As title

Been out for a run today, covered 153 miles and now experiencing rumbleing on overun, and juddering cluncking sounds when hot in slow moving traffic, gears change smoothly during normal running and would not concider anything wrong until I get into an overun situation.
No noises on hard pulling and No problems when cold.
No history on Gearbox came from a 'K' reg Sierra GT with 68000mls
Any Clues ????????????????????
My thoughts are Layshaft Bearings /

Gearbox Rebuild.!!!!!!!!!!!

Thanks in advance.

It could be layshaft bearing the needle roller end can wear a flat on the layshaft i pulled one similar to picture below out of a gearbox i had for spares.This may not be the fault you have , just my 2 pence worth.


http://i34.photobucket.com/albums/d146/Jaffacakekilla/2007_0430_215326AA.jpg

Cheers

It does sound like layshaft problems.

they normally respond well to molyslip g/box treatment.

Can you feel the noise through the gear stick? It could be a propshaft fault. If you're sure its the box, drain some oil out and check for metal particles with a magnet.

No vibrations at all through the gear lever, like I say just a rumbleing on overun and sounds like excessive backlash (Clutch judder) when taking up drive in slow traffic.

Now's the time for a long first gearbox Bill, Makes first gear so much more usable