LML converter wont spin after tightening bell housing

LBZ_Baker98

Member
Jul 8, 2016
205
2
18
Texas
Have a randys transmission that I am installing in a 15 LML for a customer, First i was sent a LBZ/LMM flex plate so I called and they sent out the correct one, now when I bolt the transmission up the converter will not spin. I have installed countless of these allisons and never had this issue. I made sure the converter is seated all the way multiple times. The flexplate bolts do stick out just a hair past the face of the flex plate, do I need after market bolts for this SoCal billet flex plate? I am wondering if maybe they sent an LMM trans since the flex plate they sent was for an LMM but Im not sure of the differences between the 2 cases. Of course randys will be closed tomorrow I am sure and I really need to get this truck out. Thanks for any help!
 

Ron Nielson

Active member
Oct 11, 2009
451
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Berryton, KS
What was the clearance between the TC (pushed back into the trans all the way) and the flex plate? I THINK 1/8" is min and 3/16 is better. Not sure where that came from, though. Mike L will tell us, I'm sure
 

Mike L.

Got Sheep?
Staff member
Vendor/Sponsor
Aug 12, 2006
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Fullerton CA
I don't like anything over 1/8 as it tends to pull the converter hub too far out of the pump drive gear. All the cases and bell housings are the same size, so that's not the issue. I have used stock flywheel bolts with the SoCal flywheel without problems. Try and mount the converter to the flywheel by itself and see if it goes flush. That will tell you if the bolts are binding. Did you put any kind of spacer behind the flywheel?
 

LBZ_Baker98

Member
Jul 8, 2016
205
2
18
Texas
I don't like anything over 1/8 as it tends to pull the converter hub too far out of the pump drive gear. All the cases and bell housings are the same size, so that's not the issue. I have used stock flywheel bolts with the SoCal flywheel without problems. Try and mount the converter to the flywheel by itself and see if it goes flush. That will tell you if the bolts are binding. Did you put any kind of spacer behind the flywheel?
No spacer behind fly wheel. Found that the stock converter seats much further then the Randy’s converter. I tried and tried to get the converter seated. After speaking with Randy’s we thing something happened in the machining process with the snout of the converter. The lugs where the converter bolts go make contact with the flex plate about 1/16th of an inch before the bell housing is flush with the adapter plate!
 

LBZ_Baker98

Member
Jul 8, 2016
205
2
18
Texas
Send the converter back to him and use a Goerend or Suncoast converter. Don't use second best.
I’m a big fan of goerend unfortunately I think that’s the converter they send with all of their 725HP builds and require that converter for warranty.