i have an original 235 with an original three on the tree but the gears are starting to loose their angles and in third it tries to pop out of gear i would like to buy a new one on the floor does anyone know one that i could buy that fits best with the original 235 and where i could get one?
SM420's The granny gear 4 speed transmissions are common since these were standard trannies in all 3/4 and many 1 ton GM trucks from roughly 1947 through 1967. The trick is to find the closed drive which will exchange right into your torque tube. You can find these trannies for $150 bucks in good working shape if your look around. The 3/4 T sm420 has the correct closed housing through 54, but it has a different U joint that will not work with the 1/2T torque tube. You will have to find a complete U joint for the 4 speed (will cost more than the tranny). I don't know if the clutch for the 3 speed and 4 speed trannies is the same in the 3100 AD's, but someone here can tell you. You will also have speedo issues with the trannies from trucks with lower rear gears. Jim
My Dad's 52 3100 had the four speed tranny they are out there. It was one of the vehicles I learned to drive with.
SM420 S 4 speed Tranny Hey Wether you diside to go fore the SM 420 or other gearbox models i know that Novac industries can give you the needed help and advice incase? Here is there adres ; Good luck Martinius. http://www.novak-adapt.com/knowledge/sm420.htm
Replacement Tranny You neglected to mention what vehicle you're working with... I'll assume it's a 1955 Task Force with open driveline , if so , any floor shift tranny from any Chevy/GMC pickup with a 6 cylinder engine made between 1955 and 1962 will plop right in and work fine . You'll need to modify the floor a bit for the shifter and tower . Be aware a four speed trannyWILL NOT make it go any faster ! . FWIW , your current tranny is a good one and it's dead simple to overhaul , bearings & synchro hubs plus a few shims for the cluster gear should set it right again for $500 in parts , the labor , if you're not able , take it to the local adult training center and ask ~ the Teachers there usually swoon over jobs like this as they're dead simple and extremely good teaching tools . Or , just go to the Task Force pages of this fine forum and read all the posts from Hot Roders and send them queries about buying the old takeout tranny as it's junk to them and will still be sitting in the garage years later so don't pay more than $75 unless it's rebuilt with reciept and warranty . I hope this helps .
What Nate said.......except you can use Trannys from late model cars and trucks all the way up in to the late 80's as well, like the fully syncro 3 speeds and 4 speeds (Muncie, saginaw and Borg Warner super T 10) These Trannys work the best. They are a lot smoother to operate.....Big Tim
Don't know much about it except it is an open drive 3 speed that was bolted to a clapped out 235. I can crack the side and check it out, but I'm in Barnwell, sc for the week. If I can sneak away this weekend I will see whats up.
Try new bushings on all the linkage ends & maybe adjust the linkage so that it goes in third futher. I have had the same thing happen 40 years ago. Dont change until you can swing a T5 from a S-10 pickup.
