Just checking...we're talking about a stock 1955 2nd series (TF) 3100 pickup...right? If so the trans just hangs on the back of the bellhousing, there is no crossmember.
If your truck has been modified we would need more info on how the current engine and trans are mounted.
Seems like a lot of work for no gain...both transmissions have a 1:1 high gear, so top speed will be exactly the same. A T-5 trans would give you OD and take about the same amount of work.
Mike B
Mike Boteler
1956 Chevy 3100 Resto Rod 1952 Willys M38 Army Jeep 1983 Jeep CJ7 Laredo 1984 Jeep CJ7 +++++ Silver Spring, MD
As I don't have a TF truck, I can't directly answer your question from personal experience.
I do have access to a TF (55.2-59) FAM (Factory Assembly Manual) in PDF format though. I took a screenshot of the diagram for a 3100 frame (attached below) and it doesn't show an actual "transmission" cross member. Just the "engine" rear cross member that supports the bell housing/transmission.
From my knowledge gained from fellow Stovebolter's, your existing 3 speed (SM318) wouldn't have a pad for bolting up to a rear cross member, unless you have a non-original 3 speed. The transmission is actually fully supported by the bell housing and rear engine cross member. Fellow Bolters, please chime and correct me if I'm wrong!
As to if the M21 will need a supporting cross member because it has an aluminum case and may be subject to more stress if unsupported at the tail housing, that is another question entirely.
Am sure that fellow Bolters that have already done something similar will chime in with their knowledge and experience soon.
Let us know how your swap progresses, with pics if you can please and thanks!
Dan
EDIT: Mike B beat me to the punch! Thanks Mike
Last edited by Gdads51; 08/27/20232:20 PM.
~ Dan 1951 Chevy 3 window 3100 Follow this story in the DITY Gallery "My Grandpa Carl's Truck and How it Became Mine" 1966 Chevelle (Wife's Hot Rod) | 2013 Chevy Silverado (Current daily driver) US Army MSG Retired (1977-1998) | Com Fac Maint Lead Tech Retired (1998-2021)
The current three on the tree I believe is original to the truck has a granny gear first gear, so basically it’s a 2 speed. I think the 4 speed is much more enjoyable to drive. 5 speed would be better, but I got a great deal on the 4 speed!
We ran a Muncie behind a Chevy 327 engine in a "Northern California Sportsman" dirt track race car without a rear support for a lot of years, running 2nd. gear against a 4.56 rear end and going from 3000-7000 RPM at full throttle twice a lap on a rough, rutted 1/4 mile track. It didn't break. I don't think a stovebolt engine can possibly stress one worse than that. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
The SM318 3 speed has never been known as a "granny gear" transmission. It does have a fairly low first gear which is not synchronized. However, the later 3 speed full synchro Saganaw transmission and some of the car 4 speeds have similar first gear ratios. Many of the engines of that era were 6 cylinders which required lower gears to make power at low speeds. The factory 3 speed with a BW overdrive (SM319) is a bolt in for those trucks. Fred
1956 3100 Pickup/Red/350/3sp OD/PS/Disc Brakes 1957 Bel Air Sport Coupe/Red/355/TH350/PS/Disc Brakes 2017 Silverado LT Single Cab SB/Black/5.3/6 Speed Trans 1947 Willys CJ2A w/F-Head engine
Tomorrow is the tear down. Going over the Muncie I picked, the bell housing bolt look to be brand new grade 8 bolts and the pressure plate/flywheel bolts are brand new ARP bolts! Nice surprise! I was going to go with those exact upgrades!
Never purchased a clutch assembly, anything I should be looking for or two avoid?
Got the flywheel back from the machine shop, just waiting for the clutch I ordered from the local Speed Shop. Could have saved a couple bucks online, but I wanted to support a local business!
Just thinking out load here. what shifter are you planning to use. The Muncie had several different tailshafts depending on the application, most position the shifter too far back to use with a bench seat. I ran into this issue while mocking up the Muncie for my '59, the shifter would have been at the floor brace for the seat. I found a company that deals with Muncie and talked with one of their Tech Reps. It turns out that the tailshaft I had would work with one of their relocation kits. The kit was cheap, installing it moved the shifter forward about 4 inches to front of the tailshaft. Take a minute and check out their site, GM Classic.com.
~ Craig 1958 Viking 4400 "The Book of Thor" Read the story in the DITY 1960 Chevrolet C10 "A Family Heirloom" Follow the story in the DITY Gallery '59 Apache 31, 327 V8 (0.030 over), Muncie M20 4 Speed, GM 10 Bolt Rear... long term project (30 years and counting)
If you don't like driving yourTruck, you won't drive yourTruck..| Living life in the SLOW lane
That is cool. I went with the Hurst Competition Plus 4 speed shifter. It has the handle to run under the floor pan and forward. Of course the handle is too low to the floor and I added a handle. Installed some 2 inch shims to move the handle to the right so REVERSE did not hit my knee. 1st two are of before I moved it over. Now the handle is centered in the middle. Best I could come up with. "R" really interfered with my right knee.
Last edited by Guitplayer; 09/08/20231:00 PM.
~ BD. "You won't find me in an old folks home" Pioneer Florida Cracker 1958 Apache Stepside 1958 Apache 1/2 ton Panel 1959 Apache 1/2 ton Panel
I have a adapter that I fabbed up that moves the shift lever up about 3 inches and to the center another inch or so. I'll see if I can get some pictures of it. The shifter clears the bench seat perfectly now though.
~ Craig 1958 Viking 4400 "The Book of Thor" Read the story in the DITY 1960 Chevrolet C10 "A Family Heirloom" Follow the story in the DITY Gallery '59 Apache 31, 327 V8 (0.030 over), Muncie M20 4 Speed, GM 10 Bolt Rear... long term project (30 years and counting)
If you don't like driving yourTruck, you won't drive yourTruck..| Living life in the SLOW lane
Nice. This one clears the seat as well nicely. The problem with the 4 speed is REVERSE is up and to the left. With the 58-59 gas pedal location its an issue for me. The handle needs to sit in the middle of the truck. Hurst makes a handle that moves it over to the right about 2 inches. But its too low. https://www.holley.com/products/dri...accessories/shifter_sticks/parts/5384084
~ BD. "You won't find me in an old folks home" Pioneer Florida Cracker 1958 Apache Stepside 1958 Apache 1/2 ton Panel 1959 Apache 1/2 ton Panel
