Death wobble

[jonfromhamilton]

Drove it through the terrible road in boronia today at death wobble prone speed and had no problem. I really am leaning towards it being something to do with the drag from the seals on the ball

[stevend34]

! FIXED !

Here is what my list looked like:

• checked wheel bearings are tight
• Swapped tires front to back
• put in caster correction wedges (then took them out as no change)
• Changed tires all together
• Back to stock shackles
• New nylon bushes in the stock shackles (no change so back to long ones)
• Made a jig up and measured for bent axel- was rough but nothing obvious
• Measured toe in – was a bit rough measurement, however I got 6mm –was happy enough with that – Greg – curious to know why your aiming at 0?
• Checked Kin pins in the aim to measure pre-load found ALL 4 WHERE BROKEN! Thought I had it at that point, but replacing them only made it 80% better - not completely fixed.
• Took swivel seals off and measured load – one direction the hub was tighter than the other (same on both sides) – assumed this is normal and went ahead and removed the only remaining shim on each side.
Also at the same time, whilst steering bar was off, changed drag link bar with a second hand one from car that had no issues. Test drive and no more wobbles!

So yes could have been the steering arm or king pin load at this point because I did them together; however I would be more inclined to say King pin load was the fix as I could not feel any wear in the steering arm.
I can just feel the slightest bit of movement still, but you only notice it if you’re looking for it.

[gwagensteve]

Your experience is pretty common Steve - and what muddies the waters is that people often throw everything at it all at once and then can't determine the fix. It's almost always the kingpin preload.

There's loads of triggers - it can be anything that starts a wheel shimmying, lack of caster, worn bearings/tie rod ends, wheel tyre and wheel balance, bent rims, mud in the rims, play in the steering box or shaft, and removing all triggers might be enough to prevent death wobble occurring, but it will always be lurking there until the wiper seals and kingpin preload are right.

Greg has a different and more persistent problem. It *might* be associated with the low rim offset but (relatively) high wheel and tyre weight, but his is resisting all the normal remedies.

With bias ply tyres, common practice is to set toe neutral. Where are you measuring the 6mm from? if it's front to back at the tyre that's a fair bit, I'd probably 1/2 that. I had 10mm measured rim-rim (just through lack of ever checking it - I didn't set it to that) and it was causing diabolical drivability issues in my car. Small changes in weight transfer left/right would make it dart all over the shop.

[stevend34]

Not fixed...

So whilst it’s a lot lot better, still have had a handful of episodes where it get the major shakes.

Neo mentioned on the weekend a jimmy part that can actually put more load on the bearing. Is that my next step?

Maybe I have worn parts I have not identified, any offers to give it the once over for me?

Neo, got a link of what you where talking about by any chance?

[jonfromhamilton]

Mine got better as the grease was lost off the steering knuckle ball but i have had it happen when i was carrying a couple of steel sheets on the racks

[neofitou]

https://www.jimnybits.com/jimny-kingpin ... m-kit.html
This is the round shim that sits between the kingpin and the bearing to increase preload.

The big square ones sit between the kingpin and the swivel hub and reduce preload.

Suzuki suggest Preload should be shimmed to 4.5kg for Jimnys in their bulletin fix doc after:
Checking condition of all rubber bushings, check everything is tight especially the panhard and replacing the kingpin bearings..

The 4.5kg Preload in this case is the amount of force that is needed to start movement of the swivel hub, measured with the seals on from the drag link hole with a fish scale.

testing with scale.jpg (107.94 KiB) Viewed 3295 times

My understanding is that from the factory, Sierra swivel hubs are made too tight and should be shimmed with the big square shims until you lower the preload to 2-3kg. My sierras and the Samurai were at the lower end of this with no shims. Sierras are getting old and worn and out of round and sloppy.

On Luke's car we actually welded in a bead and refinished where the swivel seal sits on the ball as it was so badly worn that the seal was not adding any resistance in its rest position.

Jimnys were designed to have the right amount of preload from the factory with no shims and you add shims as needed as they wear.
There is a Suzuki part number for the shims, and they are only $5 but they don't actually ever have any in stock.

I cut my own from shim sheet for my current Jimny. Its not uncommon to need more than 1mm of shims.

Other suggestions that get kicked around for Jimnys is check the tightness of the steering box, make sure you have the correct front caster angle and load up the steering by adding some toe out.

And of course adding a steering damper to help mask the problem (even if you have power steering and shouldn't need it) .

[luigi]

Hi Fellas.
Just a thought.
Is it possible that the slip yoke on the front drive shaft ( or rear tailshaft) is binding.
If it was, would it put forwards or backwards force to the axle housing. Because the diff is off centre would it cause a kind of bump steer?
I suppose the rubber mounts on the transfer box would take the movement. But if the transfer box was mounted solid?

Maybe I have too much thinking time....
Regards. Wayne.

[stevend34]

Thanks for that

Does the shims need to be hardened metal? i.e. if i happened to find a washer that fitted well, is that a bad idea? Same question applies to welding more metal onto the king pin i guess, however that method seems less measurable.

Does new king pin bearing help or is it always the ball being warn?

That link you sent to the Jimny increase load shims: are these the same size? they are in stock so if they are its seems like the best option

re tail shaft; happens in 2 and 4 wheel drive so no so sure on that. I'll try that next!

[neofitou]

They should be the same size, 14mm id and 20something od as they use the same bearings, but I did once see an ad saying they weren't for SJ models, but I think that's just because of what we have discussed as to they are for increasing preload and SJ ones should be for reducing.
If you looking at using something else I would just use shim sheet and cut your own its about $4 from any bearing shop.

All the advise I've ever seen is always replace the kingpins before shimming.

If it does it in 2wd with the hubs unlocked its not the driveshaft.

[jonfromhamilton]

If u can get the right torque on the steering arm with a fish scale isnt the king pin load right anyway?