71 750 whine in gearbox

nopdog

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• Oct 3, 2025

• #1

I’ve recently done the following, new Barnetts clutch stack and new tyres. I now have a whine I think is coming from the gear box mainly 2nd and 3rd gears. No whine before. Rear chain has plenty of slack and the primary is fine. Any advice is appreciated. Thanks

 

L.A.B.

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• Oct 3, 2025

• #2

Has the driveside layshaft bearing been upgraded to the roller bearing? If not then it's something that needs doing, the other gearbox parts can also be inspected. Also a good idea to change the layshaft 1st gear bush whenever the box is apart.

 

nopdog

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• Oct 3, 2025

• #3

Yes the layshaft bearing has been replaced by previous owner but don’t know when. I looked into and checked the gearbox about 2 or 3 years ago and all looked fine. It’s just like no whine, new tyres and clutch plates now a whine.

 

nopdog

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• Oct 3, 2025

• #4

So LAB The Andover gearbox overhaul kit 06.7279. Can this be done without removing gearbox?
Layshaft bearing and 1st gear bush can be done with gearbox in frame?
Thanks

 

L.A.B.

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• Oct 4, 2025

• #5

nopdog said:

So LAB The Andover gearbox overhaul kit 06.7279. Can this be done without removing gearbox?

Click to expand...

Yes, that should be possible. I'm surprised the kit doesn't include the quadrant and camplate bushes that would require the removal of the gearbox.

nopdog said:

Layshaft bearing and 1st gear bush can be done with gearbox in frame?

Click to expand...

Yes.