush before I could start the nuts on the studs. So the springs are OK (I checked both small and large springs anyway).

David

Joseph Baz wrote: David,do you know what the actual caster angle is at the moment? over the past couple of year I had three different diff housings on the stand with different angles machined for the spring perch,it is a fine line ,was the feel of the steering really light before the wobble,look at all the parts affected by wear before adding any wedges,too much caster will alter the angle of parallelism between the pinion centre line and the transfer case output shaft centre line causing vibration +- 1.5 degrees is acceptable.
Cheers,Joe

Sorry Joe, I twanged my back a couple of days ago and working on an Oka with a dodgy back is tiring.

I'll do a rudimentary caster angle check today (with respect to the chassis line since the wheels are off the ground). Superficially it looks like there's a few degrees of positive caster (top king pin leaning rearwards) without wedges. Should be +3º to +5º unladen according to the manual.

My front drive shaft seems fairly in line with the transfer case right now, this photo was in 2013 after I reinstalled the transfer case. Wedges under the springs would lower the rear of the diff, possibly improving this alignment, and increasing the caster angle?