6M Vrs. 7M cranks ¿What is the difference?

[oscarsupra]

Hey

Im looking for a new crank for my 7mgte.

I have heard about a 6m and 7m crank. I want to know the difference between them or if I can use both without any problem in my engine.


Which is better???

Thanks.:1zhelp:

 

[1988SupraDreams]

AFAIK they are interchangeable, and the difference is the balancing. The 7M is balanced better than the 6M.

 

[IJ.]

7m Top

7M heavier/slower to accelerate but much kinder to bearings for sustained high RPM and smoother across the whole range.

6M lighter/faster to accelerate at the cost of harshness/reduced bearing life.

No real difference in "feel" once over 6000 rpm.

 

[BJ91T]

would the 7m keep the motor revved longer in say a drag use when the clutch is applied due to the larger amount of rotating mass??? just curious as i am about to build a street/strip car (7m powered)

 

[IJ.]

Yep should have more of a reserve of kinetic energy than the 6M.

You could use a light flywheel and get it to spin up a little quicker due to the lower PMoI as the FW is such a large diameter.

 

[dbsupra90]

if i remember correctly, if you put a 7m crank in a pre 89 block you have to machine some clearances.

 

[mk3ftMFw]

^ can anyone verify... thanks for pointing that out considering i just odered a remanufactured 6m crank kit.

 

[IJ.]

From memory it's really close to the Oil pump boss and the flange on the pump but was only very minor grinding.

My 7M crank is so radically different to stock it's not even close now

7M Niterided Lightened Crank

 

[F_T_F]

what are the years of the 7m and the 6m crank?

 

[hvyman]

doesnt the 7m crank redline at 6200 as the 6m redline at 6500 too

 

[IJ.]

what are the years of the 7M and the 6m crank?

Too many years passed to say accurately but it's roughly 90 onwards have the 7M and 89 down the 6M....
(there seems to be some crossover though)
(see below )

 

[Jeff Lange]

Cars manufactured in August 1989 and on have the "7M" crank. That is the "1990" Model Year in North America, Japan doesn't use the same model year designation we do, so they would call any car made in 1989 a "1989" Supra, which confuses things.

For the USA "1990" model year was the first year of the new crank.

 

[bowsercake]

7M is balanced but the 6M is lighter. Lighter rotating mass is good, but obviously better balancing is good as well.

 

[Nick M]

doesnt the 7m crank redline at 6200 as the 6m redline at 6500 too

No, but the car does.

 

[7M-fanatic]

doesnt the 7m crank redline at 6200 as the 6m redline at 6500 too

My 7M has been through the lites at 8,000 on the tach...........
(2nd gear - automatic trans)

Red line is the function of the clock crystals in the ECU, not the crank.

 

[oscarsupra]

Hey


CAn use a 7m crank whitout any changes in my 89 down motor?????

Where can i buy a new crank or used but in good conditions(NO cuts on it)???

 

[oscarsupra]

6m crank for a 7mgte


Where can I buy it? New or used in good conditions.