4g trans belt pulley question

i got a 80 tooth set up, the one way bearing in them are junk, it blew up, so i welded it and eventually made a solid aluminum bearing replacement. If you can find a solid 100 tooth they will fit right onto the 80 shaft in its place. but you will have to get a new belt. i prefer not to have a freewheeling mechanism, i like the engine braking. but if you put a 100 tooth sprocket inplace of the 80 you will have to pull off the 10 tooth chain cog and replace it with a 12 tooth or your gearing will let you putt up a mountian but not get above 25 mph maxed out.

if you use the 100T pulley you can simply use a smaller rear sprocket to get the gearing you need

you can. But even running a40.tooth rear sprocket I still had a20/1 final drive ratio.

It is also cheaper to replace the smaller front drive cog. 12 versus 30 something dollars plus shipping for a new rear sprocket.

It is a pain in the rear end when the bearing go's

cdavid67 said:

Unbelievable. I guess I should have spent the extra $$ and got a EZM. I haven't even mounted this engine into my bike yet! Well, I think I'll just start out with the oil bushing, stock clutch and 80 tooth gear with the one way bearing and see how far down the road I get.
Thank you all for your replies and advise.

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How is your build going? I am sort of expecting the same. Just started my build tonight. Had to overhaul the rear coaster brake hub in my wally world schwinn before mounting the sprocket.... still is a POS. Did you have trouble with the key that slides into the shaft locking the clutch? wondering if i need to sand it down to fit properly without pounding on the drive shaft to get it close to the clutch.

Hey guys,

The 10T solid sprockets have a larger inner diameter than the 11T/12T freewheel sprockets. The shafts in the 80/10 gearboxes are different than the 100/12.

While I agree, it is a pain to have to sand a key down to size, it is much better that they are too large rather than too small. ANY slop would destroy the keyway and the key.

One way bearing: If you are not a welder/do not have access to one just JB weld it:
1. Make sure you use JB weld and not JB quick
2. Remove the bearing from the pulley
3. Remove both shields from the bearing
4. Remove the one-way mechanism from the bearing
5. Leave the balls and retainer in the bearing to keep the bearings spaced out correctly. This will make sure that inner race and outer race stay properly true. Use contact cleaner to remove all of the grease from the bearing
6. Fill the inside of the bearing with JB weld and let cure. You can place the shields back and wipe any excess JB weld from the outside of the bearing so that you can still install the clips.
7. An option is to grind grooves in the inner and outer race (same direction as the keyway) that will allow the JB weld to seat/bite into.
8. Re-install the bearing both keyed to the pulley and the shaft.
9. You have now made your one-way bearing a solid spacer and it will function the same as a solid pulley. The key is to make sure you let it the JB cure...wait an extra day or two.
Below is a photo of the bearing with both shields removed and the one-way bearing mechanism taken out.

Step 7 is highly recommended as the JB weld can sometimes slip on the inner race without this step.

If your bushing was rusted in the bell when you received it, contact the vendor that you purchased it from and see if they will send you a new one. These came all the way from china, so while rust in unacceptable, it should be understandable.

The shaft size may be different on the chain cog side but the pulleys all have .the same bore.

moonerdizzle said:

The shaft size may be different on the chain cog side but the pulleys all have .the same bore.

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I would really appreciate it if you could measure the diameter of the pulley bore.
thanks.

I will as soon as I get home from work.

Yeah I had to file the key down a bit, but enough for it to fit snug in the shaft groove and clutch. The bushing did have some rust too... I soaked it in marvel mystery oil overnight and yeah the overall packaging was lousy. Glad to hear I can JB weld the bearing, seems easier as I don't weld. I'm gonna run it without the weld and see where that gets me. I'll put pics up of my Schwinn cruiser someday.

The O.D. on the shaft where the one way bearing or solid pulley fits is: .590"
The O.D. on the shaft where the solid 10T sprocket fits on a 80/10 4G is: .590"
The O.D. on the shaft where the freewheel 11T/12T sprocket fits on a 100/12 is: .415"

The freewheel sprockets always fit on the shaft tightly, i usually take a little material off the shaft to make swapping sprockets quicker and easier. The solid sprockets slide on and off fine.

Take some WD-40 to the inside of the bell where the oil-lite bushing was and let it sit for 20 minutes or so. Then take a light wire brush and clean out the inside. Do this a few times and combined with proper lube on your oil-light bushing, you will be good as new. Make sure you clean all of the WD-40 off the inside of the bell with contact cleaner, don't want any clutch slippage.

BE-tech said:

The O.D. on the shaft where the one way bearing or solid pulley fits is: .590"
The O.D. on the shaft where the solid 10T sprocket fits on a 80/10 4G is: .590"
The O.D. on the shaft where the freewheel 11T/12T sprocket fits on a 100/12 is: .415"

The freewheel sprockets always fit on the shaft tightly, i usually take a little material off the shaft to make swapping sprockets quicker and easier. The solid sprockets slide on and off fine.

Take some WD-40 to the inside of the bell where the oil-lite bushing was and let it sit for 20 minutes or so. Then take a light wire brush and clean out the inside. Do this a few times and combined with proper lube on your oil-light bushing, you will be good as new. Make sure you clean all of the WD-40 off the inside of the bell with contact cleaner, don't want any clutch slippage.

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+1. very well put.

how did you remove the shields?

BE-tech said:

Hey guys,

The 10T solid sprockets have a larger inner diameter than the 11T/12T freewheel sprockets. The shafts in the 80/10 gearboxes are different than the 100/12.

While I agree, it is a pain to have to sand a key down to size, it is much better that they are too large rather than too small. ANY slop would destroy the keyway and the key.

One way bearing: If you are not a welder/do not have access to one just JB weld it:
1. Make sure you use JB weld and not JB quick
2. Remove the bearing from the pulley
3. Remove both shields from the bearing
4. Remove the one-way mechanism from the bearing
5. Leave the balls and retainer in the bearing to keep the bearings spaced out correctly. This will make sure that inner race and outer race stay properly true. Use contact cleaner to remove all of the grease from the bearing
6. Fill the inside of the bearing with JB weld and let cure. You can place the shields back and wipe any excess JB weld from the outside of the bearing so that you can still install the clips.
7. Re-install the bearing both keyed to the pulley and the shaft.
8. You have now made your one-way bearing a solid spacer and it will function the same as a solid pulley. The key is to make sure you let it the JB cure...wait an extra day or two.
Below is a photo of the bearing with both shields removed and the one-way bearing mechanism taken out.

If your bushing was rusted in the bell when you received it, contact the vendor that you purchased it from and see if they will send you a new one. These came all the way from china, so while rust in unacceptable, it should be understandable.

Click to expand...

use a small eye glass screwdriver to pop off the sheilds, or a small finishing nail could work, any thing small and pointy pretty much. *insert crude genital joke here*

having a really hard time getting those shields off... my bearing says OWC 44/15 if that means anything, seems like the shields aren't removable. Never had issues with bearings so maybe I'm oblivious to an obvious method?

Hey Ecain,

I've found that with some of the bearings, the shields are a little tough to get off. You really don't need them as they are just for keeping dirt out of the bearing. Once you make it solid, they will not matter. Re-using them was more of just a way to cover up the JB-Weld blob in the center of the bearing. You can grab a small screwdriver or pic, punch it through the thin metal on the shield, and pry it away from the bearing. It is okay if you damage anything behind it because it's just getting filled with JB weld anyway. Just try to keep the bearing retainer somewhat intact. This will keep the 9 balls inside spaced correctly and keep the inner race properly aligned with the outer race (so your pulley doesn't wobble up and down and vibrate horribly at speed).

Ok so I got the shields off with an old knife and the one way mechanism came out in pieces. I left the retainer in and filled the bearing (and I mean little to no air left) let it cure for about 20 hours. I put it back on my transmission and rode it for about 3 miles total just around my neighborhood and said hey I fixed it! But when I grabbed my backpack, tools, and a few home brews to head to a buddies place, I got on and made it down my street and the JB weld gave out. It started slipping and then totally failed... I keep getting teased with this bearing! So my question is: Did I jump the gun on letting the JB weld cure? I took the whole pulley wheel to a local weld shop and the a** hole started to TIG weld and said he couldn't 'cause it's too small. I'm just going to order a new bearing and try again I suppose since the JB weld is in the way of heat welding. Is there a solid 80 pulley with no bearing, just bored and keyed for the 80/10 shaft?