I am in the process of buying a 1988 Ford F800. The two speed axel is in the low speed and will not shift out of it. I know there is a switch on the shifter stick that is supposed to change from high to low and vice a versa. What makes things not work. Is the problem in the axel or is it electrical. The man selling says the problem is the switch on the shift stick. I am guessing a solenoid on the axel does does the shifting. I would also guess not to shift under a load. Any suggestions on the problem and how to fix it.
Take a picture of the 2 speed shifter where it is mounted on the rear axle. Check that the wires going to it are not broken or disconnected
See if you got power going to the switch then crawl underneath and see if you got power going to the shifter. If so and it doesn’t shift then either the motor is bad or is stuck in the axle. To tell that just unbolt the motor and see if it shifts in your hand or hanging down. Pretty simple system of three wires. https://www.drivetrainamerica.com/1...speed-shift-motor-retro-fit-kit-2-bolt-mount/
Does it have lucas girling brakes?
I have not seen the truck yet. The seller was busy today, tomorrow Saturday is opening Wisconsin deer hunting so he is hunting tomorrow and longer till he gets his deer. I am hoping to look at the truck Tuesday. I was wanting to find out how complicated it is to fix. how to determine where the problem is. You guys have given me a start, Thanks. I just need a dump truck to move dirt on my property, so in low now would be ok. I would rather be in High to drive it home. From what you guys have said it could be more than a simple fix.
I have been told repairs for the electric shift are unavailable, but they could be converted to vacuum. It won't shift under load, even if you change the position of the switch. It will shift as soon as the load is removed.
The motor and electrical connections at the motor give the most trouble. If you just need high to drive it home, and you do NEED high, then start there and switch it by hand if you have to, then switch it back to low when you use it at home.
Eaton Axle stopped making pieces for the Old Square style Two Speed shift motor assemblies, Now model works OK just requires a Grinder to finesse the set up on older axles. Installed a few on old friends trucks late 90s. P/N is a 120750 COULD have other issues, easy way to tell is pull shift motor assembly, move by hand from where is currently and rotate drive shaft to engage Hi Side. Have someone get in cab, put a ground jumper to housing of shift unit, have them switch Hi/Lo and back. Verify Power swaps at the plug in if does not do anything, check fuses/breakers, power supply at two speed shift button.
Shift motors are always bad. They just corrode to nothing.