Hey guys,

I'm planning on working on my 1970 442 Sports coupe a lot this summer, and the transmission is still a relative unknown. I'd like to do a 4 speed with GearVendors OD. The car was originally a manual transmission car, and being that it was born at Linden, NJ, it could possibly be one of the rare 3 speed manual cars. Regardless, the original motor and trans are long gone, so I'm rebuilding it back to the way it was when it left the assembly line. I need to know a few things:

- What 4 speed manual would have come with my car from the factory? It's got what looks to be the original 3.42 posi rear end intact with the boxed arms and HD suspension.
- What numbers should be on the trans case to make the transmission fairly correct for 1970?
- I've heard the terms "wide ratio" and "close ratio" used a bit on here. What can I expect as far as driveability and street manners from a wide ratio verses a close ratio, and will it make a difference with the GearVendors at all?

Thanks for the help!
Chris

 

Muncie 4spd with main case number ending in 660.

Henry

 

Your car likely came with an m21.
M21 is a close ratio, having a first gear of 2.20:1
M20 is a wide ratio 2.52 first. Better off the line.
I have never seen the m20 in a bbo powered 1970.
The deeper first gear is harder on it combined with the 455 h.c.
So far as your over/under, Fourth is 1 to 1 ratio in both trans.
Personally, on the street you can't beat the m21.
At the track, I think m20 is quicker if you get hook.


Get a big shaft m20 71 and up if you go that way.


I've had both in my 70. Don't like the big drop from 3-4 in the wide ratio (m20)

 

Of course, because the M20 was not available on the 442.

Not that unusual. Couldn't be paired with steep gears, so it would work fine. M20s were used with BBs other years too, including 442s, again not paired with steep gears.

 

A better, stronger and easier install would be a 5 speed O.D..and cheaper..

 

Thank you guys for the info! I'm going to put a call in to GearVendors and see what they recommend as well. If a 71+ trans would work better, I'm not that concerned with having a case with the correct numbers. I'd rather have a car that cruises well, as this car will be 100% street.


I've considered a 5 speed, but the GV will essentially turn the muncie into a 6 speed. It's pricey, but I've already got a nice chunk of money into a rechromed Hurst shifter and all replated rods and base for the 4 speed. There's just something about a big block and a 4 speed, and the GV OD will give me the fun of a 4 speed with the MPG and low-RPM cruising ability of a 6 speed, not to mention the clutchless shifting for the times when you want to bury your foot in it.

 

Another alternative might be Autogears Muncie OD gear set if you really need OD, 2.2, 1.5, 1.0, 0.85.

 

Thanks! Does anyone have any experience with this gear set? I'm guessing it turns fourth gear from a drive gear to an overdrive gear?

 

4th gear remains direct drive (1:1). Third gear is turned into OD. 3/4 lever is flipped to maintain the pattern. 2nd gear ratio is changed so the 1/2, 2/3 shifts are fairly evenly spread.
I used to see these gearsets for around $500 on ebay. I don't think they got very popular since you can accomplish the similar overall ratios by swapping a rear end and using a wide ratio Muncie.

 

Thanks Joe, could you point me in the direction of the for sale thread for that Muncie m20? I did a search but didn't find it. Even a username would be good because I can just do a search for that user's posts.

 

Another possibility, for about 1/2 the price of the GVO unit alone, you could get an upgraded Autogear wide ratio Muncie, 2.56 or 2.98 1st, and swap out the rear with a 3.08 or 2.73 rear. Good 1st gear and the 2.73 rear would give you about the same rpm as the GVO/3.42. I took this approach on my 72 with a T10 and 2.73 rear.

 

I've considered this option as well, but I'm afraid the acceleration of the car would suffer a lot from a highway gear ratio like 3.08 or 2.73. My first Cutlass, a 72 Supreme with a 350, had the 2.73 gears in it. It was an absolute pleasure to cruise with, but it was hard to get the car to move out of its own way. For a daily driver, I would absolutely follow your advice. However, I would like this car to have some bite to go along with the bark. Thank you for all of your help. I may PM you later on in the game and pick your brain about some things. It looks like you're quite a bit more knowledgeable about this subject than I am at this point.

 

Option 1) A close ratio Muncie with 2.2 1st and 3.42 rear comes to 7.5 overall, with the GVO engaged you have 2.66 in 4th.
Option 2) The standard wide ratio Muncie 2.5 1st and 3.08 rear comes to 7.7 overall, 3.08 in 4th. That combo will have better acceleration in 1st than the close ratio and 3.42.
Option 3) The extra wide ratio Autogear with 3.00 1st, combined with a 2.73 rear will be 8.2 overall, even better acceleration off the line. And 2.73 in 4th is similar to the above combo with the GVO.
With the torque band of the BBO, the wider spacing shouldn't be much of an issue.
Costs:
1) GVO $2900, Driveshaft, $200, Close ratio Muncie (used) $700+, Adjustable upper control arms (maybe) $100 (about $4k)
2) Used wide ratio Muncie (used) $400-700, 3.08 ring/pinion swap $500 (I think the 3.42 and 3.08 use the same carrier, but check on that. (little over $1k)
3) New Autogear 3.00 1st Muncie (upgraded case, etc) $2000, 2.73 rear, $250 (they give the 2.73/2.56 10bolt rears away around here.) ($2300)