Muncie Transmission ID Question
06-14-2010, 10:00 AM
#2
Le Mans Master
06-14-2010, 10:40 AM
#3
Melting Slicks
Thread Starter
06-14-2010, 10:57 AM
#4
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It's the INPUT shaft, not output (tail) shaft.
NO, you can't do it with the tranny in the car.
The 67 Muncies did not have the letter ( A, B, C) stamped at the end of the stamped date code on the right rear of the case, thus, that's no nelp either.
It would be somewhat of a hassle, BUUUUUUUUUUUUUUUT, you COULD do it with the tranny in the car.
An M20 will have a 2.52:1 first gear ratio.
An M21 (as well as M22) will have a 2.20:1 first gear ratio.
Here's how you COULD do it in the car. It's a hassle, but you CAN do it.
Remove all the spark plugs from the engine.
Place the tranny in first gear.
Jack up the rear wheels (or the whole car) and put it on jack stands.
Make a mark on the drive shaft (white or yellow, etc crayon).
Make a mark on the balancer or crank pulley.
Get a buddy to help.
Turn the engine until the mark on the driveshaft has made ONE full rotation.
Count the number of turns that the balancer/pulley made. If the balancer turned about 2 1/2 turns, then it's an M20. If the balancer made about 2 1/4 turns, it's an M21 (M22).
Tom Parsons
NO, you can't do it with the tranny in the car.
The 67 Muncies did not have the letter ( A, B, C) stamped at the end of the stamped date code on the right rear of the case, thus, that's no nelp either.
It would be somewhat of a hassle, BUUUUUUUUUUUUUUUT, you COULD do it with the tranny in the car.
An M20 will have a 2.52:1 first gear ratio.
An M21 (as well as M22) will have a 2.20:1 first gear ratio.
Here's how you COULD do it in the car. It's a hassle, but you CAN do it.
Remove all the spark plugs from the engine.
Place the tranny in first gear.
Jack up the rear wheels (or the whole car) and put it on jack stands.
Make a mark on the drive shaft (white or yellow, etc crayon).
Make a mark on the balancer or crank pulley.
Get a buddy to help.
Turn the engine until the mark on the driveshaft has made ONE full rotation.
Count the number of turns that the balancer/pulley made. If the balancer turned about 2 1/2 turns, then it's an M20. If the balancer made about 2 1/4 turns, it's an M21 (M22).
Tom Parsons
06-14-2010, 11:02 AM
#5
Le Mans Master
No easy way
There is another way. If you have a M20 you first gear is 2.52 to 1
Put car in 1st gear , back wheels of ground (jack up under differential) if you have a good car jack (floor model) so that back wheels can turn.
take out plugs so no compression. Turn engine over (take out coil wire so it does not start) one time. If rear of tranny (yoke) goes around about 2 1/2 times you have a wide ratio m20 if it goes around 2 times give or take you have a m21 or m22. M22 are rare , so it will be either M20 or m21
You need a friend to turn over motor while you watch.
You can also turn motor over by using a ratchet on balancer nut
A way to see if motor goes once around once is to put timing mark (on balancer) on 0 on timing tab and go around to 0 again.
as you can see, no easy way with tranny in car.
Jack
Last edited by Jackfit; 06-14-2010 at 11:06 AM. Reason: wrong word
06-14-2010, 11:05 AM
#6
Le Mans Master
I stand corrected
It's the INPUT shaft, not output (tail) shaft.
NO, you can't do it with the tranny in the car.
The 67 Muncies did not have the letter ( A, B, C) stamped at the end of the stamped date code on the right rear of the case, thus, that's no nelp either.
It would be somewhat of a hassle, BUUUUUUUUUUUUUUUT, you COULD do it with the tranny in the car.
An M20 will have a 2.52:1 first gear ratio.
An M21 (as well as M22) will have a 2.20:1 first gear ratio.
Here's how you COULD do it in the car. It's a hassle, but you CAN do it.
Remove all the spark plugs from the engine.
Place the tranny in first gear.
Jack up the rear wheels (or the whole car) and put it on jack stands.
Make a mark on the drive shaft (white or yellow, etc crayon).
Make a mark on the balancer or crank pulley.
Get a buddy to help.
Turn the engine until the mark on the driveshaft has made ONE full rotation.
Count the number of turns that the balancer/pulley made. If the balancer turned about 2 1/2 turns, then it's an M20. If the balancer made about 2 1/4 turns, it's an M21 (M22).
Tom Parsons
NO, you can't do it with the tranny in the car.
The 67 Muncies did not have the letter ( A, B, C) stamped at the end of the stamped date code on the right rear of the case, thus, that's no nelp either.
It would be somewhat of a hassle, BUUUUUUUUUUUUUUUT, you COULD do it with the tranny in the car.
An M20 will have a 2.52:1 first gear ratio.
An M21 (as well as M22) will have a 2.20:1 first gear ratio.
Here's how you COULD do it in the car. It's a hassle, but you CAN do it.
Remove all the spark plugs from the engine.
Place the tranny in first gear.
Jack up the rear wheels (or the whole car) and put it on jack stands.
Make a mark on the drive shaft (white or yellow, etc crayon).
Make a mark on the balancer or crank pulley.
Get a buddy to help.
Turn the engine until the mark on the driveshaft has made ONE full rotation.
Count the number of turns that the balancer/pulley made. If the balancer turned about 2 1/2 turns, then it's an M20. If the balancer made about 2 1/4 turns, it's an M21 (M22).
Tom Parsons
Jack
06-14-2010, 11:53 AM
#7
Le Mans Master
a close box will drop 500 rpm per shift, a wide box will drop 500 rpm per shift except going into 4th where it will drop either 1000 rpm or 1500, i can,t remember which....
06-14-2010, 02:19 PM
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06-14-2010, 11:53 PM
#9
Melting Slicks
Thread Starter
Thanks Guys! - Would it matter if it was a L71 or L89 435 HP car? Wound they have only a M21, instead of a M20? Or did not matter regarding the Engine HP rating?
06-15-2010, 06:10 AM
#10
Le Mans Master
06-15-2010, 12:46 PM
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06-15-2010, 01:08 PM
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06-15-2010, 01:36 PM
#13
Melting Slicks
wide vs close road test
Accuracy and fun should increase if you do this at 6k rpm.
06-15-2010, 02:09 PM
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06-15-2010, 07:21 PM
#15
Melting Slicks
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06-16-2010, 08:19 AM
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06-16-2010, 10:50 AM
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06-16-2010, 02:47 PM
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