Quote:
Originally posted by samiam4
omegabenz,
The question is *why* waste your money grinding the crank? You should be able to get a perfect used one out of a core engine for $100 or so. Ok, $100 with a little elbow grease.
Never NEVER hard chrome a crankshaft. Look it up in every engineering text book. While it does wear better than a regrind, it destroys the fatigue life of the crankshaft. That's why nitrating is prefered. You improve the fatigue life with nitrating. I cannot qoute all the numbers because my books are at work- but you can easily go from a million mile crankshaft to 10,000 mile crankshaft easily if you are not careful. Nitrating is an expensive specialized service, which MB would have never done if it was not nessary(non-turbos are not nitrated).
Problem #2 is machine shops use the radius grinding stones they have... if they don't put the correct radius- you'll increase the stress concentration and break the crank(at least the cranks I've seen break have been from this).
Michael
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(a) Try to find an MB crank for 100 bucks . . .
(b) My old 77 300D which I sold 10 years ago with a HARD CHROMED crank and a BAE TURBO is still goin' like hell with at least 475K miles on the engine I built 15 years ago . . . It runs back and forth between San Diego and Seattle almost on a regular basis . . .