OS 160 Twin Rod Failure - RC Groups
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Oct 24, 2017, 09:10 AM
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Cougar429's Avatar
Discussion

OS 160 Twin Rod Failure


O/K, on impulse may grab more than I can handle here. Looking at picking one of these with a broken rod that took a chunk out of the case. First twin and even if repairable may be the cart before the horse in that no airframe to fit it in, (just like a challenge).

Question here is if anyone has seen a weakness in the rods and any reasons for failure. Hard to tell from the pics, but it appears to be a Boxer design.
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Oct 24, 2017, 09:14 AM
the great Gassif´er
I remember something about earlier OS Boxers having aluminium conrods, and later versions rods made out of Bronze.

I am fairly sure Gary knows more about it, I seem to remember it was him posting about it.
Oct 24, 2017, 09:23 AM
Methanol, The Cool Fuel !
Gary Cee's Avatar
The aluminum rods were marginal in the area of the bearing. The bronze rods are prone to break when over-revved. (From what I have seen)

The rods are still available.
Oct 24, 2017, 10:39 AM
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gkamysz's Avatar
I found this. http://bit.ly/2gAZqHV Those must be very early production.
Oct 24, 2017, 12:07 PM
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Cougar429's Avatar
These are the pics that were sent to me. Think the rod and case are still available.
Oct 24, 2017, 06:27 PM
Engine FrankensteinerÖ
1QwkSport2.5r's Avatar
Ouch. Personally, I wouldn't touch that with a ten foot pole.
Oct 24, 2017, 07:28 PM
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earlwb's Avatar
Well theoretically, Tower Hobbies shows the crankcase on backorder until November. They do show the rods in stock at the moment. Other parts in stock or on backorder. But unless the engine is acquired for free or really really cheap, it may not be worth it to rebuild it. Unless for sentimental reasons of course. But I don't know if that helps you any since you are in Canada.

https://www.towerhobbies.com/cgi-bin...I=OSMG1160&P=Z
Last edited by earlwb; Oct 24, 2017 at 07:29 PM. Reason: add more information
Oct 25, 2017, 10:16 AM
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Cougar429's Avatar
Still awaiting total shipped, but at this point looks like $75. Other than case and rods, just learned one liner may also be toast. Another question is if this may be the same where clone bits fit and work fine.

Love challenges, which is how a few boxes of bits, as well as some spares purchased from YS ended up with a trio of beautifully running 120's. All that for less than $90.

Still, learned a good lesson from an old school body shop owner back in the 80's that have never been able to find fault: " Ifa the foundation, she no good, the housa fall down".

Basically means you can polish a t%*d as much as you like, but it will still be the same as it started. Known a few cars like that over the years and stayed away from them like the plague. Just wondered if this would prove the same.
Oct 25, 2017, 03:18 PM
Registered User
The earlier bronze rods were cast. I believe the latest part number is a billet bronze rod.

But it wouldn't be too difficult if you have the tooling to makes a couple rods from some stainless with some soft copper or brass bearing shells on the big end, and a bronze bush on the small end, wouldn't be any heavier than the billet bronze either.
Oct 25, 2017, 04:07 PM
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Reginald's Avatar
These are the 3 different rods used in the 160... top and center first and second alu versions and bottom the machined bronze...
Oct 26, 2017, 09:25 AM
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Cougar429's Avatar
Engine on the way. Will have a boo once it arrives and post more info as it comes to light.

Reginald, hard to tell from the pics but rod 1, (top) looks to have a smaller diameter pin hole.

Of all 3, which would you personally think is best? My own experience would normally lead me towards the bushed middle rod, but that casting flash leads me to think without dressing them out stress risers would be likely, especially around the bolts.

Never worked with one entirely bronze. The groove in the big end looks to improve lubrication.
Last edited by Cougar429; Oct 26, 2017 at 09:30 AM.
Oct 26, 2017, 09:58 AM
Dieselized User
gkamysz's Avatar
The machined rods are all that is available anyway.

https://twitter.com/justengines/stat...51676584460289

This post seems to say the Sanye rods do fit.

That engine has the earlier air bleed carb.
Oct 26, 2017, 10:40 AM
the great Gassif´er
Quote:
Originally Posted by gkamysz
The machined rods are all that is available anyway.

https://twitter.com/justengines/stat...51676584460289

This post seems to say the Sanye rods do fit.

That engine has the earlier air bleed carb.
If Andrew says they fit, then they fit.

He might not be worlds greatest model engines expert (actually, I do not know what his qualifications are, so I am also NOT saying he isn't....) but I have personally experienced that he is absolutely familiar with the stuff he is selling, and goes to great lengths to help a customer cross-reference parts from one engine to the other.
One thing he is NOT, is a box-pusher....
Oct 26, 2017, 10:51 AM
Methanol, The Cool Fuel !
Gary Cee's Avatar
Quote:
Originally Posted by Cougar429
Engine on the way. Will have a boo once it arrives and post more info as it comes to light.

Reginald, hard to tell from the pics but rod 1, (top) looks to have a smaller diameter pin hole.

Of all 3, which would you personally think is best? My own experience would normally lead me towards the bushed middle rod, but that casting flash leads me to think without dressing them out stress risers would be likely, especially around the bolts.

Never worked with one entirely bronze. The groove in the big end looks to improve lubrication.

I think both versions of the aluminum rod have bushed wrist pin bores but neither are bushed at the crankpin end IIRC.
The ASP/Magnum rods are available in NA from HobbyKing.
Oct 31, 2017, 01:34 PM
Registered User

OS 160 Twin


I am the original owner of this engine. I believe the rod that was used in this engine was the middle one (bronze). It was the rod that caused the problem, as the engine through a rod, then all hell broke loose. I would look at changing both rods as they develop slop and in-turn, fail. I would have tackled it except i have a NIB 160 sitting at home and this one has been sitting in this state for many years. It will make an interesting project and once rebuilt, could represent a good value. These engines are so expensive now to buy new.


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