LML Callies Durastar Crankshaft Issues??

valleyduramax

Member
Jul 25, 2010
233
4
18
Ottawa ON Canada
They are regrinding the thrust face to "true" up the surface. At least that's what we were told from the 2 we had to send back. One is in a running truck now and the other will be up and running within 2 months. We are keeping an eye on the current runner as we are skeptical of the issue being truly fixed.
 

ouellet5

Member
Sep 27, 2013
92
2
8
Hi guys, i just bought the durastar crank to put un my next built.
LML or LMM bloc
mhale cast piston 0.20 no relief
crewer rod
callies durastar crank
Socal 3388af cam.

Does i need to change for another crankshaft ? this post make scares me :)
thanks
 

ikeG

Oughta Know Better
Apr 19, 2011
2,465
147
63
Western PA
www.facebook.com
I did two engines with the durastar last year, one is a race only truck that only made a few passes. The other is a 950 rwhp street truck. They are both good so far....

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Kg_lmm

New member
Apr 17, 2020
2
0
1
I had PPE build me an engine with a durastar crank in it summer of 2019. Crank was purchased from SoCal and they supposedly checked it prior to install. I have been cutting open every oil filter and they look okay, but I’ve had a small rear main seal leak since day one. My question is do you think it’s worth dropping the transmission and checking the crank with a dial indicator? This thread makes me uneasy. Engine was 16k with no warranty, 2500 miles on the build. Any input is appreciated.
 

kidturbo

Piston Tester
Jul 21, 2010
2,539
1,375
113
Somewhere On The Ohio
www.marinemods.us
If it ain't broke, I wouldn't mess with it. If any major issues, you won't need a dial indicator, just grab the damper and push/pull to see the problem.. Good point, doesn't seem to damage anything else of value before the oil leaking becomes an issue.
 

56taskforce

Well-known member
Mar 30, 2014
1,081
56
48
Hopefully this issue has been fixed and or the 360° thrust bearing of the SoCal Deisel billet caps helps.
 

moparkxracer

Well-known member
Jun 25, 2010
2,309
33
48
Out and about
Sure looking like was just a single/early batch issue on those. Been thrashing the crap outa the ultra billets, no complaints yet. :)

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Thank you, was looking at the durastar one, not looking to make a lot of power with this one. I found a core engine that has a broke crank so was looking to build off that if the prices are right.
 

duramaxzak

Wanna be puller!
Nov 22, 2008
2,431
14
38
Minnesota
Thank you, was looking at the durastar one, not looking to make a lot of power with this one. I found a core engine that has a broke crank so was looking to build off that if the prices are right.
FYI, The block has about a 50% chance of being junk. I’ve pulled apart about a dozen motors with broken cranks, and about half of them wrecked the block.
 

moparkxracer

Well-known member
Jun 25, 2010
2,309
33
48
Out and about
FYI, The block has about a 50% chance of being junk. I’ve pulled apart about a dozen motors with broken cranks, and about half of them wrecked the block.
I figured it may be damaged, it’s a friends I’m waiting for him to get it apart to see if it’s good first. I plan on doing a 3388 cam, some SoCal rods, stage 2 heads, billet main caps and a few other things with it. Keeping it mild, I need to be able to tow with this one
 

crank

New member
Feb 15, 2021
1
2
3
I ran across this blog and it brought back some memories (screen clip below of 20+ YO email, I have other info that I probably should not send). I was involved in BBC / Allison transmission adaptation 20+ years ago. I have little knowledge of the Duramax, so this info may not be of much use.

Thrust surface alignment (thrust washers halves) during assembly is very important. Otherwise thrust loads will only be taken up initially by one of the thrust washers. This will lead to distress of the crank thrust wall which will then take out the other thrust washer half once enough wear happens to the initial contact thrust washer half.

Not sure about Duramax, but BBC should have forward thrust load applied to the crank flange (say 100 lbs) with 1/2 thrust load (say 50 lbs) applied rearward to the main thrust cap prior to and during initial tightening of the main thrust cap fasteners. The thrust loads used during assembly are arbitrary and do not need to simulate running loads. Not sure if this actually applies to Duramax though, especially if caps are doweled.

Seems like actual torque converter thrust loading should be considered. There is more to this than just T/C charge pressure.

Flexplate stiffness (axial spring rate lb/0.001") should be kept to a minimum to keep axial thrust loads to a minimum. Some thick billet flexplates have very high axial spring rates which lead to very high thrust loads. Crank thrust surface and bearing on stock BBC can tolerate 2500+ axial force when properly aligned, but will certainly show some wear at high hours. Super stiff flexplates can certainly lead to overload failure.

Are there any thrust failures associated with builds using non-stock flexplates, much thicker material, no or limited spring rate holes or billet flexplates?
 

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