The Stovebolt Site Forums The Shop Area Driveline Anyone have a '54 or '55 3100 Hydramatic 4 speed?

Just wondering if anyone would like to share their driving experience with the four speed Hydramatic on the 3100? Especially climbing hills and downshifting....

mel's55
55truck.wordpress.com 

I enjoy the one in my 54. Although the truck has a cam that I think is not real hydra-matic friendly,(too high an idle for proper downshift), It is very pleasant to drive. Crisp firm shifts. The throttle pressure adjustment is ultra sensitive. It can go from running all four gears within about 10 feet, to not properly downshifting when rounding a corner with very little adjustment. I can't really comment on driving in hills as Oklahoma is pretty much bubble level flat.

Ditto on the sensitive throttle pressure adjustment. The problem existed when they were new, and 50 years of use and abuse at times hasn't helped the situation. One thing that exacerbates the problem is the fact that the HydraMatic has a fluid coupling, not a torque converter. The fluid coupling achieves an almost 100% RPM lockup, as opposed to the torque converter's 90% best effort. That 10% slip tends to soften the shifts on a torque converter equipped vehicle.

Keep tinkering with the throttle pressure adjustment until the shifting comes pretty close to what you want. It's going to be a fairly long process, and it's never going to be completely smooth or predictable. The truck transmissions also had slightly higher main line pressures and more positive shifts than the passenger car models. You really don't want a slippy shift with a lot of RPM flare-up between gears- - - - -that wears out clutches and bands in a hurry!
Jerry

Thanks Greg H and Hotrod Lincoln. I live in Western Washington and have lots of hills, Mt. Rainier being our biggest..!

I've noticed both situations that you describe; rapid upshift to 4th gear if I'm in 1-4 and definite lack of downshift unless I give it a goose with the accelerator or come to a complete stop. I don't like goosing it though. So far I've compensated by driving in town in 1-3 (effectively cutting off 4th gear).

Is the throttle pressure adjustment difficult to do (other than requiring a lot of sequential adjustments)? I'm a newbie and appreciate any advice.

It's just a matter of shortening or lengthening the linkage from the throttle to the transmission, the one that moves as you go from idle to cruise to wide open. Some linkages push, others pull- - - -it depends on the application. Whichever way it works, moving the linkage further in the direction that represents full throttle results in a longer period between shifts, and a part-throttle downshift at a higher speed. Going to full throttle should result in a forced downshift, known as a "kickdown" or "passing gear" as we used to call it. The 1-3 position locks the trans out of 4th. speed until a safety circuit kicks in at very high engine speed to avoid scattering the engine. Some of them also had a safety circuit in manual 2nd. gear that would shift all the way to 4th. regardless of shifter position if a driver insisted on trying to hold the shifter in low range and got the engine screaming.
Jerry

On the driver's side of your transmission are two levers. The back one is the actual shifter. The front one is the throttle pressure lever. There is a lock nut on both front and back of the swivel where it meets that throttle lever. Basically, you will loosen the front or rear nut depending on whether you want to lengthen or shorten the rod. Then tighten the opposite lock nut to match. 1/8 of a turn will make a big difference. There is an adjustment jig that is designed to get you close. It is actually 2 parts. One locks the linkage to the pan rail and the other is a guage on where the lever should stop when pulled forward. Your trial and error will be your best bet as long as you don't go too far and lose your starting point.

Thank you both. Rest assured I don't like screaming motors. Mel had pretty good care from my uncle in eastern WA which is flat and he drove it mainly to work and back. I'll let you know if I adjust how it turns out. It's not too bad but this gives me some good info go on for refinement. Thanks.

I surely hate to butt in guys but, where can one get the adjustment tools for this unit? I have a 55-2 with this set-up and I need to adjust it.
Thanks for letting me in,
dg

I watched ebay and collected mine. I loaned them out once and had no problem, but they are getting harder to find and I really don't want to let them go again. Bill Hanlon has loaned his with a refundable deposit. You may try and track him down.

I would be interested in having a second set of eyes and ears on this to see how Mel is doing performance-wise - see 55truck@wordpress.com. Anybody you would recommend in western Washington?

GregH, Perhaps some pictures with measurements would enable a person to construct a set or a facsimile that would get the job done. I hate to impose on your good graces like this but I really need to get this transmission up and running.
Thanks again,
dg

I had built a few sets of 2 different tools. A throttle pressure lever positioning guage, and a related linkage lock tool. I gave them to people that had helped me out with the loan of the original tools and friends that I thought might need them. As far as band adjustment tools go, they will be much tougher to build. What exactly are you being held up by needing adjustment?

I wanted a 1954 3100 hydramatic for many years. When I finally bought my 1954 3100 hydramatic, I was surprised by how quickly it shifted up through gears 1-3 and into 4th gear. I read the 1954 shop manual and learned the hydramatic was operating as it was designed to operate. The manual recommended leaving the hydramatic in 1-3 range in town to prevent shifting in to 4th gear too quickly for in town driving. I drive the hydramatic as recommended and sometimes drive in 1-2 range when driving slow. The hydramatic shifts up and down so smoothly, using the column shift lever, I believe it was intended to operate in the manner of using the shift lever as a shift controler, under varying conditions. I think the 1954 hydramatic was not designed to operate like later automatic transmissions and should be enjoyed as originally designed. I sure have fun driving it.

That hasn't been my experience at all. I put mine in 1-4 and go until I need reverse or get where I am going. There aws a little playing with the pressure lever adjustment until I found my happy medium between good upshifts and proper downshifting when turning a corner.

I also have a 1954 3100 with a hydra-matic. Shifts like a dream. The problem is about half the time, when pushing the dash starter button there is a horrid metal on metal grinding of the starter gear on the flywheel. Perfect condition 139 tooth flywheel and newly rebuilt 12 volt starter. Can't seem to figure this out. Anyone have ideas? - Anthony

The Hydra-Matic starter is different from manual-transmission 6v/12v starters which work with manual-transmission flywheels and clutch housings. The "horrid metal on metal grinding of the starter gear on the flywheel" may be due to a mis-match?

A 139 tooth flywheel is for a 6V starter. The drive gears are different on a 12V starter.

Yikes, where am I going to find the right drive gear?

If you have the original 6v Hydra-Matic starter, you could try to use it with a 12v electrical system (you might need to change the solenoid?).

I think the Hydra-Matic 6v starter had other differences from the normal 6v starter (maybe having to do with the "snout" and/or how far the gear is pushed towards the flywheel).

Doe anyone know how many teeth are on the 54 Hydra-Matic flywheel.

Tim, my HM flywheel has 139 teeth.