4speed conversion questions

by bitterfitter Sat Dec 16, 2017 12:16 pm

So after thinking about removing my Auto trans for a 4 speed I have a few questions. I was hoping a few of you guys would chime in here.
I want to go with a Muncie trans; but which one? M20,M21,or M22? I was thinking M22.
Can I use my cross member and if so does it have to mace from where it holds my 2004-R?
What gets done with the neutral switch and back up lights switches?
What small issues am I not going to think about until it’s too late?

by Joe73 Sat Dec 16, 2017 12:18 pm

No crossmember issues at all. I would recommend going with a 5-speed. It'll give you a lower 1st gear for launching and an overdrive for highway speed. The Best of Both Worlds.

by bitterfitter Sat Dec 16, 2017 12:37 pm

What 5 speeds would slide in there easily? Also big price difference?

I have to admit it has been since high school that I played with a manual. I remember changing a clutch in my parents garage in a 1973 442 on a school night.

by Joe73 Sat Dec 16, 2017 5:23 pm

Cost could be an issue but I'd be looking at a GM T5 from a 3rd gen camaro or a Richmond 5 speed. They are a good all around trans if your not making monster horsepower. The Richmond will handle way more power than the T5. If you have big horsepower than I'd be looking at a TKO trans but the cost is through the roof and you will probably need tunnel mods due to its beefy size. But it can handle the horsepower.

If you google muncie 5 speed you will find some info about companies that sell variations of it. Some of them have an actual 5th gear and others use the existing 4th gear in like a .7 or .87 ratio to give overdrive to the normal muncie.

I have to say, I'd love a 5 speed in my chevelle. Even when I bought it, the stock M20 and 3.42 gear is a nice combo but not great at all on the highway. Now my M20 with the 4.10s out back is useless on the highway. But I can leave a traffic light in 4th gear with no bog.

by JF74chevelle Sat Dec 16, 2017 6:54 pm

I did a four speed swap just recently. I got a M20 Muncie 10 spline input shaft and 27 spline output shaft. Drive shaft was left alone and crossemmebrr was the same. Speedometer needs to be on the drivers side of the trans to hook up the cable. Long tube headers will be needed because if not the z-bar will hit the headers.

by JF74chevelle Sat Dec 16, 2017 7:01 pm

Also, I never even bothered with a neutral safety or reverse light switches lol. Make sure to get the z-bar and all those pieces from OPGI because they’re actually the right size. For the z-bar frame mount there will be two holes for bolts. The bolts will need to be self tapping. Joe was the one who guided me through my whole swap.

I had to cut a giant hole in the floor. Get a shifter boot and etc.

Also, I went with a M20 2.52 first gear... and a 2.73 rear gear so I have to ride the clutch a little to get it rolling. But I’m swapping to a 3.73 rear gear with a trutrac. A five speed would be nice but honestly, shifting a nicely built Muncie is therapy.

by Joe73 Sat Dec 16, 2017 7:03 pm

Different year muncies have different positions of the speedo hookup and they also vary by manufacturer. Muncies for our cars, 71-74, will all have a passenger side speedo hookup. Earlier muncies could be either side. BOP and chevy switched sides from time to time. The tail shafts are interchangeable and not expensive. If you have a turbo 350 trans now and get a drivers side muncie, the cable will hook right up. All 71 and later muncies will be a 26 spline input with 32 spline output (uses turbo 400 yoke). The 71-74 are the strongest muncies that GM produced. They all had a 1" countershaft (which actually started in 68 if I remember correctly). The 71-74 versions are also either a 1/2" or 3/4" longer than previous years. Previous years used a 3/4" countershaft which is not a strong.

by bitterfitter Sat Dec 16, 2017 10:33 pm

WOW. Great info. I am going to get shopping. Will all these trans handle 430hp and 430tq without a problem?

by Joe73 Sun Dec 17, 2017 8:14 am

With those numbers I'd only be looking at a 71-74 muncie. They were put behind the big power big block motors. Why take chances? Other choice would be an Auto Gear trans. Google them, they make great trannys to handle all kinds of power. You occasionally see one for sale brand new on craigslist or facebook. Another option is to check out Craig Wright and Alexandra on facebook. https://www.facebook.com/groups/907860045969439/?ref=bookmarks

https://www.facebook.com/alexandra.kelleher.7

I've dealt with Craig and he's great. I've dealt with and been to Alexandras shop and her knowledge and inventory is unbelievable. She also custom builds trannys to your needs. She has a wall of Muncies for every applications.

I purchased my Muncie rebuild kit from Jodys Transmissions, http://www.jodystransmissions.com/ Another great guy, builds custom boxes and is in Pennsylvania. I've spoken with him on the phone and his knowledge is great. I would not hesitate buying from him.

by bitterfitter Sun Dec 17, 2017 8:35 am

So I am wondering if the shifter on a manual transmission is located in a different location on all the different transmissions? I guess I could always just remove the console and go with a boot if it is not going to come up in the same place as a factory transmission.

by Joe73 Sun Dec 17, 2017 9:38 am

Only the muncie, borg warner T10 and super T10 (all 4 speeds) will line up in the stock location on the floor. Most 5 speeds have the shifter on top of the tail shaft with internal linkage. Richmond 5 speed has an external shifter with linkage on the side like a muncie and bw.

Just a side note, shifters for a muncie and BW are the same but their linkages are different. They look close but dont interchange. Not a big deal, just different rods and their readily available.

by bitterfitter Sun Dec 17, 2017 9:45 am

So after a little looking around the web, I see there are a ton of gear ratios in these trans. It seems pretty important to get the right ratios when buying. As I am running 3:73 rear gears, should I be concerned about too low of a 1st gear?

by Joe73 Sun Dec 17, 2017 9:54 am

GM always used an M21, which has a 2.20 first gear with all rear axles 3.73 gear and numerically higher. They used the M20 muncie with gears numerically lower than 3.73. The most common first gear ratio for the M20 is 2.52. There are other variations but 2.52 is the most common.

For a "fun" car to drive you need to be around the number "9". That is your first gear ratio TIMES your rear gear ratio. Your rear gear is 3.73.

M20 2.52 x 3.73 = 9.39
M21 2.20 x 3.73 = 8.02

There are aftermarket gear sets for a muncie that can change your ratios. Saginaws came in 3 different first gear ratios.

I'm running a M20 with 4.10s. 2.52 x 4.10 = 10.33. Launches like hell but very tough to control wheel spin.

by Joe73 Sun Dec 17, 2017 9:56 am

And I dont advise any sticky tires or drag radials with a manual trans. You will break things constantly. Unless you master letting off a bit before launching to preload the driveline. The "HIT" of a dumped clutch causes havoc on the driveline. As opposed to a trans brake on an automatic which puts the car in forward and reverse at the same time. Way less hit.

by bitterfitter Mon Dec 18, 2017 12:00 pm

I have seen a few super T-10 transmissions for sale that are reasonable. What do you guys think of these for a 4 speed option? Also it looks like the speed hook up is on the passenger side. How do I get around this? change the tail shaft ?

by REVINKEVIN / Mr. 600+HP Mon Dec 18, 2017 12:42 pm

I had a TREMEC TKO500 in my 1970 Camaro. First gear in it was to much for .373 gears. It would easily handle your power levels. The best choice for a 5-speed, in my humble opinion, is the TKO600 RR. This would give you a very strong trans that would handle 600lb/ft of torque and have a first gear that is perfect for .373’s. You can put any tire you want on there and have fun.

by Joe73 Mon Dec 18, 2017 12:52 pm

Just get a longer speedo cable.

by fasrnur Mon Dec 18, 2017 4:42 pm

First off, I would love to have an old school Muncie in my car, but as I've gotten older I've come to realize that having a non-stock engine under the hood and a high pressure pressure plate behind it can make for a not so fun drive in traffic. I like being able to jump in, put it in gear, and stand on it knowing that I just have to stab and steer. Very Happy

I remember back in the mid 70's when if you didn't have a stick in your car, you weren't cool. Then as advancements came along people figured out that an Auto could out shift and even be faster than a stick.

Like I said, I'd love to have a stick in my car, but I drive the living crap out of mine and I DO get stuck in rush hour traffic from time to time and having a stick in those situations is not fun.
So I'll stick with my good old auto trans and unusual shifter. Very Happy

by brownbomber77 Mon Dec 18, 2017 5:48 pm

Other things to consider for the Tremec is the hole you have to cut in the tunnel.... It's not crazy, but the wide A$$ body of the top side of the TKO won't fit any muscle car chassis without cutting.

by 73ss Mon Dec 18, 2017 6:28 pm

I was gung-ho on a 4-spd swap 10 yrs ago. Then I realized I wouldn't be gaining anything with the 1:1 final, other than the cool factor. A 5-spd was too far out of reach cost wise. I ended up going with a 200 4-r. Great trans and glad I did the swap. I'll never go back to a 3-spd.

by Joe73 Mon Dec 18, 2017 9:09 pm

A 700r4 with a 3.73 rear is hard to beat. Great first gear for a great launch and overdrive for the highway. I highly recommend the overdrive auto with 3.73.

by bitterfitter Mon Dec 18, 2017 9:17 pm

So have you guys all turned on me?! Sounds like you guys are saying to stay with the automatic.

by Joe73 Mon Dec 18, 2017 10:05 pm

I'm a 4 speed guy. Always loved them and I bought my ss as my first car and it had to be a manual. I love it. But if I were building a car now and had to be a manual, it would be a 5 or 6 speed. But the best for all around, to me, is an auto overdrive with 3.73 gear and a stall speed converter.

An auto overdrive has a numerically lower first gear so when you do the math like I did above you get a launch better than any muncie. And to have overdrive to handle the highway, to me, its the best all around.

As for a clutch, I'd recommend a Centerforce dual friction diaphram. But I'd snip the wire and slide the weights off the pressure plate. A lot of guys say they get some rust on them over time and then dont slip properly which causes a vibration. So snip the wire and remove the weights.

by fasrnur Mon Dec 18, 2017 10:51 pm

I wasn't trying to switch your mind at all. I was just saying why I personally won't have a stick in my car.

Has the pedal conversion been brought up yet?

by bitterfitter Mon Dec 18, 2017 10:58 pm

You guys make great points for both sides. I think I will take some time over the holidays to weigh both options and decide if I want to make this conversation.

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