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Cox Engine of The Month
August-2024
balogh's
![](https://i.servimg.com/u/f95/15/46/86/41/1_balo14.jpg)
"Cox TD09 R/C Beast of Burden featuring Kamtechnik head and DIY metallic fuel nipple"
![](https://i.servimg.com/u/f95/15/46/86/41/sponso12.png)
PAST WINNERS
balogh's
![](https://i.servimg.com/u/f95/15/46/86/41/1_balo14.jpg)
"Cox TD09 R/C Beast of Burden featuring Kamtechnik head and DIY metallic fuel nipple"
![](https://i.servimg.com/u/f95/15/46/86/41/sponso12.png)
PAST WINNERS
Wobbly Crank
Page 1 of 1
Wobbly Crank
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
gvc- Moderate Poster
- Posts : 18
Join date : 2019-06-02
Re: Wobbly Crank
3 am in the morning, worrying 'bout a wobby crank? Well WELCOME to the Forum!
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.
![lol!](https://2img.net/i/fa/i/smiles/lol.gif)
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.
Marleysky- Top Poster
Posts : 3618
Join date : 2014-09-28
Age : 71
Location : Grand Rapids, MI
Re: Wobbly Crank
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.
gvc- Moderate Poster
- Posts : 18
Join date : 2019-06-02
Re: Wobbly Crank
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.
aspeed- Platinum Member
- Posts : 790
Join date : 2013-01-18
Location : Leamington Ont. Can.
Re: Wobbly Crank
Yup, goes to show @gvc fits in with the rest of us!Marleysky wrote:3 am in the morning, worrying 'bout a wobby crank? Well WELCOME to the Forum!![]()
![Laughing](https://2img.net/i/fa/i/smiles/icon_lol.gif)
![Wobbly Crank 2022-036](https://i.servimg.com/u/f53/18/91/97/52/2022-036.jpg)
![Welcome](/users/3015/29/34/60/smiles/2120589027.gif)
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](/users/3015/29/34/60/smiles/1347041234.gif)
Another place to inquire is at Stunt Hangar: http://stunthanger.com/smf/index.php
Again, welcome to the forum!
![Thumbs Up](/users/3015/29/34/60/smiles/1541798026.gif)
GallopingGhostler- Top Poster
Posts : 5513
Join date : 2013-07-13
Age : 70
Location : Clovis NM or NFL KC Chiefs
gvc- Moderate Poster
- Posts : 18
Join date : 2019-06-02
Re: Wobbly Crank
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
davidll1984- Diamond Member
- Posts : 2307
Join date : 2020-02-12
Age : 39
Location : shawinigan
Re: Wobbly Crank
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](https://i.servimg.com/u/f58/20/16/70/92/img_2339.jpg)
its this engine Look the front this is the result and i made it anodized
![Wobbly Crank Img_2339](https://i.servimg.com/u/f58/20/16/70/92/img_2339.jpg)
its this engine Look the front this is the result and i made it anodized
davidll1984- Diamond Member
- Posts : 2307
Join date : 2020-02-12
Age : 39
Location : shawinigan
Re: Wobbly Crank
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.
aspeed- Platinum Member
- Posts : 790
Join date : 2013-01-18
Location : Leamington Ont. Can.
Re: Wobbly Crank
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
I used a bit of all sorts of things until it worked
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
![Huh...](/users/3015/29/34/60/smiles/3929217648.gif)
![lol!](https://2img.net/i/fa/i/smiles/lol.gif)
davidll1984- Diamond Member
- Posts : 2307
Join date : 2020-02-12
Age : 39
Location : shawinigan
Re: Wobbly Crank
I somewhat resolved the wobbly crank by using a crankcase from my parts box. Thanks for all the responses.
gvc- Moderate Poster
- Posts : 18
Join date : 2019-06-02
gvc- Moderate Poster
- Posts : 18
Join date : 2019-06-02
Venom self destructed
Well I bought a new in box Venom 2 from a oldtimer fellow C\L fanatic, and was intending to use it to power my girls Man Win trainer. Straight out of the box I noticed that the crankshaft was very wobbly, you could see with a prop on it that the prop tips would move 1\4" side to side. It was like a joystick, not to mention the thrust slop. I ponder it for a few days and concluded that maybe the Venom was manufactured loose for more power..boy was I wrong! I should have gone with my gut feeling to find another crankcase and crank even though it was brand new. I decided to start it, and on the third rich tank.it locked up..broke the connecting rod right where it connects to the ball in the piston..Crazy! Never in 30 yrs flying nitro have I seen a broken connecting rod.
Michpatriot- Gold Member
- Posts : 157
Join date : 2023-01-12
Re: Wobbly Crank
I have had/seen a broken rod that went through the case of a TD, a rod that wore through the top of a piston in a swap meet motor, broken cranks at the crank pin.... Later cranks had a thicker web in the TDs and I believe the reedies too? Maybe your piston/rod socket was loose?
aspeed- Platinum Member
- Posts : 790
Join date : 2013-01-18
Location : Leamington Ont. Can.
Re: Wobbly Crank
Hi All,
I had a pull start Cox Sanblaster rig,
To put on my new RC (Heathkit) equipment.
Good Luck,
Dave
I had a pull start Cox Sanblaster rig,
To put on my new RC (Heathkit) equipment.
Good Luck,
Dave
HalfaDave- Platinum Member
- Posts : 609
Join date : 2022-12-06
Location : Oakville, Ontario
Re: Wobbly Crank
broke a controd on a piston where it connects to the piston. TD at absolute full cry on 42 foot steel tent pegged
Plane was a write off engine seemed surprisingly ok, quick cleanup disassemble on launch table and clean and into another plane. To my surprise started perfectly, ran great! Launched plane, flying around, all was good, and then silence. The engine just stopped.
Had a look, didnt turn over so good anymore.
![Wobbly Crank Piston10](https://i.servimg.com/u/f68/20/35/75/62/piston10.jpg)
Cant really blame Cox for that one though.
Yabby
![DAMMIT!](/users/3015/29/34/60/smiles/2949197080.gif)
![Paranoid](/users/3015/29/34/60/smiles/221949261.gif)
![Huh...](/users/3015/29/34/60/smiles/3929217648.gif)
Had a look, didnt turn over so good anymore.
![Wobbly Crank Piston10](https://i.servimg.com/u/f68/20/35/75/62/piston10.jpg)
Cant really blame Cox for that one though.
![lol!](https://2img.net/i/fa/i/smiles/lol.gif)
Yabby
Yabby- Platinum Member
Posts : 711
Join date : 2021-06-08
Location : Yorke Peninsula South Australia
Re: Wobbly Crank
Hi Gvc , there was a guy on here that did a repair on the journal with a valve guide from i think was a Porsche , so you said you were looking for someone I would try engine machine shop they do this work as in replacing guides and could possible turn on down on a lathe and press in in for a FEE ! Don't cost much to find out and beeing in CA. in am sure there are some good shops out there
And I would have sent that Venom back for a refund off of eBay as soon as i seen the slop !
Wow here is one for sale Bid > I would ask him what he means about the Bad crankshaft , Maybe the pin us broken the shafts very seldom wear out. https://www.ebay.com/itm/266096417685?
![Small Cox Logo](/users/3015/29/34/60/smiles/7356.png)
![Happy New Year](/users/3015/29/34/60/smiles/3568862115.gif)
Last edited by getback on Mon Jan 23, 2023 6:02 am; edited 1 time in total (Reason for editing : add on)
getback- Top Poster
Posts : 10326
Join date : 2013-01-18
Age : 67
Location : julian , NC
Re: Wobbly Crank
Thanks getback - I contacted the seller with the RR1 parts, you guessed it, the crank pin is broken off. Thanks for the lead. I may bid on the parts and hope that the crankcase is better than mine.
gvc- Moderate Poster
- Posts : 18
Join date : 2019-06-02
Re: Wobbly Crank
Nice looking engine , may try a new/difft. glow plug and see if it starts easier . Those parts only come around ever few years from what i have seen ( just keep that I mind ) Is that old castor at the front drive plate ? Good luck if you decide to bid .
![Small Cox Logo](/users/3015/29/34/60/smiles/7356.png)
getback- Top Poster
Posts : 10326
Join date : 2013-01-18
Age : 67
Location : julian , NC
Re: Wobbly Crank
I suppose it is baked on castor oil. I bought the engine used and was disappointed with the worn crankcase. I think the buyer sold it in good faith and worked with me a little when I pointed out that the engine was unusable.
gvc- Moderate Poster
- Posts : 18
Join date : 2019-06-02
Re: Wobbly Crank
In salvaging the situation restoring the engine to a great runner, I'd say that now you have a story teller. That hybrid engine, uniquely customized by you, restored to fine running condition is a potential winner for the next COX ENGINE OF THE MONTH CONTEST as is. But, you could possibly highly polish the Babe Bee crankcase to a mirror finish, and send chills up @fredvon4's spine.gvc wrote:[...]
I suppose it is baked on castor oil. I bought the engine used and was disappointed with the worn crankcase. I think the buyer sold it in good faith and worked with me a little when I pointed out that the engine was unusable.
![Very Happy](https://2img.net/i/fa/i/smiles/icon_biggrin.png)
GallopingGhostler- Top Poster
Posts : 5513
Join date : 2013-07-13
Age : 70
Location : Clovis NM or NFL KC Chiefs
Re: Wobbly Crank
Awesome setup you have there!
Michpatriot- Gold Member
- Posts : 157
Join date : 2023-01-12
Re: Wobbly Crank
WOW it fetched a pretty good price >> https://www.ebay.com/itm/266096417685
![Small Cox Logo](/users/3015/29/34/60/smiles/7356.png)
getback- Top Poster
Posts : 10326
Join date : 2013-01-18
Age : 67
Location : julian , NC
Re: Wobbly Crank
I’ll say, I was stunned. It looks like I should be happy with the Babe Bee crankcase. Here’s another, I wonder if it will go for the asking price?
https://www.ebay.com/itm/115514154846
https://www.ebay.com/itm/115514154846
gvc- Moderate Poster
- Posts : 18
Join date : 2019-06-02
![-](https://2img.net/i/empty.gif)
» My crank said No!
» 049 crank vs. 051 crank
» Finished cleaning the chopper engine (baby bee)
» Tee Dee crank
» TD 049 crank mod
» 049 crank vs. 051 crank
» Finished cleaning the chopper engine (baby bee)
» Tee Dee crank
» TD 049 crank mod
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