Gearbox Inner main shaft bearing fit

I'm rebuilding my gearbox and find that the new inner main shaft bearing is a tight fit on the shaft.
When I tried to re-install the inner gearbox cover the main shaft was such a tight fit that It would have required excessive force (IMO) to get the box closed. I got the shaft slightly seated in the bearing before I stopped. When I removed the inner cover it pulled the main shaft and all the gears out of the box. The original bearing is a snug sliding fit on the main shaft and my previous Commando gearbox rebuild was the same. The end of the main shaft measures .625"

I returned the bearing to my parts supplier and he claims it fits on his main shaft just fine.
Isn't inner main bearing supposed to be sliding fit on the end of the shaft?

Re: Inner main shaft bearing fit

Never had this issue but would re-think gear cluster assembly and selectors first.

Re: Inner main shaft bearing fit

You have not bought some new gears have you? If so I trust you are aware that sone of the gears changed in size..same number oif teeth but different pitch diameters and have to be changed as pairs. One of the pair became slightly bigger and the other slightly smaller. From Memory , without looking up my revords it was 2nd gears done, so I understood, to get the lumps through U.S. noise tests...

At one time Many YEARS AGO a certain UK company manufactured complete gear sets which ended up in the cellars of a Birmingham warehouse(long gone) full of ex NVT finished and part finished stock. A complete set inc shafts cost (FOR CASH ONLY) £20. The gears were black in colour and they managed to manufacture the wrong size gears. It was possible to get the inner cover on the shafts..just..but I bet that a few miles down the road it locked up solid....... My dealer friend bought one set and had me assemble a box with them to check them out.... I advised him not to buy any more sets but that as individual items the shafts and gears were a bargain.
Many years later some people were still manufactureing gears leaving stress raisers at the base of the engaging dogs and also not splining the centres of the gears so they were correct to the outer teeth.......there are some clever souls out there flogging crap to owners.......

Yes, gears and selectors are all just ducky. Thanks for asking.

However....... my question pertains to inner main shaft bearing I.D. fit on the main shaft.
Shouldn't this bearing be an easy slip-on fit on the main shaft? The inner cover should be able to be installed and removed without any excessive force right?
(C'mon Hobot. Where are you when I need you?)

mschmitz57 said:

The inner cover should be able to be installed and removed without any excessive force right?

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Right! Either your bearing is under size or your shaft is oversize.
I have a shaft on the shelf that I will measure up. You do the same and we'll compare notes.

My bearing surface OD on the shaft measures .6245 to .6250. I do not have a bearing to measure the ID but I believe it should be .625.
http://www.bearing-king.co.uk/bearing/l ... j-rhp/3446

I have to believe that if hobot could be here, he would be.

pete.v said:

mschmitz57 said:

My bearing surface OD on the shaft measures .6245 to .6250. I do not have a bearing to measure the ID but I believe it should be .625

I have to believe that if hobot could be here, he would be.

Click to expand...

Click to expand...

This is exactly my finding as well. I've used a micrometer and a digital caliper and both read .6245 to .6250 (depending on how much coffee I've had).
I can't seem to reliably measure the ID of the bearing with my caliper. It's a poor choice of measuring device for this part.

My parts vender has no problem slipping it on a new main shaft, and all the other bearings in stock slip on fine as well.
I'm asking him to measure a new main shaft.

Thanks Pete.

.6250 (5/8") is correct according to The Bearing Boys listing for an RLS5 bearing.
http://www.bearingboys.co.uk/LJ5_8_Impe ... S5_-5617-p

If the id of the bearing is .625 , and the shaft is .625 , then it wont fit . There needs to be a bit of clearance .
Cheers

ausnorton said:

If the id of the bearing is .625 , and the shaft is .625 , then it wont fit . There needs to be a bit of clearance .
Cheers

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The od is .6245

If the part that changed was the bearing, of course it's the wrong bearing, nothing to do with the shaft which would be EXTREMELY UNUSUAL to find an off-sized part.

That's the conundrum. I have an old bearing that fits the main shaft fine. I have a new bearing that is too tight on the shaft. The main shaft is the correct diameter (.6250).
I returned the new bearing to the The vendor and he says it fits fine on a new main shaft. He also checked the new main shaft and it mic's out at .6250.
I have an old Norton dealer nearby so I may just go see if he has a new bearing in his dusty parts bins.

I know I can always polish the end of the shaft to fit the bearing, or polish the inside of the bearing to fit the shaft but I hate doing this when it should fit.
I'll try a 2nd bearing first. I'll figure it out.
Thanks for all the help.

mschmitz57 said:

I'll try a 2nd bearing first. I'll figure it out.

Click to expand...

That's the thing to do.