Trans Rebuild

KarlJS

KarlJS

Senior Member
I live in Riverside California and am wondering if there are any recommendations for someone to rebuild a3 speed top loader out of my 39' 1/2 ton truck. Thanks
 
They are really easy to work on. Pick up Tardell's and Van Pelts transmission books and do it your self. Van Pelts will have all the parts you need.

I never worked on a trans in my life and about a month ago I replaced all the gears and guts in my 39 top loader with gears and guts from a 46 48 side shift trans. Took about an hour and I had no parts left over on the bench. That in itself is a success sometimes.
 
I think if you can get it out yourself then you must be fairly mechanically minded... From there take a look yourself. As said get the book.
 
X3 on doing it yourself. Hardest part is getting it out of the frame and onto the workbench. I too had never tackled a transmission but did it in a day (39 toploader) after I got Van Pelt's book and parts. His products are great as is his information. He also answer's his phone and is quite helpful.
 
Hey Karl: They are pretty easy to do - just need a few tools and measuring devices. Make sure you have high quality parts - some of the repop stuff is junk (like all the repop transmission shafts!). If you need help, feel free to drop me a PM. Another guy that might be able to help you (if you want somebody to build one) is Dennis Lacy. He and his Pops are really great people and they are in your area:

Early V8 Garage
1217 Azusa Canyon Rd.
West Covina, CA 91790
626-338-2282
 
You can rebuild it yourself. I did my '39 transmission myself and then the side loader for my 1940. I had VanPelts book handy and if you have any questions you can call Mac and I will talk you though them. You can do it!
 
Down to the point to remove the main drive gear. The book almost ready like the main shaft is 2 pieces. One comes out the front with the ball bearing then the rest comes out thru the top. I was feeling so confident too.
 
Discovered that yes it is two pieces but mine will not split apart, any ideas on how to make one into two?
 
The first step is to remove the shaft for the cluster gear to allow it to drop down into the bottom of the gearbox. With the cluster gear out of the way the main drive can be removed from the front of the gearbox after unbolting the bearing retainer (the sleeve that holds the throwout bearing collar). With the front shaft out, remove the rear bearing retainer and lock ring from the main shaft (rear) bearing and drive the bearing forward into the gearbox to remove the mainshaft with the synchro hub, intermediate gear and low/reverse slider in place on the main shaft.
 
The front shaft and back half will not separate, I've removed the parts that you said to. Any ideas on how to separate the two pieces?
 
I'm no expert on these transmissions, but I'll throw this out. Perhaps he has a transmission with an earlier case that had been previously rebuilt with later gears. Isn't there a "trick" about installing the main drive gear in these from the inside?
 
After the counter shaft cluster drops down a bit, there is nothing to hold the input drive gear and main shaft together unless there is a bad bearing in there. With the front bearing and throw out sleeve support removed, the main drive gear should pull out. Sometimes you have to tap on the side of the gear with a soft face hammer while you pull. If that doesn't work, you'll need to rig up a slide hammer with some form of choker or pin puller on the front stub of the main drive gear. I've never had one that wouldn't come apart yet but there is always a first time.
 
Counter shaft dropped, rear bearing removed. Won't slide out the front because of syncro. Was thinking same about blocking front and using slide hammer at the rear to break it loose. Going to soak with penetrant for a few days.
 
Karl, put down your slide-hammer, soft face hammer and anything else you might think about beating on your transmission with.

1. Count the number of teeth on the main drive gear ... the top gear, front attached to the input shaft.

2. Locate the part number cast into the lower back of the transmission case.

3. Post this information.
 
The main input drive gear only meshes with the synchro hub sleeve when the sleeve is pushed forward by the shift fork. The synchro inner hub is splined to the main output shaft so it isn't physically attached to the main input drive gear. There is a hollow in the gear and a stub on the front end of the main output shaft with only a bearing between the two. If the bearing has rusted up, then there might be something to hold them together. The two shafts should rotate independently of each other when the trans is in neutral position.

I suppose there could be an oddball main input drive gear in it but it still has to come out somehow.
 
Why not post a picture?? If it is a 48 case and has the 29 tooth cluster with the 15 tooth main drive gear, they can be tough removing because the teeth for the Synchronizer on the main drive gear hits the cluster.. Still can easily be done.. Take Hoop's advice.. You'll tear up too much beating away on it and run a strong risk of cracking the case
 
Mercury cars used the 15/29 set and possibly a few others. It also depends on whether it is a 48 case or a 78 case. The 78 was set up to use the 15/29 and has a deeper bowl down in there. A 1939 Commercial should have a 78 case but could have either the earlier or later type gears. Lots can happen in 70+ years.
 
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