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

[baz]

Is the case cracked between the two bearings?

Yes he says it's cracked between bearings in reply 4

 

[htown16]

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.

 

[TJBaker57]

Yes he says it's cracked between bearings in reply 4

The way I read post #4 he says they are NOT cracked. "isn't suffering....".

At least as far as he knew at that time.

Am I reading this wrong?

 

[NPeteN]

The way I read post #4 he says they are NOT cracked. "isn't suffering....".

At least as far as he knew at that time.

Am I reading this wrong?

"On the bright side, the gearbox isn’t suffering from that crack between the bearings"

You are reading correctly.

 

[mdt-son]

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.

The undampened torque pulses may also be the root cause.

- Knut

 

[SteveA]

The undampened torque pulses may also be the root cause.

- Knut

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)

 

[Mofosheee]

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

 

[marshg246]

@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.

 

[concours]

"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?

 

[velo54]

"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?View attachment 122789View attachment 122790

That's called super finishing!

 

[concours]

@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.

Looks a lot like these:

 

[concours]

ok

That's called super finishing!

it's called spalling.

 

[MikeG]

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]

https://cdn.skfmediahub.skf.com/api...edium/093168a92d25cc46_pdf_preview_medium.pdf. Spalling is also very common in automotive wheel bearings. I used to see badly spalled tapered wheel bearings off heavy trucks and semi trailers all the time. Always caused by improper preload or overloading, never imperfections in the bearing surface.

 

[marshg246]

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.

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.

 

[acotrel]

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.

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.