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Connecting Rod small end bearing material

Connecting Rod small end bearing material

Connecting Rod small end bearing material

I've a few 500cc air cooled English motorcycle engines, circa 1950, to rebuild.

The original small end bush appears to be of an aluminum alloy.  

Can someone recommend a modern bearing material and quote a ASTM or SAE number for the material?



RE: Connecting Rod small end bearing material


I personaly can't, but if you repost this in the engine and fuel engineer section, I'm guessing you'll get a better response.  I hate suggesting that, because I'd like more traffic throught the motorcycle engineering forum, but for an question like this, it's the best place.

Good luck.  What are the motors out of Triumph singles?

RE: Connecting Rod small end bearing material

Thanks for the response.   I'm going to need more than luck.

I'm feeling a little kicked around, sort of like a bastard step-child.  Seems like a guy named Dave Murphy who runs this Eng-Tips web site chased me off Automotive and sent me here to Motorcycle Engineering.  

The bikes in question are Norton singles, ann AJS/Matchless.

Best wishes,

RE: Connecting Rod small end bearing material

Fear not, Dick.  Some of us are in both forums.
My 500cc 1948 Norton was rebuilt a couple years ago by an outfit up in Van Nuys and they used a standard automotive bush, a bronze/brass alloy of some sort I suspect.  Seems ok so far. On my Mini Cooper race engine I converted the rods/pistons to a push fit by simply honing the rod small end to a > 0.0005 fit. No bush, just steel pin on steel rod. I have used this procedure on a Lotus twincam engine that used Nissan L-18 rods and it lasted several years in competition...still have the parts and wear to the rods is minimal...now I haven't looked at the pins lately!  The idea here is that by the time I rebuild the engine, after a couple seasons, maybe more, (it is "vintage racing") I will replace all the affected components.  I am not sure I  would do this to a street engine where lubrication is not as well controlled.


RE: Connecting Rod small end bearing material

Thanks Rod:  My problem is we changed from a stock piston to a modified Harley piston.  This changed the pin dimentions so the small end bush needs a smaller ID than stock bushings.

I need to find the best material for making up some bushes.

The Dixter here still searching!!


RE: Connecting Rod small end bearing material

If it was me, i'd use some sort of phosphor bronze.

RE: Connecting Rod small end bearing material

pre evo Harley wrist pin bushings are available. I forget their OD, but I'd estimate their finished wall thickness at around 0.06 inch.  The sportster bushing was much shorter than the big twin bushing.

RE: Connecting Rod small end bearing material


These people might be able to help, or failing that have you tried any of the owners club sites?

Good luck with your projects, as a Brit it breaks my heart to see a country that once produced so many great cars and bikes in the state it is now in.

RE: Connecting Rod small end bearing material

Hi Ajack1:   I share your views on the phight of Blighty. Unfortunately, I believe the US of A is rapidly headed in the same direction.

I think this thread is completed.  Bunting Bearings Corp. provided the best service with a wealth of data supporting their recommendations.  The folks @ AMPCO were marginal at best: the engineer they provided did not know what a conecting rod was, and was unwilling to make any recommendations for "liability reasons".  Frankly I was was expecting the current and ever popular default Nine - Eleven excuse.

In any event, thanks to all of those who responded, your recomendations helped me find the answer.  CDA93200 far outways CDA95400 in this application.

Dick, with a happy face, in Seattle

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