Knucklehead Transmission

[samsmc1]

I need some advise on assembling a trans for a '47 Knuckle.
I have a new Andrews main drive gear that measures 1.0025" ID. The mainshaft has no groove or ware and measures .987. The clearance is just over 0.015. Is this correct for the early 4 speed transmissions or am I missing something here?
I'm also curious to see what should be used in the in the main drive gear as a seal. If I'm looking at the parts book correctly, HD doesn't show a seal untill 1965 or thereabouts. This can't be right. Will the seal from later models press into the main drive gear? If yes like I think it will, which seal should I use (I see several parts numbers)?
Thanks
Sam

[T. Cotten]

I need some advise on assembling a trans for a '47 Knuckle.
I have a new Andrews main drive gear that measures 1.0025" ID. The mainshaft has no groove or ware and measures .987. The clearance is just over 0.015. Is this correct for the early 4 speed transmissions or am I missing something here?
I'm also curious to see what should be used in the in the main drive gear as a seal. If I'm looking at the parts book correctly, HD doesn't show a seal untill 1965 or thereabouts. This can't be right. Will the seal from later models press into the main drive gear? If yes like I think it will, which seal should I use (I see several parts numbers)?
Thanks
Sam

Pretty sure the mainshaft should be a full inch, Sam!

And Andrews obviously supplies them with 'idiot clearance', as nobody seems to know to stress-torque a sprocket and spacer upon them before fitting the bushing to the shaft. (Indian protocol.)

The metal-housed -65 seals installed the easiest.

...Cotten
PS: If the mainshaft journal is indeed sweet and true albeit undersize, it would make sense to cut an under-sized replacement bushing for the gear, and fit it properly.

I would re-inspect the original gear before dedicating the repop!

[samsmc1]

Thanks for the reply. I should have some old gears that are still usable in one of my containers. I'll look tomorrow. Making a new bushing should be no problem.
This bike came from a mass exodus out of Mexico in the mid 80's when the new presidente declared that he was going to really come down on Mexican citizens who had illegally smuggled all types of motor vehicles into Mexico in previous years without properly paying the duties.
I know the cat who brought it back and sold it to the older gentleman I bought it from.
I'll bet they had the shaft reground and a new bushing made in Mexico many years ago. They didn't have parts, so they made things work.

Thanks again
Sam

[dukekleman]

Sam,
All new main drive bushings come undersized. There is no need to make a "one off bushing" .
The Jim's USA is the most undersized main drive gear bushing that I'm aware of. It should suit your needs in this scenario.

Hope this helps,
Duke Kleman

[T. Cotten]

Sam,
All new main drive bushings come undersized. There is no need to make a "one off bushing" .
The Jim's USA is the most undersized main drive gear bushing that I'm aware of. It should suit your needs in this scenario.

Hope this helps,
Duke Kleman

So the JIMS bushing is close or less to .987" on the ID, Duke?

Makes sense if you are going to lathe-bore it!

(An associate brought me a gear to fit, with a fresh Clevite bushing from the Dealership. Pressed it in and honed just enough to de-burr, only to find it was already over-spec: Idiot clearance for unskilled Dealerships.)

....Cotten

[dukekleman]

Cotton,
No, the Jim's bushing measures around .996" prior to installation. After installation, obviously smaller.

As you mentioned, a main shaft should measure 1.000".
Sam stated in his first post that his main shaft measured .987" with no groove or wear.

This is highly unlikely. I've done a lot of these and have not encountered one that measured that with out wear.

I believe a mistake was made in measuring because those numbers give you 0.013" of main shaft wear. Take into account the required 0.002" running clearance required and you have the 0.015" that Sam came up with...

So, either the shaft is worn or a mistake made measuring. Leaves you using a Jim's bushing or purchasing a new main shaft from Andrews in my opinion...
My apologies if I'm wrong in my assumption...
Duke

[duffeycycles]

Andrews gear is probably cut for the seal.OEM was not.

[T. Cotten]

...So, either the shaft is worn or a mistake made measuring...

Or was re-ground in Mexico, which brings us back to a one-off bushing, Duke!

A note on fitting the main drive gear: When torqued to sprocket and spacer, the nut end of the bushing widens.

MDGHONE.jpg

After fitting on the hone, and the sprocket/spacer is removed, the bushing closes back up slightly, but returns to 'true' when installed in the transmission and the sprocket is assembled to the same torque spec.

The fit of the bushing cannot be accurately measured unless stressed.

....Cotten

[dukekleman]

Personally I would treat the new Andrews main drive gear Sam currently has to a proper new Andrews main shaft.

Duke

[T. Cotten]

Personally I would treat the new Andrews main drive gear Sam currently has to a proper new Andrews main shaft.

Duke

My experience with that brand of mainshafts, Duke,..

Wasn't anything that would make me prefer one to a serviceable OEM.

But that was a couple of decades ago, and I'm certain their QC has improved!

....Cotten
PS: Just curious since I haven't dealt with transmissions for so long, but are new gears boxed up with 'idiot clearance' for shafts, or can they be properly fitted?

Only curious, as all of my tooling is for sale.

[dukekleman]

My experience is that Andrews quality has been very good.

To the best of my knowledge, with other brands I've worked around, Andrews is the bench mark currently.

Duke

[T. Cotten]

My experience is that Andrews quality has been very good.

To the best of my knowledge, with other brands I've worked around, Andrews is the bench mark currently.

Duke

You mean benchmark for repops, Duke?

How high is the 'bar' these days? (I thought it all went to hell when JIMS did, so many years ago.)

By definition, OEM must remain, for want of a better phrase, the gold standard.

(And I've certainly never loved the MOCO all that much, ... .. .. )

...Cotten
PS: My previous question was if the mentioned brand of Main Drive Gear comes out of the box un-fitted, or fitted with idiot clearance. Thanks from everyone who might need to know, now or in the future,...

[dukekleman]

The main drive gear comes out of the box from Andrews property sized to their main shaft.

So yes, if your fitting the Andrews main drive gear to a worn, out of dimension main shaft, the clearance is improper and excessive.

Duke

[T. Cotten]

The main drive gear comes out of the box from Andrews property sized to their main shaft.

So yes, if your fitting the Andrews main drive gear to a worn, out of dimension main shaft, the clearance is improper and excessive.

Duke

Please indulge me Duke....

Are these fresh MDGs tighter at the nut end, or are they blown out with idiot clearance?

If they are concentric, you will lose bearing surface, stability, and longevity under the stress of installation.

Catalog crap will always be catalog crap, bless them!

...Cotten

[samsmc1]

This is an interesting dialog. I always heard that both Andrews and Jim's were good quality stuff. That they were American made and equal to OEM. In all fairness, I heard this from salesmen that called on me from Tucker and in the early days, Drag Specialties.
I may be getting old, but my eyesight is 20 20 (eyes got fixed years ago) and the mainshaft out of this trans is smooth and shows no visual signs of being worn out except for the size.
What problems are showing up with the repro stuff? Do they break or just get worn out in a hurry - what's wrong with them??
Even though I've spent 50+ years in the motorcycle business, my Harley experience is with late models since the twin cams came out, so this is all new to me.
I didn't find any of these pieces in my containers this morning, but I haven't looked upstairs yet. Figuring that I don't find any good usable parts like I thought that I had, what do you recommend for a mainshaft?
Thanks for the education
Sam