I honestly would trust IJ probably more than 95% on this site as far as this information goes. He's cut most of the M engine pieces in half for research purposes.
Here we go again--spun bearing
- Thread starter rustfarmer
- Start date
I am seeking all the input I can get on this issue (no offense to IJ) and one shop which does retreat/harden cranks for race engines says my crank should be fine in a "stock" engine, as cutting nitrited cranks 30 thou is done all the time. Problem is, engine is already modded some, and if we ever get it running well and broken in, my son will likely turn up the boost and drive the crap out of it. The shop in question also says they can re-treat the crank for $125 plus shipping. Does anyone think this solves the issue? Seems like cheap insurance, and I do realize the crank will need careful checking and perhaps polishing as the treatment may cause size to increase a small amount. Other ideas?
Bump, does no one have an opinion on re-treating the crank? I did ask Aaron at Driftmotion and he said he would advise scrapping this crank and get another one. If most of you feel this is the only way to go I guess I can eat the $200 I will have in this crank when it comes back from being re-hardened, but then I'm stuck trying to find a better one. I've been told some of the shops which sell these crank kits are not new, but welded up and turned units. Hard to trust they would be any better than what I have.
All ideas gratefully welcomed. Oh, and anybody got a good crank for sale?
All ideas gratefully welcomed. Oh, and anybody got a good crank for sale?
you can retreat cranks but I'd be sure it was straight and balanced. if it's not you can pick up a 7m crank so easy you're better off starting with something else. I picked up a second crank and block for $100, it did have a spun bearing and will need to be re ground slightly but it tested straighter than my 6m crank.
also these cranks should be heat cycled after being straightened to make sure they hold their new alignment as they like to spring back sometimes.
also these cranks should be heat cycled after being straightened to make sure they hold their new alignment as they like to spring back sometimes.
Toyota Induction harden their cranks it's a shallow process, even states in the Manual NOT to go below 10 thou and Toyota DON'T sell bearings any thicker....rustfarmer;1996274 said:
I know all of this as I've "Been there done that" with my 7M, Having the Crank Heat Treated, Niterided and Straightened is a very expensive prospect and far beyond what replacing the crank will cost..
I played musical Cranks at one stage so have a fair idea of what I'm talking about.
I have been unable to find a replacement crank for cheap. Ebay shows one unmolested and stock size for $500, and crank kits with bearing are about $450. Ohio Crankshafts is re-nitriting my crank for $125 (plus shipping and me constructing a box from 2x8 wood).
I'll eat the cost of turning and re-treating mine if I can find a better crank, preferably the fully counter weighted 7M version.
I'll eat the cost of turning and re-treating mine if I can find a better crank, preferably the fully counter weighted 7M version.