hard shifting

[rollie]

I have a 93 f-150 2wd with a 302 v8 overdrive auto tranny. it has about 109K miles.

ever since I bought this truck last spring it shifts hard sometimes, it also down shifts and up shifts if I am going between 40 to 50 mph with out any load,{ just easy cruising.} sometimes it shifts normally smooth, but it shifts hard most of the time. how hard does it shift? enough to feel like a sack of cement was dropped into the bed.

any suggestions?

[mark v]

40 to 50 MPH is where the area where OD kicks in so if you go under 50 OD will turn off and over 50 OD will turn on. (OD= Over Drive)

Change the Transmission fluid.

[theoldwizard]

If your changing the ATF yourself, don't forget to drain the torque converter. Good time to replace the filter.

[BroncoJoe19]

Changing the trans fluid is probably overdue, so you should probably take ther advice and do it or have it done.

Regarding your shifting problem it may be due to a vacuum leak, a flaky TPS, VSS, or MAP sensor.

Pull Diagnostic Trouble Codes (DTCs) From your onboard computer.
Your engine and transmission are computer controlled.
The computer uses sensors to tell it a number of different things and it controls actuators that push or pull mechanical levers (kinda). If one or more sensors aren't working properly, the computer goes "blind" and doesn't know what to do. If the computer can "see" but one of the actuators is broken and therefore can't follow the commands of the computer; the engine won't run correctly. The computer is preprogrammed with set values for each of its sensors, and each of its actuators. It will run a self check of all systems, like the space shuttle; it will compare its set value(s) to the value(s) it recieves from its sensors, and actuators. If any sensor or acutator is out of the "normal" range the computer will generate a "code." It will generate some codes on the fly, and others will be stored while you are driving. There is a simple method to "pull codes" out of the computer for one to use for diagnostic purposes.

Earlier versions of On Board Diagnostics OBD 1983-1995 can flash the error code to the dash board and can be pulled in one's driveway without any special tools.
Later versions of On Board Diagnostics OBDII some 1995, and pretty much all 1996 and newer, require one to use a code reader or scanner tool.

Some auto parts stores will scan your engine codes for FREE, you may want to call around. Some will scan OBDII but not the older (prior to 1996) OBD systems.

SO here you go...
How to scan FORD on board Diagnostic Trouble Codes (DTCs) in your driveway
Howto Pull Codes 1983-1995 Mustang, F series Trucks, Econolines, Broncos, 302, 351 and more

[chiapcs05]

If it keeps on hard shifting check for a worn or broken tranny mount