carhead22000

hi guys,got a little prob hope you guys can help.switched my auto trans to a m-22 4speed,does have the launch the auto had.do i need gear ratio?it has 342,s. its a 383 stroker running around 400hp,425 ftt pounds of tourqe.its a close ratio trannie.??????

angel71rs

A genuine M-22 would have a 2.20 1st gear, and yes, it's a close ratio tranny. If you aren't happy with how the car launches with the new tranny, consider going with 4.11s in the rear.

Last time I ran an M-21 (also 2.20 1st) I used 4.88s and it felt great, but when nearby track closed (OCIR) I went to 3.73s and it lost a lot of takeoff in 1st. Considered going to an M-20 (~2.54 1st) for better 1st gear takeoff, but ended up selling that car.

These days a 5 or 6 speed is a much better choice over the old Muncies. GM T-56s used in most 4th gens had a 2.66 1st for good takeoff in 1st, but .74 5th, .50 6th so freeway cruising pulls much lower rpm.

Welcome to the board.

carhead22000

so the 342,s would be flat in the car then right?it just don,t work like a stroker.my automatic would rip the tires off for two blocks,lol.my first couple drives have been disapointing.gonna go410,s.don,t think 373,s would make that much diff.thanks for reply

byrons1502

The auto used a converter that multiplied the torque output and made it feel stronger out of the hole. Plus it had a deeper first gear ratio. Get a lot of comments on people putting in manuals where an auto resided and thinking the car was doggish. If u dont care about rpms then go with 4.11's but might be a little to much gear and run out of rpm at the end of the track if u race.

Yenkohead

How high are you revving it in first gear? I had a 383 stroker with an M-20 and about 300hp/350Tq with 3.31 posi and it was hard NOT to spin through 1st and 2nd gears. I was running old BFG radial T/As and shifting about 6200-6400 rpm. Like already suggested, if you go more than 4.10 or 4.11 you may run out of gear at the top end of the 1/4 mile.

It's still more fun to shift gears than push the pedal and hold on.........IMHO.

Have fun!

Grandpa's 99Z

Take the 2.20 first gear ratio X the rear end ratio & that is your launching ratio. The M-22 really works great with a 3.73 or higher. Remember the old Z-28's had a 4.11 rear end so the lauching power is above 8. The lower the total ratio number will cause more clutch disc wear sooner. The M-21 & M-20had a 2.53 first gear. The downside is that your rpm's will be higher in the cruise mode on your engine with the 3.73 or higher rear end.

If you can afford it, look at a Tremac with a 2.87 first gear & .82 5th gear. It's a easy to look at the rpm reduction. It's simple math. Minus 18 % of your crusing speed.

Good Luck.

vmatt350

Grandpa took the words right out of my mouth.

I have a very similar set up as you do and Im not comfortable driving at highway speeds for very long. I have the 3.73 rear with the M22W (same 4th gear) and at about 55 mph I am taching over 2500rpms. Bring the speed up to about 60-70mph and the engine will be screaming, at least from my perspective. I dont go on the highway much so its not an issue at the moment. I may look at putting one of the TKO 5 speeds in it in the distant future.

Grandpa's 99Z

Just build a new motor for my 68 Camaro 383 9.5 compression 450HP on Dyno.

Mated it with a Tremac 5-speed .82 OD & turn 2000 rpm's @ 65mph with 3.08 gears & 235/60/14 tires.

Injuneer

M20 - 2.52 or 2.56
M21 - 2.20
M22 - 2.20

http://www.5speeds.com/muncie2.htm