The Stovebolt Site Forums The Shop Area Driveline 3-speed tranny woes

This happened several months ago and I’ve been too embarrassed to post it in the forum, so here goes……

On the way from San Antonio to New Braunfels (35 miles) my three-on-the-tree started jumping out of third gear. I would clutch it and drop it back down into third and it would be good for a few miles, and then suddenly jump out of gear again. I was worried but continued, and had a good day with my truck buddies. On the return trip the tranny wouldn’t stay in 3rd gear for more than 100 ft. Then it got so bad that it wouldn’t even go into 3rd. I limped all the way home in 2nd gear. Anyone want to take a guess what the problem is?

Thanks!

Could be a worn synchronizer, first not allowing it to be fully engaged, then blocking it completely. I think you're going to have to open the tranny up to see what's going on.

I would check the linkage first. It may be so sloppy that it doesn't go into gear all the way. The shift forks in the shift cover wear and they jump out of gear but I don't think it would get progressively worse that quick. Have you checked the oil in the transmission? If it isn't the linkage, there is a good chance you are ready for a transmission rebuild.

Since you have conveniently forgotten to mention which vehicle you were driving, it's hard to give any specific suggestions. All of the ones in your list have torque tubes, however, and one just might have a vacuum-assisted column shifter. Those things were notorious for getting stiff and not letting the transmission go into gear, or get partially engaged and wear out the drive lugs of the gears. In any case, a disassembly and inspection is probably in order, followed by a search for some scarce and very expensive parts. Good luck!
Jerry

My apologies Jerry! It’s the 3-speed in my 1950 Chevy half ton.

I’ll crawl underneath it this weekend to check on the linkage, but I’m not expecting to find anything out of adjustment. I figure it’s in the gears, or synchronizer, as klhansen suggested.

Unfortunately, the most likely culprit, the 2-3 synchronizer assembly, is scarce, and extremely expensive when you manage to find one. You're more likely to be able to find a complete transmission from someone who has removed the stovebolt six and column shift 3 speed and replaced them with a "belly button" ("Everybody's got one") small block V8.
Jerry

Sounds like yours went quick. One day the 3-Speed in my '66 GMC popped out of 3rd. Overtime time it would pop out a little more and a little more. It finally got to where I had to hold it in 3rd. Then I was fighting it to stay into 3rd, lol. Bad synchronizer. Put in another Trans and my misery was over.