The Stovebolt Site Forums The Shop Area Driveline 1957ish 3-Speed OD Trans Rebuild Starting - Tips?

Mixed results. Trans shifted much smoother, with a more positive throw on the shifter. First sounded quieter, and second sounded about the same. No crunching, no grinding (except when I downshifted from second to first, which was the same behavior it had before).

BTW, you did fill the od w/ gear oil as well though the pipe plug, pass. side aft od housing?

Two ways not to grind as you have a non-synchro 1st gear.

1) Shift into 1st from a complete dead stop

2) rolling at low speed shift into neutral then second gear then first

1st gear in that transmission should not be relied upon be used to down shift to slow the truck IMHO. Anyways the old adage is...

"What's cheaper new brake shoes or a new transmission?" the answer brakes of course.

Next step is to pull that trans while your boy is still home and get that shim in as Fred suggests. Ten years or so ago Fred gave me this advice and it served me well, very well as I had the exact symptoms, solved by Fred's shim suggestion.

Jim if it's any consolation to you...13 years ago I had to take the trans out 3 times as I mistakenly placed the blocker ring in backwards and she could not go into overdrive, better pictures (such as the ones you have taken) and better information such as Deve's website links and of course The Godfather of Overdrive, Fred, (sorry Fred, couldn't help myself) is here to guide us through this tortuous, yet fruitful and fulfilling path. Last but not least you have openly discussed your adventure through all it's pitfalls, pratfalls, cul-de-sacs, successes. This has a measure of courage we all admire as we encourage you on your journey.

Regards,

Cosmo

Cletis,

No. I used straight mineral (COSMO's suggestion when we were planning on tearing into this last spring).

COSMO, I know you're right. As is Fred. Might as well get it done now I guess. Thanks for the encouragement. And, I DID fill at the OD side plug first until it ran out, then moved to the main trans side fill plug until that ran out.

COSMO and Fred; Can I just pull the clutch gear, assuming the roller bearings come with it?

Edit...

Okay, let me work through another thought just as an added 'maybe'...

Ever since I bought the truck, the side cover and linkages have been a continuing minor issue. Shifts fine, in fact a little too easy between second and third.

When I bought a couple of other side covers while trying to fix the linkage (and dog-binding) issue, I found out a couple of things. Mine used a ball-detent type construction, but another 4-bolt one I bought used a scissor type. When I took mine apart and tried to cobble a single working one out of the parts, I found that the bb that rides in the detent area was pushed a little too far into the shifter shaft on the 2-3 shaft. The spring was still inside, but it was a bit bent and may have been serviced before. I freed the bb from the stuck end of the shaft and it seemed to function normally.

When I shift from second to third, it takes very little effort. As a matter of fact, it is easy to move the shift dog by hand and I had to hold it still while I worked the linkages so I did not move it out of neutral when aligning things.

So, the question is: If by sorting out the transmission and replacing everything that needed replaced, returning it to (basically) factory new, yet using my original side cover; Did I simply put one part of the 'popping-out-of-gear' problem back into the equation?

In other words, should I give a new, stiffer side cover a go before tearing down the trans again? I mean, if I have this thing back to new, this would have had to have been a major problem for GM 3-speed transmissions if the spacing of the clutch gear was the only culprit.

Or is my logic flawed?


Jim

Both the ball bearing type and the scissor type side covers were used in that era. I believe they finally settled on the ball type in later years. It could have a weak spring as you noted it was pushed inside the shift fork. I would replace it. It should shift smoothly but you should be able to feel the detent. As we discussed there isn't much that holds them into gear so any weak link is a problem. It shouldn't pop out of gear this soon though, it usually happens on a long run when it is warmed up.
You can pull the clutch gear out without disturbing anything. Remove the side cover and the bearing retainer and pull it out.
If some of the needle bearings dislodge just pick them up with a magnet.
Fred

Thanks Fred,

I'll start with the side cover, test that when done, then move to the clutch shaft if I see no improvement.

Jim

Okay...bit the bullet and decided that, while I had my strong son home from college, I would just go ahead and pull the transmission out again and attend to both the clutch shaft 'fix' and the side cover.

I'm getting much better at dropping this transmission and disconnecting all the ancillaries along the way. I wasn't rushing things and, even given the amount of time I took to build a small jig to more safely handle the transmission on my floor jack, I had it out in less than an hour. Another shot of the two 2x4 jig I built (with an indexing hole for the drain plug; An idea I borrowed from COSMO).

Checking the innards for any issues, I found that all was in great shape. The gear oil had air bubbles in it, which I hadn't expected, but I did drive the truck to warm up the oil in preparation for draining this time.

Tried to remove the clutch gear without disturbing the roller bearings. No such luck. Spent the better part of 1.5 hours making DANG sure I lifted all of the roller bearings out with a magnet and praying they did not drop into the sump. If they had, I would have needed to completely disassemble the transmission. I counted the bearings at least twenty times to make sure I had the required 24 front, 14 rear. Left out the 14-stack thrust washer to make up for the planned reward relocation of the clutch shaft, then pressed off the bearing, added a 1.4" snap ring, pressed the bearing back on, reassembled and made new gaskets for the bearing retainer and side cover. On the side cover, I changed out the ball bearing spring and tightened up the detent system as much as it would allow.

Now assembled, I put the jig back onto the transmission and my son and I hefted it into place on the truck. Reattachment took some time, but no where near as long as putting more 90-weight oil back in at 38 degree ambient temperature. Literally slow as molasses. Remember that now as we take out first test drive...

The first test drive we did, before the transmission was up to temperature, was disappointing. The transmission popped out of third under load around 64 mph. Not as noisy, but it still popped out. I say 'around 64' because I did not hold my mouth right when reinstalling the speedo cable and it did not work until I stopped at the gas station and reinstalled it.

The second test drive however, was more encouraging. With the trans up to temp and shifting very well, I tried to get it to repeat the previous behavior. Went up hills and down, rocked the trans by varying the speed with the accelerator, and drove around 60-65 most of the way. It did not pop out of third. You can hear me say "Thank you Fred" at the end of the video (if you waited that long...sorry for the length of the video). And I meant it. Thank you Fred. Incidentally, you can see the red shop rag I tied around the shaft of the OD lockout handle I installed. Another reminder to a feeble mind not to allow the OD to engage before it's time. Probably not an issue since the solenoid is not yet powered, but better safe than sorry...

So, right result. I will be test driving it more in the near future. I will also be adding the electronics next week and will report on both of those tests.

Jim

Good Job! And nice video.

Excellent work.

Okay. Test drives taken...

The first test drive, I was not sure if I had it hooked up right. I could tell by feel that there was more going on under the truck than before, and as I tried to slow down to turn, I noticed I was freewheeling. So that was something at least. Compared the drive to regular (non-overdrive) operation, and if there was a difference, it was very subtle. My fancy test light (an extra instrument panel light that I had wired to the solenoid relay and into the cab) did not work. Did not know why.

I called Fred and told him about the symptoms and came away with a few more things to try.

Yesterday was a different story. I started by reconnecting my test light in the cab and testing it to make sure that it illuminated when the relay powered the solenoid. Fred told me how to ground one of the terminals on the relay to test the power.

Got in and headed down the road. I let the transmission warm up for a bit since it's been cold here. When I hit 28 mph, my little light came on. I finished climbing the hill I was on in second gear and, on the flat, I pulled my foot off the accelerator. Bingo. I felt the transmission shift into overdrive after about a second. On my previous test, I don't think I took my foot off the peddle long enough to complete the shift; Something Fred told me I may be doing wrong.

I accelerated in second OD up through speeds and rpms that normally existed only in my standard third gear. Cool.

I dropped it into third and repeated the process. Next thing I knew, I was cruising at 70 mph with very little foot pressure and an almost idle-sounding rpm. Amazing. As COSMO said, it's a totally different driving experience. Quiet, comfortable, and smooth as silk.

I will be hooking up my dwell meter and running it to the cab somehow so that I can confirm my low rpms, but I know for sure that it worked this time.

I also noted that I could now kick down into standard drive because I adjusted my switch paddle up enough to depress the switch the required .18 inches. That was slick as I prefer to use transmission braking when slowing down.

All-in-all, I was very pleased with the performance. I can't wait for my next long-range trip to see what this thing can do. 70 mph has a tendency to reveal shortcomings in the steering gear, so that's probably my next job.

Thanks everyone for their inputs here. I will post another video when I run the dwell test.

Jim

Shot a video of yesterday's test drive, but it came out too poor to post. Sorry.

Here, though, are the results:

With Freelance GM Engineer SWEET in the truck, we recording the following:

Speed (MPH), Standard Drive (RPM), Overdrive (RPM)

50, 2200, 1600
65, 2800, 2100
70, 3000, 2200

Test was done about 8 times in relatively flat areas. Standard drive test was mechanically locked out of overdrive (with my handy-dandy rusted and pitted overdrive lockout T-handle cable that looks like it belongs there). Used a Sunpro dwell meter run to inside the cab to get the readings.

Fred told me I'd develop a "feel" for when the OD is kicking in. I have.

So, to my eye, the numbers bear out what I am hearing and feeling in the cab; The OD is letting my tired old 235 strain less at steady speed. The drive yesterday was worth every minute I put into rebuilding this thing. I am sure that over time, it will have been worth the money too. I am incredibly happy that the solenoid, kickdown switch, governor, and Delco relay that were hanging by rotted wires from my firewall and transmission were all functional and just needed a cleanup.

Thanks to everyone for your great tips and suggestions. A special thanks to SWEET, COSMO, and rfs56trk for the over-the-phone hand-holding.

Jim

What awesome results! This is more than a great project. Inspirational comes to mind!
thanks for all the documentation and pictures.

Very nice indeed.

Thanks Alec.

Just hope it helps a novice like me down the road...

Best Wishes,

Jim