Knocking / rattling inside primary drive case + backfire

[marshg246]

Same here !

One problem is that, as best i can tell, the Atlas and Commando have different threads. I tried to install a cNw version on a 72 Commando and it would not thread on, but it threaded on just fine on my 74. The owner of the 750 told me the gearbox was from and Alas so I didn't look any deeper. The 72's clutch nut would not screw onto me 850 which also implies different threads. I could be all wet - I haven't research anymore than I just said!

 

[L.A.B.]

One problem is that, as best i can tell, the Atlas and Commando have different threads.

Yes, but the thread wasn't the problem. It replaced the original clutch nut but was over-length and clashed with the diaphragm spring centre.

Found on the old RGM website and in an old paper copy.

Frames

"040373M, CLUTCH LOCATION NUT, FITTED WITH SMALL GARTER SEAL FOR CLUTCH PUSHROD, C, "
"C" = Commando.

Edit:

The owner of the 750 told me the gearbox was from and Alas so I didn't look any deeper. The 72's clutch nut would not screw onto me 850 which also implies different threads.

All Commando mainshafts and clutch centre nuts are the same parts and the Commando clutch doesn't fit the Dominator/Atlas mainshaft.

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[Fast Eddie]

Yup, same trouble for me, was too long, protruded too far and fouled the clutch.

 

[Mart UK]

Same here !

Same here x2.

 

[B+Bogus]

Yup, same trouble for me, was too long, protruded too far and fouled the clutch.

My RGM seal fitted fine after I skimmed about 1/8” off it; maybe more. As delivered it was unusable.

 

[marshg246]

Yes, but the thread wasn't the problem. It replaced the original clutch nut but was over-length and clashed with the diaphragm spring centre.

Found on the old RGM website and in an old paper copy.

Frames

"040373M, CLUTCH LOCATION NUT, FITTED WITH SMALL GARTER SEAL FOR CLUTCH PUSHROD, C, "
"C" = Commando.

Edit:


All Commando mainshafts and clutch centre nuts are the same parts and the Commando clutch doesn't fit the Dominator/Atlas mainshaft.

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Ok, that only leaves that the threads were recut the bike I was working on since the cNw parts fit my 74 but not the 72. And the 72 parts would not fit the 74. What he told me never sounded right.

The DynoDave and the cNw parts are only about 2-3 threads deep - WAY narrower that the picture of the RGM version.

 

[L.A.B.]

The DynoDave and the cNw parts are only about 2-3 threads deep - WAY narrower that the picture of the RGM version.

Yes because the Dynodave seal is an additional item and doesn't replace the nut but it (or the nut) could still need thinning down and that was what I had to do.

rodseal2

"3. You may reduce the depth of the clutch seal down to .120” by grinding or filing.
Typically .140” is actually exactly two threads of engagement.

4. Last, you can grind down the thickness of the clutch center nut 060895 (04373) which is .375/.383” thick. Thinner than .350" would not be typical."

 

[worntorn]

There is a different dynodave clutch rod seal for Dominators.
I've used his Commando type seal on the MK3 and on the 920, which uses a 71 750 box.
They fitted fine.
I installed his Dommie type seal on the 650SS. That also went on without a problem.

Glen

 

[marshg246]

Yes because the Dynodave seal is an additional item and doesn't replace the nut but it (or the nut) could still need thinning down and that was what I had to do.

rodseal2

"3. You may reduce the depth of the clutch seal down to .120” by grinding or filing.
Typically .140” is actually exactly two threads of engagement.

4. Last, you can grind down the thickness of the clutch center nut 060895 (04373) which is .375/.383” thick. Thinner than .350" would not be typical."

Ya, I've read/done that with both. No offense to the creators, but something more in line with a valve seal would make more sense to me. Since I use the later tab washer and thin washer there is very little thread for these.

FYI to those about to tell me to use Locktite and no tab washer - I'm not listening so you're wasting your time telling me! Triumph people love tab washers, Norton people hate them - don't know why, don't care why.

 

[marshg246]

There is a different dynodave clutch rod seal for Dominators.
I've used his Commando type seal on the MK3 and on the 920, which uses a 71 750 box.
They fitted fine.
I installed his Dommie type seal on the 650SS. That also went on without a problem.

Glen

Is it a thread difference? Will a Dommie gearbox work on a Commando or will a Dommie mainshaft work in a Commando gearbox?

 

[L.A.B.]

Is it a thread difference?

The nut and therefore the thread go back to the early Dominator and continued to the 850 Mk3.

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'1A'

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'18'.

Will a Dommie gearbox work on a Commando

Yes, with the Commando mainshaft.

 

[MichaelB]

Looks like the Primary will be dealt with, then we can move onto the Backfire.....

 

[worntorn]

I can't recall the differences between the two seal types only that the Commando type seal is not meant to work on the Dominator main shaft.

Glen

 

[texasSlick]

I can't recall the differences between the two seal types only that the Commando type seal is not meant to work on the Dominator main shaft.

Glen

Or vice versa. Dave's seals are definitely intended for use specific to Commando OR AMC type clutch.

Slick

 

[marshg246]

The nut and therefore the thread go back to the early Dominator and continued to the 850 Mk3.

I'm convinced (already was) just confused about the problem I had. In my fasteners database I have 04.0373 as BSC (CEI) 5/8"x20 and I've added your note. Do you know if it is also right for Matchless and AJS?

 

[Fast Eddie]

My RGM seal fitted fine after I skimmed about 1/8” off it; maybe more. As delivered it was unusable.

Well that’s what I thought. But I put it on the shelf to do later and just used a standard nut. That was 10 years ago and I have never yet suffered from gearbox oil leaking into the clutch, even though I’m running a dry belt.

The OP might wanna think about that before he gets his knickers in a twist about all this …

 

[M-Hawk]

I’m not going to worry about the Dynodave mod for now. But noted for the future, cheers.

 

[Fast Eddie]

FWIW….

This oil is designed for primary, gearbox, and wet clutches.

And it makes for a nice smooth shift... I use it as ‘standard’ in all my old bikes for the nice shifting qualities.

Use it in your gearbox and your primary and you never have to worry about one contaminating the other again!

Sport Transmission Fluid. 1 Litre

DescriptionBel-Ray, Sport transmission fluid. 1 litreDetailsSport Transmission Fluid has been developed for the unique demands of XL Sportster transmissions equipped with wet clutches. Bel-Ray Sports Transmission Fluid flows freely for better clutch cooling and provides positive clutch...

www.hogparts.co.uk

 

[mdt-son]

I'm convinced (already was) just confused about the problem I had. In my fasteners database I have 04.0373 as BSC (CEI) 5/8"x20 and I've added your note. Do you know if it is also right for Matchless and AJS?

It's the same nut as used on Dominators and G15/P11.

- Knut

 

[L.A.B.]

In my fasteners database I have 04.0373 as BSC (CEI) 5/8"x20...

However, CEI would be obsolete by this time and the 20 TPI series was discontinued after CEI had been adopted into British Standard, (CEI becoming British Standard Cycle thread in 1938), therefore, 5/8" x 20, also 9/16" x 20 at the other end of the mainshaft, also the nuts could in fact be 55° special Whitworth (Whit Form) and not 60° Cycle thread.

BSW/UNC Caution

We (especially those in the US) tend to call all British threads Whitworth. In truth not much BSW (British Standard Whitworth) is used in British motorcycles. BSC (British Standard Cycle)/CEI (Cycle Engineers Institute) are much more common (26 tpi). Then there's the BSF (British Standard Fine)...

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