Transmission ID
Thread Starter
Burning Brakes
Joined: Dec 2005
Posts: 1,164
Likes: 224
From: Pawleys Island, SC
Transmission ID
I know this has probably been rehashed a hundred times. I'm trying to ID my 4-speed as close or wide ratio. '77 L82, 3.70 rear ('OC' marked on the diff). No painted letters on the trans. No metal tag. Found the vertical marking on the left rear of the trans near the cover. I don't have a date code with 'A', 'B' or 'C' There is only the last 7 digits of my VIN# and 'WM7' and '62'. Anybody seen anything like that? Anyone know what it means?
Melting Slicks
Joined: Sep 2004
Posts: 3,223
Likes: 666
From: Northeast
In 77 Borg Warner was installed that is why there is no abc. Those letters were used on the Muncie.
This site will help: http://pontiacpower.org/BW.htm
Looks like Warner, December 7th, 1976, 2nd shift.
Assume your build date tag is a few weeks after that.
This site will help: http://pontiacpower.org/BW.htm
Looks like Warner, December 7th, 1976, 2nd shift.
Assume your build date tag is a few weeks after that.
Burning Brakes
Joined: Oct 2013
Posts: 1,113
Likes: 520
From: McClellandtown, Pa.
The metal ID tags on the Muncies ended in 72 for the corvette. Probably because the M22 was no longer an option on the 73's. Just two choices for manual trannys. M21 & M20.
Regards,
Jimmy
Regards,
Jimmy
Thread Starter
Burning Brakes
Joined: Dec 2005
Posts: 1,164
Likes: 224
From: Pawleys Island, SC
Since my transmission case markings don’t seem to provide any indication as to whether it’s close or wide ratio, figured it out myself. Easily done once you think about it. In both the close and wide ratio gearing, the % difference is pretty much the same between 1st and 2nd and 2nd and 3rd gears. The difference in gearing is between 3rd and 4th gears.
Close ratio:
2.43 to 1.61 34% (1st to 2nd)
1.61 to 1.23 24% (2nd to 3rd)
1.23 to 1.00 19% (3rd to 4th)
Wide ratio:
2.64 to 1.75 34% (1st to 2nd)
1.75 to 1.34 23% (2nd to 3rd)
1.34 to 1.00 25% (3rd to 4th)
Just picked a speed and noted the RPM for both 3rd and 4th gears. My RPM at 30 MPH is:
3rd gear 1850 RPM
4th gear 1500 RPM
A difference of 19%, indicating it’s the close ratio trans.
Close ratio:
2.43 to 1.61 34% (1st to 2nd)
1.61 to 1.23 24% (2nd to 3rd)
1.23 to 1.00 19% (3rd to 4th)
Wide ratio:
2.64 to 1.75 34% (1st to 2nd)
1.75 to 1.34 23% (2nd to 3rd)
1.34 to 1.00 25% (3rd to 4th)
Just picked a speed and noted the RPM for both 3rd and 4th gears. My RPM at 30 MPH is:
3rd gear 1850 RPM
4th gear 1500 RPM
A difference of 19%, indicating it’s the close ratio trans.
