1976 L82 Borg Warner 4 speed with M21??
Thread Starter
Safety Car
Joined: May 2008
Posts: 3,751
Likes: 719
From: Lafayette Louisiana
1976 L82 Borg Warner 4 speed with M21??
Please help clarify something for me.
I have a 1976 L82 4 speed stamped WJ852
Is that a close ratio or a wide ratio? M20 or M21??
I thought I read in a Corvette Restoration book by Prince that if the last digit was 1, then that was a wide ratio.
However, the link below says that the last digit is the production shift
http://fiedlerh.home.att.net/BW.htm
If the link is correct, how do you tell if it is a M20 wide ratio or M21 close ratio, or are all 1976 L82 4 speeds close ratio?
Much thanks.
I have a 1976 L82 4 speed stamped WJ852
Is that a close ratio or a wide ratio? M20 or M21??
I thought I read in a Corvette Restoration book by Prince that if the last digit was 1, then that was a wide ratio.
However, the link below says that the last digit is the production shift
http://fiedlerh.home.att.net/BW.htm
If the link is correct, how do you tell if it is a M20 wide ratio or M21 close ratio, or are all 1976 L82 4 speeds close ratio?
Much thanks.
Racer
Joined: Aug 2000
Posts: 434
Likes: 3
From: Cleveland Ohio
Should be a Borg Warner Super T-10. Would need to know how many grooves are on the input shaft for the ratio's. check the following link.
http://www.dandltransmission.com/borgratio.html
http://www.dandltransmission.com/borgratio.html
Racer
Joined: Jun 2008
Posts: 269
Likes: 0
My Corvette Fact book says that '76 L82 cars could have either the wide ratio or close ratios. The L48s do not have that choice. So your car could have either.
I realize this info doesn't really help you much. I just thought it might answer one of your questions.
I realize this info doesn't really help you much. I just thought it might answer one of your questions.
Drifting
Joined: Apr 2007
Posts: 1,970
Likes: 45
From: Cameron Park CA
If you don't have to remove the tranny for any reason other than to figure out the ratios, it would be easier to figure them out mathematically. Here's a formula I found in the Sept. 2006 issure of Corvette Magazine, pg. 81.
Overall Gear Ratio = (RDXRPM)/(MPHX336)
RD is the rolling diameter of the rear tire - if you have a modern tire you can probably find that at Tire Rack's site. Or you could measure it.
"336 constant is a remnant of turning rolling diameter into tire circumference, multiplying the revs per minute by 60 (to get revs per hour), and then backing everything out again through algebra. Save yourself the headache and just use 336."
When you have the overall ratios for all the gears, you'd have to back the final drive ratio to determine the other gears ratios.
Good luck,
Pete
Overall Gear Ratio = (RDXRPM)/(MPHX336)
RD is the rolling diameter of the rear tire - if you have a modern tire you can probably find that at Tire Rack's site. Or you could measure it.
"336 constant is a remnant of turning rolling diameter into tire circumference, multiplying the revs per minute by 60 (to get revs per hour), and then backing everything out again through algebra. Save yourself the headache and just use 336."
When you have the overall ratios for all the gears, you'd have to back the final drive ratio to determine the other gears ratios.
Good luck,
Pete
Racer
Joined: Sep 2007
Posts: 286
Likes: 0
From: Pensacola Fla
Just going by the Corvette Black Book,the L 82 got the M21 close ratio transmission and the base 180 hp engine received the wide ratio transmission and I think that may have been a Saginaw while the M21 was a Borg Warner book does not state manufacture of transmission.
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Drifting
Joined: Sep 2006
Posts: 1,259
Likes: 2
From: MS
All 76 manual trannys were the Warner T-10.
M20 and M21 just means wide or close ratio and has nothing to do with Muncie.
WJ852 is the date code but tells nothing of ratio.
L82 had the M20 (2.64) standard with M21 (2.43) optional so you could have either one.
There was a 2-letter ink stamp on the driver side that would tell the ratio (HS-2.64, HW-2.43).
Can also check the axle ratios, if you have the 3.70 then you will have the M21,
the 3.55 could be either tranny. If you have A/C, then you will have the 3.55.
Axle codes OB - 3.55, OC - 3.70
Also check for a metal tag, will say something like AS9-T10X with the X being a letter, S-2.43, W-2.64.
M20 and M21 just means wide or close ratio and has nothing to do with Muncie.
WJ852 is the date code but tells nothing of ratio.
L82 had the M20 (2.64) standard with M21 (2.43) optional so you could have either one.
There was a 2-letter ink stamp on the driver side that would tell the ratio (HS-2.64, HW-2.43).
Can also check the axle ratios, if you have the 3.70 then you will have the M21,
the 3.55 could be either tranny. If you have A/C, then you will have the 3.55.
Axle codes OB - 3.55, OC - 3.70
Also check for a metal tag, will say something like AS9-T10X with the X being a letter, S-2.43, W-2.64.
Melting Slicks
Joined: Apr 1999
Posts: 2,010
Likes: 3
From: Moon Twp. PA USA
No factory installed Saginaw 4-speeds in '76. All BW ST10s with various ratios.
My information is from the GM Corvette owners package that was available a few years ago.
Le Mans Master
Joined: Sep 2002
Posts: 5,236
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From: Myrtle Beach SC
Instructor
Joined: Feb 2007
Posts: 114
Likes: 18
From: McKinney TX
For you sentimental types:
The GM transmission plant in Muncie IN suffered gradual decline for years throughout the 80's and 90's, falling from 3000 employees to only a few hundred by 2005. The plant was finally closed in 2006.
The facility was demolished earlier this year.
http://www.mcmmanagement.com/muncie+...ion+plant.aspx
The GM transmission plant in Muncie IN suffered gradual decline for years throughout the 80's and 90's, falling from 3000 employees to only a few hundred by 2005. The plant was finally closed in 2006.
The facility was demolished earlier this year.
http://www.mcmmanagement.com/muncie+...ion+plant.aspx
