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My transmission in my truck messed up, it hasnt been ran in years and I got it running and was just going to move the truck to another spot in my driveway. When I put it in reverse to back up it popped out of gear. I tried to hold it in gear to back up but it only just kept popping. I was going to try to find another transmission but I can't find exactly what it is.I have searched the search engine with no luck. My truck is a 50 chevrolet. But the engine is a 1960 235. Transmission is a 3 speed. The rear end has been changed out to a regular drive shaft rear end. The casting number on the transmission is 3830210. Any help is appreciated.

About the time that they start popping out of gear, that's just about the time that they need to be replaced, has always been the knowledge I was taught.

Hy dads51, a picture would be a big help. Could you tell us how many bolts hold the side cover on, and what the overall length of the transmission is.

hi, the overall length of the transmission is 23 inches from the front of the shaft to the end of the tail shaft. It has 4 bolts that hold the side cover on. I did decide to take the side cover off to have a look and the gear that slides has teeth broken on it, I guess thats my problem. I would post pictures, but Im not sure how to do that. thanks for your help. I was just trying to find out what transmission it was maybe to find a rebuilt kit or a replacement.

Also I forgot to add that the truck did go in first gear and move with no problems, only reverse was the problem

If its just the first and reverse sliding gear it shouldnt be too expensive.Did someone get mad when they got stuck? Ive seen the side of the case busted out and the reverse idler laying on the ground.

Hy dads51, that sounds like the three speed used in the 55B or 2nd series through at least 59, I'd have to measure one to be sure, the 55 - 57 Chev cars used the same transmission, the later car transmissions were shorter. I tried to find the designation for it, but I can't, I think it might be called an SM318 but I'm not sure, hope that helps.

ok, retired wrench Im not sure what may have happen to it. The truck has sat for 20 years. I just got it running and wanted to move it and found this problem. If its just that sliding gear, where can I find one? And do i need to take it to transmission shop or is it something I can do at home without special tools?

I would try a dealer first for the parts. As for special tools I cant think of any you would need. As to can you do it? Thats a tough one to answer because I have no idea of your mechanical skills.They are pretty simple as transmissions go. The way I always look at it is its broke now what can I hurt.

What you have is an SM318 3 speed trans which is the most common 3 speed trans used by GM in the mid 50's through the mid 60's. They came in the long tailshaft version - about 23" and the short tailshaft - about 15". There is also an overdrive version. The internal parts are the same on all models (except Corvette). Parts should be available through a transmission parts supplier in your area. If not, I can provide you with a supplier that I am familiar with in So Cal. I would double check the reverse idler gear as it could be damaged as well. These transmissions are usually available at most swap meets for a reasonable price. Depending on what other components are worn or damaged, it may be better to look for a replacement.
Fred

Retired wrench, I am pretty skilled at doing things like this, but never a transmission. I always wanted to see what these things are made out of anyways.. I can usually figure out how things work..
rfs56trk... thanks for the info..if you can send me that supplier name I would appreciate it..In the meantime, I will look around for another tranny and see what the best option is.. If I rebuild it myself, then I know what I have, if I buy another one, I dont know what I am getting..but thanks all for the info everyone, its a great help

Make sure your linkage is working properly, and is shifting the mechanism completely into reverse. Disconnect the shifter from the transmission and see if the lever on the transmission will move further into reverse- the lever moves forward if I remember correctly. If the truck will move without jumping out of gear that way, you need to adjust the external shift levers so the internal mechanism moves the gears fully into mesh. The 1st/Reverse fork may also be worn, and not moving the sliding gear fully into reverse. Otherwise, worn/broken internal shaft bushings and bearings may be preventing the gears from engaging fully. Also, misalignment between the transmission case and bell housing will cause the transmission to jump out of gear, but in that case, the disengagement usually doesn't happen until you have driven a ways- maybe several miles.

Harvester

thanks for the info harvester, I did disconnect the linkage and it is going all the way in gear. I looked at the slider gear and it has teeth chipped off the edge of it.. not sure how that happened, but i think that is my problem. Maybe I will get it figured out soon

First and reverse are non-syncro. That's how that happens.
As harvester said, it is either the shift linkage not pushing it in all the way, the shift fork worn or there could be a problem with the detent or lock-out on the side cover.
The shaft of the shift fork can be loose but more likely they have wear on the inside of the fingers. The detent will hold the shift lever in position, if it is going all the way into the detent and gear.

Chipped corners on the teeth shouldn't hurt anything. It might make it slightly harder to downshift into first while rolling.

I think Im going to just open it up this weekend and look at all of the gears to see whats going on. I did take the side cover off and look at the shift fork and it didnt appear to be worn, but Im not sure what they look like new. Also, the shift linkage was going into gear as far as it would go by hand after i took all of the linkage loose to the shifter.

The slider gear is the weak spot in that trans. Years ago we used to get the slider gear at the local parts house. I seem to remember some concern that the slider gear and the barrel it's on were a set. I worked for an ex-Chev Service Manager at the time and he didn't consider it a problem to replace just the slider.

The 3spd is an easy trans to work on. IIRC about the only thing you have to do is pull the main drive to replace the slider. The back of the main drive is an inverted cone with two sets of roller bearings. Just watch where all the rollers go when you pull the main drive. Then grease them up good and re-install.

Larry

You have to separate the case to get the syncro drum and the 1/R slider out. Anaheim gear in Anaheim, CA has parts for these transmissions. 1-800-477-1103
Fred

Ok, Im going to get it apart this weekend to see what i need. If I just redo it myself, then I know what I have. Thanks for the info everyone