Low speed vibration on x300

Hi all. Ive got a 1997 x300 sovereign and it has developed a weird vibration.
Between 26 and 30 mph on light throttle i am getting what i can best describe as a transmission vibration.
Below or above that speed, nothing. Harder acceleration produces no vibration.
The autobox had a filter and oil change earlier this year due the previous owners lack of maintenance.
Ive also had the rear subframe off and rebushed it, along with new shocks etc in an ongoing quest to bring the old girl back to good mechanical condition.
I realise its hard to diagnose over the internet, however any advice on where to look would be great. The car drives beautifully other than this and i would love to find the issue.
Many thanks

Transmission mount?

Cheers
DD

1 Like

A few decades ago I worked at the dealer when an X300 sedan came in for work.(maybe an oil change?)
I noticed that the gearbox mount cross member was broken in two and the right side was resting (held up) on the exhaust pipe.

The only reason the propshaft was not on the ground was the exhaust system.

The car did feel different and a little louder when I drove it in and put it on the lift.

Many thanks for the quick replies and i will take a look as soon as i have a ramp free at work.

Not that I would think it would make a difference, but your profile says you have a '96 MY and in your post it says '97 MY. ? :confused:

< waving to Motorupman ltns :wave: >

Driveshaft universals?

I’ve had a similar problem with my X300, but at speeds ranging from 45 to 70 mph. Over a period of 3 years I went to see 6 experts and spent literally thousands of euros checking and replacing all kinds of parts, and although some of those parts definitely needed replacing others didn’t. They just added to the bill and nothing really solved the vibration problem.
The last expert I saw was convinced that it was a problem with the lock up converter. Although I think he may be right, that would mean a complete overhaul of the transmission or fitting a second hand one (which is hard to find for an XJR). Both options would cost me another 2 000 euros or more.

In the end what I did was put an additive into the transmission that was recommended to me by another Jag owner. I am normally not an advocate of additives to fix problems, but I must confess that the vibrations have diminished significantly since then. The additive I used was ‘Rislone transmission repair’ (2 fluid bottle). I got it from a supplier in the Netherlands, but I’m sure you can find it elsewhere.

PS: check whether the vibrations disappear for a short while when slightly touching your brake pedal (without actually braking - if necessary do something you are not supposed to do: slightly press both your throttle and brake pedal at the same time). If that’s the case I am quite confident it is a similar problem.