Main Bearings and Rod Bearings

[JoeMadoo]

I finally got my bearing shells after a month of waiting. They are all .25mm over and I had my crankshaft ground to .25 also. I threw everything on, using moly-based assembly lube, torqued it, and now for the life of me, i cant turn the crankshaft. Even with the main bearing caps loose, it will barely turn.

[dark89e30]

Awww, shit. What did you do? But more importantly, I HIGHLY recommend completely disassembling the engine, doing a thorough inspection of EVERYTHING. Did you check the machine shops work? Plastigauge? You NEED to use that stuff before you assemble the bottom end to measure clearances.

[JoeMadoo]

I did not check the machine shops work, maybe i should have. So you think they didnt grind it enough?

[dark89e30]

You never know, maybe they send you the wrong bearings... Are you familiar with plastiguage?

[JoeMadoo]

No I'm not, I'm learning about it right now actually. It just seems like the crank is too big for the bearings. I have more confidence in the BMW bearing shells being .25 over than the reground crank being .25 under. I might take it over to my machine shop and have them measure it. Or maybe I'll try plastigage.

[JoeMadoo]

Well after some good advice from my buddy Jason it seems that the center thrust bearing is too fat for the crank, causing it to bind, so I'll have to either have the crank milled or the bearing shells milled.

[dark89e30]

Can you just get a stock thrust bearing? It sounds like they sent you one of those .025" over also? What a bitch... Did you measure the lash (I think you need a dial indicator). Other than that, I wouldn't know how to even measure how much to tell the machine shop to take off do to limitations and availability of specifications. The only way I can think of is to measure a stock crank and a standard thrust bearing thickness. I take it you had the #4 crank main journal machined?

[JoeMadoo]

All I'm going to do is take the crank and the thrust shells to the machine shop and have them grind the shells to fit in the crank within spec (so there is the right about of front/back movement).

I had all the main bearings jornals and rod journals ground to 25 over. I guess the machine shop was suppost to grind the part where the thrust bearing goes and they didnt, thats why it wont fit.

[dark89e30]

Word. I still wouldn't hesitate to check all of them with plastigauge though... They might have a tough time grinding the shells though. They will have to take material off of the inside though, to leave all of the babbit material. They will just have to measure the overall width if the thrust bearings and figure out the difference and machine off of the crank. Good luck.

[JoeMadoo]

Bearings are a nightmare.

[backtrail69]

I'm surprised you even needed to machine your crank at all. My M10 with 300k miles had virtually no wear at all.

[JoeMadoo]

You didn't see my old bearings