6m crank

sleepersupra

sleepersupra

i hate this car
Nov 5, 2005
311
0
0
Broken Arrow, Ok
i am in the middle of doing yet another hg job and i have the complete engine pretty much disassembled and was looking at my crank today and noticed it said 6m on the crank.

i'm just wondering if the 7m's have cranks that say 6m on them
 
1

1200det

New Member
Nov 16, 2005
36
0
0
Australia
Yes there certainly are differences although sleepersupra asked if the 7M`s have a crank with a 6M stamped on them. obviously a bit concerned he had an incorrect crank LOL

Cheers for the pics though good to see the comparison
 
sleepersupra

sleepersupra

i hate this car
Nov 5, 2005
311
0
0
Broken Arrow, Ok
well i wasn't concerned that i had the WRONG crank, i was just wondering why it said that and what the differences are, if any.... i guess is the 7m crank better or worse than the 6m.

thanks for the pics and all.
 
Silent Smith

Silent Smith

Jerk.
Nov 30, 2005
59
0
0
Mississauga
It's all a matter of balance, each throw on the 7m crank has weights whereas only half (?) the 6m throws are weighted. So the 7m crank should be better balanced but if your getting your engine done a 6m crank balanced properly should be more then enough. The 7m crank is also heavier since they're is more material to it.


Let's make this interesting. Anyone know if there is a difference in durablility? I don't mean in bearing life because of better balance but more so in terms of nitriding or some other difference like oil holes chammfered etc. I"m done with supras so I don't overly care but it would be nice to have a better final answer then the countless "better balance" or "heavier/lighter" threads. Anyone ever gun drill the throws on either of these cranks?
 
Nick M

Nick M

Black Rifles Matter
Sep 9, 2005
8,885
38
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U.S.
www.ebay.com
The only published info I have seen is in the general description in the factory repair manual. The original 7M crank, where ever it came from (6MGE) had 8 counterweights for the 6 pistons. The updated one is listed as 12. I never saw a TSB for it going into further detail, or any for that matter.

However 52 lbs vs 57 lbs is chicken shit. Try a small V8 crankshaft at 75 lbs before thinking you have a heavy crankshaft.
 
Jeff Lange

Jeff Lange

Administrator
Staff member
Mar 29, 2005
4,919
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Sunnyvale, CA
jefflange.ca
86.5-89 Cranks were "6M" stamped with no counterbalances on cylinders 2 and 5.

90-92 Cranks were not stamped with anything, and have counterbalances on all 6 cylinders. This is commonly called the "7M" crank, and weighs 5lbs more than the early cranks.
 
Jeff Lange

Jeff Lange

Administrator
Staff member
Mar 29, 2005
4,919
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Sunnyvale, CA
jefflange.ca
What about below stock redline? I'm just curious because in the cars I'd been in they seemed very similar. I could see it making a larger difference in the higher rev range.
 
n2fishin69

n2fishin69

Work-a-holic
Jan 25, 2006
61
0
0
55
Way down South, in Dixie
Guys,
I tore down my 86.5 Supra. There was a stamp with 6M on the crank. That bought me back here to Supramania to look to see if anyone else had the same issue. Sure enough, it didn't take long to find this thread.
Thanks
N2fishin69
Satsuma, AL
 
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