intermittent transmission noise

[hot66]

on a couple of occasions I have heard a funny noise from my transmission.

It has always happened when I have accl up through the gears to about 200kph+ (on a private test track of course) then let off until about 100 - 120 kph & cruise. I get a real coffee grinder kind of rumble. If I cruise carefully for a bit & give it throttle a couple of times the noise goes away.

This has only happened 3 times & it was all on the same journey when I 1st got the car. Have not heard since but then again I have not had the use of a private test track

I don't think it could be the tyres even tho one of the rears needs changing.

any ideas?

BTW I have not checked the gearbox oil

[Nick Moss]

It would be useful to try the test in 4th and 5th gear. If the noise is in both gears it could be the diff, CV joints or wheel bearings. Weaving (gently) will tell you if it's the wheel bearings

[hot66]

when I had the car serviced by Strasse in Leeds ( didn't have time to do it myself ), I asked them to check the cv's as I did think there might be a prob there ( a clunk when I reverse, turned out to be worn bushes on the rear swaybar & maybe spring plate bushes could need replacing sometime soon). Report back was Cv's were fine.

Pretty sure it isn't bearings.

I thought it might be the diff from the location of the sound. Maybe when it gets a bit too warm?

[Nick Moss]

Next thing is to drain the oil and look for "bits"

[hot66]

think I'll get the new tyres on, take it out for some long high speed runs & see how it goes. As I said i havent heard the noise since the first journey out ( it had been sitting for a good 8 months)

Don't really want to pull the engine & box until I've got my vw restoration near completion. Can't handle both my toys off the road.

As long as I get to Le Mans & back I'll be happy :D