48mph wobble??????? help/advice wanted please

Hi,
2013 Jim done 30k on Duellers 20psi all round - took to GOOD local "proper" garage (but not Jimny experts) with a sloppy feel on the front end and a wobble under braking - they investigated road tested etc - balanced all 4 wheels and replaced front brake discs and pads which has made a big difference BUT Whilst generally the car feels a lot better and tighter I am left with a quite specific problem in that when the car is on normal county roads (not a by pass) and hits between 45-50 on the speedo (quite specifically on 48!) a wobble starts up and if the speed can be kept constant the wobble develops into something with quite a bit of energy to it through the steering wheel.
The garage have asked me to engage with you guys to save me paying for wasted ideas and investigation time as they have checked everything and can't find anything loose or worn - is there a family failing that could be the cause - the car has been with me for 6 months and has had quite a bit of rough country road potholes type driving whereas before I think it had a pretty quiet life with its 2 previous owners using it for shopping trips.
Thanks in anticipation of your help
Cheers
J

It's likely that you have a worn kingpin bearing.
Any oil around the swivel?
It's the top of a long list of things that can cause wobble, but it's at the top. All the steering components add friction, or damping, as they wear the damping is reduced until the natural frequency of the Jimny Wobble (45 - 50mph) sets in.

So check for any vertical movement in the front wheels or oil around the swivels and report back.

You can fit a steering damper which helps (now standard on the Gen4), but I would say that if it starts without hitting a pot hole you have something in the steering that is worn or failing. Without external influences (hole or rough road) wobble will not start on a Jimny in good order.

Thanks - I'm trying to build up a consensus to give the garage a short-list of things to check out - kingpins do seem to be a definite favourite.
Speed build up creates the circumstances of the wobble not a specific issue like a porthole etc
Once I have a short-list I will re-engage with the garage and report back but it may be a while coming............
Thanks again.......

Hi,

This is a well known problem on Jimnys, so much that when I bought mine 2011 last year I took my hands off the steering wheel at around 50mph to check. I don't think the sales man noticed me doing it. Anyway there is a slight wobble of the steering wheel between 45 and 50mph on my Jimny even on a smooth road, its more annoying than anything else and I try to avoid the speed range for any length of time.

Mine is not that bad, my passenger doesn't notice it, just me. I am going to check the King pins when I get chance and nothing showed up on a recent MOT/service so mine is probably okay.

Mike has probably set you on the right track, but see this article for a full description.

www.bigjimny.com/mediawiki/index.php/Death_Wobble

Robin

Thanks - I have identified a local 4x4 specialist (I didn't know we had one) and they instantly said kingpin/swivel bearings and are working out a price - if its do-able I'll let them have it to test validate and fit.

My long(er) standing garage who are VG can continue to maintain our other car - hopefully keeping everyone happy and moving forward.

Am I running too low a pressure at 20psi all round?

Also what about the theory of old tyres also not helping this issue - these could just about be the originals although from the mileage history more likely 5 years old

Are some tyres better than others in "helping" avoid this issue happening again?

J

Everything is a contribution, but standard sized tyres that are a little old are not going to impact much. Larger tyres can highlight the issue more.
The swivel bearings actually have a preload which helps to damp things down. As they wear this preload reduces and everything loosens up, so wobble becomes more apparent. So it's possible for the bearings to not show any external signs that they are failing, but the preload has long gone. More often they are a rusty mess that just fall apart when you change them.
Your tyre pressure is lower than the Suzuki recommendation (about 23 front 26 rear), but lower pressure is better on a Jimny than higher.

I run a steering damper to help with the feel of the steering, I personally found it a little light. It also has the benefit of helping with any oscillation, but it's not a fix for worn out steering components. Martin (big Jimny) also sells preload washers to add the the kingpin bearings to help achieve or increase the load on the kingpin bearings. It should be noted that Suzuki don't fit the washers, so if everything else is in good order just changing the bearings should be sufficient.
Mike