Crankshaft checkup advise

We purchased a 2000 C2 Coup project car a few months ago and have the block and heads ready to go to LN next week. We need to find someone who can checkout our crankshaft. Does anyone know of a experienced M96 machine shop in the central Pennsylvania or northeast we can reach out to? I've attached a picture of the questionable journal as the car had bearing failure. John

That needs polishing, or regrind. Then measure it for specs. I am pretty sure it is not useable as it is.

The journal hasn't turned blue, so that's a good sign but to quantify it needs to be polished and measured.. The m96 cranks have a very thin layer of "Nitriding" on the journals that is so thin it can't be ground without grinding through the Nitriding.....Very few shops can "re-nitride" a crank, so it will need a crankshaft specialist to repair. Then there are no oversize bearings available from Porsche, so that brings on another issue. I have seen some claims of oversize bearings but most just source a good used crank ( less cost and trouble)

Thanks Doc and yelcab for the advice. If I source a crank in good condition is it OK to use our current carrier or do they need to be matching set?

The crank carrier has to be assembled and all the clearences checked. Chances r it needs to be machined even if u reuse your crank. Do u have the assembly video from LN-E? Not sure if its all covered in that vid but it has a ton of info for assembling a m96/7 motor correctly. Btw it does.look much better then mine.

So we finally got our crankshaft cleaning and polished and also purchased a Mitutoyo micrometer for 10,000th accuracy for perform a more accurate assessment. Here are our numbers. I also understand from Jake Raby Porsche never released crank specifications but thru searching the forums did find this rod range 2.0855-2.0862, although I can't confirm accuracy. So please give me your opinions on if we should look for another crank or is this within tolerance. Also we think cylinder 1 is slight out of round by .001 so is that a show stopper regardless or the other measurements? From the flywheel end 2.08575 2.08570 2.08570 2.08555 2.08580 2.08475

Well, you're almost 1 thousands undersized on a rod journal (#1 ?) from the specs you listed. Was that the journal that showed wear in your pics and got micro polished..? All the other journals are almost at minimum size. Did you measure the journal in 8 spots evenly around that journal, to see if its at least still round..? What are you going to do with this engine. Will it be a track rat, or DD, or weekend cruiser..? Or is this getting put together for a quick sale..? If journal is still round and just worn undersized by .0008" like your measurements show, and you must use this crank, it would probably work for a weekend cruiser or depending how you DD it, might be ok for that also for a while. You could see if one of the bearing coating companies can heavy coat bearings for you to take up some of your crank journal slop. Oh ya, its important that you got this crank magnafluxed to check carefully for cracks if it suffered a bearing/crank failure like you say... If it were me, and was getting the LN nikies for this build, it would be time for a perfect crank. balanced, micro polished, measured and magnafluxed, even if new.... jmo

Allcool, This car will be just a weekend cruiser nice weather driver. My brother did the measurement and also took it to the NAPA machine shop for their measurements. I'll have to ask how he measured #1 and assessed it was out of round. That journal did have excessive bearing wear and separation. We were under the impression that M96 cranks can't be machined and very few shops have experience in recoating. Also since over sized bearing aren't an option is it better just to source another crank in better condition? We did send our block and heads off to LN for their Nickie's process. Unfortunately they don't do any crank services so were looking for options. John

I think it is best for you to get another / new crank that is in good shape.

thanks everyone for the input, we'll probably just get a refurbished one from LN. Better safe than purchasing one form Ebay and it's also out of tolerance.

Quotes source post: 19266611

Although we do not advertise it, we do work with a local high end (non-Porsche) engine builder that does all our magnafluxing, checks for bend and twist, and also polishes and cleans cranks for us, but if there is any damage to the journals on an M96/M97 crank, we always recommend replacement. I recommend against cutting the cranks for available repair bearings which are pretty much only used by those trying to salvage a crank that shouldn't be reused. The factory bearings are really good and the only thing you can do to further improve them would be to have them coated, but then you need to verify and adjust clearances, depending on where you have them coated. All our used cranks go through the same processes above, problem is sometimes it's hard for us to get them in the condition we require and the cost goes up significantly when supply is scarce.