Gear box compatibility

Production K Models

Gear box compatibility

Postby RHK » Wed Dec 15, 2021 6:00 am

Hi Guys,
I've just bought the remains of a '53 Model K. I've always wanted one but never found one here in the UK. Unfortunately, its missing the entire gearbox internals.
I was hoping someone could advise on which gear box parts are compatible with later model Sportsters etc. Any pre '70 stuff over here is very rare.

Thanks,

RHK
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Re: Gear box compatibility

Postby JerrryR » Wed Dec 15, 2021 10:06 am

Hi RHK, I will be watching this thread with interest myself. For now I will simple add that your 52-53 K right side case used a countershaft with a larger right end and larger bearing. The right side cases' countershaft race is larger to accommodate the larger shaft.

Countershaft Table Group.jpg
Countershaft Table Group.jpg (175.49 KiB) Viewed 5765 times


Countershaft Table Versions 52-54.jpg
Countershaft Table Versions 52-54.jpg (149.7 KiB) Viewed 5765 times


Countershaft Table Version -58.jpg
Countershaft Table Version -58.jpg (92.09 KiB) Viewed 5765 times
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Re: Gear box compatibility

Postby RHK » Thu Jan 06, 2022 11:59 am

Hi JerrryR, Thanks for your response and sorry that I'm slow with mine. I'm still trying to work through the info you posted as I'm not getting much downtime at the moment.
This rebuild is going to be very interesting to say the least. I will post whatever I manage to do with the situation. I think total originality will be impractical, so I shall just do the best I can to get a working rideable bike.

Thanks again.

RHK
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Re: Gear box compatibility

Postby Tim The Grim » Fri Jan 07, 2022 4:13 pm

There may be some info here you could interpret as well. It’s Ironhead stuff but the part #’s will still reference K years and changes.

http://sportsterpedia.com/doku.php/tech ... ansfinal02

If you’re not doing a resto and just building a rider, you want to be sure to put a reinforcement ring around the tranny countershaft boss and
Delete the speedo drive ring from the gear.

Image

***Credit for that pic goes to Dr Dick *** with all due respect and thanks.
54KHK (Current Build),2013 XL1200V “72” Hard Candy, 97 Honda Valkyrie
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Re: Gear box compatibility

Postby EKHKHK56 » Mon Jan 10, 2022 2:41 am

It’s recommended to use the transmission as a set, mainly for Shaft/Gear compatibility and it is always a good idea with any used parts to have matched if possible. These parts are all strongly built and survive mixing fine if in specs. Basically the -58 and up is strongest mainly due to C shaft and progressively stronger gears. -54 and up fit -52,53 cases with a simple Bronze Sleeve pressed in case to accept smaller OD C shaft Bearing on right side. If I remember correctly it is exactly 1/8” wall.
Last edited by EKHKHK56 on Mon Jan 10, 2022 3:05 am, edited 1 time in total.
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Re: Gear box compatibility

Postby EKHKHK56 » Mon Jan 10, 2022 2:47 am

The reinforcement ring with Speedo Drive delete is fine idea, however if you are going permanent a welded in support plate around Bearing Boss and to Case makes it even stronger by stabilizing entire Boss. Don’t weld all the way around on case, just attach securely.
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Re: Gear box compatibility

Postby RHK » Mon Jan 10, 2022 9:24 am

Hi Guys, Thanks for the info, very welcome. I've located a and bought a '58 gear cluster, so getting excited about making some progress. Making a bearing sleeve and reinforcement ring shouldn't be a problem.

Thanks again.

RHK.
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Re: Gear box compatibility

Postby JerrryR » Mon Jan 10, 2022 9:58 am

If you are going to use a 58 gear set you will have to use a -58 countershaft. The -56 mainshaft will require a different left end release rod than a 53K would have used.
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Re: Gear box compatibility

Postby EKHKHK56 » Wed Jan 12, 2022 12:17 am

Good points Jerry, also the -58 gears will not go on earlier C shaft as they have different internal splines on gears.
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