1 kart! 8HP GX240 on Yerfdog frame, some problems..

[Murray92589]

I bought a torque converter, http://www.gokartsupply.com/tavapp.htm .. i had to grind some places out to make it bolt to my motor properly, now the drive shaft wont go all the way through the driven side of the converter... can a machine shop lengthen my drive shaft? or is there a extension I can buy? what are my options?

I had it running at 38mph with a comet clutch, but i wanted more torque..

 

[Buick455]

Do you have some pictures?

 

[Murray92589]

no i guess i should take some lol. check tomorrow.

 

[Murray92589]

here is a link to some pictures:

http://www.facebook.com/album.php?aid=81632&id=600621405&l=f8284

 

[Buick455]

holycrap that is short

I have heard of extensions for the crank but haven’t seen one in any of the shops I go to (online or in town). Just how long is the shaft? How much keyway do you have before it starts arching upwards?

Hopefully someone here will have dealt with something like this before. If it were me I would rig up some sort of an extension, good luck...

 

[Murray92589]

im going to take it to a metal/welding shop tomorrow, hopefully they will have some ideas. does anyone know if its okay to weld the clutch to make it one piece?

 

[Buick455]

Well that TAV expands and contracts.. I'll show you in a picture I made a few days ago for someone else.. Its kinda rough but you will get the hint..

 

[Murray92589]

ah, so id have to make sure it could still slide over the 1st piece... this is frustrating.

 

[Buick455]

Yeah, the TAV and the bigger 30/40/44 work by changing your gearing by motor rpm. The Driver pulley (on the crank) starts out small, while the Driven pulley starts out big. As the motors RPM's increase the Driver gets bigger & then pulls the belt deeper into the Driven making it expand and get smaller.

I think your best bet will be to make something to extend your crank. When those belts tighten they put some torque on the jackshaft and the crank (I had a 40 Driven on a 1/2" X 12" jackshaft, with bearings at each end, Driven in the middle and the torque managed to bend the shaft). How much of the crank is actually making contact with the inside of the Driver pulley?

 

[Murray92589]

the driver comes in 2 pieces, the first piece fits on and takes up the entire shaft, the second piece does not make contact at all...

what if i use a little spacer behind the first section to push it out and add another shaft under that section so that the keyway of pulley section one is at the joint of my two shafts.. see this picture:
http://www.facebook.com/photo.php?pid=1991337&l=31b75&id=600621405

 

[Murray92589]

or another option would be if somebody makes a driver pulley that does not come in two pieces?

 

[Buick455]

I'm wondering if you could get away with a 1" OD piece of drill rod with a keyway cut into it and an extra long HIGH grade bolt. With that crank you have being so short I would want something to help take the load off the one end of the pulley.

 

[Murray92589]

yeah thats what im thinking of... did you see my picture i drew? if i make that drill rod you posted meet under my first pulley section and stick the bolt through it all will that work?

 

[Buick455]

I'm not going to say 99.9% it will work, but its better then what you got. What would be even better is if you could bolt the adapter I drew to the crank with a through bolt, then bolt the pulley down with another bolt to the adapter, but I'm afraid that the added material removed from the adapter will just weaken the adapter, not to mention add more failure points to the mess.

I think the adapter & a long HIGH grade bolt that threads to your crank is the best bet. Just make the bolt that threads into your crank passes through the adapter tight but not so much that it eats the threads. My crank bolt is 3/8" not sure what size yours is. Also the adapter should be cut to length so it’s just under the length you need (like a hair shorter) so the crank bolt pulls the whole thing together...

If you make the adapter, or get it made at a shop post pics, I want to see it


Edit: Don't forget the washer if the TAV didnt come with one.

 

[Murray92589]

ok one other option, i think this would be safer, use the adapter but also if i buy the 40 series driver and driven will it fit on the plate that came with the tav 2?

 

[Buick455]

The 40 onto the TAV? That one you’re going to have to wait for someone else. I have no clue if it will fit, the 40 driver pulley is 6", Driven is about 8" and they are 8" center to center of each other on my kart. You also need to think about the money, the 40 Kit is like $230 without a belt I think and it doesn’t fix your crank problem you will still need something to make it longer. Hell the adapter could be cheap if you can find the parts or someone to do it. I would give it a go and if it frags chalk it up as a learning experience, lol.

 

[Buick455]

I had a new idea for the adapter... Check out the picture, this seems allot safer and stronger. Washer 1 & Locknut 1 will be to hold on the adapter. Washer 2 & Locknut 2 will be to hold on your pulley. The adapter will need to be made to length including the washer and locknut to fit under/inside the pulley.

The threaded rod will need to be burried into the crankshaft, pass through the adapter, then bolt down the adapter, then bolt down your pulley. You get the hint, lol

 

[Murray92589]

Im having a machine shop make the adapter for me, should be ready next week. ill post some pics when i get it.

 

[thgrahamjr]

If you are taking it to a machine shop then I would do it right, I would remove the crankshaft and do what Buick455 said but I would bevel the two pieces and weld them together and have the machine shop machine the weld down and match the key ways. Here is what I'm talking about:

 

[Murray92589]

the machinist put the extension in so tight that it holds my two clutch pieces together so there isnt a pic of the extension by itself, im having my chain put on right now, but by running it without a chain it seems to hold up fine at full throttle.

http://www.facebook.com/album.php?ai...5&l=ed1aa2215a