Thread: Transmissions

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I just bought a 55 Chevy with a small block and 3 speed trans and I want to replace it with a 4 speed muncie box.

Here is the question: Will the 3 speed bell take the 4 speed muncie trans or do I need some sort of adapter or a new bell?

Thanks in advance for any help.

Frank

Welcome to CHR!!

The 3 speed manual and 4 speed muncie are identical in bolt pattern and input shaft dimensions. It's a simple R&R, other than checking the drive shaft length and transmission yoke. Some of the muncies had different output splines, as I recall?

55 to 57 Chevies all used a front saddle mount, no mounts on the frame, and the bellhousing mounted to an extension on the frame which left the transmission hanging in the breeze. I fyours is mounted in that manner I would suggest adding a rear transmission mount. You will also need a floor shifter for the 4 speed. You also might want to check the condition of the clutch disc and pressure plate while you have the tranny out.

If its a 55 v-8 car its more valuable as an original 3 speed than with a 4 speed-if it was a 57 different story

Did you use the yerm Muncie Trans/ Box because that's what you have to swap?? the earlier trans were Borg Warner and input shafts have been 10 and 26 spline so you might have to change clutch disc also--and if you don't already have a trans your going to use, then look for one with a tail shaft mount and shifter location that's patable with your seat-------do not let the trans hang from the bell housing--------

Originally Posted by jerry clayton

Did you use the yerm Muncie Trans/ Box because that's what you have to swap?? the earlier trans were Borg Warner and input shafts have been 10 and 26 spline so you might have to change clutch disc also--and if you don't already have a trans your going to use, then look for one with a tail shaft mount and shifter location that's patable with your seat-------do not let the trans hang from the bell housing--------

...or if you don't already have the 4-speed think about a Tremec TKO500 or 600 - TKO 5-Speed Transmission Three shifter positions to choose from, and overdrive is super nice!!

Thanks guys I appreciate the info.

Also, check the front bearing retainer diameter, there were a variety of sizes. That retainer is the indexing item and the hole in the bell housing needs to be the correct size to support/align the trans properly.

What do the different M numbers stand for a 4 speed Muncie?

From Muncie 4 Speed Information.....

"All wide ratio transmissions are designated M20 and close ratio transmissions are designated M21 or M22 depending on the gear set. From 1963 to 1965 the close ratio M21 was ordered under the M20 RPO code and the factory decided whether to install a wide ratio M20 or close ratio M21 depending on the rear axle ratio specified. From 1966 on, the customer could decide the transmission selection.

The M20 and M21 have the same cut to the gears, the M22 is a straighter cut resulting in a greater strength. Since the M20 and M21 look the same one way to tell them apart (aside from the grooves on the input shaft) is the tooth count on the cluster gear."

Straighter cut gears will whine more than conventional gears. That's why the M22 sounds so menacing....I love it....

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Thanks for all the info guys.

Ok guys I bought a 4 speed Muncie and the trany looks great, it looks as though it was just rebuilt. It's a 10 spline with a 26 output. The gears look fairly new. Here's the issue: the spedo hole was plugged off. So I bought a speedo setup with a plastic gear. Opened the tail and the speedo gear just slides on the shift. There is a clip but there is no hole in the shaft for the clip which I think there should be from what I remember from the ones I worked on years ago. My Munice rebuild book says I should use a metal gear and sweat it on. Here's the question: what gear do I buy like size? Going to a car show tomorrow and will see if anyone is selling a gear I'll bring the plastic one with me to see if the metal ones have smaller inside diameters. Any ideas guys? Any help on this?
Thanks
Frank

Originally Posted by fcompoccio

Ok guys I bought a 4 speed Muncie and the trany looks great, it looks as though it was just rebuilt. It's a 10 spline with a 26 output. The gears look fairly new. Here's the issue: the spedo hole was plugged off. So I bought a speedo setup with a plastic gear. Opened the tail and the speedo gear just slides on the shift. There is a clip but there is no hole in the shaft for the clip which I think there should be from what I remember from the ones I worked on years ago. My Munice rebuild book says I should use a metal gear and sweat it on. Here's the question: what gear do I buy like size? Going to a car show tomorrow and will see if anyone is selling a gear I'll bring the plastic one with me to see if the metal ones have smaller inside diameters. Any ideas guys? Any help on this?
Thanks
Frank

Speedometer Driven Gear Calculator
http://www.cartechbooks.com/techtips...e-speedometer/

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Thanks but I'm looking for the inside diameter of the gear. The plastic one I bought is loose on the shaft. Are there different inside diameter gears?