Rework bearing seat of the gearbox shell due to a crack

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Lorenz

Lorenz

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Hello to everybody.
I have a really huge issue where I like to ask for your appreciated support.
After a gearbox defect by destroyed ball bearing of layshaft, I disassembled the whole gearbox.
I discover that there is a small crack between the layshaft bearing seat and the main shaft bearing seat. The crack is between the booth bearing crossing.
Hope you understood which point I mean. The smallest point spacing of both bearing seats.
Can I use the shell or do I have to rework the crack?
The bearing seat itself is fine. Only the surface area behind the layshaft bearing seat has lightly worn out.
I guess this is the easiest issue. I can clean it easily.
But how about the crack?
A friend of mine is able to weld Alu. Make it sense to weld it and rework the seat by the boring head?
Or is such crack no problem at all?
Thank you in advance.
Regards Lorenz
 
A most common problem. I suspect all boxes crack eventually due to the tiny amount of material between the bores. Don't think welding will hold for
long. You could use bearing loctite but the best way probably is to pin the bearings with small grub screws twixt bore and bearing.
My method was to install a TTI box. Best thing I ever did. Hey, sometimes you just need an excuse to loot the family fisk.
 
Lorenz said:
Hello to everybody.
I have a really huge issue where I like to ask for your appreciated support.
After a gearbox defect by destroyed ball bearing of layshaft, I disassembled the whole gearbox.
I discover that there is a small crack between the layshaft bearing seat and the main shaft bearing seat. The crack is between the booth bearing crossing.
Hope you understood which point I mean. The smallest point spacing of both bearing seats.
Can I use the shell or do I have to rework the crack?
The bearing seat itself is fine. Only the surface area behind the layshaft bearing seat has lightly worn out.
I guess this is the easiest issue. I can clean it easily.
But how about the crack?
A friend of mine is able to weld Alu. Make it sense to weld it and rework the seat by the boring head?
Or is such crack no problem at all?
Thank you in advance.
Regards Lorenz
Click to expand...

Your verbal description is very good. Most all do that tiny crack in the taint area. Accepted opinion is, it’s ok to re-use reliably. I did, no troubles.
The wear behind thelayshaft bearing, as long as it did no perforate will be fine.
 
If you weld the crack, it will need machining afterwards.

Just beware it may be easy to spend £200 or so on welding and machining and a new, stronger shell is available from AN for around £270 + vat.

I fitted a new AN shell to my 850 as I had the same crack as you.

Many say it’s fine to run with the crack. With my luck, I decided not to!
 
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Dear All. I have to say thanks for that great support.
Good to have you all.
I will use the Shell as it is without welding the crack.
My idea is also to glue the bearing.
Also the surface is not perforated.
So, fortunately, no need to loot the family "fortune" what will bring me in big trouble. :D
Best Regards Lorenz
 
I've wondered if using some penetrating Threadlocker 290 might be good to seal such a crack to prevent any seepage.
 
Rework bearing seat of the gearbox shell due to a crack
rvich said:
I've wondered if using some penetrating Threadlocker 290 might be good to seal such a crack to prevent any seepage.
Click to expand...
The pattern failure crack described by the OP is completely internal to the trans, so seepage will not be an issue.
 
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L.A.B. said:
As a matter of interest, was it brass or steel cage? Any manufacturer's name or other markings?

Replace with the roller bearing upgrade....:
https://andover-norton.co.uk/en/shop-details/17267/layshaft-roller-bearing-18337-b2-322-

...or 6203TB.P63 ball bearing.
Click to expand...

I'm sorry, but I not 100% sure about that question.
I guess you ask for the cage of layshaft bearing?
I don't find any colored chips inside the shell, so I assume it was a steel cage.
Also I assume there was NO ball bearing installed, due there is no round groove in the outer ring.
It seems it was a Roller Bearing. Type and Producer not readable anymore.
The bearing you proposed is already ordered. But it seems the whole gearbox has to be maintained.
All pinions have pitting and worn out at the flank of the tooth.

Hope these informations are you looking for?
Regards Lorenz
 
rvich said:
I've wondered if using some penetrating Threadlocker 290 might be good to seal such a crack to prevent any seepage.
Click to expand...

Luckily, the crack at the bearing seat is ONLY inside, so no crack to the outer surface of gear shell. In such case welding would be a necessity. But I saw at other bikes owners repair such crack by tinning solder ( REIBLOT in German) I guess "tinning solder" does not give the exact definition of this special soldering material for Alu!
Link: It is in German but you see how it works. I have used such a tinning solder to repairing an Alu Fender strut of a Harley. I was surprised by how stable it was.
Regards Lorenz
 
Lorenz said:
I'm sorry, but I not 100% sure about that question.
I guess you ask for the cage of layshaft bearing?
I don't find any colored chips inside the shell, so I assume it was a steel cage.

It seems it was a Roller Bearing. Type and Producer not readable anymore.
The bearing you proposed is already ordered. But it seems the whole gearbox has to be maintained.
All pinions have pitting and worn out at the flank of the tooth.

Hope these informations are you looking for?
Regards Lorenz
Click to expand...

Thanks for answering.

So it was actually a roller bearing that failed as you said previously it was a ball bearing!
Lorenz said:
After a gearbox defect by destroyed ball bearing of layshaft,
Click to expand...


Lorenz said:
Also I assume there was NO ball bearing installed, due there is no round groove in the outer ring.
Click to expand...

If you mean originally, then yes, it would certainly have had a (6203) layshaft ball bearing installed but that is a 'one-piece' bearing, the inner and outer races of which can't normally be separated so it could not have been used with the outer race of the roller bearing Edit: or the roller used with the ball bearing outer race.
 
Sorry, it seems I've mixed up the words.
The bearing was totally destroyed. No way to see what kind of bearing was grinded.
Only many peaces of metal chips and the outer and inner bearing ring gives me an idea it was a bearing!

Hope nobody of you will hit by this sneaky defect.
I have to recommend: If you see that the Kickstarter is moving, or an ungood feeling with the condition of the gearbox hit you: Check the box. It is no big deal to dismount both outer shells and helps to prevent unnecessary costs.
;)
 
Lorenz said:
Sorry, it seems I've mixed up the words.
The bearing was totally destroyed. No way to see what kind of bearing was grinded.
Only many peaces of metal chips and the outer and inner bearing ring gives me an idea it was a bearing!
Click to expand...

OK. Failure of the NJ203E upgrade roller bearing is unusual.
 
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