The Stovebolt Site Forums The Shop Area General Truck Talk shift box

I think my 3 speed gear box is worn on my truck(1953) what are the signs? Th shift box I am refering to is on the steering mask where the two rods connect, any thoughts?

Do a search on here and you'll learn a lot, but I'm in the same boat. I just ordered a rebuilt one cause I'm sick of it getting stuck in a gear. Lots of the old school guys put shims on either end of the box to tighten things up and make it shift better. Mine already has those, but if the fluid in the trans is low it'll shift like crap too (mine does). Try thickening the fluid, it'll hide some problems too. If you haven't already, take the cover off the box and take a peek at what happens in there. It's not as mysterious as it seems, and it's easy to work on. I forgot the vendor I ordered it from(had it a few months), so let me know if you need to know who's the cheapest. Have fun!! Dan

I put a rebuilt one in my 52 from Jim Carter. Much better but not perfect. I got a good tip from Bob Adler. He said to make a distinct "H" pattern with your shift rather than just shoving the lever up from 1st to 2nd. As long as I do that I have no problem.

My truck shifts fine, it never gets stuck beween gears however I keep having the third gear jump out into neutral.I ordered another box from a guy and will send it t jim carter for rebuilding

jumping out of gear [common on the old 3 speeds] is bad synchros or worn gears, not the shift box, who's only malfunction is jamming between gears - save yer money on that rebuild, for the trans

Bill

Im with Red on the tranny,bad synchro in 3th gear.you'll have to pull the tranny for repair.I also have a 3 speed tranny.I have parts left over from my street rod project.All the stock running gear

it actually isnt the synchronozer its the sliding collar that the synchros are on.

This collar you are refering to is it a round cly with a lip on it? I bought one from northwest transmission parts.I had it installed and it still jumped out third gear. If I rest my hand on the shift level it dosen't jump. Somehow I think it's something small, I put some grease in the shif box and it did not jump out like it had been doing,that's why I think it's the box. I am waiting on Patricks 4 speed if things contiue this way I may convert to 4 speed.

Ours finally stopped one day.
We had two minor shift lock-ups but were able to un stick the jam. but one day after a 60 mile trip she locked up @ a stop sign. I'm happy to say that was the straw... we'll just have to change horses. we're taking the T5 route & OD.
gooday
jim

It's the synchros.

My dad owned an auto salvage for 30 years beginning in 1960, the prime years for stovebolt parts selling! One of his good selling parts was the 3 speed transmissions for Chevys. We just couldn't keep enough good used ones so he began to repair and rebuild the exchange units. He did literally hundreds! In addition to the synchro, the main drive gear was the biggest culprit in the jumping out of high gear problem. The splines that engage the synchro become worn and 'push' on the syncro ring causing it to jump out of gear.

One trick all the trans shops used back then, was to grind a very slight curve into the side of each spline facing the direction of rotation. This was done freehand with a stone in a die grinder or drill. The stone was about 2" in diameter to cut a long curve. The object was to reverse the push created by the worn spline, and pull the synchro ring into, not out, of gear.

If you open it up to replace parts, examing the Main Drive Gear closely, it it shows any wear at all in this area either change it or try the trick above.

I have an extra trans I just bought from a yard, thing is I don't know what a main drive gear looks loike or a syncro. Are there any folks out there that still know how to rebuild these trans. I would hate toconvert to 4 speed as this is my grand fathers truck and I only remember the 3 speed in there, my kidsonly know the 3 speed I have to fix it before they get it or I will wind up with a 350/350 comminaton.

I rebuilt a couple of these transmissions years ago when I was a kid. They're fairly simple (once you get past the weird enclosed U-joint setup). As I recall the main drive gear would wear and cause problems with the synchro rings because either and/or the front bearing in the transmission had too much clearance or, in some cases, the pilot bearing in the crank was worn and allowed the splined shaft the clutch plate was on to jump around. Kind of a progressive failure, so to speak.