Vibration at 50mph and when coasting over 50mph

[Matt1986]

Hi all. I'm experiencing an irritating driveline vibration at around 50mph which I quite noticeable when driving and also I feel the same vibration when I take my foot off the accelerator and coast when I'm doing over 50mph. 

I've had the car up to speed on a ramp and can't see anything obvious however the mechanic did note that my diff was slightly noisy and that the left rear wheel wouldn't turn when on the ramp (non LSD?) but there was a slight movement of the driveshaft on that side. 

Could the vibrations be the diff? Feels like something out of balance in the rear. 

I have had full rear suspension arms replaced with genuine parts and wheel balance on new tyres and still it persists

Thanks in advance. 

[ambermarine]

I had this issue on my Mark 1 and it was the trailing arm bushing both sides that caused it,when you had the suspension renewed were these done ,a noisy diff combined with a worn drive shaft sounds ominous and combined could cause vibration in neutral but so does worn bushings.

Get your tech to check the bushings on all of the suspension components ,if they are not suspect then your prop shaft  bushing and rubber doughnut coupler need a look at as well.

If you can find a garage with a rolling road run the car in reverse at about the speed the vibration starts, if it is the trailing arm bushings the vibration will not occur if the body side connection is worn, as the load is taken off the down side.

[Cotswold Pete]

Can you sense whether the vibration is coming from rear or front of the car.

If rear then could be trailing arms,  or worn drive shaft (not nice) as Phil suggests.

However could be handbrake, I had issues with odd vibrations (more like juddeering) at around 40mph, but handbrake was more or less totally siezed, but strangley no overheating.

Also what is the status of your shocks, my fronts which are the originals cause a 'sense' of vibration between 30 and 45mph, and seems to vary with tempature, so I am having them replaced next week.  Osaka of Newport said all other bushes fine (apart from ARB - they are being replaced at same time), so maybe consider shocks as a key.

Best of luck, as over the years have had various vibrations on my Mk4 and Mk3, and never easy to diagnose without going to someone who knows  the LS inside out.

[Matt1986]

The vibration I think is from the center or rear of the car. It's not violent but its noticeable. I had all the rear bushes replaced with genuine lexus parts plus the hub bushes replaced recently. New tyres and wheel balance. It's had a new trans mount as well in the last 6 months. I did all this due to worn bushes and in the hope it would remove this vibration. 

It's possible it's the handbrake I hope so! We couldn't see any obvious wobble in the driveshaft or diff when on the ramp though. 

As far as I'm aware the shocks are all original with 149k miles on them

[Malc]

10 hours ago, Matt1986 said:

shocks are all original with 149k miles on them

mine are too and now at 220k miles ...........  no problem seems to be there for me ( yet )

Malc

[ambermarine]

The suspension from what you say can be ruled out the next moving parts on the centre line are the engine mounts and having the trans mount renewed may have highlighted wear in the rubber body of the mounts the 150k mileage is significant on bushings and mounts and changing to new on the transmission could have a effect on the centre line.

As an afterthought I recently viewed a video of a diff on a lexus were the bushings were worn and hardened it was not obvious until the drive shafts were removed and the torsion taken away the diff then moved about quite a lot on its mountings.