64 slim jim 10?

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G-46523

Hello! I’ve got this THING of a 3 speed automatic tranny that has no torque converter, just a clutch plate looking thing with springs in it and it has been rebuilt but shifts very rough and I was wondering if I might need a new clutch plate looking thing because I believe the springs are loose in it and maybe it’s not doing it’s job? Any Ideas people? Thanks! -Don
 
Tranny was rebuilt years ago and when I had the rebuilder drive the car, he attributed the roughness to the engine . Since then the motor has been rebuilt and it’s still the same. So I’m wondering if it’s that plate with the springs in it.
 
G-46523 said:
Hello! I’ve got this THING of a 3 speed automatic tranny that has no torque converter, just a clutch plate looking thing with springs in it and it has been rebuilt but shifts very rough and I was wondering if I might need a new clutch plate looking thing because I believe the springs are loose in it and maybe it’s not doing it’s job? Any Ideas people? Thanks! -Don
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The clutch plate looking thing with springs is a Damper Assembly.
Instead of a torque converter it has a "torus" (a.k.a. internal torus torque multiplier) that acts as a torque converter, and it becomes hydraulically coupled in first gear. The gear ratio starts out at 3.50:1 in first gear, then jumps to 2.93:1 after the hydraulic coupling of the torus. After that point is when the shifting feels rough. It is a 3 speed 4 range transmission.

Explanation of Roto Hydramatic 375.

From the link: The shifting sequence was very different and much rougher than the Hydra-Matics that preceded it, or the Super Turbines and Turbo Hydramatics that followed it. The shift from 1st to 2nd or 2nd to 3rd range was long and drawn-out, ending with a harsh shift. The reason for this was that three things were happening. Not only was the transmission shifting to a very much higher range ( 2.93 to 1.56, but it was also simultaneously emptying the fluid coupling and making a mechanical lock-up. The wide gap in the reduction ratio between first and second gears combined with the direct mechanical connection to the engine to create a shift that could be firm enough to lug the engine. Because of the mechanical lock-up, there was sometimes a shudder felt as the transmission shifted into third gear (fourth range) by refilling the fluid coupling. Direct drive (1:1 ratio) is achieved by splitting engine power between the fluid coupling (used for first gear) and the front clutch (used for second gear), which are both applied to provide third gear, effectively locking the planetary gearsets and forcing them to spin at engine speed. The design is unique in that it provides third gear by applying first and second gears at the same time.

The transmission is operating the way it was designed. If the Damper Assembly has all six springs that will be as smooth as it gets shift wise.
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Ok. When I got the car, I didn’t know jack about it and the tranny worked actually smooth like any other. Now, I have to manually shift it cuz it’s not doing it’s job and it’s been rebuilt as has the motor. However this “damper plate” has loose springs jiggling around in it and I’m guessing it needs replacing but I’m not throwing money at it only to find out that wasn’t it. Should all the springs be tight in the plate? Also, when I come to a stop it doesn’t downshift right. Just shudders like crazy until I shift it myself. Thoughts? Thanks!
 
G-906360 said:
Ok. When I got the car, I didn’t know jack about it and the tranny worked actually smooth like any other. Now, I have to manually shift it cuz it’s not doing it’s job and it’s been rebuilt as has the motor. However this “damper plate” has loose springs jiggling around in it and I’m guessing it needs replacing but I’m not throwing money at it only to find out that wasn’t it. Should all the springs be tight in the plate? Also, when I come to a stop it doesn’t downshift right. Just shudders like crazy until I shift it myself. Thoughts? Thanks!
Click to expand...
Did you contact the company in post 2?
 
G-906360 said:
Ok. When I got the car, I didn’t know jack about it and the tranny worked actually smooth like any other. Now, I have to manually shift it cuz it’s not doing it’s job and it’s been rebuilt as has the motor. However this “damper plate” has loose springs jiggling around in it and I’m guessing it needs replacing but I’m not throwing money at it only to find out that wasn’t it. Should all the springs be tight in the plate? Also, when I come to a stop it doesn’t downshift right. Just shudders like crazy until I shift it myself. Thoughts? Thanks!
Click to expand...
The springs might be worn. I replaced the whole damper on mine, it had missing springs, but that was back in 1994, when parts were more easy to get.

You might also need to adjust the dash pot idle stop for your carburetor. It is held open by vacuum and when coming to a stop the engine tries to stall, the engine loses vacuum, it will push open the throttle to keep the engine from dying.

If you need to replace and have trouble finding a dash pot, you can shift to neutral when coming to a stop to avoid stalling, and put the car back in gear once you are stopped. It gives a chance for the transmission fluid to be pumped back into the torus, with less load on the engine.
 
You blew my mind with the dashpot thing. I remember it being there before I had the motor rebuilt but since I made it a 4 barrel it never made it back on the car. However it was not downshifting prior to my rebuild when it was still there so I’m thinking it was bad anyway so I’ll get a new one but I gotta say THANKS! for bringing that up!
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G-360487 said:
You blew my mind with the dashpot thing. I remember it being there before I had the motor rebuilt but since I made it a 4 barrel it never made it back on the car. However it was not downshifting prior to my rebuild when it was still there so I’m thinking it was bad anyway so I’ll get a new one but I gotta say THANKS! for bringing that up!
Click to expand...
When you said it was shuddering when coming to a stop that is what happens with a missing or misadjusted dash pot. Until you get one, all you have to do is drop the car in neutral just prior to stopping when it starts to shudder, then put it back in drive after the car is fully stopped. If you don't catch it at the right time and the car stalls, you are already in neutral and can restart the car.

Good luck.
 
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