Hi!

Im considering buying a used muncie 4-speed from a '69 camaro, to build in my '84 camaro with a 413hp-458tq 383.

is it true those tansmissions can hold 500hp at least?

where to look for if im going to see that trans, what are the weak spots i should check before forking over the money.

how can i easily see if its a muncie 4 speed, and not a saginaw or a muncie 3 speed?

thank you

RR

First let me say many of these muncies have been thrashed over the years, keep in mind there almost 40 years old now. That doesn't mean they can't be rebuilt into a strong gear box. I have never seen published torque figures on how much power they can handle. I can tell you if the whole drivetrain is not up to the task and I mean heavy duty clutch, u-joints and shaft and rear something will fail. A 4 speed combination can be pretty shocking on the muncie. A 500 hp engine is most likely going to make in excess of 450 ftlbs at the flywheel, if your car dead hooks with slicks on it and the clutch dont slip much, I would think eventually something will give. If its a street driven car with radials you probably will be ok, if the tires are spinnig the load is coming off the trans. I run one behind a 540 in my ragtp although it has a supercase/super tail/ iron mid plate and masero gears, Im in the mid 11s with it and it doesn't dead hook yet, still getting one or two rotations of the tires on launch with hoosier QTPs. If I go to a full slick, I will be praying the gear box holds together, they do shift nice and can handle some good power. I guess it all depends on how you plan on using the car.

They condition of these old gear boxes varies greatly, the obvious from the outside. They have a 7 bolt side cover, 3/4 shifter shaft in the front 1/2 shifter shaft in the back and only those two shifter shafts in the side cover. Reverse shifter shaft is in the tail housing behind the mid plate. look closely for cracked mounting ears, and where the cluster shaft comes through the bottom of the main case make sure its not leaking gear oil. The cluster shaft is an interference fit into the case and some times gets opened up from many rebuilds and force from the cluster gear trying to get pushed out the bottom of the case. They can be bushed although it does add to the cost of the rebuild. Move the shifter shaft to 2nd gear and remove the side cover, inspect gears for cracks/chips/ pitting/ blue color(lack of oil). Also engagement teeth on gears can get pretty worn down over the years from banging gears, brass syncro ring inspect. If it looks like the exxon valdeze it will need a rebuild new gaskets/ shifter shaft seals etc.

I personally would not buy a used box at a swap meet or through the want adds unless I new it was built by someone reputable.

Hope this helps some - rich

Do search on "Muncie" and you'll find a ton of information.

I'll second Rich on his post. There's no set number for how much horsepower a muncie can take. It will depend a lot on how much your car hooks up. You'll be fine on street tires with your combo. You'll want to find out which muncie you're getting "m-20, m-21, or m-22". The gear ratio is different between the m-20's and the m-21/22. Your rear axle ratio will determine which one you want. Make sure you check the tranny over real good to see if there are any cracks in the case or if any repairs have been made to it before buying it. I imagine there aren't too many muncies to choose from in the Netherlands, so it might be a good deal if it's priced right.

Here's a good web page for Muncie info. Hope this helps.
http://www3.sympatico.ca/atkinsom/

Mike

Man, I've been banging gears with Muncies for 35 years now. They can take a good bit of abuse, but they need to be setup correctly. As was stated a used Muncie could have 30 or 40 years of thrashing on it. At that point, you better have a connection to a superior Muncie rebuilder because every last part in the tranny will be worn. My current Muncie took four rebuilds to get perfect (last two times were minor problems). Two different race shops worked on it, both reputable shops with lots of experience.

If I was in your shoes I'd seriously consider brand new. Try these guys: http://tbtrans.com/muncie_4_speed.htm Brand new M-21's for about $1,500 and M-22's for $1,700.

I have a much milder combo than you 350ho putting out about 350 horse now, it was dynoed at 291 rwhp. I had the first tramsmission rebuilt by a reputable shop, and it blew up about 1500 mile later. I then had one built with a cast iron mid plate by a guy who did an awesome job. However they are all 40 yrs old and I blew that one up too. But it was the smoothest shifting trans I've ever had. My next one will be brand new.

As was said earlier, the lifespan of a Muncie greatly depends on the ability of the car to hook up. Serious drag racing with slicks and full-power shifts through all four gears will lead to a very short Muncie life, maybe not even one run. Whereas in a street car like mine, making 440 dyno'd rear-wheel horsepower, my tranny will probably last as I only run regular BF Goodrich radials, which lose traction pretty easy.

Also, I never full powershift 2-3 or 3-4. I'll easily do the 1-2 shift under full power, but the others are hard to hit without a little grinding. I've blown a few Muncies, but never on the 1-2 shift.

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Powershifting? Are you saying not using the clutch?

Powershifting? Are you saying not using the clutch?

In my vernacular, "powershifting" means keeping the gas pedal to the floor while shifting. Some race trannies will allow you to shift with no clutch, but in my street cars, I always use the clutch.

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In this neck of the woods we called powershifting by not using the clutch and speedshifting using the clutch while keeping the gas pedal to the floor in both cases. I personally never seen or heard of anyone not using the clutch. I wonder if it is at all possible with a Muncie. Although I wouldn't want to try it on my trans.

...........I personally never seen or heard of anyone not using the clutch. I wonder if it is at all possible with a Muncie. Although I wouldn't want to try it on my trans.

As I'm sure you know, some race trannies (such as Lenco) allow shifting with no clutch. Muncies could be fitted with "crash box" syncro rings, but I believe you still had to use the clutch. I don't think a Muncie would last long if you didn't use the clutch for a powershift, like probably not even one shift, LOL.