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Transmission & Driveline Transmissions and Differentials

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  #1  
Old Dec 14th, 08, 05:47 PM
Melrose RS Melrose RS is offline
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Default Stock Muncie torque/hp rating?

All the talk about TKO 500 and 600's and Keisler's new RS T-45 has me wondering-

What really is the max rating for a stock M21 or M20?

I'd assume the M22 can take more than 450 hp and ft/lbs because they were offered behind LS6 cars, right? But what about M20 and M21's?

Thanks-
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  #2  
Old Dec 14th, 08, 08:52 PM
Straight-line-69 Straight-line-69 is offline
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Default Re: Stock Muncie torque/hp rating?

Hard to say. Street tires will help you get by. Back in the day, Chevy (and Pontiac, etc) put the Muncie behind some pretty snotty BB's, such as L-88 and ZL-1. For the record, there's no guarantee the TKO's won't grenade either.

I'd run the Muncie until it breaks, if it breaks.

FWIW
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  #3  
Old Dec 14th, 08, 10:52 PM
67SS&99SS 67SS&99SS is offline
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Default Re: Stock Muncie torque/hp rating?

Quote:
Originally Posted by Melrose RS View Post

I'd assume the M22 can take more than 450 hp and ft/lbs because they were offered behind LS6 cars, right? But what about M20 and M21's?

Thanks-
I've got a M20 behind the motor in my sig and I've had no problems.
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  #4  
Old Dec 15th, 08, 06:00 AM
L72/RS L72/RS is offline
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Default Re: Stock Muncie torque/hp rating?

Here is some test data from the 2.96 ratio Muncie transmissions that I used to build.
All standard helix units failed at ~320 ft-lbf of torque with about 0.030” case stretch.
All of the low helix sets failed at ~390 ft-lbf of torque with about 0.050” case stretch.
All of these cases split at the small end of the counter shaft and shredded the small end of the counter shaft and 1st gear.
The pin holes for the large end of the counter shaft also stretched from 0.002” to 0.008”, but no cracking was evident.

This data was collected from around 20 tests using a hydraulic lock on the transmission output shaft and force transducers at two points on the drive mechanism.

Because someone will ask, I used to make 2.72 and 2.96 custom ratio Muncie transmissions for use with 277 to 310 CID small block engines.
You should be able to figure the torques for the M20/M21 ratios from the 2.96 test data.
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  #5  
Old Dec 15th, 08, 02:22 PM
Moonpie Moonpie is offline
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Default Re: Stock Muncie torque/hp rating?

When I was 17 and clueless I had a '65 Tempest with a 455 with a few light modifications. It had a Muncie with a compitition plus 4 speed and a Zoom clutch. It was a brutal torque monster and I drove it hard,racing it a lot with full throttle bang shifts. Broke a pressure plate,popped the gears on the rear end once and finally grenaded the motor. The Muncie was still in fine shape.
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  #6  
Old Dec 15th, 08, 05:34 PM
pdq67 pdq67 is offline
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Default Re: Stock Muncie torque/hp rating?

Probably 425 for the M-20, 450 for the M-21 and 500 for the M-22 and a schosh over 600 for the high zoot bells and whistles Italian gear set M-22 Supercase w/ the iron mid-plate, imho!!

pdq67
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  #7  
Old Dec 17th, 08, 06:05 AM
JOE58 JOE58 is offline
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Default Re: Stock Muncie torque/hp rating?

Quote:
Originally Posted by L72/RS View Post
Here is some test data from the 2.96 ratio Muncie transmissions that I used to build.
All standard helix units failed at ~320 ft-lbf of torque with about 0.030 case stretch.
All of the low helix sets failed at ~390 ft-lbf of torque with about 0.050 case stretch.
All of these cases split at the small end of the counter shaft and shredded the small end of the counter shaft and 1st gear.
The pin holes for the large end of the counter shaft also stretched from 0.002 to 0.008, but no cracking was evident.

This data was collected from around 20 tests using a hydraulic lock on the transmission output shaft and force transducers at two points on the drive mechanism.

Because someone will ask, I used to make 2.72 and 2.96 custom ratio Muncie transmissions for use with 277 to 310 CID small block engines.
You should be able to figure the torques for the M20/M21 ratios from the 2.96 test data.
You tested 20 Muncie transmissions to distruction?

That sounds interesting. Do you have any pictures?

How did you apply the torque during testing?
Was this done at a transmission shop?

I have read that the lower gear tooth angle of the M22 was done to keep the case from blowing open. Do you think that is correct?
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  #8  
Old Dec 17th, 08, 09:32 AM
L72/RS L72/RS is offline
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Default Re: Stock Muncie torque/hp rating?

Joe,
Yes, but at the time I had a couple hundred cores and numbers didn’t really mean much to me. All of the cases got welded, bushed, and later used.
Sorry, I don’t have pictures of the setup.

The drive engine cradle was trunion supported with two transducers to measure the torque peak at each end of the cradle. The output coupler had three dual caliper discs and one transducer. The clutch was released using a hydraulic solenoid mechanism similar to a line-lock. The transducer data with inertia correction yielded the numbers that I posted.

I think there are one or two members here that are still running my 2.96 transmissions in their Z’s. One is Kerry Stanley’s cross-ram Z. The other guy had a DY Z with white interior from Florida, but I can’t remember his name.

The lower helix angle for the M22 was used to decrease running temperatures for road racing purposes. The lower angle also decreases the end thrust load on the case.

The M22 were also stronger, IMHO, due to a larger 1st gear tooth cross-section area and the 9310 gear material vs. the 8620 material that the M20/M21 gears were made from.

9310 material strengths:
normalized => sy=82 kpsi ; su=132kpsi
Q&T => sy=130kpsi ; su=155kpsi

8620 material strengths:
normalized => sy=52kpsi ; su=92kpsi
Q&T => sy=118kpsi ; su=139kpsi

The 9310 material is ~10.4% stronger that the 8620 material.

Hope this info helps.
Eric
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  #9  
Old Dec 18th, 08, 10:52 AM
mikes69z mikes69z is offline
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Default Re: Stock Muncie torque/hp rating?

Hi Eric,

Good to see you posting again.

BTW - that 2.73 GM gearset I got from you has been in my car 2 years now and running great. Thanks again :-)

Hope all is well and BTW - excellent posting on the all tests you ran on the Muncie - very informative.

Have a great holiday,

Mike
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  #10  
Old Dec 18th, 08, 12:07 PM
jmartorana jmartorana is offline
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Default Re: Stock Muncie torque/hp rating?

Here's some info from 5speed.com

After 29 years.... the Muncie Transmission is back! General Motors stopped installing "Muncie" 4 speeds in 1974. Complete units were able to be purchased from GM until the late 1970's. Parts trickled out of inventory by the late 1980's. With the quality of used Muncie transmissions getting worse in the last 7 years, the idea of making new improved Muncie parts was becoming a reality. We were contacted by Autogear Company (Syracuse NY ) to help them conceptualize newer designed products for the Muncie. First we started with gears, then the Supercase. Soon after design concepts for endurance racing followed with iron midplates, sealed inputs, extra close ratios and rollerized 1st gears. In less than 3 years a complete new 4 speed became possible. With the proper rear end gear a new M22 can handle close to 700HP!
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  #11  
Old Dec 18th, 08, 12:18 PM
jmartorana jmartorana is offline
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Default Re: Stock Muncie torque/hp rating?

Sometime next year I plan to remove my M21 and have it rebuilt using the Masiero (Italian Gearset) M22W ratio's with the Iron mid plate by D&L Transmissions here in Long Island NY. 2.56 first gear.
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  #12  
Old Dec 18th, 08, 12:35 PM
green z green z is offline
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Default Re: Stock Muncie torque/hp rating?

I have the auto gear in my BB 67 camaro. I just put it in this fall. 2.55 nickel 1st gear. Got about 30 runs on it . So far launching @ 4000-4500v with 10' tires. Plan on higher launches in the spring. 1st geart sounds like a old school bus. Seems to be working fine. I would like to try have a little steeper 1st gear but I believe 2.55 was the steepest they offered
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  #13  
Old Dec 18th, 08, 01:51 PM
rszmjt rszmjt is offline
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Default Re: Stock Muncie torque/hp rating?

Quote:
Originally Posted by jmartorana View Post
Here's some info from 5speed.com

After 29 years.... the Muncie Transmission is back! General Motors stopped installing "Muncie" 4 speeds in 1974. Complete units were able to be purchased from GM until the late 1970's. Parts trickled out of inventory by the late 1980's. With the quality of used Muncie transmissions getting worse in the last 7 years, the idea of making new improved Muncie parts was becoming a reality. We were contacted by Autogear Company (Syracuse NY ) to help them conceptualize newer designed products for the Muncie. First we started with gears, then the Supercase. Soon after design concepts for endurance racing followed with iron midplates, sealed inputs, extra close ratios and rollerized 1st gears. In less than 3 years a complete new 4 speed became possible. With the proper rear end gear a new M22 can handle close to 700HP!
Maybe with todays clutches that slip, but you try that with conventional generic speed shop clutches with todays tires and you will be taking the M22 home in a Dixe Cup. MHO.
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  #14  
Old Dec 18th, 08, 04:05 PM
pdq67 pdq67 is offline
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Default Re: Stock Muncie torque/hp rating?

Eric,

"Probably 425 for the M-20, 450 for the M-21 and 500 for the M-22 and a schosh over 600 for the high zoot bells and whistles Italian gear set M-22 Supercase w/ the iron mid-plate, imho!!"

This is my gut feeling after reading everything on the Boards as well all the mags through the years of what guys have actually ran.

I would like to see real world testing of actual peak, right after dumping the clutch just before breakaway of real slicks at launch torque numbers in a car and I just picked up on Autogear saying, "With the proper rear end gear a new M22 can handle close to 700HP!", and I mention this b/c you can reach a point where you unload the tranny in low gear b/c of too steep a reg, imho.. Again, imho.

An M-20 and a 4.10 w/ 8.00 slicks will live a lot longer than the same M-20 w/ a 3.07 and the same tire IF the clutch holds! I figure this is b/c the load will lessen upon the tires spinning is all!

If the clutch holds and the tires DON'T spin, then the tranny, u-joints/driveshaft and rearend had better be able to handle the full t of the engine at max output!

All bets are off if the clutch doesn't hold or the tires spin!

Please come back on this b/c we all really need to figure out a way to come up w/ a relatively CHEAP, 4-speed tranny that can hold at least 650 t, imho! I know I probably do b/c of my about 580 t 496!

And I sold my good MOPAR A833 b/c I didn't want to hassle w/ installing it or an old '60's Ford Top-Loader that I figure that both have more strength than our Muncies.

pdq67
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  #15  
Old Dec 18th, 08, 04:17 PM
67SS&99SS 67SS&99SS is offline
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Default Re: Stock Muncie torque/hp rating?

Quote:
Originally Posted by pdq67 View Post
And I sold my good MOPAR A833 b/c I didn't want to hassle w/ installing it or an old '60's Ford Top-Loader that I figure that both have more strength than our Muncies.

pdq67
I've got one of those A-833 4 speeds in my 'Cuda, and I can tell you that it will definately take some abuse. Cast iron case to boot. The only component I'm worried about it in its drivetrain is the stock driveshaft and U-Joints. I'll be going with spicer joints before long so it should take everything this high rpm 340 can throw at it.
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