Muncie trans ID
Thread Starter
Burning Brakes
Joined: Aug 2001
Posts: 1,002
Likes: 0
From: Bay City MI.
Muncie trans ID
Just pulled the trany out of my 71 coupe, like some help on info for the trany. I was told by the previous owner that it is a M-21, here are the numbers : GM 3851325 and on the back tube part the number is : 3846429.
Thanks in advance.
Thanks in advance.
Race Director
Joined: Dec 1999
Posts: 19,610
Likes: 778
From: Forked River NJ
Re: Muncie trans ID (467-Ratman)
You will need the numbers that are stamped int oteh side of the case. These numbers you gave are just the casting numbers. Is the input shaft a 26 spine or 10 spline,
Melting Slicks
Joined: May 2000
Posts: 2,125
Likes: 9
From: Crescent City, CA
Re: Muncie trans ID (467-Ratman)
Two ways to tell.
1) There will be either no groove around the input shaft splines or one or two grooves. No groove is a M-22, one groove is a M-21 (close ratio) or there are two grooves M-20 (wide ratio).
2) On the side of the case (passenger) there is a number that date codes the trans (it is stamped) it will end in either A, B or C. A M-20, B M-21 or C M-22.
Hope this helps
Terry
1) There will be either no groove around the input shaft splines or one or two grooves. No groove is a M-22, one groove is a M-21 (close ratio) or there are two grooves M-20 (wide ratio).
2) On the side of the case (passenger) there is a number that date codes the trans (it is stamped) it will end in either A, B or C. A M-20, B M-21 or C M-22.
Hope this helps
Terry
Race Director
Joined: Dec 1999
Posts: 19,610
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From: Forked River NJ
Re: Muncie trans ID (467-Ratman)
Are you sure tha tis a Muncie. i checked those numbers and they don't seem to match up. The casting numbers don't look right. The number with the F in it is it stamped in or cast in. My 72 has a casting number on the case of 3925661 and the tail shaft casting is 3978764. I have a very early 72 so 71 should be similar. The number stamped into the case should start with a P. http://www.5speeds.com/ Try this website for the ID numbers and Muncie ID
Thread Starter
Burning Brakes
Joined: Aug 2001
Posts: 1,002
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From: Bay City MI.
Re: Muncie trans ID (Gordonm)
The previous owner said that it was a muncie, but I have found many things he said to be not true. I do know that the car was an auto to start with and he converted it to a 4 speed. Sounds like I have some kind of GM trany, that most likely is not a Muncie!!
Drifting
Joined: Oct 2000
Posts: 1,825
Likes: 56
From: Shawano WI
Re: Muncie trans ID (467-Ratman)
That is a Muncie. It is a 7/8" clustershaft model that was built prior to 1965.
With no grooves on the input shaft it should be an M-20 with a 2.56 first gear.
They didn't built M-22's until late 1966 model then popular in 1967.
[Modified by Pete79L82, 6:35 PM 3/3/2002]
With no grooves on the input shaft it should be an M-20 with a 2.56 first gear.
They didn't built M-22's until late 1966 model then popular in 1967.
[Modified by Pete79L82, 6:35 PM 3/3/2002]
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Race Director
Joined: Dec 1999
Posts: 19,610
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From: Forked River NJ
Re: Muncie trans ID (Pete79L82)
But why would it be a fine spline. All Muncies built prior to 70 had the 10 spline coarse shaft. From 70 on they had 26 splines. the case numbers do look like early Muncie numbers. Are you sure it has 26 not 10 splines on the input
Race Director
Joined: Aug 1999
Posts: 18,126
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From: WI
Re: Muncie trans ID (467-Ratman)
Tom,
Try this, http://www.gearzone.net/muncie2.htm
...redvetracr
[Modified by redvetracr, 6:53 PM 3/3/2002]
Try this, http://www.gearzone.net/muncie2.htm
...redvetracr
[Modified by redvetracr, 6:53 PM 3/3/2002]
Drifting
Joined: Oct 2000
Posts: 1,825
Likes: 56
From: Shawano WI
Re: Muncie trans ID (redvetracr)
The 1-2-3 groove identification that redvetracr refered to is correct for trans made after 1966. Prior to that there was only two identifications.
No rings = M-20
One ring = M-21
The stamping numbers don't seem to match anything that GM did. All there stampings started with a P designating a Muncie. GM did outsource Muncie trans to American Motors(Rambler back then) that were identical to the GM models. I am not sure how there stamping numbers went.
As redvetracr mentioned the casting number only indicate what the trans was originally. Measure the cluster shaft pin to see if it is 7/8" or 1". Someone may have rebored the cluster and replaces the input and clustershaft to something newer.
No rings = M-20
One ring = M-21
The stamping numbers don't seem to match anything that GM did. All there stampings started with a P designating a Muncie. GM did outsource Muncie trans to American Motors(Rambler back then) that were identical to the GM models. I am not sure how there stamping numbers went.
As redvetracr mentioned the casting number only indicate what the trans was originally. Measure the cluster shaft pin to see if it is 7/8" or 1". Someone may have rebored the cluster and replaces the input and clustershaft to something newer.
Thread Starter
Burning Brakes
Joined: Aug 2001
Posts: 1,002
Likes: 0
From: Bay City MI.
Re: Muncie trans ID (Gordonm)
Dumb question, but is the input shaft the one that conects to the yoke then drive shaft or is the input shaft the one that goes to the clutch. Mine has 10 spine to the clutch and on the back of the trans its a 26 spline to the drive shaft.
Drifting
Joined: Oct 2000
Posts: 1,825
Likes: 56
From: Shawano WI
Re: Muncie trans ID (467-Ratman)
Dumb question, but is the input shaft the one that conects to the yoke then drive shaft or is the input shaft the one that goes to the clutch. Mine has 10 spine to the clutch and on the back of the trans its a 26 spline to the drive shaft.
With the 10 spline input/no rings/3851325 casting it looks like a pre 65 M-20.
