Gen4 - rocking side to side at speed

Maybe Gadget could describe what he experienced a little more clearly - to me, a "side-to-side rocking" is a very different thing to a "noticeable wobble in the steering wheel".

I think I've experienced what Martin describes as "tramlining", wheels on one side of the vehicle riding in a rut left by a larger heavier vehicle, and then because the vehicle you're in is narrower, it will randomly hop so that the wheels on the opposite side are riding in the other rut from the other wheels of the larger vehicle - it's not common on the roads I frequent, and it's not what I imagine from Gadget's description.

I personally would not want to be driving a Jimny with a loaded roof box, I've never done it, but I can tell you a 70 series Troopy with a loaded roof rack will sway side-to-side in an alarming fashion.

I can't argue for the Gen.3 as I never had one and my Gen.2 was so far back in time that I can't remember but I agree that my Gen.4 is happy at about sixty mph and with current vehicle numbers on the roads I don't see much point in exceeding it. Also the road surfaces in Worcestershire, although better than Herefordshire are so poor that deviating to miss potholes is the norm.

As an aside, the slack in my steering column is approx. 70mm. Is this normal after 17,000 miles?

Roger

Roger Fairclough wrote:

As an aside, the slack in my steering column is approx. 70mm. Is this normal after 17,000 miles?
 

Is this slack as measured at the steering wheel rim?  70mm seems excessive to me, the Jimny owner's manual suggests 0~30mm as acceptable.  I want to suggest measuring it with the engine off as I find the power steering assistance can make a difference.

I have just checked the W.shop manual ( I was in sloppy mode but I have switched back to normal ) and to answer my own query, the max. slop is 18mm. Better start checking.

Roger

Thanks for all the input, it's too hot for me to lie under the car at the moment, but I will get around to looking at it soon. With regard to some of the questions:

There's nothing felt through the steering wheel, rather it feels as if someone is pushing the car from the side, rocking it onto the left hand wheels then back onto the right.

I don't think it's tramlining, I've experienced that in other cars and the road/lane didn't make any difference.

Anyone know how to check shocks for effectiveness? They seem the most likely culprit to me, as the sensation is as if they're not damping side to side motion.

Gadget wrote:

Thanks for all the input, it's too hot for me to lie under the car at the moment, but I will get around to looking at it soon. With regard to some of the questions:

There's nothing felt through the steering wheel, rather it feels as if someone is pushing the car from the side, rocking it onto the left hand wheels then back onto the right.

I don't think it's tramlining, I've experienced that in other cars and the road/lane didn't make any difference.

Anyone know how to check shocks for effectiveness? They seem the most likely culprit to me, as the sensation is as if they're not damping side to side motion.

Over the years several people have posted about this happening with gen 4’s.

At first I thought it must be them not being used to a narrow 4x4. But my Jimny also started doing it.

A couple of years back it suddenly started rocking back and forth when travelling at motorway speeds. As you say a sort of rocking motion. One of the front upper anti roll bar mounts had come undone. The dealer tried to blame me. As a bolt was missing and the rubber bush had moved. Fixing this instantly solved this.

However…. When I say resolved it. Maybe not 100%.

Previously the vehicle felt solid. There is a bit of dual carriage way near me that you can leave one round about and go flat out in each gear before the next, being wide open throttle in 5th as fast as the vehicle will go. It is a slight up hill, so not the vehicles true top speed. But high speed shall we say, limited by engine power and drag. There is a sweeping left handed bend before the next round about. I used to be able to go round this corner no probs. But since the anti roll bar issue it has felt less stable. Despite everything looking and feeling fine. This was 100% stock suspension. But some other mods.

Over time this has got worse and entering this corner gives a similar but not 100% sideways rocking motion. The car feels very unstable and is quite a butt clencher forcing you to drop 10-15mph. The vehicle was pretty low mileage 18-26k I have, early part of this year the swapped the stock suspension for a 2” Black Raptor Premium lift. New shocks and springs. And it has completely solved this rocking issue I have been experiencing. Now able to keep the throttle fully pegged on that same bend.

The first issue I suspect is unrelated to the 2nd. But the 2nd issue is what I think others have reported. I’d assume the shocks or something must have been at fault as the issue was getting progressively worse. And nothing else was changed to impact or fix it.

I think it's more common for shocks to fail, so to speak "soft", allowing the vehicle to bounce more than it should, rather than becoming rock hard as described above.

This is just my experience and it may be related to the type of shock, if a single tube shock sustains an impact, the body can deform to the point where the shock binds restricting piston travel, something which is a lot less likely to happen with twin tube shocks.

Apart from physical damage, shocks can fail in many ways, seals leak, they lose their nitrogen preload, they lose oil, and so on - most of these failure modes do not impact travel, but they do cause a reduction in damping which allows uncontrolled movement.

This could potentially be a shock problem but I would expect OME shocks to last more than a "few years".

I considered my G3 shocks good, passed all corner "bounce" tests and visual inspections. However when towing they lacked something so I swapped them. It was only when they became disconnected from the vehicle it was obvious they had failed. One offered no resistance at all, but on the vehicle it appeared fine. So if you suspect the dampers I recommend you check with at least one end disconnected from the vehicle.
 

Scimike wrote:

I considered my G3 shocks good, passed all corner "bounce" tests and visual inspections. However when towing they lacked something so I swapped them. It was only when they became disconnected from the vehicle it was obvious they had failed. One offered no resistance at all, but on the vehicle it appeared fine. So if you suspect the dampers I recommend you check with at least one end disconnected from the vehicle.

 

My general experience parallels this - many vehicles will pass the bounce test with defective shocks - that said, on a number of occasions I have been able to detect bad shocks from the driver's seat, even when they pass a bounce test..

My 8 month old 6500mile Gen4 LCV done this for the first time Big Jimny Meeting this year, the rear started swaying and gradually it worse until it felt like it would loose control (easing off the throttle stopped it), I did have more weight in that usual, tried different tyre pressures, reduced the weight which didn't help, and I re torqued up the wheel nuts and that seemed to make it better, but could have been a coincidence

When you say you re torqued up the wheel nuts, is that just a general tightening of the wheel nuts or is it a torqueing to spec. of the wheel nuts?