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Crank resurfacing

Posted: Mon Jul 03, 2017 4:51 pm
by ga_goosh
Has anyone ever turnes a 42mm crank to use with 40mm rods? Is this even possible due to the hardened journals?

Re: Crank resurfacing

Posted: Tue Jul 04, 2017 3:39 pm
by jondee86
Based on the fact that crankshafts can be reconditioned by grinding the journals
down to the first undersize and fitting oversize bearing shells, I suspect it could
be done. Best to talk with an engine shop that has a crankshaft grinding machine
to be sure.

Cheers... jondee86

Re: Crank resurfacing

Posted: Wed Jul 05, 2017 7:31 pm
by ga_goosh
I ask because out of all my parts cranks seem to be the the part that i cant seem to locate. I have both 40mm and 42mm jounal engines that need cranks. Reconditioning the 42mm crank as a 40mm is the closest i can get to a working engine. Thanks Jondee ill have to find a crank specialist in my area and find out if it is cost efective to do this.

Re: Crank resurfacing

Posted: Fri Jul 14, 2017 8:52 pm
by Rogue-AE95
Why not get a set of rods for the 42mm crank? I imagine it's more worth keeping the 42mm crank as-is than modifying it.

If you're interested, I have a set of 42mm rods with ARP rod bolts I want to get rid of. They will need reconditioning, as the lackwit I bought them from (someone here) didn't ship the rods with the caps attached, or with packing materials. I was quoted around $80-$110 from local machine shops to have the rods reconditioned.

Everyone says that the 40mm crank isn't reliably proven past 200 HP. I have to wonder if the fully counter-weighted 42mm crank turned down to 40mm would be capable of handling more horsepower than the 40mm crank.

Re: Crank resurfacing

Posted: Sat Jul 15, 2017 3:52 pm
by mr2mk1hero
I have a 40mm crank that needs to be turned. It experienced quite a bit of rod knock. I am willing to sell it for very cheap if you are willing to pay the international shipping for it.

Re: Crank resurfacing

Posted: Wed Jul 19, 2017 10:39 am
by ga_goosh
Rogue-AE95 wrote:Why not get a set of rods for the 42mm crank? I imagine it's more worth keeping the 42mm crank as-is than modifying it.

If you're interested, I have a set of 42mm rods with ARP rod bolts I want to get rid of. They will need reconditioning, as the lackwit I bought them from (someone here) didn't ship the rods with the caps attached, or with packing materials. I was quoted around $80-$110 from local machine shops to have the rods reconditioned.

Everyone says that the 40mm crank isn't reliably proven past 200 HP. I have to wonder if the fully counter-weighted 42mm crank turned down to 40mm would be capable of handling more horsepower than the 40mm crank.


I have 42mm rods the problem is the crank is undersized from a spun rod bearing. so if i get it machined down to 40mm then i could potentially still use it in my 40mm engine. and not have to buy 2 cranks.

mr2mk1hero wrote:I have a 40mm crank that needs to be turned. It experienced quite a bit of rod knock. I am willing to sell it for very cheap if you are willing to pay the international shipping for it.


sorry im not into international shipping of heavy parts. also from my experience once the bearing spins then the crank is toast. finding undersized bearings is near impossible.