Which rear gear set for a 4 speed with overdrive?

[Rick Henderson]

Here goes............Muncie M22 with Autogear overdrive (2.199/1.506/1.000/0.859), tires are 275/60/15. I imagine the motor is around 425-450hp range. Its for my 70 convertible.

Ring and pinion-----tire size---- speed----- trans ratio-------- rpm

2.73 ---------- 27.99----------60----------0.859----------1671
3.08 ---------- 27.99----------60----------0.859---------- 1886
3.42 ---------- 27.99----------60----------0.859----------2094

Any ideas?

[DaWildcat]

I'd run at least 3.42:1. I think Larry's running 3.73:1 with his overdrive setup.

Devon

[Rick Henderson]

Looks like Larry's combo would be going down the road at 2284 rpm, with my tire size...........

[DaWildcat]

In general you need enough cruise rpm to stay above the start of the cam's power band for any lengthy driving.

Devon

[Floydsbuick]

Your not over driven very much w an .85. 3.42s -3.55s spin a 1 to 1 pretty good on the highway. If you want some road trip-ability, I'd say your in the 3.55-3.73 range.

[kick71]

wow I'm jealous. I want to get one of those in next year after I drive my newly converted 4 spd with new motor for awhile.
Please report back after you are up and running on how you like or dislike the 4spd OD M22

Mike

[The Old Guy]

I run a 3.31 axle with a 200-4R tranny. The overdrive is .68 and it cruises great on the interstate! I also runa 275/60 X15:Do No: :Do No: :Do No:

[Rick Henderson]

In general you need enough cruise rpm to stay above the start of the cam's power band for any lengthy driving.

Devon

Makes sense. I don't recall the cam thats in the motor now. Well it put the white 70 into the 11's on a regular basis with 3.42 gears and a t400.

[Rick Henderson]

wow I'm jealous. I want to get one of those in next year after I drive my newly converted 4 spd with new motor for awhile.
Please report back after you are up and running on how you like or dislike the 4spd OD M22

Mike

Will do.

[bostongsx]

I run a 3.23 in my vert with that tranny and like it.

[Rick Henderson]

I run a 3.23 in my vert with that tranny and like it.

Thats what I was thinking of putting in it. Great. Thanks. I pulled the cover on the rear that is under the car now and its a 8.5, 10 bolt with a 2.56 gear.....:Dou:

Going to have to find a 3 series carrier and some gears now.

Thanks Guys!

[crash]

You would be better off with a 2.88CC ST-10, and leave the 2.56 rear alone... You will have a better final drive in first gear with the ST-10, and the 1 to 1 4th gear is lower than the O.D. final drive will give you...

Some thing to think about... Crash

[Rick Henderson]

You would be better off with a 2.88CC ST-10, and leave the 2.56 rear alone... You will have a better final drive in first gear with the ST-10, and the 1 to 1 4th gear is lower than the O.D. final drive will give you...

Some thing to think about... Crash

Tranny is already built. The overdrive was a gift also. But thanks for the info.

[70 gsconvt]

I would go with the 3.42's. I currently have a 3.73 rearend with my 200-4R trans. 2100 rpm's on the highway with a 28" tall tire. Great cruising speed on the highway at 70 mph.

[kick71]

I run a 3.23 in my vert with that tranny and like it.
Rick where are you getting the trans from?

Herb,
How long have you had M22 with the OD? Any issues bolting it up or with its function? Where did you get it from?

Mike

[jdk971]

you want the combo to cruise at your engines power band. big block probably
around 2000 rpms. anything lower than 1800, would probably lug the engine
and not give you your best mpg. i had a 5 speed in a corvette small block with a 3.08 and the rpms were too low for the 5 gear. waste of money. jmho
jim

[Rick Henderson]

Mike,
I got the parts from Erickson Gear in Seattle, WA. The owner became a good friend to me. We call him Muncie Bill as he is extremely knowledgeable of Muncie's (my interest) along with just about any manual transmission.

Bill has cancer and doesn't have long to live. He has difficulty lifting trannys by himself now.

[kick71]

Hey Rick did you get the trans in and running with new gear ratio yet?

Mike