At 280.000kms, it seems that the gearbox of my RR is begining to go out. Sometimes when I go on 4th or 5th as low speed, I feel a vibration and seems to sleep. I have to give more revs to the engine to go on. On Sport mode it wont happens so often.
It is a repairable issue or it is better to replace the entire unit?
Jus for curiosity it is possible to fit a ZF 6 speed in this RR?
Another question:
I've heard a lot of good references about Lucas transmission fix and I ad one liter of that in the gearbox and it does nothing.
Someone have done the same with good results?

Cheers

RRPhil is an extremely knowledgeable person to chip in with the real technical details of the gearboxes.

As regards the issues ... the GM is known to wear out and the valves are a commonly replaced / upgraded aspect to address the some of the common issues ( search for sonnax valves upgrade - basically a rebuild effort ). In sport mode, the shifts are made with more force so that the gears change quicker and snappier ... this may explain by it changes better in sport mode.

It also means that in normal mode the box is struggling.

Have you ever serviced the box and changed the fluid / filters, or have you just added a litre of fluid into whats already there. If I'm honest, adding a snake oil fluid to a box ( which wasn't designed to have that fluid in it ) thats showing signs of failing is only trying to mask the issue ... and postpones the inevitable.


A 6sp ZF box is not a drop in fit ... i think the ZF box is a lot smaller i think. V8 or else ...

Hi Fisha

thanks for the reply.Every time I replace the transmission fluid I remove the sump replace the filter and replace the fluid 5,5 Lts +-.
I use Dexron III, is there a better one?
Those Sonax valves you mentioned can be replaced with the unit on or must be removed from the car?
Cheers

If that's whats meant to go in, then its fine.

Its my understanding that the valves sit in the bit that you can see when you remove the sump and filter, and that is removable from the box with it in place.

All that being said, there is always the possibility that its not the valves and there is wear in other parts of the system causing the issues. I'm not knowledgeable enough to link the symptom you Others are describe to a particular area of the box. there is a fair amount of info out there if you search for the model of the gearbox and sonnax valves etc. V8 or else ...