Slight vibration from drive train

[LRD414]

Experienced a strange slight vibration from the drive train while towing the camper trailer that is only there under certain circumstances and not there at all when not towing.

When travelling at around 105 kph and 1600 rpm you can feel a vibration through the seat that seems to come and go about once per second in a regular cycle. The throttle has to be light and steady, not accelerating and also not coasting. I experienced it when in Drive or Sport or holding a single gear on CommandShift, which is 8th for those revs at that speed. The camper trailer weighs about 1500kg (loaded).

The road surface has to be smooth because the vibration is not large. It has a definite ebb and flow to it, not staying constant with a constant speed. And it disappears once you move away from the 1600 rpm, even by a little (~100rpm).

When not towing anything, there is zero vibration felt at that speed/revs combination. And I have not detected it at any other speed sitting at 1600 rpm in a different gear. However, this is harder to replicate so is possibly present but I don't recall feeling anything when in 7th at 1600rpm.

Whenever accelerating, towing or not, everything feels good, pulls well and no issues detected. Same for coasting, no issues felt. I even checked for error codes with the Gap iiD and nothing. It's not wheel alignment. I've just had alignment checked and anyway, it's not felt through the steering wheel at all. My wife could feel it too (through passenger seat) when I drew attention to it.

It is an MY14 TDV6 so is under warranty but obviously these conditions are quite hard to replicate with a dealer technician without some convincing and planning. I am wondering whether I need to take a "wait and see" approach and see if it develops. Or organize for a dealer mechanic to come with me down the highway while towing the camper. But even then, I'm not sure what the next step would be.

So I'm wondering if anyone has any ideas or experiences like this.

Regards,
Scott

[Nicky]

Look at the universals on the rear propshaft.

[Nomad9]

Hi LRD414,
I had a similar issue with a second-hand vehicle, (not a LR Disco) suspension related only when towing my camper trailer. I did what you are possibly thinking about doing, I took my camper trailer to the dealership and I drove the vehicle as I drive it to demonstrate the fault. I was given the advice that as long as you get the fault noted on the vehicle history notes if you have a fault later you can reference the visit you made and the outcome of the assessment. If you play the "wait and see" game the outcome of that might be you stuck by the side of the road.
Based on my own experience I would take the camper and demonstrate the fault you are seeing / feeling when towing with your vehicle. I was only dealing with a 3 month warranty at the time so maybe not as relevant in your case, however getting the fault recorded might not be such a bad idea. You never know the fault could well be acknowledged and a remedy given, this would then remove that element of uncertainty that comes with "wait and see".

[LRD414]

Look at the universals on the rear propshaft.
Nicky, I will but what would I be looking for? Excessive play or stiffness or something else? Seems early (14k km) for that type of issue and I would have thought more widely felt. But maybe it's just very early that I've noticed it.


.... however getting the fault recorded might not be such a bad idea. You never know the fault could well be acknowledged and a remedy given ....
Good point Marty.

Cheers,
Scott

[Graeme]

This reminds me of the time I stopped several times on a journey looking for a problem with one of the car's tyres or driveline as a vibration steadily worsened. Eventually I spotted in the left mirror the trailer wheel jumping up and down due to a huge bulge in the tread and the case about to explode.

Have you checked the trailer tyres?

[scarry]

My work van had a vibration,only on overrun,above 95km/h.
As soon as the speed was below 95k,it disappeared.

Bulge on right rear tyre was the problem,the tyre was actually under pro rata warranty,to my amazement.It had done around 60000k's,60% worn.

[Nicky]

Nicky, I will but what would I be looking for? Excessive play or stiffness or something else? Seems early (14k km) for that type of issue and I would have thought more widely felt. But maybe it's just very early that I've noticed it.

Cheers,
Scott

Depending on the torque phase, the universal may be sticking.
Put the car on a hoist and run in drive, you may notice a shudder.
Early? Mine was noticeable at 1,200 km!

[Tombie]

Sounds possibly like you are hitting a harmonic frequency..

Towing at 1600 rpm forcing it into holding 8th is probably not doing any favours :D

Certain tyres, loads etc can create a harmonic.... It can drive you crazy once you know its there...

Click the cruise speed up 1 press :cool: :angel:

[BobD]

Do you have an ediff? Mine does that and I think it is the ediff clutches slipping when not fully locked up under acceleration (pulling a camper) around corners. I can notice it a lot when turning using rock crawl, especially if the surface is grippy, even under light loads. However, it is also there on the road when accelerating around a corner. Traction control without an ediff might also cause a similar sensation.


I should add that this is not occurring when there is actual slippage of the inside wheel, but appears to be due to the amount of preload the car applies when accelerating around corners and is only felt when the wheels have full traction.

[LRD414]

.... huge bulge in the tread .... Have you checked the trailer tyres? I haven't checked trailer tyres but I will. I think unlikely because the camper is almost new at about 1,100km traveled, all on highway. I'll have a look.


Do you have an ediff? No ediff Bob and also issue not evident when accelerating (straight or turning), so must be something else.


Sounds possibly like you are hitting a harmonic frequency....Towing at 1600 rpm forcing it into holding 8th is probably not doing any favours :D I did think about harmonics Tombie and I still suspect this now. I didn't force it in 8th though. I first noticed it in Drive and that led to trying Sport and then finally CommandShift. I'm pretty sure it sits at 1600 in 8th when in Drive naturally (when towing). I was changing between 8th/7th/6th as required by the terrain and don't recall the vibration in 7th at 1600 at whatever speed that was, or 6th either.

Anyway, it was such a narrow band of speed/revs which produced the vibration that this suggests harmonic to me.

Thanks for all ideas so far.

Cheers,
Scott

[Graeme]

Include the centre bearing mount in the rear tail-shaft in the list of possible causes.