Are crankshaft adapters viable for a clutch?

[robgmn]

I have a Predator with the 3/4" shaft and a dual-sprocket clutch setup that is for a 7/8" shaft.
Would an adapter sleeve work for this, or would I just be creating a time bomb?

If it matters, the clutch is from a 1969 Rupp with the two-speed jackshaft.
'Hoping to avoid spending $$ (as always) on a new clutch if I can use the one I already have.

 

[metal man]

Should work for ya

 

[markus]

I have a Predator with the 3/4" shaft and a dual-sprocket clutch setup that is for a 7/8" shaft.
Would an adapter sleeve work for this, or would I just be creating a time bomb?

If it matters, the clutch is from a 1969 Rupp with the two-speed jackshaft.
'Hoping to avoid spending $$ (as always) on a new clutch if I can use the one I already have.

The H50 rupp engine used the 31826 crankshaft, it measures .750 output.....3/4" :shrug:

 

[robgmn]

The H50 rupp engine used the 31826 crankshaft, it measures .750 output.....3/4" :shrug:

I'll have to re-measure when I get home tonight.
I'm pretty sure the hole on the clutch (?)cover is 7/8". I put it on the Predator shaft and it flops around a lot.
Unless the brass bushing got really worn?
To be continued...

 

[robgmn]

This is where it gets weird.
The clutch plate center hole is .7405" ID.
The sprocket "bell" center hole is .890" ID.

The (?)bronze bushing is in place, but seems fairly thin. Maybe it just got bored out?

 

[markus]

maybe just need a new bushing. But since your are working with a 48 year old clutch assembly, you may want to go ever the entire thing to make sure everything else is in working tolerances :thumbsup:

NOS genuine 69 Rupp Roadster Ram Goat 2 speed engine clutch bushing/bearing | eBay

 

[robgmn]

OK, another Smack My Head moment.
The crankshaft on the original motor is 7/8" OD, but is machined to 3/4" OD at the end.
The clutch "plate" with the 3/4" ID mounts on the end of the shaft; the clutch bell with the .89" ID "floats" on the larger portion of shaft between the fixed plate and the crankcase.

My original concern with an adapter was that the groove for the key would potentially eat the bushing.
Now, I'm thinking if I can get a fully cylindrical tube with the proper ID (3/4") and OD (7/8"), I can just slide that on the shaft and slide the clutch bell over it.
Then, the clutch plate just slides on to the Predator crankshaft and locks down.

 

[markus]

OK, another Smack My Head moment.
The crankshaft on the original motor is 7/8" OD, but is machined to 3/4" OD at the end.
The clutch "plate" with the 3/4" ID mounts on the end of the shaft; the clutch bell with the .89" ID "floats" on the larger portion of shaft between the fixed plate and the crankcase.

My original concern with an adapter was that the groove for the key would potentially eat the bushing.
Now, I'm thinking if I can get a fully cylindrical tube with the proper ID (3/4") and OD (7/8"), I can just slide that on the shaft and slide the clutch bell over it.
Then, the clutch plate just slides on to the Predator crankshaft and locks down.

There is a part of your clutch assembly stuck the original crankshaft, I can assure you its not a 7/8 shaft turned down at the end to 3/4 :laugh:

 

[robgmn]

There is a part of your clutch assembly stuck the original crankshaft, I can assure you its not a 7/8 shaft turned down at the end to 3/4 :laugh:

And it looks like a sleeve is on there! I can't tell if the sleeve is stepped at the crankcase side or if it's just a plain one.
Not budging (and too dang cold to want to spend any time playing with it), so I guess my own sleeve is the direction I'll be taking .

 

[neo71665]

Yeah that sleeve "should" come off.

 

[Dr. Shop Teacher]

Take some PB Blaster and spray on the sleeve, let her sit for a while. It'll take some work to get it off without tearing it up...I used a screw driver as a pry bar with a wooden wedge. You may have to heat it lightly to get it to break loose. A new Max Torque clutch is about 75 bucks, btw. The old clutch may not like 6.5 new ponies too much.

 

[markus]

And it looks like a sleeve is on there! I can't tell if the sleeve is stepped at the crankcase side or if it's just a plain one.
Not budging (and too dang cold to want to spend any time playing with it), so I guess my own sleeve is the direction I'll be taking .

View attachment 94885

View attachment 94886

scary thing is the dimple in the sleeve which looks like a keyway guide does not exactly look like its in the keyway!! I've never had one of those clutches, someone like Joe51 might be able to give you some insight if thats just a mark from someone pounding on it,a keyway dimple, or a spot that helps retain lube for the bushing. Also be worth talking to someone that actually knows to see if that sleeve is separate/removable from the hub or if something went wrong

Since your talking 2 speed and clone on a rupp, have you test fitted all this together :shrug: Will you even have room to clear the high gear clutch and all that? If I am not mistaken its takes some work to squeeze a clone on one of the later 60's bikes. Think you have to block the up off the engine plates just to clear simple jackshaft.

Good luck with it!

 

[scootercat]

Looks like that sleeve has turned a bit,the dimple should line up with the keyway....tap with a small blunt rod while holding the shaft and try to turn the sleeve back to line up with the keyway then use a puller that fits between the sleeve and the crank stop edge....

 

[robgmn]

Thank you all for the good advise and help.
The sleeve and clutch are going to stay on the original engine, which is going to get well-oiled and crated for a possible future restoration (or sale).
I managed to get a new two-speed Max torque clutch for about half price, so I jumped at it!

Pressed the new torrington bearing in the sprocket when I got home today, and the new seat was sitting on the kitchen table when I went in the house.
My son is getting very excited for the christening ride...