'75 4spd transmission specs
Thread Starter
Racer
Joined: Dec 2011
Posts: 284
Likes: 4
From: Philadelphia Pennsylvania
'75 4spd transmission specs
What are the transmission/drive ratio specs for a stock '75 l48 4spd?
From my research I think it should be a 2nd-gen Borg-Warner Super T-10 with a 2.64 1st gear and a 3.36 rear axle.
What kind of torque can this handle? I've seen people mention 400tq as upper limit, with a bunch of others claiming far more without issues.
I ask because:
1) I'm thinking a ZZ4 is in my future
2) I need a new clutch anyway and I assume this means trans needs to come out
3) My tranny might be leaking, gotta take a closer look.
From my research I think it should be a 2nd-gen Borg-Warner Super T-10 with a 2.64 1st gear and a 3.36 rear axle.
What kind of torque can this handle? I've seen people mention 400tq as upper limit, with a bunch of others claiming far more without issues.
I ask because:
1) I'm thinking a ZZ4 is in my future
2) I need a new clutch anyway and I assume this means trans needs to come out
3) My tranny might be leaking, gotta take a closer look.
Drifting
Joined: Sep 2010
Posts: 1,412
Likes: 50
From: Laguna Niguel California
Your ratios are right. As for handling additional power, I ran a Super T-10 (not the original number match) behind a supercharged L-82 for many years in the 1990's with out a problem. They are very sturdy. You can identify the ratios by the rings cut into the splines on the input shaft, 3 rings is the 2.64 first, 2 rings is the 2.40 first. If you are going to do something with the engine, definitely use something with modern technology heads like the ZZ4 or build with AFR's or something similar.
Melting Slicks
Joined: Sep 2011
Posts: 3,372
Likes: 215
From: Peoria Arizona
Sorry to sort of hi-jack your thread Brian! I have wondered this and not been able to find any info. I've never even seen anything about the 2 or 3 rings on the input shaft prior to this (ours has 3).
Thanks!
Adam
EDIT - think I found this info on Nastyz28.com. 2 rings is the close ratio with 2.40 first. 3 rings is the m20 wide ratio with 2.64 first. I guess there are 3, 4 and 5 rings as well.
http://www.nastyz28.com/forum/showthread.php?t=181903
Last edited by AdamMeh; Jun 13, 2012 at 03:58 PM.
Thread Starter
Racer
Joined: Dec 2011
Posts: 284
Likes: 4
From: Philadelphia Pennsylvania
Your ratios are right. As for handling additional power, I ran a Super T-10 (not the original number match) behind a supercharged L-82 for many years in the 1990's with out a problem. They are very sturdy. You can identify the ratios by the rings cut into the splines on the input shaft, 3 rings is the 2.64 first, 2 rings is the 2.40 first. If you are going to do something with the engine, definitely use something with modern technology heads like the ZZ4 or build with AFR's or something similar.
Melting Slicks
Joined: Aug 2008
Posts: 2,200
Likes: 3
From: Lehigh county Pennsylvania
Borg-Warner 4-speed from '74-'81.
Take some of the previous posts with a grain of salt as they seem to commingle attributes of the T-10 and Muncie.
Take this verse from AdamMeh's link for example:
A Borg-Warner trans is NOT a Muncie and never the twain shall meet. M21 is a close ratio Muncie designation...always has been, always will be.
Take some of the previous posts with a grain of salt as they seem to commingle attributes of the T-10 and Muncie.
Take this verse from AdamMeh's link for example:
On A WARNER SUPER T-10 Two ring grooves on the input shaft is a CLOSE RATIO M21 with 2:43 FIRST...
Last edited by 69 Chevy; Jun 14, 2012 at 11:10 AM.
Melting Slicks
Joined: Sep 2011
Posts: 3,372
Likes: 215
From: Peoria Arizona
Borg-Warner 4-speed from '74-'81.
Take some of the previous posts with a grain of salt as they seem to commingle attributes of the T-10 and Muncie.
Take this verse from AdamMeh's link for example:
A Borg-Warner trans is NOT a Muncie and never the twain shall meet. M21 is a close ratio Muncie designation...always has been, always will be.
Take some of the previous posts with a grain of salt as they seem to commingle attributes of the T-10 and Muncie.
Take this verse from AdamMeh's link for example:
A Borg-Warner trans is NOT a Muncie and never the twain shall meet. M21 is a close ratio Muncie designation...always has been, always will be.
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Brett Foote
Had a 1976 L-82, 4-sp
Joined: Mar 2011
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From: Some days your the dog and some days your the hydrant.
Royal Canadian Navy
My '76 has transmission code M21 - close ratio B-W ST10.
Drifting
Joined: Jun 2007
Posts: 1,404
Likes: 1
From: Ansonia/NYC CT
L81 came with the close ratio Super T-10, and the L48 came with the wider ratio. If it's an L48 4 speed, it's likely the wide ratio, with the 3.36 rear...but CHECK the rear!!! I have a 76' L48...with a 3.08 rear. How did THAT happen? Easy way to check is to just go out on the road, get to a cruising speed, and check RPM, the plug that info into a calculator. OR, jack up the rear, mark the tire and the drive shaft with chalk, and rotate tire, counting drive shaft rotations. Less precise, but it'll get you a ball park number. 3 turns = 3.08, 3 1/4 -3 1/2 turn = 3.37, so on and so forth.
And to answer the question, these trannies can handle a lot. A lot of circle track cars use them with better rear gears (3.55-4.11), which multiplies the torque a bit, PLUS they are using racing slicks, and running big blocks.
I don't imagine they are getting a HUGE amount of mileage on them...but it's enough so that THOSE are the trannies they use.
So I'd say that 400tq is pretty safe...just don't tub it, put drag radials on it, and drop it from 3K too often, lol.
And to answer the question, these trannies can handle a lot. A lot of circle track cars use them with better rear gears (3.55-4.11), which multiplies the torque a bit, PLUS they are using racing slicks, and running big blocks.
I don't imagine they are getting a HUGE amount of mileage on them...but it's enough so that THOSE are the trannies they use.
So I'd say that 400tq is pretty safe...just don't tub it, put drag radials on it, and drop it from 3K too often, lol.
Thread Starter
Racer
Joined: Dec 2011
Posts: 284
Likes: 4
From: Philadelphia Pennsylvania