54 Hornet Hydromatic Woes

harry54 wrote:

I just got back from a 120 mile round trip to old Saybrook Ct. Had a great time but started feeling and old familiar noise. My 54 Hornet sedan received a transmission rebuild at Fatsco about 4months ago. It was having downshift problems . The car was fine going through the gears on the way up but when you came to a stop light or stop sign as it would downshift it would bang hard into first. It got so bad that I thought it would do damage to the rest of the drive line. The other thing that it use to do was slip in first and then when it warmed up it would start moving. I would make sure that I would completely warm it up back then. Fast forward 3 months.
It's beautiful for the first ten minutes now and then the abrupt down shifting started. My wife and I were on the highway for an hour and when we pulled off the exit the abrupt downshift started again. She looked at me and I at her and we thought here we go again.
I don't wan't to project. However, this trans got a full rebuild from Fatsco and was good for about 1000 miles. Is it possible that this could be a linkage adjustment ? The kick down works great and all other aspects of the trans seem to be in order. IT's just that when you've been driving for a while this harsh downshift back into first and slightly from 3rd to 2 nd.
Any thoughts ? Any suggestions ? I know that I have to call Fatsco and I will but maybe there is something simple ......

Harry.... Sage advice from Ken U and 51 Hornet...

Let me add some kibitzing to those comments... The fluid in a rebuilt trans should be checked every time you drive the car for any distance... you are looking for indications of slippage and contamination. At the point of 1000 miles you should drain and replace that fluid with new...now I have perked the interest of those who will say why... well for one thing the cleanliness of the transmission is the key factor in it's proper operation any hesitation on a valve or check ball brings undo pressure to the internals of the transmission ... small hesitations in a check ball movement translate to failure to completely tighten a shift band or move a gear into full position... just think ... rough to violent shifting ... maybe a check ball is holding position a few seconds too long. When the presssure is high enough for the ball to move it could have reached a level higher than that required for the normal shift to occur. The fluid is now raceing at a higher pressure to catch up it's normal tasking at the wrong time and with too much force. The result is a violent down or up shift! This type of failure is an artifact of contaminated fluid and/or dirt in the transmission. To counter act these failures you maybe able to Drain and refill everything including the torus to correct the shifting irregularities. To assure all right with the transmission make the checks necessary to assure that the linkage is adjusted correctly. YOU CAN NOT adjust it correctly without the throttle level gauge. If this gauge shows out of tolerance arm postion it must be bent to change that tolerance. To correct the lever position the proper bending gauge is required.

Aside from these checks ... if the carburetors (twin H) or carburetor (single carb) are not adjusted properly or operating improperly ... the down shifting could be attributed to induction problems. There are also throttle postioning guages that set the length of the throttle rods once the transmission throttle arm is properly postioned.

See the pictures of the tools I have posted ... they are needed to adjust the trans regardless of what else you do...


Good Luck

#1 make sure linkage is set correct at carbs and bellcrank,also that engine is at correct idle speed,as too fast will give you harsh downshifts. 32 be sure that that throttle pressure lever and shaft were not bent during shipping or install. As for having to bend lever with tool , as it had worked pryor that would be last resort after all other adjustments have been tried. These units are sensitive to proper linkage adjustments, so get manual out and go for it. Not having the Hudson special tool to set bellcrank use correct size drill bit to lock linkage in place. GOOD LUCK Lou