Technical 47 Chevy Fleetmaster transmission rebuild

Got my old car roadworthy and drove about 300 miles in total. Transmission started making grinding noise in 2nd gear and wanted to stay stuck there. I had tolerated what seemed like a jerky clutch since getting the car going, hoping it would wear and smooth out whatever caused it to seem like it was grabbing at several points around the disk. Always smoothed out when clutch was released fully.
Issue #1 was that the bushing in the torque tube supporting the universal joint was shot, allowing both the joint to flop around - and as some of you know, the open design of the ujoint "cups" allows the cross to move about 1/8" on each side of center. This is what makes the bushing so critical - nothing else will keep the u-joint aligned. Also, as many of you know, once the drive shaft flops around a bit, it wipes out the seal - and the lube from the transmission and u-joint works it way down into the rear axle. In my case, there was evidence of a previous catastrophic u-joint failure, and unfortunately, the mechanic replacing it decided to clamp the output yoke bearing surface in a vise - scarring it on each side for the full length. This prolly accelerated the wear of the poor bushing in the torque tube.
Issue #2 was that the 2nd/3rd clutch, when back in the 2nd gear position, traveled far enough that the synchronizer ring for 3rd gear could disengage from the clutch gear teeth, and the clutch gear teeth nearly wore off the 2 teeth on the synchronizer. The 2 teeth on the synchronizer should always be engaged in the 2 matching (large) grooves on the clutch gear teeth. Since there are only 2 large grooves on the clutch gear for the synchronizer ring, once the ring's teeth were out, it would stay stuck in 2nd gear until the ring eventually aligned with the large grooves again. If the teeth were not meshed, the 2nd/3rd clutch would always be pushed over into the 2nd gear position. Right now, I'm not positive what kept the 2nd/3rd clutch from moving too far, except for possibly the 2nd/3rd clutch fork (now worn). At least I know why it was sticking in 2nd and what was grinding - the clutch gear and synchronizer ring teeth. I'll look at the other end and see if it can travel too far that way also, as well as what limits the travel that way.
Issue #3 was that the spring for the 3rd gear synchronizer is missing, and it was jumping out of 3rd gear frequently. The spring is a sort of ring made from material having a "D" shaped cross-section. This sits in a groove between the driving teeth and the gear, on both the clutch gear and the 2nd speed gear. As the 2nd/3rd clutch moves, the spring contacts the 2 teeth on the synchronizer ring and stops the advancing synchronizer ring - this pushes the ring into the brass cone of the 2nd/3rd clutch, which has a braking action to make the 2nd/3rd clutch speed match the gear you're going into. As the 2nd/3rd clutch continues to advance, the 2 teeth on the synchronizer ring compress the circular spring and pop over it. When you're leaving 2nd or 3rd gear, the 2nd/3rd clutch pulls the synchronizer ring and it pops back over the circular spring. I attribute my car jumping out of 3rd to the lack of a spring to hold it in gear, and the fact that the universal joint was flailing about on the rear of the transmission and trying to wobble the front end of the main shaft.

I found a hole directly below the speedo gear that goes thru to the inside of the u-joint area. This allowed lube to leak out. Some cars seem to have that hole filled by a bolt holding a bracket on - but this didn't exist on my car.

I want to point out some extremely helpful videos on the transmission, on the u-joint, and on the torque tube bushings by "The Jayhawker" - these were essential for me, as it would seem impossible to get the transmission apart without a knowledge of how to do it beforehand...

So this leads me to my questions: Where can I get the circular spring that the synchronizer ring slips over, and where can I get a new synchronizer ring? I think I can make a spring, and I may try TIG welding some buildup on the teeth of the synchronizer ring and shaping it like the 2nd gear ring's teeth.

 

I'd be looking for another transmission or two, to get parts from.

 

Contact 'The Filling Station' in Lebanon, Oregon. They specialize in early Chev stuff.

 

Good idea! I glanced thru eBay and didn't see one like mine, but I may need to get serious about that....

 

Will do! I actually have the reverse idler gear bushing on order from them now, and some other stuff from "Chevs of the 40's". I keep forgetting that at least with "Chevs of the 40's", there is more in the catalog than I can find online - and calling them is an important step I keep forgetting. Thanks for the reminder!

 

Rebuilding is progressing.... However, the bushings from The Filling Station were for the countershaft (or cluster gear). I guess either their description should have omitted "reverse idler gear", or some cars also had a 7/8" reverse idler shaft? Mine is 3/4" for the reverse idler shaft. The bushings would have fit my countergear (or cluster gear) -both OD, ID, and length were correct for that application, but I'm not replacing those. I found bushings at McMaster-Carr that look as though they would fit my reverse idler gear, but they are not steel-backed like I think the originals are - and depending on the fit, they could need reaming after installation. The lost motion in my countergear/cluster gear is within the 0.010" spec in the video I watched - but no so for the reverse idler gear - it was worse and I measured 0.004" wear on the shaft itself. I decided to compromise on that - and ordered a section of 3/4" polished/hardened shaft from McMaster-Carr. It looked like the right stuff (I don't have a hardness tester) and I cut it to length and then drilled it at an angle for the retaining pin. I also took a piece of 1/8" music wire (hardened spring wire) and slowly ground one side flat to make a spring for the 3rd gear synchronizer ring detent. Took some doing, but I got it on the input shaft/clutch gear and sitting in the groove just like the one for the 2nd gear detent. And believe it or not, I found a NOS shift fork for for 2nd/3rd gear! I used the TIG process to weld up where the synchronizer ring teeth were worn, and got those shaped up like they should be. Test fit the parts yesterday, and I'm sure the 2nd/3rd shift drum cannot overtravel again to allow the synchronizer ring teeth to disengage and get ground down again. I got new bearings, and in the case of the input shaft/clutch gear, I got a sealed bearing - and will remove the seal on the inner side. Hopefully, the bearing seal on the outer side will help retain the oil in the transmission. I got a new u-joint from Chevs of the 40's, and it has needle bearings in it - unlike the original. Additionally, the new one has closed end caps and doesn't seem to have the extra endwise lost motion like the original - so it looks like it will keep the output yoke centered better without relying so much on the bushing in the drive shaft tube. I took an empty 90 gram CO2 cartridge and made a bushing remover to pull the old bushing from the drive shaft tube. Got some health issues in the family, so it may be a while before I can complete the rebuild....

 

Don't rule out placing an ad in the ''wanted'' classifieds. Some of us have milk crates full of those parts for sale or trade ..

 

Thanks for the info! I (incorrectly) assumed I'd need to buy an entire transmission without knowing the condition of the internals... The manual says to replace the detent springs for the synchronizer rings if they are removed - and yet does not call them out separately on the exploded diagram. So I guess I'd need to look for a used clutch gear/input shaft with the spring intact - that is if the one I made doesn't work. Thanks!

 

Does anyone know if the guts of a later fifties or sixties, open driveshaft Chevy 3 speed will interchange with the earlier torque tube model? I have a torque tube Chevy and a couple of spare later model transmissions and was curious. If they share parts it would make parts easier to find.

 

If you were close to Ohio a local junkyard has a few of them

 

I search the Filling station's catalog a lot and find that the more generic search you use The better chance you have of finding what you are after.