Has This Gear Reach The End Of It’s Useful Life?

How does op plan to use the bike. I reused gears that had some spalling in my 72 but it was mainly a sunny afternoon two lane cruiser. Lasted at least 7 years before I sold it. As far as I know it is still going.
 
ludwig said:
Almost every Commando gearbox with some mileage will show that kind of wear.
Caused/aggravated by a heavy clutch. If you want to be nice to your gearbox, make the clutch as light as possible. Switch to a belt drive and fibre plates.
Click to expand...
The undampened torque pulses may also be the root cause.

- Knut
 
mdt-son said:
The undampened torque pulses may also be the root cause.

- Knut
Click to expand...
That means he should also check the state of his rear hub/cush rubbers!

My Rickman does not have any cush drive, anywhere in the transmission and there is evidence of this type of wear on the TTi gears.

(and no a belt drive does not provide any shock absorption, as in the belt itself, but yes, reduced rotating weight should help)
 
My bearing fell out as well.
With no indication of cracks, I peened the bearing surface and applied Loctite 649 bearing retaining compound to the bearing and have had no issues
 

Attachments

  • Has This Gear Reach The End Of It’s Useful Life?
    Xmission.jpg
    82.8 KB · Views: 69
@stuck amals stopped by to see me yesterday.

His case has no crack between the bearings. However, a gorilla worked on it at some time in the past. The dreaded ball bearing was in it and in shocking good shape (of course, not going back in). The hole for the layshaft bearing showed gorilla damage and will require some cleanup and bearing fit compound.

The sleeve gear bearing hole is not as tight as it should be but at least not gorilla damaged. The sleeve gear had two bushings, but both were all the way inward and worn so the sleeve gear could rock on the shaft quite a bit - probably what made the sleeve gear bearing looser than it should be.

All gears and bushings inspected. Replaced the sleeve gear with a good used one and replaced two bearings gears with a good used. In the case of the original question, that gear is good - that's a metal flaw that was there when the bearing gear was case cut and the mating bearing gear is perfect. Edited out the "auto complete" mess I missed while writing.

Checked the main and layshafts for straightness - both are some of the best I've seen - no measurable bend.
 
Last edited:
"In the case of the original question, that gear is good - that's a metal flaw that was there when the bearing was cut and the mating bearing is perfect."


Any (better) images?
Has This Gear Reach The End Of It’s Useful Life?
Has This Gear Reach The End Of It’s Useful Life?
 
Last edited:
marshg246 said:
@stuck amals stopped by to see me yesterday.

His case has no crack between the bearings. However, a gorilla worked on it at some time in the past. The dreaded ball bearing was in it and in shocking good shape (of course, not going back in). The hole for the layshaft bearing showed gorilla damage and will require some cleanup and bearing fit compound.

The sleeve gear bearing hole is not as tight as it should be but at least not gorilla damaged. The sleeve gear had two bushings, but both were all the way inward and worn so the sleeve gear could rock on the shaft quite a bit - probably what made the sleeve gear bearing looser than it should be.

All gears and bushings inspected. Replaced the sleeve gear with a good used one and replaced two bearings gears with a good used. In the case of the original question, that gear is good - that's a metal flaw that was there when the bearing gear was case cut and the mating bearing gear is perfect. Edited out the "auto complete" mess I missed while writing.

Checked the main and layshafts for straightness - both are some of the best I've seen - no measurable bend.
Click to expand...
Looks a lot like these:
Has This Gear Reach The End Of It’s Useful Life?
Has This Gear Reach The End Of It’s Useful Life?
 
Looks like it all takes place at the root of the tooth where clearances are less and pressures are greatest. In tje OPs picture the wear is at the top of the tooth. In either case, a manufacturing defect in one cant really explain identical wear in the tooth in meshes with.
 
MikeG said:
Looks like it all takes place at the root of the tooth where clearances are less and pressures are greatest. In tje OPs picture the wear is at the top of the tooth. In either case, a manufacturing defect in one cant really explain identical wear in the tooth in meshes with.
Click to expand...
I don't follow what you are saying - there is no wear/damage/mark on the mating gear and only one tooth has the "damage" in the gear shown. The "damage" at the bottom between the teeth next to the tooth in question it is never touched by a gear tooth, so it is inconsequential.
 
marshg246 said:
I don't follow what you are saying - there is no wear/damage/mark on the mating gear and only one tooth has the "damage" in the gear shown. The "damage" at the bottom between the teeth next to the tooth in question it is never touched by a gear tooth, so it is inconsequential.
Click to expand...
So the load is being transmitted through a small area on the teeth of the gear ? I cannot remember if there are spacers in the Norton box. A gearbox explosion and lock-up usually means a crash. So do not get it wrong.
 
marshg246 said:
@stuck amals stopped by to see me yesterday.

His case has no crack between the bearings. However, a gorilla worked on it at some time in the past. The dreaded ball bearing was in it and in shocking good shape (of course, not going back in). The hole for the layshaft bearing showed gorilla damage and will require some cleanup and bearing fit compound.

The sleeve gear bearing hole is not as tight as it should be but at least not gorilla damaged. The sleeve gear had two bushings, but both were all the way inward and worn so the sleeve gear could rock on the shaft quite a bit - probably what made the sleeve gear bearing looser than it should be.

All gears and bushings inspected. Replaced the sleeve gear with a good used one and replaced two bearings gears with a good used. In the case of the original question, that gear is good - that's a metal flaw that was there when the bearing gear was case cut and the mating bearing gear is perfect. Edited out the "auto complete" mess I missed while writing.

Checked the main and layshafts for straightness - both are some of the best I've seen - no measurable bend.
Click to expand...
I’m sorry for not responding earlier. I would like to thank Marsge for spending a couples hours going over the gearbox for me. I will be assembling the g/b after Christmas. It will quite a while before this project is ready to ride though.

I would like to thank every one who after help and advice!
 
Thanks again for all the comments and suggestions.

After a few attempts I was able to get everything to click and go together. It was when I tried to install the inner cover I ran into another problem.

As you can see in the attached picture, the layshaft isn’t centered in the kickstart opening.

It is my guess I didn’t cleanup the layshaft bearing pocket well enough and the bearing is slightly cocked in the pocket.

I will need to heat the case to remove the layshaft bearing and try to clean up the pocket..again.

Just how hot can I heat the case. From what I read 250 to 300 degrees is the maximum for aluminum. Will that be enough to loosen the 680 locktite?

I’m thinking that I should junk the case and find a replacement. That bearing pocket sure looked ugly
 

Attachments

  • Has This Gear Reach The End Of It’s Useful Life?
    image.jpg
    869.1 KB · Views: 31
stuck amals said:
From what I read 250 to 300 degrees is the maximum for aluminum.
Click to expand...
  • NSF/ANSI 61 certified up to 82°C (179.6°F)
So the loctite 680 will release its grip at 82C which is well below the 150C you would look to get the shell up to so the bearing slides out especially as it was loose.

Aim for the shell being hot enough to sizzle a drop of water.
 

Similar threads

ashman
Seems to be a debate on use of clutch when stopped
2 3 4 5 6 7
Replies
134
Views
13,854
ashman
ashman
M
This may interest Norton owners as I have seen the use of decompressor buttons on high comp Norton engines.
Replies
10
Views
1,227
o0norton0o
o0norton0o
ashman
Seems a lot on here have different ways of doing thing on their Norton's
2
Replies
36
Views
4,993
Jonez69
Jonez69
acotrel
Jack of all trades
Replies
7
Views
1,006
acotrel
acotrel
grandpaul
The end of a good photo hosting site
2
Replies
33
Views
4,577
acotrel
acotrel
Back
Top