Gearbox output bearing

Information relating to the Matchless G5 or AJS Model 8 350cc Lightweight
Nigel Leppard
Posts: 12
Joined: Sat Feb 29, 2020 11:21 am
Location: Buckinghamshire UK

Gearbox output bearing

Post by Nigel Leppard »

Hi ,
Having sorted the clutch basket wobble ( we some expert advise from members)I now have another issue. I have stripped the gearbox as I need to sort out oil leaks etc and need to replace the output bearing.
As you can see, the one supplied by the club is the correct replacement part but my shift is approximately 2mm undersized.
The box has a non standard bearing fitted so has the output shaft been turned down or am I missing something??
I'm hoping that the great minds can shed some light on the issue.
Thanks for your help.ImageImageImageImage

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Mick D
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Joined: Mon Mar 24, 2014 5:44 pm
Location: Aberdeenshire

Re: Gearbox output bearing

Post by Mick D »

Hi

First thing I'd do would be to remove the old bearing and search for a part number on the concealed areas, then check availability of that with the major manufacturers.

Failing that measure the ID, OD and thickness and input these dimensions into the search facility on the supplier's websites eg:

https://simplybearings.co.uk/shop/?gcli ... gJUXvD_BwE

Regards Mick
Greybeard
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Location: East Yorkshire

Re: Gearbox output bearing

Post by Greybeard »

Ive never come across a roller bearing that runs directly on a gear shaft - all the bearings of that type Ive come across have been matched with a hardened inner race. Are you sure its the correct one? Every gearbox Ive worked on has had caged ball bearings like the one fitted in your g/box case.Having said that Ive never worked on a lightweight p :|

Steve
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clanger9
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Location: Chester, UK

Re: Gearbox output bearing

Post by clanger9 »

Unfortunately, your output shaft has been turned down. Here's one with the correct journal diameter (should be 32.0mm):
IMG_0044.jpg
The bearing from the club is correct. The one in your gearbox is incorrect - the correct bearing is a floating design that allows the output shaft to move.
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Last edited by clanger9 on Tue Aug 11, 2020 5:57 pm, edited 1 time in total.
1989 Moto Morini Dart 350
1993 Ducati 750SS
Greybeard
Member
Posts: 456
Joined: Mon Jun 29, 2015 8:49 pm
Location: East Yorkshire

Re: Gearbox output bearing

Post by Greybeard »

clanger9 wrote:The bearing from the club is correct. The one in your gearbox is incorrect - the correct bearing is a floating design that allows the output shaft to move.
Well, you live and learn. Cheers Clanger9

Steve
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clanger9
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Location: Chester, UK

Re: Gearbox output bearing

Post by clanger9 »

It's certainly an unusual design. There must be a logic as to why they went for a floating bearing.
1989 Moto Morini Dart 350
1993 Ducati 750SS
Nigel Leppard
Posts: 12
Joined: Sat Feb 29, 2020 11:21 am
Location: Buckinghamshire UK

Re: Gearbox output bearing

Post by Nigel Leppard »

Well thanks for all your comments and help. I thought I was going mad as I new it was an unusual design.
The chance of me finding another output gear is remote to say the least so I suppose the best thing to do is replace the bearing like for like and hope the P/O had the gear hardend after it was ground.
I appreciate everyone's advice.

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Mick D
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Location: Aberdeenshire

Re: Gearbox output bearing

Post by Mick D »

Nigel Leppard wrote:hope the P/O had the gear hardend after it was ground
Hi

Not so important if you replace like with like as the shaft is not now acting as the inner race.

Regards Mick
Nigel Leppard
Posts: 12
Joined: Sat Feb 29, 2020 11:21 am
Location: Buckinghamshire UK

Re: Gearbox output bearing

Post by Nigel Leppard »

I was wondering if that would now matter as the bering now has an inner race.
I'll build it back up see what happens. I've realised that most things with these bikes are not what they seem but it keeps you on your toes !
Thanks again.

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Steve S
Posts: 123
Joined: Fri Sep 30, 2016 12:03 pm
Location: Hertfordshire United Kingdom

Re: Gearbox output bearing

Post by Steve S »

Hi Nigel, I bought a new old stock output main gear from Norvil two years ago, so worth a try asking them if they still have some.

Steve S.
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