ccjersey - 1/25/2023 19:50
As you know the ST has a truck manual transmission and clutch, so not the greatest fro up/down shifts under load, but lots of choices of speeds and parts and expertise to fix it all is common.
The PTA series Steigers have an Allison automatic so that eliminates the clutch and shifts up and down are simple, but at the expense of speed/gear choices. I think they were all 4 speed transmission with a drop box/range shifter that you must stop to shift.
Then there the CaseIH models with 12 speed power shifts that the controller is probably NLA. I’ve got one of them. I’ve had an occasional sudden drop out for no discernible reason. I asked here and was told to unplug all the connections to the bank of solenoid coils that control the transmission, spray with contact cleaner (I use DeOxIt) and reconnect.
If there is an error code displayed, that usually points to a specific solenoid coil bad and will not fix itself. Time for a new solenoid valve. A ground down open end wrench is nice because there isn’t room for a standard wrench to get on the flats of the valve. I have a friend that’s an expert on those transmissions and since I’ve just been replacing solenoids the first time they glitch and throw a code, it’s rare that I have trouble. Still, I keep one or two new solenoids with coil on hand. I’ve also had the proximity switch on the clutch pedal get some steel filings on the magnet and the tractor fail to move from a stop.
Then there’s a 24 speed trans that I think is basically a 12 speed manual? plus a powershift hi-lo? Saw a video online about a tech fixing one of those he owned. He had a source of parts in N. Alabama or they had rebuilt trans if you wanted to just swap it out. So, even though I have heard a lot about how there’s nothing available for the 24 speed, I don’t think I would be afraid of them.
With any of those old tractors you have to know who has parts and knows how to work on them. That ain’t CaseIH in most cases.
My 9170 12 speed definitely has to have a minimum voltage to engage the transmission. Tried to keep running with a failed alternator to finish a field…..nope, it stopped pulling. Put jumper cables on it while changing the alternator and it pulled right off when we cranked it back up.
Here the video of the 24 speed rebuild - its 3 episodes: https://www.youtube.com/watch?v=IcH98u1fbAE&t=0s&ab_channel=DGHD