yerf dog 3203 jack shaft help!

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r97

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A 3/8" jack shaft, is that a typo? What does the bore of your driven measure? What does the bore of that jack-shaft housing measure (the part that the bearings fit into)? When people use a 40 series clutch I suggest that the jack-shaft have support bearings on both sides of the driven. From what it looks like in the pictures, you may need to move/replace your jack-shaft mount for the driven to fit/be aligned properly.
 
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r97 said:
A 3/8" jack shaft, is that a typo? What does the bore of your driven measure? What does the bore of that jack-shaft housing measure (the part that the bearings fit into)? When people use a 40 series clutch I suggest that the jack-shaft have support bearings on both sides of the driven. From what it looks like in the pictures, you may need to move/replace your jack-shaft mount for the driven to fit/be aligned properly.
Click to expand...

lol, im sorry, I meant its a 3/4'' driven pulley. It wont slide on the old 5/8'' jack shaft. I need help finding a 3/4'' jack shaft that will slide in the yerf dog jack shaft housing. It will be a lot of work unbolting the engine and the frames cage to replace the whole engine mount. I drilled two holes on right side of the frame and the left side, the bolts are through the original holes for the ex27.
 
r97

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If you are set on using that jacks-shaft mount you will have two options. You could get a 3/4" jack-shaft, and have part of it turned down to fit inside the bearings. As an alternative, you could possibly get some 3/4" bearings that fit into the housing (measure the housing's ID). With either of those options you should be installing another bearing, so that the jack-shaft is supported with bearings on both sides of the driven.
 
OzFab

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Sorry, but I see a problem with both options:

r97 said:
You could get a 3/4" jack-shaft, and have part of it turned down to fit inside the bearings.
Click to expand...

To do that you'd need to turn down the ends so the bearings can slide on, negating the use of 3/4" shaft.

Although, leaving one end @ 3/4" will work, as long as the sprocket is 5/8".

r97 said:
As an alternative, you could possibly get some 3/4" bearings that fit into the housing (measure the housing's ID).
Click to expand...

the bearings needed to do this would be an odd size &, therefore, expensive.

A third option is to stay with the 5/8" shaft & use a spacer/shim & a deeper keystock.

Come to think of it, the larger key may not be necessary as the spacer would only be 1/16" thick
 
OzFab

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Yep, that will work but, do some research into bearings to fit both the shaft & the housing

"No threads or splines." Copied & pasted from the description
 
r97

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Fabroman said:
Sorry, but I see a problem with both options:



To do that you'd need to turn down the ends so the bearings can slide on, negating the use of 3/4" shaft.

Although, leaving one end @ 3/4" will work, as long as the sprocket is 5/8".



the bearings needed to do this would be an odd size &, therefore, expensive.

A third option is to stay with the 5/8" shaft & use a spacer/shim & a deeper keystock.

Come to think of it, the larger key may not be necessary as the spacer would only be 1/16" thick
Click to expand...

I don't like the options I suggested either, but if he is set on using the existing jack-shaft bearing housing they are the best options I can think of.

Using spacers could work, but if he doesn't add the support bearing I mentioned, moving up to a 3/4" jack-shaft would be even more important. I would say the oversize key would be necessary, the driven or the jack-shaft's key-way could end up engaging only 1/32" of the key's height. That sounds like trouble just waiting to happen.

Do you know the ID of the bearing housing? Until the OP measures I can't know for sure. If it is 1 3/8" (likely) then the required bearings would be an odd size, but how do you know it isn't 1 5/8"? Although .75" ID by 1.375" OD ball bearings are uncommon, they can still be found. I purchased some from Blaz (go karts of Texas) a year or two ago, they were a little expensive, but nothing ridiculous.

I'm not at all seeing what you are saying about my first suggestion not working. Take a 3/4" keyed shaft, turn down one end to fit the bearings. Slide that end through the bearings, and install something on the small end sticking out of the bearings to secure it (ie. a locking collar). Then you have a 3/4" keyed shaft sticking out of the bearings that you can place the driven, a sprocket and a support bearing.

I believe that a 40 series setup should look almost exactly like THIS (sprocket can go on either side). Sure it will cost you a bit more, and yes you will probably need to remove the engine (four bolts?), but I think that having it built solidly will be worth it. If you put in the extra effort now you will never have to mess with it again.

mdj89, the length of the jack-shaft is something that you are probably going to have to figure out on your own.
 
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qtband

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MFG Supply has a 1 3/8 x 3/4 bearing.
http://www.mfgsupply.com/9-327.html
Please tell us the housing ID.
I'd be willing to try replacing the bearings first. It's the most economical solution. I don't think that Yerf dog is a real heavy kart. Anyway, it's worth the try. IMO.
 
OzFab

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r97 said:
I'm not at all seeing what you are saying about my first suggestion not working. Take a 3/4" keyed shaft, turn down one end to fit the bearings. Slide that end through the bearings, and install something on the small end sticking out of the bearings to secure it (ie. a locking collar). Then you have a 3/4" keyed shaft sticking out of the bearings that you can place the driven, a sprocket and a support bearing.
Click to expand...

That's what I meant by the second comment. The first was a temporary aneurysm before I realised this was what you were thinking:roflol:
 
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