[rrrbeee]

Good evening to all. I learned this afternoon that my 4 spd (non numbers matching M20? / M21?) transmission is shot and not worthy of rebuilding.

I have opted to go with a new M22 replacement transmission with a wide ratio gearing

I had the rear(chevy 12 bolt) rebuilt and and upgraded the gears to 3:73

400/350 original 69 GTO motor recently rebuilt and tweaked to include aluminum heads, RAIV manifolds, edelbrock intake, Rochester quad, electronic ignition and Comp 270H cam. Bored .30 over forged rods and crank dyno 380HP)

Is this the right way to go? and a good street combination

Thanks RRRBEEE

[The Champ]

The M22 and M21 , as I understand it, are [b]close ratio[b] 4spds with a 2.20 to 1 first gear.

The M20 is the wide ratio with the 2.56 1st gear.

The M21 was the standard duty close ratio - the M22 (or Rock Crusher) was the HD unit.

3.73 rear gears would compensate for the first gear of the close ratio tranny, but you may not like the RPM's on the highway with those gears.

I've got 3.42's, with 27" rear tires and an M20 and I'm running about 3,000 RPM at 70 MPH.

You'd be up at 3250 RPM with 3.73's assuming the same 27" tall rear tires.

[ra96]

RRRBEEE let me know if you go go the new muncie route what the outcome is im in a similar situation with my 68 bird- and yes as i understand it the- new- muncies can be ordered with M20 gear ratios in an M22 ive also read that the new case is more reienforced than the original -please keep me posted

[Singleton]

I have one of the new Autogear M22 wide ratios along with 3.90 rear. Works pretty well. I think with your 3.73 rear the wide ratio will be just fine.
The only thing that I don't like about the new M22's is the fact that the gear whine of the old m22 is gone. Too quiet

[The Champ]

Obviously I'm an idiot...

I didn't realize that Auto Gear was making this tranny.

[importsmasher]

I have one in my 74 GTO. I love it. It shifts beautifully and should hold up to a pretty good pounding. I have the close ratio gears though.

Importsmasher

[Region Warrior]

Chevy had a wide ratio with 2.56 1st gr available.
Pontiac used a 2.52
My long time chevy buddy been rebuilding muncies since the 70's.
Prefers wide ratio even with 4.11's and higher.
Used to run a 4.56 gr, and claims had faster ET's vs use'n a close ratio.

[ANDYA]

I have the Autogear M22 wide in my 69 Bird with a 428 and 3.73 rear. So far it's working good. With the wide ratio and 3.73 be sure to use a tall rear tire (27"-28") as the first gear multiplication is steep. If I had to do it again I would have went with a 3.42-3.55 rear.

[Blued and Painted]

I had a close ratio 21 in my 68gto with 373 rear.
It was great in race mode but hard to drive just poking around town.

[ra96]

ANDYA does your car have a console ? if yes or no did the shifter mount up in the same location i ask because i understand that the reinforced tail shaft section of the case is wider thas=n orig and will not accept the horseshoe stye shifter mount -if you are useing an orig style shifter mound ( side case ) did the shifter go back to its original position or did you have to modify something ? thanks

[ANDYA]

Originally Posted by ra96

ANDYA does your car have a console ? if yes or no did the shifter mount up in the same location i ask because i understand that the reinforced tail shaft section of the case is wider thas=n orig and will not accept the horseshoe stye shifter mount -if you are useing an orig style shifter mound ( side case ) did the shifter go back to its original position or did you have to modify something ? thanks

No, I'm not using a console. The shifter is a Hurst super street shifter and required some trimming of the trans tunnel to fit. The shifter does not come out in the stock location.

[tripwr1964]

i am running the autogear m22 wide ratio with 3.73's, 472ci, and 255/60/15's. works great. run about 2800rpm 60-65mph. i had this gear for my 389 and 400. 3.55 prob be better with the torque i have now.

[Scarebird]

Running the M22Z w/ 2.98 first and 2.93 8.5 out back. If done again would go with 3.08's... The m22 still has that whine unless in 4th.

[rrrbeee]

Thanks to all for the great responses
will let you know how it works out

[robg8r]

nothing like the sound of that m22

[rexs73gto]

I run an M22 in my 73GTO with the 3:73 rear gears & 295/50-15"s at 27 inches tall. On the hwy. it is turning about 2850 at 70 mph. i've had mine in there for about 30 years now & i love it. I wish at times I had a 5th gear but the M22 is a great trans to use & wouldn't trade the whine for anything. That lets me know I've got a strong trans under me. My 462 is 530HP & 585 TQ @ 3000. Haven't hurt it yet.

[geeteeohguy]

Couple of things, none of which are real important: I'm with the Champ: my '65 with a 3.36 rear and 27'' tires is about 3,000 rpm at 70 mph. It has a 2.56 first gear ratio muncie m-20 (the '64 and '65's had a 2.56, and the '66-up had 2.52), and works out as a good compromise. I have no idea how Rex can run at 2850 rpm with 3.73's and a 27" tire....when my car had 3.55's it was more like 3500 rpm at that speed!!

[The Champ]

From every gearing/rpm calculator that I'm familar with:

70 MPH, 3.73 Gears, 27" Tires = 3249 RPM

http://www.csgnetwork.com/multirpmcalc.html

My "Garage Buddy" app on my Android smartphone gives me the same answer.

[Larry Navarro]

I'm very interested in this Autogear M22 wide gear trans. Can someone post the link that gets you straight to the trans info.
Thanks!!

[Singleton]

http://www.5speeds.com/newm22.html