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Post  gvc Wed May 25, 2022 2:17 am

I have a RR1 with play in the crank.  When the piston is at the lowest you can make it go up and down slightly by “rocking” the crank.  I assume the journal is worn.  Apparently the crankcase can be re-sleeved.  I would like to find out if there is anyone out there who can do that.  Thanks
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Post  Marleysky Wed May 25, 2022 7:19 am

3 am in the morning, worrying 'bout a wobby crank? Well WELCOME to the Forum! lol!

you assumption is probably correct. do you have any other Cox 049 engines you can swap cranks and crankcases with to verify the slop in the journal? do you know the history of your RR-1? Must have been run without proper fuel/oil mixture to wear that much off the journal, usually that is where castor oil congeals, heats up and slows the RPMs down. I'm not a machinist, the closest thing I have to a lathe is a hand drill. I'm sure someone in the group could tell you if its possible to re-sleeve the crankcase. If I were going to run it, I'd find a substitute crankcase, or NOS replacement.
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Post  gvc Wed May 25, 2022 9:01 am

I did change out the crankcase with another but had to use the RR1 crank because it has that little pin used to drive the rotary valve. The wobble improved significantly. I wanted to keep the RR1 stock and use that cool gold ribbed crankcase. Thanks for the reply.
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Post  aspeed Wed May 25, 2022 3:14 pm

I bushed a few many years ago with some brass as it was just available. Made a sleeve with a thin wall and just reamed the case on a drill press. The fit of the crank was very close until it was pressed in. Then it got tight and had to be refit. Took quite a bit of time. On the old cases like yours it is very thin where the bushing gets pressed in. This wear is very common on the Bees and gives an erratic run. Foxes are pretty sloppy after a lot of running too. I have had a few Thunder Tiger .07s that were loose from new as well. I doubt very many guys have rebushed them because a new case is pretty cheap. The RR1 case is pretty rare.
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Post  GallopingGhostler Wed May 25, 2022 6:49 pm

Marleysky wrote:3 am in the morning, worrying 'bout a wobby crank?  Well WELCOME to the Forum!  lol!
Yup, goes to show @gvc fits in with the rest of us! Laughing

Wobbly Crank 2022-036

Welcome to the forum, gvc!

Marleysky wrote:you assumption is probably correct. do you have any other Cox 049 engines you can swap cranks and crankcases with to verify the slop in the journal?  do you know the history of your RR-1? Must have been run without proper fuel/oil mixture to wear that much off the journal, usually that is where castor oil congeals,  heats up and slows the RPMs down. I'm not a machinist, the closest thing I have to a lathe is a hand drill. I'm sure someone in the group could tell you if its possible to re-sleeve the crankcase. If I were going to run it, I'd find a substitute crankcase, or NOS replacement.

Personally, I don't have an RR-1, so can't contribute much regarding re-sleeving your crankshaft journal bearing surface. However, please give some time for the others to respond. Also, it would be helpful if people knew your approximate location, so they could steer you to someone.

There is another in this forum who also sells machined products for Cox and a few other half-A engines on:

https://kamtechnik.com/contact-us/

If he doesn't or can't do this service, may be he can direct you to someone who can. Popcorn

Another place to inquire is at Stunt Hangar: http://stunthanger.com/smf/index.php

Again, welcome to the forum! Thumbs Up
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Post  gvc Wed May 25, 2022 11:10 pm

Thanks for the leads. I am in Northern CA.
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Post  davidll1984 Thu May 26, 2022 8:06 am

First hello I think it would be impossible to do a buching to repair because the particularity of this crankcase would make it fragile or even detach a part of the front with the grooves this is the line in the piece it leaves very little material to machine Could be possible but not 100% sure It would be possible to make this feature on another crankcase with a swan neck and anodize gold color
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Post  davidll1984 Thu May 26, 2022 8:17 am

I have already managed to repair one with a pipe cutter I have worn out the round cutting wheel and I have place tight on the crankcase then turned a few turns, tighten and repeating until the crank turns with a small friction restriction !!!! dont cut the crankcase Wobbly Crank Img_2339
its this engine Look the front this is the result and i made it anodized
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Post  aspeed Thu May 26, 2022 9:28 am

Interesting method. I noticed on my worn ones that the wear was on the bottom of the case at the back. The front was not too bad. Maybe a short bushing at the rear would not weaken the case too much. It would have to be machined in very carefully.
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Post  davidll1984 Thu May 26, 2022 10:16 am

On the back i used the Ball reset tool tink or it was a tool box I'm not sure I remember I asked m'y self the question for a while the principle is to use a round object with a taper inside so as to crush the outline of the hole inside or it could be a punch to make holes in the leather I I don't remember anymore
Huh... I used a bit of all sorts of things until it worked lol! After the anodizing it was tight I did a polish with car polish and a dremel tool To lap the crankcase and crankchaft To mate them perfect and i have To use two thrust washer on this one One is over the wide part of the crank and one on the drive plate spline as usual but this engine did not have it was very worn I also had to install a buching in the piston conecting rod
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