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Hi all, noticed in the recent cold spell my super v8 has developed a very slight pulse coming from the gearbox accompanied by the revs fluctuating by about 100 rpm, only apparent between about 30 and 50 and under light throttle loads, after about twenty five mins of moderate driving it disappears (quicker if I drive in a more spirited fashion). I presume this is the dreaded torque converter that needs replacing, I know these things can cost £2,000 to replace, so was just wondering if driving as Is and putting up with it for a few months would damage the gearbox?

This sounds like mine did a while ago before I changed the gearbox oil. If you haven't done so already change the oil. It makes a huge difference.
Good luck!

Many thanks for your reply, alas, just did the gearbox oil and filter, has not seemed to make much difference.

depending on mileage, a second fluid change and then drive like Miss Daisy until the box relearns its settings MAY help

however, if miles are up, and you are still getting the "cattle-gridding" a box swap is the best option, if you do go this route from memory Supercharged cars have a couple of VIN change points on the gearbox

EuroJag have a mountain of 350 boxes with matching torque converters

I'd also try another fluid change before condemning it.

I had what sounds like a similar minor vibration in my 4.2 x350 when on a very slight incline, light throttle, just below 50mph. I had read good things about Miller Oils Millermatic ATF DM fluid which is their LT 71141 equivalent. Other owners said that they had eliminated the vibration issue after using this fluid. So I decided to use this fluid for the next change.

It is coloured pink as per basic ATF, which confused my dealer who thought I had provided the wrong fluid. I showed them the fluid spec and they then willingly did the oil change for me.

And sure enough, the vibration disappeared after the fluid change. So I used the same Millers fluid in the subsequent changes on the car. I've also now used it in my Jaguar-engined Supercharged Range Rover which replaced my x350.

Also, if you originally just did a simple change rather than a full flush, a second change will help to get rid of more of the original contaminated fluid.

Good luck

Paul

All useful advice, many thanks all.