Best source for 3.2 crank reconditioning

[al lkosmal]

I have a 3.2 crank that needs to reconditioned. Spun the #4 rod bearing and the journal is out of round, out of spec. Needs to be reground, nitrided, polished etc.
Who would you recommend to do this work?

regards,
al

PS: I do have some good sources, but would like to research the alternatives, based on your experience

[Jeff Alton]

For other cranks, we have used Marine Crankshaft with good results and reasonable turn around times. Have not sent them an aircooled crank but I believe Henry may use them for that.

Cheers

[KTL]

I had Marine go through my 3.0L SC crank years ago and David Eden was a great guy in the process. No nonsense and extremely knowledgeable.

Marine cross-drilled it, plasma nitrided, straightened and polished the journals, balanced it (because I had it lightened- not necessary and probably not recommended by most) and tapped all the plug holes for set screws to make it easier to clean in the future.

Yes the #4 main bearing is grooved and some will say grooving the bearing is better. I figure if the #1 main journal is grooved originally, probably not the end of the world if the #4 is grooved.







If shipping wasn't so expensive and sketchy nowadays, i'd send Marine another one for my 3.2L rebuild. I believe Marine is the company who, last I heard years ago, manufactures Henry's Supercranks?

[targa72e]

Depending on what you are building here is another option. You can have the 3.2 rod journals turned down to 3.0 size. This allows you to use 3.0 (or titanium Pankl gt3) rods. These have the advantage of bigger (stronger) rod bolt and longer rod for better ratio. You need to have pistons made to work with longer rod but can also go with 22mm pin at same time for less weight.

john

[Ken911]

I sent mine to Turbokraft. Knife edged cross drilled polished and they matched individual porsche motorsports bearings to each journal. Took over a pound out of the weight of the crank.

[tocobill]

Ive used Marine Cranks as well. He ground/welded 2 rod journals on my 993 crank. Cross drilled and grooved #5 bearing similar to Kevin's. David is great to deal with.

[rothaus]

Originally Posted by tocobill

Ive used Marine Cranks as well. He ground/welded 2 rod journals on my 993 crank. Cross drilled and grooved #5 bearing similar to Kevin's. David is great to deal with.

I found some pitting on 2 of the rod journals of a 3.2L engine crankshaft. Is this the sort of repair you had done on the crankshaft ?



Thanks
Engelbert

[mepstein]

Shipping is easy. A couple harbor freight moving blankets and a plastic crate. Line a black and yellow plastic crate from the box store with cardboard. Wrap the crank in cardboard and then roll up in the blankets. Zip tie the lid to the crate.

[tocobill]

I had a spun bearing on the #5 journal. They welded and reground to spec. The crank was also cross drilled and grooved at that time too. The crank was given a once over prior to shipping back to me. Its hard to say how they may fix that. I looks deeper than what polishing will remove. Id give Dave a call at Marine Crankshaft to see what he thinks.

I would recommend wrapping the crank in blankets and cardboard as suggested. I used a wooden box which worked well. I have seen packages of cracks with the hanging half outside the box via the side.

[tocobill]

I had a spun bearing on the #5 journal. They welded and reground to spec. The crank was also cross drilled and grooved at that time too. The crank was given a once over prior to shipping back to me. Its hard to say how they may fix that. I looks deeper than what polishing will remove. Id give Dave a call at Marine Crankshaft to see what he thinks.

I would recommend wrapping the crank in blankets and cardboard as suggested. I used a wooden box which worked well. I have seen packages of cracks with the hanging half outside the box via the side.

[mepstein]

Dp

[rothaus]

So cross drilling and grooving of #4 or #5 bearing will provide better oil supply to the rod bearings ? Is that what it is for ?

Thanks
Engelbert

[tocobill]

Originally Posted by rothaus

So cross drilling and grooving of #4 or #5 bearing will provide better oil supply to the rod bearings ? Is that what it is for ?

Thanks
Engelbert

Cross Drilled for better rod oil supply on #2/#5 rod journals. Yes, that is the theory. The pros have said this may not be needed for street driven cars. Based that my crank had a spun bearing I decided to opt for it while the crank was out. The rest of the engine was beefed up on so it made sense.

[Zuffenwerker]

https://shaftech.com/

[ahh911]

Originally Posted by rothaus

I found some pitting on 2 of the rod journals of a 3.2L engine crankshaft. Is this the sort of repair you had done on the crankshaft ?



Thanks
Engelbert

Are you sure that's not from the factory? I had some pitting on my bmw m3 rod journal, had the best looking bearing of the lot. It was from the factory, guys on the board started with the while it's out there stuff and just do it right comments but no, it went back in and that was the correct choice. Mind you, yours looks like the top metal wants to flake off but it's probably just and illusion. Just the shape of your "defect" I'm no engine builder, but how would that zig zag come about if not from manufacturing? Probably been there all along.

e46 m3 crank, best rod bearing came from this journal.

[Jeff Alton]

In your BMW case, crank was failing... Cause, who knows. But those E36/46 (if that is what you have) M3 engines are known for issues in this area...

The crank should not have journal material issues as a defect from the factory.

Cheers

[ahh911]

Originally Posted by Jeff Alton

In your BMW case, crank was failing... Cause, who knows. But those E36/46 (if that is what you have) M3 engines are known for issues in this area...

The crank should not have journal material issues as a defect from the factory.

Cheers

Nah, not failing. Looked like shot peening or some other technique removed imperfections after the forging but before it was machined. Like I said, when I replaced all the rod bearings as preventative work on this model the least worn bearings came from this journal. Most other rod bearings showed sections of copper, this one was like new. I'd suppose if failing the metal bits would have scratched the bearings at some point, but who knows. You just look at it from surface area as well, that little bit of pitting vs the entire area is nothing and the oil flow would be more than adequate as it sits in the well and travels over the top, bmw quality control would know this as well. I've joked in the past, if the other journals had been the same, would I have needed to change any bearings? I've put over 40k miles many at 8000 rpm since then and no lead in oil analysis. Thankfully my Dad who was a lead machinist at a major airline saved me from taking extra risk of removing and having it uneccessarily machined. He immediately understood it's origin.

Maybe if I'd zoomed into the picture even further you'd see how it's different then the 911 cam pitting for example, it had clean sharp rimmed edges with very steep walls almost 90 degrees into the holes, I think the machining took place with the pitting pre-existing.



I mark every bearing on the way out (as well as top or bottom) so I can go back and check things later vs cylinder just for this sort of thing.

[rothaus]

OK, I made a box for the crankshaft.



This should do it.

[boyt911sc]

Originally Posted by rothaus

OK, I made a box for the crankshaft.



This should do it.

Rothaus,

Do you remember the approximate dimensions of the the plywood box? Any special cradles or padding inside the box? Thanks.

Tony

[john walker's workshop]

Maybe that 3.2 crank was previously welded up and reground, leaving a few pits. Never seen that on a stock 911 crank.