Nitriding Crankshaft

Question on Nitriding Crankshaft Depths?

Most or all 4340 race cranks are Nitrided for bearing surface hardness to a .010 to .020 inch depth. This process is done while the cranks are brought up to temperature and the gasses are put into the same room to harden the surface to a desired depth.

Question is simply this? If you spin a bearing and have it turned and straightened should you run as normal with "H" bearings or should you change to a "P" bearing or should you throw in the towel and get another crank.

I currently have an old 4.300 stroke crank that I had some oiling issues with and spun a lot of bearings until I figured out the oiling mods and bushed the lifter bores. I just changed everything, got a new crank, started over, and now have no issues but I do still have this old crank in the corner and was wondering if it was salvageable. If the answer is simply send it out to have it re-nitrided it would cost more than a new crank to do so.

I guess what I am looking for here are the pro engine builders take on the subject from a metalurgical standpoint.

Adrian

Good answer!

I was looking for a little more than that but I was just quoted $500 .......guess I do not have the connections you do.

Could you possibly share the contact info?

Is that the process you take on every 4340 spun bearing issue? Is it o.k. to to grind only 0.010 and at .020 you would re-nitride or is it standard practice to re-nitride after any grinding?

If you take it to a crank grinder I have heard everything from buy new to.......o.k. to grind 0.010......to chrome it.

Looking for any knowledge that can be shared

Adrian

$500 is way too much......I think any more than $300 is not a good bargain. Buy you a new crank if thats the case

I'll stop buy and give you a $150 for the crank......

You should be able to get it Ground, Nitrated and New Bearings for under $500ish as long as it doesn't need additional repairs.

As a side note here. I had some bearing issues on a Bryant forging and spent some time on the phone with them during that process. The guys there tell me that the new Nitriding process they use only penetrates .004 so they recomend renitriding after any regrind. Something about the deeper process creating a hard skin as it where on the crank surface that could possibly cause issues when the metal is twisted under load.

I am not a pro engine builder or even an engineer just repeating what I was told by the guy's at Bryant.

dkp

Thanks this is what I was suspecting.