NKII Rear Hub Squeak

Tornado. How much space do you have between speedo gear and hub? Can you fit a feeler gauge in? Mine is rubbing with less than 60 ft-lb.

Ok just completed a 250 KM "test ride" in 28-31 Cel. At 50-60 MPH for around and hour, Speedo drive stayed a wee bit above ambient based on bare finger temp guage. Brake hub over pad contact area also slightly warmer than ambient (with no rear braking applied for past 30 min).

Will try to get a measure later for you, but I can clearly see a gap 'tween cover and drive. So likely 1/16-1/32" -ish.

Tornado said:

Will try to get a measure later for you, but I can clearly see a gap 'tween cover and drive. So likely 1/16-1/32" -ish.

Click to expand...

BTW, it takes two to tango. I have seen hub covers that were not shaped correctly rub against the speedo drive when there was nothing wrong with the speedo drive. Best to remove the speedo drive and be sure the hub cover is sitting tight to the hub.

marshg246 said:

BTW, it takes two to tango. I have seen hub covers that were not shaped correctly rub against the speedo drive when there was nothing wrong with the speedo drive. Best to remove the speedo drive and be sure the hub cover is sitting tight to the hub.

Click to expand...

Only thing that has changed since rear bearing replacement was a new speedo drive. There was not an issue with hub contact before. May need to find a spacer/washer to make up the 1/16" or so.

Speedo drive testing. The drive that was on the bike was extremely bowed and I could get no useful info from it. The used one shown below is from another 69S that works (just). The other is a new EMGO drive. The same spacer (06.7629) is used for all measuring and testing. The bike has been upgraded to a cush drive hub and the axel is standard but in stainless steel. The axle threads are slightly lubricated.

With the used drive installed, hub cover to speedo drive gap at the tightest point:
25 ft-lb. 0.005”
35 ft-lb. 0.005”
45 ft-lb. 0.004”
55 ft-lb. 0.000”, scraping
65 ft-lb. 0.000”, wheel hard to turn

Overall thickness of the drive .964” before and after testing but that measure was hard to get consistently since the felt retainer is somewhat mangles (see second picture).

The third picture shows the damage to the inside where the metal is thinned and lipped when it squeezed into the inner spacer (I think). This is what LAB showed earlier. I check over twenty non-Norton speeddo drives and none had this problem.







Measured the overall thickness of the EMGO drive before installing and after testing: 0.928”
With the EMGO drive installed, hub cover to speedo drive gap:
Snug 0.075”
25 ft-lb. 0.071”
35 ft-lb. 0.071”
45 ft-lb. 0.065”
Backed off to 35 ft-lb. and the gap was still 0.065”
Saw no point in going tighter - as I never will.







During testing I realized that I generally tighten to 30-35 ft-lb. Since this one is stainless and slightly lubricated, that’s probably 40-45 ft-lb with OEM hardware.

This picture shows the gap with the EMGO drive installed and tightened to 45 ft-lb.



Another test was measuring the thickness of the metal in the center. Since the test one was already squeezed I measured several non-Norton ones and they all were nominally 0.100". The EMGO is 0.147" so about 50% heavier metal in the area. All in testing were Smiths except the new EMGO.

Thanks Greg...useful.
What torque do the speedo's experience on other bike types? Is there any significant differences in how the drives mate and clamp up to the hubs?

What are we to conclude from your tests? Does the pot metal drive actually extrude under loading, which distorts the unit toward the Norton hub cover?

Tornado said:

Thanks Greg...useful.
What torque do the speedo's experience on other bike types? Is there any significant differences in how the drives mate and clamp up to the hubs?

What are we to conclude from your tests? Does the pot metal drive actually extrude under loading, which distorts the unit toward the Norton hub cover?

Click to expand...

I have several theories but don't actually have a clue. I just know that if not over tightened, there is no issue as far as I can tell.

The outer spacer and gearbox spacer have the same ID and OD so no issue there. However, the gearbox spacer must fit into the internal spacer and that is somewhat sloppy. Hence the little ridge LAB reported, and I found. Also, (I think) that is why that spacer can be so hard to get out.

The EMGO drive: "This gearbox is brand new production and has been carefully hardened to slightly exceed the OEM specifications for increased longevity." Don't know exactly what that means or if it's true, but the metal in the area is more substantial.

I don't know about the Triumphs affected by Norton, but the ones I do know of have and inner and outer spacer with the same ID and OD and have no need for a drive spacer - in other words, the axel fits the speedo drive.

I know only British bikes from the 60s and 70s and I've never worked on the quickly detachable Triumph or BSA hubs. Every rear axle I've ever tightened was with a standard 3/8" drive ratchet. Until tonight I had no idea how tight that actually was. With the stainless axle and thick washers (un-lubricated) and the axle threads slightly lubricated, I was pulling with 35 ft-lb. That probably means a bit more with non-stainless, un-lubricated.

I think I forgot to state that the EMGO overall thickness was 0.928" before and after testing and that the felt retainer was not fully seated when I took it out of the package, so I correct that before doing anything else.

Since the Norton rear hub is quickly detachable, there's a lot more going on than in others. Triumph has a simple one-piece axel and two bearings - the cush is in the clutch center. It could be that misalignments or flexing have something to do with the issue - I don't know.

Greg,

Can you explain which spacers you are referring to? Is it the top hat spacer 06-7629 and bearing spacer 06-7704?

marshg246 said:

However, the gearbox spacer must fit into the internal spacer and that is somewhat sloppy. Hence the little ridge LAB reported, and I found.

Click to expand...

However, the speedo drive in my picture is from a T140V (rear disc) wheel that has a large diameter flat outer washer, not a top hat spacer although I believe the internal spacer (looking at other pictures) has a chamfer so that probably accounts for the similar "ridge".

Sorry to be confused as I am getting old but this is what is confusing.

The outer spacer and gearbox spacer have the same ID and OD so no issue there. However, the gearbox spacer must fit into the internal spacer and that is somewhat sloppy.

My pea brain sees 3 spacers. Outer, gearbox and internal.

Cuppy said:

Sorry to be confused as I am getting old but this is what is confusing.

The outer spacer and gearbox spacer have the same ID and OD so no issue there. However, the gearbox spacer must fit into the internal spacer and that is somewhat sloppy.

My pea brain sees 3 spacers. Outer, gearbox and internal.

Click to expand...

Yes, outer '4', top hat '34', and inner, '31'

L.A.B. said:

Yes, outer '4', top hat '34', and inner, '31'

Andover Norton Parts Drawings - Genuine Andover Norton Factory Parts - Commando Parts

Andover Norton Parts are the only Norton spare parts in the market manufactured to original drawings, within the factory-approved tolerances, from the correct materials, and with the correct finish.

andover-norton.co.uk

Click to expand...

Got it now.

L.A.B. said:

However, the speedo drive in my picture is from a T140V (rear disc) wheel that has a large diameter flat outer washer, not a top hat spacer although I believe the internal spacer (looking at other pictures) has a chamfer so that probably accounts for the similar "ridge".

Click to expand...

Ya, forgot that but it is interesting that the speedo drive metal will squeeze into whatever gap there is.

Cuppy said:

Sorry to be confused as I am getting old but this is what is confusing.

The outer spacer and gearbox spacer have the same ID and OD so no issue there. However, the gearbox spacer must fit into the internal spacer and that is somewhat sloppy.

My pea brain sees 3 spacers. Outer, gearbox and internal.

Click to expand...

There are 3 involved and I talk about three spacers here.

BTW, the last picture in my post #85 answers the question about the gap you were asking in post #81.

Cuppy said:

Tornado. How much space do you have between speedo gear and hub? Can you fit a feeler gauge in? Mine is rubbing with less than 60 ft-lb.

Ok just completed a 250 KM "test ride" in 28-31 Cel. At 50-60 MPH for around and hour, Speedo drive stayed a wee bit above ambient based on bare finger temp guage. Brake hub over pad contact area also slightly warmer than ambient (with no rear braking applied for past 30 min).

Click to expand...

OK currently my Smiths speedo drive measures around .045-.055" but it is tough to get consistent measure as the brass felt holder is a bit warped and the hub cover is a bit rough from previous self-machining work ;-)