crankshaft conversion

has anybody ever converted a crankshaft from bushing to rollerbearking?

Re: crankshaft conversion

If by rollerbearking, you mean replacing the stock rod with a roller bearing ended rod, the answer is yes. Not hard to do. Really only cost effective on stock cranks that are impossible to get after market cranks for (ZA50, other brands that I don't know much about)

1. Buy the connecting rod

2. Take the crank and connecting rod to you local machinist

3. Pay the man

4. Enjoy

Re: crankshaft conversion

i meant more like taking the stock connecting rod, drilling the spot where the bushing is to the proper size, and putting a rollerbearing on the stock connecting arm.

Re: crankshaft conversion

Pablo Puchasso /

I'm trying to do this myself. Anyone have any luck?

Re: crankshaft conversion

you can do it with a tapered reamer and a caliper (digital is best)

you need to know when to stop and lube it. for best results stop just shy of the number you need and get a ball reamer and press it thru. it will harden the inside bore


Re: crankshaft conversion

yeah... someone was telling me they found a bearing out of a weedeater or something that went from 15mm od to 12mm id, and that this was relatively simple.

Re: crankshaft conversion

please excuse my ignorance on this but what is the advantage? the bushing is constantly lubbed up, why is the bearing better?


Re: crankshaft conversion

Needle roller bearings.

Re: crankshaft conversion

yeah, its constantly lubed. but the constant metal on metal rubbing causes a lot of heat and fatigue, especially at high rpms. its not really a problem on stock engines, but on kitted engines, you can destroy that bushing pretty quickly.

a roller bearing has much less friction and therefore less heat and stress.

Re: crankshaft conversion

I heard somewhere it wouldn't work. I think the roller bearing needs to ride on heat treated steel, while the bushing does not. I think the bearing will wear the con. rod and create too much play. Someone correct me if I'm wrong.


Re: crankshaft conversion

we'll just treat our steal i guess. i dunno why it would make a huge difference. especially if you do it the way that freddie mentioned. that would harden your steal a little bit. if you really wanted to harden it just heat it up till it's red hot and dip it in oil or water.

quench that shit.

of course then it's more brittle, but i'm pretty sure connecting rods are brittle to start with.

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