Gen4 - rocking side to side at speed

Bit of a weird one. Have been on holiday in the Jimny and on the motorway experienced some quite scary side-to-side wobble. I don't think it's death wobble, as you don't feel anything through the steering wheel, but the whole car rocks side to side as if you're being hit by gusts of wind.

Car was full loaded, two adults, one teen, luggage in car and roofbox. We've travelled with an identical setup before over thousands of miles and never experienced this. 

I shifted all the weight in the roofbox down into the car which improved things slightly, but it was still doing it to some extent, even with the roofbox removed.

If I didn't know better, I'd think some of my shocks had failed - but they're OME units that are only a few years old, so seems unlikely? If I bounce the car when stationary it stops after one bounce which seems normal.

Tyres were at 28psi. Don't know if relevant but it only started after the last Jimny meet - could I have damaged something?

It's driving me mad. Any ideas?

Could there be any mud stuck behind the wheel making it unbalenced or lost weights from the wheels?

How fast were you going and how much weight did you have on the roof? Is the front stabilizer (anti sway) bar still fitted and what condition are the mounts & end links in? What tires are you running?

If I recall correctly rear tires take a higher pressure when the vehicle is fully loaded, I don't recall what it is, and my wife is out with the JB so I can't just run out & check it - the JC takes 29 at the rear fully loaded, but I don't really see being 1psi low as making a huge difference to stability.

It certainly wasn't "wobble of death", wobble of death, if you ever experience it, is an unforgettable event - a violent shaking of the steering wheel, and only to get out of it, is to bring the vehicle to a stop.

What you're describing sounds more like a top heavy vehicle, they tend to "wallow" as you steer into the sway, you're always lagging the event, I have experienced something similar but not a Jimny.

jlines wrote:

Could there be any mud stuck behind the wheel making it unbalenced or lost weights from the wheels?

No significant mud, but hadn't considered weights, I'll have a look, thanks.

fordem wrote:

How fast were you going and how much weight did you have on the roof? Is the front stabilizer (anti sway) bar still fitted and what condition are the mounts & end links in? What tires are you running?

If I recall correctly rear tires take a higher pressure when the vehicle is fully loaded, I don't recall what it is, and my wife is out with the JB so I can't just run out & check it - the JC takes 29 at the rear fully loaded, but I don't really see being 1psi low as making a huge difference to stability.

It certainly wasn't "wobble of death", wobble of death, if you ever experience it, is an unforgettable event - a violent shaking of the steering wheel, and only to get out of it, is to bring the vehicle to a stop.

What you're describing sounds more like a top heavy vehicle, they tend to "wallow" as you steer into the sway, you're always lagging the event, I have experienced something similar but not a Jimny.

60mph. First time it happened I probably had 30kg on the roof, but after the first time it happened I reduced that down to about 15kg. I've certainly not removed any sway bars, will have a look at the various connect-y bits, although not sure I'll spot if they're knackered! Tyres are 215/75R15 Yokohama Geolander G015 A/T, have had them on for about 5 years and had runs to Scotland and Switzerland with no issue.

Could radius arm bushings be a cause? Had my dad rocking the car and there looked to be a lot of flex in the rear drivers side bushing, unsure if the amount is normal or not.

The side aspect of a Jimny is similar to a brick on edge so a gusty side wind may have been the cause plus the standard shocks are not up to much and add 30 kg (the max.) on the roof with a full load inside and you are likely to experience odd behaviour.

Roger

Gadget wrote:

Could radius arm bushings be a cause? Had my dad rocking the car and there looked to be a lot of flex in the rear drivers side bushing, unsure if the amount is normal or not.

This is certainly worth investigating - what do you mean by rear drivers side bushing?
On each side of the car, there will be two radius arms, front & rear, each with three bushings, two at the axle end, one at the frame end - I don't think there should be enough flex in any of them to be noticeable simply rocking the vehicle, and the axle end bushings do come under a fair bit of twisting if/when the vehicle is used off road.

With an 18 to 24 inch flat ended pry bar get under the car and try to get anything with a rubber bush to move either side to side or up and down ,it will be fairly obvious as to which are soft as you shouldn't be able to make metal parts touch each other without going full green rage monster. But honestly it's more likely a control thing than a worn bush thing so I wouldn't be discounting the dampers even old man emu as they are technically a wearing service item especially if you are regularly running loaded.

Tramlining? The inside lane is often ridged with the tracks of the 40 tonne plus lorries. It's currently particularly bad on the M4 from J10 to j8/9 at the moment, even pulls the 2.2 tonne range rover around

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The gen4 isn't great above 60mph.  It's nervy, noisy, and the fuel consumption is tragic.  The gen3 was more suited to 70mph cruising.

That's not really the ideal use case for a Jimby, though.

I had/have something similar in my Gen 4, normally I don't go much over 55-60mph even on the dual carriageways and motorways, I just think it is happier below 60mph.

However, I was a tad late the other day so cruised along the main A road near me at 65-70mph, there was a noticeable wobble in the steering wheel, but even relaxing my grip the car didn't wander. It is possibly a wheel balance or tyre pressure thing. Once I got on to the A1(M) at 65-70mph, the wobble was hardly there so it might have been a more worn surface on my local A road.

Anyway I am not bothered, I don't often travel above 60mph and all the way to BigJimny and back at similar speeds, I never noticed it.

Gadget, perhaps what you noticed was just more extreme form of what I noticed, but the extra weight on yours made it worse?

Robin

Rogerzilla wrote:

The gen4 isn't great above 60mph.  It's nervy, noisy, and the fuel consumption is tragic.  The gen3 was more suited to 70mph cruising.

That's not really the ideal use case for a Jimby, though.
 

Having gone from a Gen 3 (2011) to a Gen 4 (2020) earlier this year, I find my Gen 4 much more suited to faster roads, it's running the exact same tyres as I swapped them from my Gen 3 to Gen 4 when I changed car.

My Gen 4 has a lot more power for faster cruising and I find the Gen 4 much more stable.  Fuel consumption takes a hit, but I average nearly 40mpg in the Gen 4 (mostly slower roads) whereas I could only manage 33mpg in my Gen 3.  If I was to drive at 70mph and check fuel economy it would dip, but I am willing to bet it is still higher than my old Gen 3.

I don't often go on the motorway/fast A roads and then keep the speed under 60mph.

Robin