# Chain Ring Wobble



## Kscheel (May 27, 2014)

I am in the process of assembling my 1948 Roadmaster Luxury Liner and I'm finding that there is some troubling wobble in the chain ring. About 1/4 left to right movement.

I did remove the bearing cups when working on the frame, but they did not appear to be bent. Currently booth appear to be fully seated into the bottom bracket. How can you really tell though?

The bearings are original. When the wobble is occurring the bottom bracket is tight, no slop or looseness anywhere.

What's the deal here? Is the chain ring bent? If it's not the chain ring what could be the culprit?

Thanks


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## Freqman1 (May 27, 2014)

1/4" is pretty significant and you should be able to see this when you spin the crank or take it off and lay it on a flat surface. If bearing cups are seated then I would inspect the chainring. V/r Shawn


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## Obi-Wan Schwinnobi (May 27, 2014)

Chain ring.... All mine have a slight wobble... throw it in a vice and give it a good tug...

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## bikecrazy (May 27, 2014)

May be time to get out the rubber mallett.


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## Kscheel (May 27, 2014)

Okay, now the question is which way do I bend it? Do I bend it towards the frame or away from the frame? Would seeing pictures of how close and how far it is from the frame help in determining that?


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## bikecrazy (May 27, 2014)

Take off the chain and spin the crank. Check the distance between the ring and the frame tube and you should come up with a feel as to where it needs to go. Use light taps because the ring will bend easily. There are other ways to do this, but this is my favorite. Keep in mind that the origional bend may have forced the other half of the ring to be bent in the other direction. Again, light taps at first.


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## jpromo (May 27, 2014)

bikecrazy said:


> Take off the chain and spin the crank. Check the distance between the ring and the frame tube and you should come up with a feel as to where it needs to go. Use light taps because the ring will bend easily. There are other ways to do this, but this is my favorite. Keep in mind that the origional bend may have forced the other half of the ring to be bent in the other direction. Again, light taps at first.




This. Rubber mallet should work. I'd keep it all mounted on the frame and you'll tell exactly what needs to happen. For those who aren't dainty, use a large crescent wrench closed to the width of the ring. Find the high point and wrench the other way.


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## rollfaster (May 27, 2014)

*Rubber mallet*

This worked well for me, my roadmaster sprocket had to be tweaked a bit as well. Light taps as you watch the sprocket while turning the crank.


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## Kscheel (May 27, 2014)

Okay, so the chain ring is not bent. Took it off the crank and laid it flat, no high points. When assembled on the bike I noticed a gap is observed between the bearing race and back of the chain ring. As you rotate the crank the gap comes and goes in sequence with the  observed wobble. I am using new bearings as well.

I'm not sure what is going on here.


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## THE STIG (May 27, 2014)

the crank has a bow between the races, usually when they get bent ( arm offline ) and bent back, most dont know to check for that .


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## Kscheel (May 27, 2014)

How would I fix that?


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## THE STIG (May 27, 2014)

a pointy stick n big rock (JK) 

i use a press.  take the ring off and lay the arm flat, you should see whats going on with it.


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## bikeyard (May 27, 2014)

*Wobble*

Have you tried your chainring on a different crank?


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## Kscheel (May 27, 2014)

The only other crank I have is a schwinn and it has a different thread pattern for the bearing cones.

Below are two comparison photos. The crank on the left is the schwinn, right is the luxury liner. 














Thoughts?


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## THE STIG (May 27, 2014)

Bazinga !!!!!


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## Kscheel (May 27, 2014)

So that's not just a unique early luxury liner crank? Both arms should lay flat link the schwinn?


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## THE STIG (May 27, 2014)

YUP, you can vise it up on the flat between the races and a long pipe over the arm and put it back easy .


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## Obi-Wan Schwinnobi (May 27, 2014)

Just put the schwinn crank on it  

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## Kscheel (May 27, 2014)

Well okay, I feel dumb now for not realizing the offset arms are out of the ordinary, oops. I just bused it up and bent it back. The initial test fit shows the wobble to be significantly lessened. Still needs more tweaking. The other problem I haven't mentioned until now is that the crank arm on the sprocket side is very close to the frame, to the point of occasionally nicking it. How can that be resolved?

Also I would just use the schwinn piece but the luxury liner uses 66 beatings while schwinn uses 64. The hardware from the luxury liner crank will not fit on the schwinn crank as the thread pattern is different.


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## Obi-Wan Schwinnobi (May 27, 2014)

I know... I was being facetious

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## THE STIG (May 27, 2014)

some have thin washer-spacer between the race n ring. not sure if this had one originally, but will solve that issue .


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## Kscheel (May 27, 2014)

Thanks for all the help STIG. It is much appreciated. I guess sometimes you just miss the most obvious solution. I've pretty much gotten the crank straightened out. Just a little more tweaking and it should be good. Third times the charm right?


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## THE STIG (May 27, 2014)

before you assemble it, screw the pedals into it on the inside of arm and lay it flat, (check'n for a twist in the arms) pedals should be inline with center of crank .


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## Kscheel (May 27, 2014)

It looks good. The final tweak took even more wobble out, maybe only 1/8 or 1/16 of an inch now. I now have 1/8 clearance between the sprocket side arm and the frame. Shoul I shoot for more or am I good at this point?


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## THE STIG (May 27, 2014)

straighter is better, caus theres more to it....... any offset will give runout on the ring too (tight n loose chain on rotation)


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## Kscheel (May 27, 2014)

I tweaked it a little more and I'm happy with the final product. This bike won't be a daily rider so, I don't think I'll have any issues. If something does arise I'll just get a new crank as I doubt I could ever get it any better than it is now.

Thanks again Stig!


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