the old 5/8" shaft and 3/4" torque converter CVT problem

[beltbuckle]

I am midway through a build and am having problems adapting the torque converter (with 3/4" bore) to a 5/8" shaft on the predator.

I have the sleeves to adapt the shaft diameter to 3/4", so that is not a problem.

The problem is that the torque converter driver (piece 1024 below) has a built-in standard depth key. This is not deep enough to go past the sleeve into the actual keyway of the shaft.

built-in key

tav2_driver


I know several people have mated the driver to a 5/8" shaft - looking for help on what others did to get this to work.

 

[wayne z]

Hmmm, Maybe you could cut/file a slot on the other side of the adaptor bushing, leaving a 1/4 inch of stock at one end to keep the halves attached, and fit a key there to catch the crankshaft, and fit the TAV key to catch the original slot.

 

[beltbuckle]

Thanks Wayne I'll give that some thought.

Last night I was thinking of maybe just welding the sleeve/bushing to the shaft with a few rosette welds and make it a "permanent" 3/4" shaft. only issue there would be to find a way to get the driver the correct distance away from the engine but might be able to use a collar or something.

 

[Ibedayank]

Silver solder does not need as much heat as a weld and most likely for this would be stronger and less chance of warping the crank


not acid core but real silver

 

[beltbuckle]

well i think this will work. there is probably a better or easier way but i couldn't think of one.

i used a total of two of these bushings, and drilled and deburred three 1/4" holes in each bushing


20120616_123617.jpg


i put a collar part way on them and the key in during welding to keep them compressed tight and aligned to the shaft.


20120616_141854.jpg


after welding, ground the welds down smooth and finished with a paddle disc on a hand grinder. the collar will keep the engine-side piece of the driver from floating.


20120616_142416.jpg

CVT test fit.. it fits.


20120616_144726.jpg



20120616_144252.jpg



i think 6 rosette welds should be strong enough to keep it from spinning on the shaft, time will tell. they welds are quick and i don't think the heat on the shaft is too much of a problem. it probably did soften the heat-treated shaft a bit around the welds but my gut feeling is that at the 3HP range this is strong enough.

on to the next problem.

 

[Mac]

That rosette weld idea will work for sure, only thing is if you need to take the motor apart, you may have to grind the whole "sleeve" off to pull the engine side cover.

R/Mac

 

[beltbuckle]

that's a good point. as cheap and reliable as these engines are though i have no plans of ever opening it up.

 

[MEASURE TWICE]

I was wondering how the weld held on the crankshaft adapter?

I also am thinking of a torque converter the Comet 30 series individual component build type for 5/8 inch shaft. The driven comes in 5/8 inch but the driver is 3/4 inch or 1 inch only with the key permanently installed. If in the driver if it was not a built key a special key height would suffice.

I posted recently on the Take a tip leave a tip asking how to solve the problem:

http://motorbicycling.com/showthread.php?p=534539#post534539 Page 85 post 843

I came up with an idea without welding I posted there.

I think I like Wayne Z's post with two keys slots in the bushing reducer and they can be easy to make.

Modifying Wayne Z’s idea, I thought of this:

The 30 series Comet separate components type Torque Converter for the driver is 3/4 inch or 1 inch option and the built in key on both. I’d use the ¾ inch driver.

What I may try is use from Grainger their 5/8 inch to 3/4 inch bushing reducer that has the full length 3/16 keyway cut away axially in line down the bushing reducer. I think about 8 dollars for a pack of three.

They are 1 an 1/4 inch long and another version I think 1 and ½ inch long. I may use two or all three of them so that cut off shorter 1 or 2 of them. I can center one left uncut at 1 an 1/4 inch or 1 and ½ inch so I can have the slot for the built in driver key centered and aligned.

Alternately I may have to use just two of them and span the slots across ends of just two bushing reducers.

I’d cut a slot for the driver, but only the length of the built in key. It would be 180 degrees opposed to the full length slot for engine shaft.

The key for the engine would be 3/16 inch by 5/16 inch rectangular full length almost 2 inches.

The built in driver key would be fixed at 3/32 inch just shy 1/32 inch of the 1/8 inch thickness of the bushing reducer ¾ inch to 5/8 inch.

Still contemplating this use of a torque converter as it is not too often I am needing to change the overall ratio on my dual purpose OHV trail riding / art vehicle motor bike.

Trail riding I have now set at 21:1 ratio 10 mph. A not too often 45:1 ratio under 5 mph would allow the clutch to run cool for parade use when it has the art fish looking cover I am finishing making for the motor bike.

I have to otherwise disassemble one or two of my dual jackshafts and change sprockets and associated chain lengths, which is not something done very quickly.

MT

Trail riding OHV / art vehicle motor bike:

http://motorbicycling.com/showthread.php?t=29678&page=16

 

[Cheeseman]

I had the exact same issue. I ended up using a Ironton 208cc (with 3/4 shaft) instead of the 79cc Predator I wanted for a minibike. I'm happy with the power, but wanted to keep it small.
I pretty much settled on the 'shaped spacer' idea, like most of y'all...Using 3/4 conduit with the keyway cut in.
I figured the motor only turns CCW, so one fixed key in the clutch would HAVE to be spun by the key in the motor shaft....IF the play in the bushing / adapter wasn't too sloppy.
Good luck.
Here's the first one with the big 6hp on it. And the plan I found online...a 1951 Popular Science reprint. If you do this, make your frame an inch wider, and about 3 inches longer in the rear. Also, I used cheap 5/8 pillow block bearings instead of the odd parts on the jackshaft. AND...as tight as their frame dimensions were, I added a cheap bicycle disc brake to the jackshaft instead of the go-kart band brake. Easier and more elegant.

http://www.vintageprojects.com/mini-bike/gas-Scooter.pdf

 

[Tony01]

@Cheeseman

 

[MEASURE TWICE]

Cheeseman thanks for posting anyway!

I started out back in the 70s looking at the Honda 70 others had and for a tight budget then I actually bought plans from ad in the back of Popular Mechanics Magazine. Drilling a hole in a bike frame to funky mount an edger engine and no welding was kinda a rip off of my think 10 dollars paid.

I can say I probably am not going to try using a torque converter on the bike I of the last 5 or so years have been using I built. The making the art cover went on hold, but have it still running as a dirt bike with a slightly bigger and less old, better shape 3.5 Briggs with now chain and toothed clutch. Only the rear wheel sheave and one pulley still use V-belt.

As time allows, the art cover parts are still stored away and was also looking at a hover craft idea, this when things are situated better.

The thread creater was I checked last seen in 2013.

MT

 

[curtisfox]

I had the exact same issue. I ended up using a Ironton 208cc (with 3/4 shaft) instead of the 79cc Predator I wanted for a minibike. I'm happy with the power, but wanted to keep it small.
I pretty much settled on the 'shaped spacer' idea, like most of y'all...Using 3/4 conduit with the keyway cut in.
I figured the motor only turns CCW, so one fixed key in the clutch would HAVE to be spun by the key in the motor shaft....IF the play in the bushing / adapter wasn't too sloppy.
Good luck.
Here's the first one with the big 6hp on it. And the plan I found online...a 1951 Popular Science reprint. If you do this, make your frame an inch wider, and about 3 inches longer in the rear. Also, I used cheap 5/8 pillow block bearings instead of the odd parts on the jackshaft. AND...as tight as their frame dimensions were, I added a cheap bicycle disc brake to the jackshaft instead of the go-kart band brake. Easier and more elegant.
View attachment 101187

http://www.vintageprojects.com/mini-bike/gas-Scooter.pdf

This would of done the trick for the 79..............Curt

https://www.amazon.com/Adapter-Pull...coding=UTF8&psc=1&refRID=JRJJ652EJD7MGBRQKEJY

 

[MEASURE TWICE]

This would of done the trick for the 79..............Curt

https://www.amazon.com/Adapter-Pull...coding=UTF8&psc=1&refRID=JRJJ652EJD7MGBRQKEJY

I don't think that does it.

What he welded up does make perfect sense.

See the picture of built in key on the torque converter (common with newer stuff now):

http://farm8.staticflickr.com/7085/7189932991_4dbf5197f3_o.jpg

See what he did after the welding and removing the key and leaving just the sleeve with the slot that would match up with the 3/4 bore torque converter part with built in key.

http://farm8.staticflickr.com/7084/7381859580_532536be58_o.jpg

MT