86sidestep

hey fellas, my truck is having trouble getting into gear and shifting up. she just revs like a @?#!% and refuses to get out of 1st, maybe not even in 1st at all...wont go over 35 mph. i dont think it's a leak because the trans fluid is full. any thoughts ?

thanks,

86sidestep

Braggs

There's a few things that could be causing this. I'll address them all, but first, since I don't know your knowledge level, I'll explain things as simple as I can. You likely have a C6 or AOD transmission. This transmission works on a combination of road speed, engine speed, vacuum pressure, and transmission fluid pressure. If the fluid doesn't get to where it's supposed to, the transmission doesn't work right. The clutches have pistons in them that are activated with transmission fluid pressure behind them (like a hydraulic cylinder). This compresses the clutches and transfers rotational force from the input to the output.

The valves in the valve body are spring loaded and allow the flow of fluid based on the fluid pressure and vacuum switches. There's a governor on the output shaft of the transmission that uses centrifugal force to activate a couple of valves that allow or prevent the flow of fluid to the valve body. This is how it knows your road speed to create up/down shifts.

So, what could be causing your issue? Several things:

• Age. Being over 30 years old, your transmission likely needs a rebuild if it hasn't had one in the last 10 years. Inside the transmission is a lot of rubber gaskets and seals that get hard with age and quit sealing as good which doesn't let the piston squeeze the clutches as hard as they should (if at all). This will cause it to not engage into gear or allow the clutches to slip which will deteriorate your clutch material which could flake off and get lodged in one of the valves.
• Debris in the fluid. If you have flakes of clutch material floating around in your fluid, this could block one of the valves from opening or closing which would/wouldn't allow the fluid to go where it's (not)supposed to and would prevent the vehicle from shifting gears properly. Recommend cleaning the valves in the valve body and the governor when rebuild is done.
• Low ATF fluid levels. Transmissions work using principles of hydraulic pressure using transmission fluid as its medium. If you don't have enough fluid, it can't build up the pressure that it needs to activate the valves and pistons.
• A loose/worn intermediate band could also prevent shifting into higher gears. Make sure this is adjusted properly.
• Loose/disconnected shift linkage. If you're moving the gearshift but nothing is working, check the linkage first before removing the transmission. It should be nice and tight and actuate the shaft sticking out of the transmission.
• Problems in the transfer case. If you have a shift lever that breaks its plastic shifter tabs and the transfer case becomes disconnected, this would prevent movement even if the transmission is working properly.
• Malfunctioning torque converter.

klricks

Make sure the AOD TV (Throttle Valve) cable is adjusted properly. If not adjusted properly or broken then the transmission will be destroyed in a handful of miles.

The TV cable is sometimes mistaken for a 'kickdown' cable but it is NOT that.
Google [Ford AOD TV adjustment] for tons of info on how to adjust.

If the TV is adjusted properly then it's time for a tranny rebuild or swap.