The Stovebolt Site Forums The Shop Area Driveline Need some help re my SM420 transmission

Hi Everyone,
I have an all original 1949 Chevy 5 window pick-up truck. The problem that I'm having is the transmission gets stuck in between gears every now and then. The only way to fix the problem is to take the top of the transmission cover off and slide the shifting forks back into the neutral position. There is a lot of play in the shifter, so I pulled the shifter out and it had a ball shape on the bottom. So to take out the play in the shifter I welded it up to make it look like a T at the bottom. I put it all back together, the play was all gone and it shifted great for a while, but now the problem is back. ( The weld I made is still T shaped) My question is, what is the shifter supposed to look like? Should it have a "T" on the bottom with straight edges? Or should it have round edges ? Or could something else be causing the problem ? Such as the shifting fork detent spring, balls, etc. ? Everything else in the transmission looks good.
Thanks for all your help in this matter,
Terry

When you say it was welded T shape. How about a picture of what your talking about. Easy to post pictures here.
Go to the full editor and down to the Attachment Manager and drag your photo where it says to put it.

Used shifters are available on Ebay, and brand new ones from Novak. No point in wasting time and money welding on one as it destroys the tempering of the metal and it will wear very rapidly. That worn metal has to go somewhere, so it falls into the transmission and makes a good grinding compound along with the grease, which wears out the gears.

www.ebay.com/itm/196374978184?

Enlarge the pictures to see what the shape of the bottom of the shifter is supposed to look like.
Jerry

I wonder if both sides of the lower end of the shifter is the same. Gotta find my spare shifter rod.

Couldn't find my spare shifter rod so when my truck wasn't looking, I quickly pulled the shifter out of the truck. Here are some pics of the shifter rod bottom end

The arrow (in the first two pics) is marked on the sides pointing towards the front. The black dot is on a frontal view (3rd pic).


( Left side, Right side, Front, Rear)

Here are the pictures with what I refer to as a “T” on the bottom. Thanks for any help you can provide.

I sent pictures of my shifter. Was wondering if you could measure the length from the bottom of the ball to the bottom of the shifter? Also how thick the and or wide the end or as I called it a “T”. The rounded part at the bottom. Kinda hard to describe. Sorry. Thanks so much for your help. It’s shifted fine for 10 years although it’s driven mostly on weekends to avoid the crazy traffic where.

I’m getting 3-7/16” + . See pics. Also took a pic of the bottom end of the shifter shaft, showing no wear. Also thickness (flat side to flat side) of the bottom end is about 5/16”.

Hello Mums49,
May not be helpful but I had a problem with our SM420 hanging up between 3rd and 4th gear. I was lucky enough to have a retired transmission mechanic living near us. He had a great amount of years of experience with these transmissions. He went through my transmission and rebuilt it completely. When I went to pick up our transmission he had all the replaced parts on his workbench. He had me look them over to see if I could find the problem. Everything looked fine to me. He picked up the narrow 3rd to 4th brass synchronizer gear and said,"see that even groove around the middle of the gear - it's not suppose to be there". It was occasionally catching on that groove and hanging up. That was 8 years ago, with no problems since. Just thought may be of help or to others.
Chuck52