MG Car Repair: gearbox noise, hub assemblies, thrust washer

Question
QUESTION: after an engine rebuild and gearbox we ran the car on blocks and at an idle while in gear there was a clanking noise coming from the gearbox. if you accelerate through the gears there wasn't any noise but only at idle in any gear. could this be a missing or misplaced thrust washer?

ANSWER: What kind of car is this?
Howard

---------- FOLLOW-UP ----------

QUESTION: I'm sorry,MG midget. we have since removed the gearbox and inspected it and everything is in order. could the rattle just be the straight cut gears and cam overlap at idle.

Answer
Hi Joe,
If you have the rear wheels off the ground and in gear at idle you will hear a lot of noise in the gears due to free play in the straight cut gears and the helical cut gears of 2nd and 3rd gear plus the rattle sound of the syncros. To test this just apply a little amount of hand brake. If the noise stops then that is what you hear. All Midgets did that even when new.

That don't mean that you don't have a problem. If you checked the end float of all the gears and hub assemblies on the main shaft and the end play of the laygear and they were close to specs it should be ok in that respect.

The noise is very noticeable with the rear wheels off the ground and in gear especially at low RPM and no load. Also this is more noticeable when you use engine oil in the gearbox.

Howard