The Stovebolt Site Forums The Shop Area Driveline Proper Way Of Shifting a Hydramatic

This might be a FNG question. I got a 1957 chevy 3100 with the N 1-4 1-3 1-2 R Hydramatic transmission. Sometimes i get a loud noise, im thinking because im not shifting property. What is the proper way of shifting throught gears? taking off? Any help appreciated.

CenCal53 the 1955 Chevrolet Truck 2nd Series Shop Manual should be close enough for you...

Place the indicator in the 1-4 position and drive it.

When you drive it as Builder describes, note the MPH when it shifts. Let us know when it shifts and when it makes odd noises.

Thanks Healingbear thats sums it up. I still got to find out why there is a loud bang sound at times. Also got to get my speedometer working so i can be more specific when that occurs. Would i need a special speedometer cable for the hydramatic? And also, what would be a good rear end swap with 6 lug for freeway gears. Right now i believe it tops off at 55mph. thanks in advance.

It sounds like the transmission needs a throttle pressure adjustment. There's a piece of linkage connected from the carburetor to the transmission. It moves a spring-loaded lever on the side of the transmission that times the shifting according to throttle opening. Too much movement, and the shifts will be delayed, and VERY positive when the shift happens. You'll also get downshifts too soon, with very little change of throttle position. Too little throttle pressure, and you'll get a mushy, slippy shift. Bad juju! Adjust the length of the linkage (There's a turnbuckle adjustment in there somewhere) to get the best compromise between shift firmness and slip. Hydramatics are supposed to have a firm shift, but they shouldn't rev up high and bang into the next gear!
Jerry

I had that Hydra-matic in a '59 panel, and 1-4 is "drive" as mentioned. I adjusted the pedal pressure linkage and it helped some, but still banged, thumped, or whatever on either 2-3 or 3-4 shift, I don't remember which. A friend who had the same tranny in a Pontiac said to have the clutch bands replaced, or it will fail....His left him with first and second gears only after stopping at a toll booth! I've heard those trannys are expensive to service these days, but they are unique and cool when rebuilt!

It was explained to me that they have very soft clutch faces and band material. The original trans fluid is no longer available. Dextron is as close as you will get anymore. Using a fluid like type F will kill the friction materials in a heartbeat.

The original "Type A- - -Suffix A" fluid used in the HydraMatic stopped being made back in the mid-1960's. The problem was that it used a small percentage of whale oil in its formula, and the bunny huggers raised so much stink about whaling that a synthetic fluid had to be developed. Type F fluid has a lot of very aggressive friction enhancers designed to work with the hard black clutch material used by the Ford FMX type transmissions, and it's death on GM clutch material. Dexron is the closest match to the old Type A, but it's not perfect.
Jerry

if 55 is your top speed you probably have a 3.90 gear set.

in 1956 GMC half tonners came with a Dana Spicer 45 rear end.

they had 3.07 gears and in 1958 3.92 gears and posi units that should be able to interchange back through 56.

if you have a 3.90 rear, that is why you shift hard and as the tranny wears out you can get a bangin noise you hear.

You may be able to adjust the shift of your tranny to soften it but several manuals advise against any adjustment because it may accelerate the impending failure of it.(the banging noise you here)

Good luck finding a spicer 45 rear. they are not that common and because parts are hard to find its very hard to pry one away from someone who knows what they have. drums and wheel cylinders are impossible to find.

look around hot rod shops that customise trucks alot as most often the old rear is emoved to install later rears.

I did not know that about the Dextron vs. Ford tranny fluid

1954 3104 Hydra-Matic fluid thread...

Im sure the rear end got swap out at some point since there is a yellow mark with "55" written on it like if it came from a junkyard. Thanks for all the info, il look into it, i'm sure i'l be asking for questions down the line. How would i verify i have a 3.90 ratio? And was was the correct gear ratio for my truck from the factory? 411?

1957 3100 3.90:1 unless it came with an overdrive transmission.

Guess you learn something new everyday. This information is invaluable. To be on the safe side i checked the oil on the transmission and its all good not sure if its ford or Dextron but its at a proper level. I also noticed the tranny has a slight leak to it,any suggestions? rebuild?, new gaskets? Where can i find parts?

CenCal53 more info...

Hydra-Matic Shift Points

Diagnosis of oil leaks- 54 Shop Manual

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