[71HO4SPD]

I have a M22 four speed that I put in an '80 T/A. I need to know a good rear end ratio for highway usage. Currently it has 2:56 in it. I also have another M22 in a '71 with a 3:42. What is a good in between ratio? Want to drop my rpm's lower on the highway than a 3:42, but the 2:56 seems like the it will not launch to well from a stop.

[chiphead]

For a 455, I'd use a 3.08. For a 400, a 3.23 would work. Tire height plays into the deal, as shorter tires can use higher ratios and vice versa.

[Sirrotica]

Not only won't it launch from a stop, the clutch is going to be doing much more slipping to get the car moving. I had a 70 Judge with 3.55 gears that I destroyed and because I had to drive the car I used an axle out of a 67 LeMans with 2.56 gears, it was not a pleasant car to drive other than mileage was great on the highway. I used it to flat tow my race car in the signature picture with it and you never used 4th gear at all while towing, RPMs were too low. It was only temporary anyway as some woman turned in front of me coming the other way a few months later and the car was pretty much destroyed, although not totaled.

I concur with Chiphead, his choices are probably right on for a street car.

[69Customs]

Total first gear ratio should run between 7:1 to 10:1 That's what the factory ran. Most of the time they never put less than 3.23 rear with a manual close ratio rear even tho there is literature out there that states a 3.08 rear was an option in a couple years I don't believe it was offered with the close ratio.
2.56 rear is an automatic rear end.

[geeteeohguy]

Having driven all of the mentioned ratios, I too agree with Chiphead 100%. Right on the money. A 3.23 can't be beat for a 389-400 4 speed car ratio, and a 3.08 is perfect for the bigger 455. The only reason I'm running a 3.36 in my 4 speed '65 is because a 3.23 carrier won't fit. I am running and loving the 2.56 posi I swapped into my '67 automatic car, though. Great mpg and cruising at high speeds.

[Steve Barcak]

Those trans with the 2.20 low are really a bad choice to use with hiway gears or even mild street ratios. They are very hard on clutches. I had a 72 GTO 455HO with M-22 and 3.31 and it was very hard on clutches and very lazy off the line as well. in the 60's they normally did offer that trans unless you ordered a 3.90 ratio or lower.
Can you change the trans to a wide ratio or similar? The close ratios are good choices for those who do not use their car/just car shows, etc but, not good from someone who is going to drive it much.
You going to be compromsing something with that trans- mileage, engine rpm or clutch life.

You would be happier swapping the trans and leaving the rear end in place.

[71HO4SPD]

Thanks for the info. Now, I failed to mention the engine I am running. '71 350 250 hp. Would a 3:23 work with that low hp?

['ol Pinion head]

The 2.20 1st gear M22 (or M21) is a poor choice for what you are trying to do. Most vehicles with Pontiac 350's will need more torque multiplication out of a gear box in 1st gear.

There are aftermarket gearsets built which are cut at the same pitch as the M22 gears, if you have to have the noise. Could order a set & have them installed in your current Muncie. Ck your PM's

[blueghoast]

Get you self a saginaw 4-speed.
One with the 3.50 first gear ratio
or with a 3.17 first gear ratio.
That would work great for your 350 cu.
I run a 3.50 one in my tempest. 3.31 rear gear.

GT.

[chiphead]

Wow, I didnt realize the M22 was the close ratio. You will have to slip the clutch or bog the engine to get it moving. A deeper 1st in the tranny would really help with highway gearing.

I ran the 3.23 with my 350. It ran really well and was fun on the highway. I was running a TH350, so the converter helps overcome the lugging issues.

[71HO4SPD]

Well, looks like I will have to shelf the M22 for a highway trans and 3:23's. OPH you reached your space limit.

[Region Warrior]

Look for a 64-65 out of a chevy.
They where wide ratio w/a 2.56 1st gr.

[Silver Judge]

Another resource to consider-------

AutoGear has a 2.52 first gear ratio option available with their SuperCase Muncie M22 kits.
That really improves starting line ratio compared to that conventional 2.20 first gear ratio

I picked up this option in my supercase muncie M-22 and I like it

[1971WARBIRD]

if you can find a Borg/Warner ST-10 from a late firebird or camero with a 301/305 they have bigger first gears. i have found 3.42 geared in 81 TA's. not suppose to be good with a big horse/torque engine, but 350 or mild 400's should hold up.