Im new to Fords and just picked up a 97 F150 lariat v8 automatic. It has 150k on the speedo. Just noticed when taking off it starts to move then it feels like it kicks in gear with what feels like being bumped from behind.

Seems to only happen in 1st or 2nd gear. All other gears are nice and smooth and truck seems to run good otherwise.

Anyone have any idea what this could be and what the fix is? Thanks in advance for any input.

 

The trans is electrically controlled by the engine computer that directs it when to shift by operating internal solenoids.
After that takes place fluid is directed through valve body passages to a spring loaded valve to allow fluid pressure to the servo that either compressed clutch discs or tighten a band.
If there is no transmission code involving the electrical part of the operation, the spring loaded valve in the valve body could be broken or the valve sticks.
This spring softens the fluid pressure application to the servo.
If it is broken or sticks, a harsh engagement could take place by slamming the servo with fluid under high pressure instead of a more controlled application of fluid pressure.
Good luck.

 

I have a 03 F150 4.6 XLT with a little over 184,000 miles on it and hard shifts between 1 and 2 and at times when i accelerate at higher speeds it seems to hesitate between gears for moment before kicking in. Searching in to the past few days I read a Lot folks say its normal and what not. The one thing I kept reading here and there was to use Lucas transmission fix. Hadn't used it yet. Yesterday I spent time looking it to that product and tomorrow I am going to try it out. What I gathered when mixed properly will stop that. I'll inform a yay or nay reply tomorrow evening.

Read alot on what Bluegrass wrote just not explained in depth detail.

 

Harsh shifting is not a normal operation in the design.
There is no reason to allow it to happen, from a design stand point.
I have 284k miles with no harsh shifting.
Good luck.

 

Thank you very much for that informative reply. One question though, if it was a sticky or broken pressure valve, wouldn't the hard or sudden engagement happen throughout all the gears?

Mine seems to only happen first or second gear.

Second question would be how hard is it to check the pressure valve? Is that inside trans?

Thanks again for your time and help. I might try that Lucas oil if it works!

 

The valve body and solenoids are located on the bottom of the transmission assembly.
To get to it the fluid has to be drained and Pan removed.
The valve body has "multiple" spring loaded valves and Ball checks to control the fluid path through the body passages to the respected servos for upshifts and down shifts..
Additive won't fix that. It may modify it to some extent but it's not a fix.
Additives are mainly to cause a bit more friction from worn clutches and bands and expand leaking seals to buy a little more time.
It has to come apart to inspect for the fault.
Good luck.

 

Some of the 4R70Ws are infamous for breaking one of the springs in the 1-2 accumulator. It's fairly easy to get to. Only the pan has to be removed. It's located towards the front driver's side. I'm not an expert on these transmissions but I did change the springs in my 95 Mark VIII 1-2 accumulator to quicken the shift. My 2002 truck has double springs in the place of the one that usually breaks.

 

I had this issue with my old 2000 F150 towards the end of my ownership with it. It got to the point where it wouldn't shift from 1st to 2nd gear in drive but you could go from 1st to 2nd manually. Done for for a few days before I got rid of it the day I traded it in for my 2005 it shifted from 1st to 2nd in drive but was a very hard shift.