[Young Pontiac Guy]

http://www.autogear.net/pdf/HighPerf..._orderform.pdf

Alright guys. Getting ready to purchase one of these M23 trans. This is after blowing up my first Saginaw transmission! (Woohoo! If anyone wants pics of that carnage, I can provide...)

Car is a street car (Bird) that will get some track use. Will be a 3.08 rear gear car. 400 Poncho that has a little beef, more to come down the pipeline. Car has 2802 Summit cam, really starts making power about 25-2700rpm.

Here is my question, would like some opinions:
Go with the M23W or the M23Z? They recommend the M23Z with a 3.08, which I had planned to go with. However, Ponchos have lots of torque which made me second guess my decision.
Here are the ratio differences:
M23W: 1st 2.56, 2nd- 1.908, 3rd- 1.483, 4th- 1.0
M23Z: 1st- 2.99, 2nd- 2.225, 3rd- 1.468, 4th 1.0

I can also space out that 1-2nd gear drop a little more with the M23Z if I like but that would decrease the strength of the trans.

Let me know your thoughts. The biggest purchase I have made next to the engine work here in one fell swoop...

[SD421]

I would go with the one that has the 2.56 to 1 first gear ratio.
Plenty of torque for that setup. The 2.99 will be too low forcing you to shift into second really quick.
-Don

[nytrainer]

The M23W 2.56 first (it's comparable to an M-20's 2.52 first) with a 3.08 R&P rear is the tallest R&P gear I would want to run (for longevity sake of the clutch and fun factor) and would still work well with a stock cammed, torquey 400 IMO. The 2.99 first gear (with your 3.08 R&P) would be like an M-20 (2.52 first) with a R&P of between a 3.55 and 3.73 (actually works out to 3.65).
Obviously at cruise speeds the rpms would be the same for both. I think your cam 's power range might dictate the need for the M23Z's 2.99 first gear.

[geeteeohguy]

Tough call. I have a 2.56 first gear in the Muncie M-20 in my '65, and a 3.36 rear gear, and first gear feels and is pretty tall. About right, but pretty tall. With a 3.08 I dunno....it would be even taller. My mill is a 389 that's plenty healthy, but cammed for mid range and higher. I think the best ratio would be something like a 2.75 first gear for your combo. How tall are your rear tires? If stock height or less, the M23W would probably be ok. If taller, the 2.99 first gear may be a better choice.

[Scarebird]

How many of you guys are actually running this trans?

I am running a M22Z (2.98 1st) behind a roller 440 - no issues. Rear is a 2.93 8.5"

2.93 x 2.98 = 8.73 final in 1st.

Equivalent to a 3.42 rear with M20 trans, just a wider spread across the board.

[nytrainer]

Originally Posted by Scarebird

How many of you guys are actually running this trans?

I am running a M22Z (2.98 1st) behind a roller 440 - no issues. Rear is a 2.93 8.5"

2.93 x 2.98 = 8.73 final in 1st.

Equivalent to a 3.42 rear with M20 trans, just a wider spread across the board.

Thanks for clarifying that.
OP, Please ignore my previous post since I am not "actually" running that trans. I couldn't possibly give you any real insight on gear ratios, etc.. because of that. . Guess I should have waited for an expert to help you. My bad..

[Scarebird]

insight<experience.

If you want expertise, talk to AutoGear, they do answer the phone and will advise the best trans for a given setup. The M22Z and it's follow-on the M23 were indeed designed to run with 3.08 cogs, and if I was to do it again would use 3.08's vs the 2.93's...

[Young Pontiac Guy]

No guys, its all good. I appreciate all the feedback.

When there is over $2000 on the line in one purchase, I want more than one opinion.

I did talk to Auto gear. Nate is amazingly helpful there. Great customer "pre-order" communication. Great details. Told me that the M23Z if you are going to do it and want to be able to do hard launches and said the gear ratio portion is up to me- they allow you to change up the ratios between all the gears as you like.

I am leaning towards the M23Z, as is. This puts the 1 and 2nd gear closer than say the M22Z- the disconnect between 1 and 2nd is less between the 2.

Thank you Scarebird. I will take your advice, M23Z. Can you describe your abuse and motor thus far to the trans? Any issues?