Sleeve gear Problem?

snowdr · 2026-07-30T09:07:26-0600

I rebuilt the gearbox about 3500 miles ago with all bearings and bushes replaced together with mainshaft 1st 2nd 3rd gears and layshaft 2nd 4th. The gearbox has been operating perfectly since, but I have been suffering with a noise, a whining noise, which has recently been getting louder. It appears to come from the left hand side, and my first thought was the primary drive, but I have been unable to find a problem there. As the noise has been getting more obvious, I have been able to analyse it more. I cannot hear it with the bike stationary, revving, with clutch in or out. It does not occur in top gear, only in the lower 3. It varies in character with power on and off.

I drained the gearbox a couple of days ago, and found metal shavings on the drain plug magnet. So I reluctantly decided to strip it all down to investigate, but I have found nothing obvious. Layshaft 3rd gear has some slight scuffing, but apart from that the gears look good. The bearings all feel good. The sleeve gear bushes look dry, particularly the outer bush. The mainshaft is a very easy sliding fit in the bushes, as is the sleeve gear itself in the bearing. Should they be that loose?

I suspected the sleeve gear, given the symptoms, but, really, I’m not sure where to go from here. Can someone offer some advice, or suggest what could be causing the whining noise.

I will be very grateful for any help.

Thanks

Ray

1973x75 · 2026-07-30T09:17:24-0600

Check to see if your primary chain is too tight

kommando · 2026-07-30T09:19:01-0600

I had a similar noise on a B40 that I had put a new sleeve ball bearing in. This was my first ever bearing replacement and when I first learnt about bearing internal clearances, I had fitted a CN when it should have been C3 and when changed to a C3 end of noise. Well it was actually dots on the bearing which was before ISO so shows you how long ago it was.

Skoti · 2026-07-30T09:44:28-0600

snowdr said:
I rebuilt the gearbox about 3500 miles ago with all bearings and bushes replaced together with mainshaft 1st 2nd 3rd gears and layshaft 2nd 4th. The gearbox has been operating perfectly since, but I have been suffering with a noise, a whining noise, which has recently been getting louder. It appears to come from the left hand side, and my first thought was the primary drive, but I have been unable to find a problem there. As the noise has been getting more obvious, I have been able to analyse it more. I cannot hear it with the bike stationary, revving, with clutch in or out. It does not occur in top gear, only in the lower 3. It varies in character with power on and off.

I drained the gearbox a couple of days ago, and found metal shavings on the drain plug magnet. So I reluctantly decided to strip it all down to investigate, but I have found nothing obvious. Layshaft 3rd gear has some slight scuffing, but apart from that the gears look good. The bearings all feel good. The sleeve gear bushes look dry, particularly the outer bush. The mainshaft is a very easy sliding fit in the bushes, as is the sleeve gear itself in the bearing. Should they be that loose?

I suspected the sleeve gear, given the symptoms, but, really, I’m not sure where to go from here. Can someone offer some advice, or suggest what could be causing the whining noise.

I will be very grateful for any help.

Thanks

Ray

Probably slight brinelling on 2nd and 3rd gear teeth, that's maybe why you don't get the noise when in 4th gear.

2nd gear is believed to be more prone to that on some 850's, I think the gear ratio gap between 1st and 2nd was altered to maybe try and also reduce that wear problem.

You could renew the gears again but I've read that some members on this forum have noticed the wear returning again after a few thousand miles.

I think some minor metal shavings on the drain plug after a rebuild is probably the result of the normal bedding of rough edges from the new gears etc.

Did you soak the sleeve gear bushes in gear oil overnight before assembly?

Nice sliding fit of the mainshaft and sleeve gear seems correct to me.

Have you seen the Mick Hemmings gearbox DVD that he done for NOC?

Torontonian · 2026-07-30T09:48:10-0600

The steel shavings are attracted to the magnet . The bronze dust circulates in the gearbox oil .
Examine the oil for bronze particulates , put a bit on glass and hold it up to a light .
A tight chain is hard on the sleeve gear bushes .

concours · 2026-07-30T11:59:43-0600

Thread 'Some Andover Norton transmission parts quality escapes (2015)'

Jun 9, 2015

I had the opportunity to repair my failed transmission (still working, but 2nd had a funny "thump, thump, thump" noise.
Disassembly revealed a LOT of damage....

Some Andover Norton transmission parts quality escapes (2015)

I set to work inspecting (the case, sleeve gear and first gear lay were the only usable moving parts) and ordering parts. When I began assembly, the first stoppage was the second gear main would not slide all the way onto the splines on the new mainshaft :x Note the spline cut DEEP in one index only. I tested the OLD gear, would not go on. Tried the NEW gear on the OLD shaft, fit right on, so it...

TEST, don't guess. Inspect your sleeve gear.

Carl H · 2026-07-30T14:23:11-0600

In my experience even OEM original Norton / Norton Villers and NVT gears are not made with the right stuff or have great quality machining and finishes. and the aftermarket and bootlegs are even worse. And now with increase in prices, transmission repairs even for a few replacement gears is very costly.

I long for the days of Quaife gears, "they could take a licking and keep on ticking." Triumphs do not suffer gear tooth abrasion.

If I could afford one, I'd love to buy a complete new Andover transmission to inspect it to see the machining quality and to use it gently for a thousand mile to see how it "wears in" or "wears out" as the case maybe. But I kinda have a feeling what the outcome would be.

snowdr said:
I rebuilt the gearbox about 3500 miles ago with all bearings and bushes replaced together with mainshaft 1st 2nd 3rd gears and layshaft 2nd 4th. The gearbox has been operating perfectly since, but I have been suffering with a noise, a whining noise, which has recently been getting louder. It appears to come from the left hand side, and my first thought was the primary drive, but I have been unable to find a problem there. As the noise has been getting more obvious, I have been able to analyse it more. I cannot hear it with the bike stationary, revving, with clutch in or out. It does not occur in top gear, only in the lower 3. It varies in character with power on and off.

I drained the gearbox a couple of days ago, and found metal shavings on the drain plug magnet. So I reluctantly decided to strip it all down to investigate, but I have found nothing obvious. Layshaft 3rd gear has some slight scuffing, but apart from that the gears look good. The bearings all feel good. The sleeve gear bushes look dry, particularly the outer bush. The mainshaft is a very easy sliding fit in the bushes, as is the sleeve gear itself in the bearing. Should they be that loose?

I suspected the sleeve gear, given the symptoms, but, really, I’m not sure where to go from here. Can someone offer some advice, or suggest what could be causing the whining noise.

I will be very grateful for any help.

Thanks

Ray

Look for abrasion of the teeth on all the gears. Usually 2nd gear seems to whine the most. Also adding Lucas gear oil additive can reduce the whine.

With the damage concours suffered, he is lucky his ride didn't end up in the ER via a life flight helicopter.

Sleeve gear Problem?

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