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3 piece wide crank set won't tighten without crushing bearings

4 stroke motorized bicycle engine kits are great if you want reliability or do not want to mix your oil and gas. Learn from each other how to get the most out of your 4 stroke bicycle engine


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  #11  
Old 09-01-2013, 10:15 AM
atombikes atombikes is offline
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Default Re: 3 piece wide crank set won't tighten without crushing bearings

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Originally Posted by worksuxxx View Post
Just installed another 4g kit last night. I got the crank nice and tight with no play. But a lot of resistance and noise. Had to take off pedal sprocket and after four taps on right crank with mallot to remove right crank it loosened the crank shaft. I think the threads are crap. Retighened and loctited but have not ridden yet. I know after first ride its gonna go loose. Other bike loosens every time I ride it.

So I reread the posts here. I can't seem to get it straight. I have the lock ring on the pedal side. Is this not correct?
When in doubt, go to the master Sheldon Brown.

http://sheldonbrown.com/gloss_bo-z.html#bottom

scroll down to "bottom bracket". What we are discussing here is a cup and cone BB. In the pic it is the first one on the left. The lock ring is on the non-bicycle side. Also notice that on the Ashtabula crank, the lock ring is also on the non-bicycle drive side.

This is convention. Unfortunately, the 3 pc wide cranks I have force me to switch this around, which is why I'm thinking there's something wrong with them.
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  #12  
Old 09-01-2013, 10:55 AM
KCvale KCvale is offline
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Default Re: 3 piece wide crank set won't tighten without crushing bearings

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Originally Posted by worksuxxx View Post
Ok, I have toasted two sets of crank bearings in under 12 hours. I can't seem to get the crank tight enough without allowing for any play.
The non-cartridge BB for 4-strokes is a royal pain to make go right, it is just a poor system design.
What seems to work is:
1. Make sure you have good solid bearing cups in the BB up flush against the frame before you even start.

2. Put the bearing holder part of the enclosed bearings to the inside in the cup.

3. Screw the right pedal side crank arm retaining nut in first all the way AND DON'T LET IT OR THE SHAFT MOVE AGAIN.

4. Put on the big left side ring up pretty snug but not tight enough to grip the crank shaft and then the really tricky part, you need to keep that but in place while you screw the retain nut up against with some good torque against each other to keep them from moving WITHOUT LETTING ANYTHING ELSE MOVE.

OR...
You could just replace those bearing cups with cartridge cups for $12.
http://www.sickbikeparts.com/catalog...4b5j9a8bo0stj2

Then put in a cartridge BB crank shaft wide enough for a 4-stroke for $15.
http://www.sickbikeparts.com/catalog...s/153mm-BB.jpg

Notch the shaft where you want your pedal sprocket to go and use the kits crank arms and be done with it.
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  #13  
Old 09-02-2013, 03:19 PM
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worksuxxx worksuxxx is offline
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Default Re: 3 piece wide crank set won't tighten without crushing bearings

OK. I just did two bikes with the bearings facing outward. Tightened perfectly without wobble. Been out riding and not coming loose. Did the lockring on the pedal side. Finally. I was getting very frustrated with this. The one bike I had been having problems with when I pulled the crank set apart the bearing housing was again crushed. I guess putting the bearings outward work so I'll be doing that from now on. If it's not the proper way I don't care, it works!
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Old 09-03-2013, 02:34 PM
KCvale KCvale is offline
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Default Re: 3 piece wide crank set won't tighten without crushing bearings

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Originally Posted by worksuxxx View Post
OK. I just did two bikes with the bearings facing outward. Tightened perfectly without wobble. Been out riding and not coming loose. Did the lockring on the pedal side. Finally. I was getting very frustrated with this. The one bike I had been having problems with when I pulled the crank set apart the bearing housing was again crushed. I guess putting the bearings outward work so I'll be doing that from now on. If it's not the proper way I don't care, it works!
Glad I could help ;-}
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Old 09-03-2013, 09:51 PM
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Default Re: 3 piece wide crank set won't tighten without crushing bearings

I just picked up some bearings today for tomorrow's build. I am gonna just put bearings in with no bearing cage. Interested in seeing how that works. I will post the results in a few days after some time on bike.
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Old 09-03-2013, 10:29 PM
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Default Re: 3 piece wide crank set won't tighten without crushing bearings

The cage should face the cone and the balls should be out towards the races.
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