LMM Crankshaft thrust bearing clearance?

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57ringo

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Oct 4, 2015
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Emporia ks
I'm putting an LMM together and only have .0025 crankshaft endplay with new thrust bearings and .003" with the old ones.
The spec is .0016-.0081 I've never checked an engine that had that little endplay before. Would this be to tight & cause a problem? Anyone else ran onto this?
 
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S

S Phinney

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Aug 15, 2008
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57ringo said:
I'm putting an LMM together and only have .0025 crankshaft endplay with new thrust bearings and .003" with the old ones.
The spec is .0016-.0081 I've never checked an engine that had that little endplay before. Would this be to tight & cause a problem? Anyone else ran onto this?
Click to expand...
There will not be a problem on the thrust clearance. It would be nicer to be in the.004 to .006 range. You can block sand the block surface side with 1500 wet sanding paper to get to that clearance.

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gmc502

gmc502

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Jan 16, 2011
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S Phinney said:
There will not be a problem on the thrust clearance. It would be nicer to be in the.004 to .006 range. You can block sand the block surface side with 1500 wet sanding paper to get to that clearance.

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Click to expand...

and make sure the surface used for sanding is very flat.
 
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57ringo

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Oct 4, 2015
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Emporia ks
I ended up taking the front Thrust bearing to a good friend that's the computerized machine tool engineering technology instructor at the local Vo tech. He used the surface grinder with a magnetic table and took .003" off. It's smooth and perfectly flat. I installed the crank and have .006" end play now.
 
x MadMAX DIESEL

x MadMAX DIESEL

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What's the absolute minimum anyways ran? I just put a new engine together and forgot to check it before I put the rods and Pistons in. I don't have much time to take it back apart and sand it to say the least!! I'm sitting at .001!! Brand new plates
 
Chevy1925

Chevy1925

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Undo all the rod caps, push all the Pistons to TDC, then pull the crank. Shouldn't be all that hard or long to do
 
x MadMAX DIESEL

x MadMAX DIESEL

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Yeah I could probably do that. I've heard is engines can run very tight and live. Just wasn't sure on this. I know ppl usually run the loosest of specs on a lot of things with these engines


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Chevy1925

Chevy1925

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the new engine im working on right now came out to .0026. one of the bearings had a high spot in it and so i sanded it down. shes bang on to .0041 now and flat bearings. i wouldnt run it that tight, specially if you dont know if its .0010 or .0019. that tight makes it hard for oil to stay in there
 
x MadMAX DIESEL

x MadMAX DIESEL

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You just put it on a flat table with sand paper then work the plate by hand? Or you have some fancy tool for it? I had Lucas assembly lube on it all when checked that is thick stuff. And I meant to say LS engines in my last post not is lol. I just used a .000 caliber to check. I was about to check with my bore gauge caliper but figured it's to tight either way


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Chevy1925

Chevy1925

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x MadMAX DIESEL said:
You just put it on a flat table with sand paper then work the plate by hand? Or you have some fancy tool for it? I had Lucas assembly lube on it all when checked that is thick stuff. And I meant to say LS engines in my last post not is lol. I just used a .000 caliber to check. I was about to check with my bore gauge caliper but figured it's to tight either way


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Click to expand...

i have a hard/flat sanding block you would use for sanding down a paint job and i put the bearing on a flat/clean piece of steel to work it down. light pressure and take your time so you keep it flat. a piece of masking tape upside down with the ends taped down will hold the bearing while you work it. that 1500 grit sand paper works well. even with assembly lube, you should be looser than that if you put a decent amount of pressure back and forth on the crank, specially with a twist or two of the crank.
 
Chevy1925

Chevy1925

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if you take that much off, be sure to mic the bearing in 3-4 spots so you dont get a high spot or taper to it.
 
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