I own a 1999 F150 4x4 with a 4R70W and ever since I purchased this truck the 1-2 shift has been hard, really hard! Reading through past posts lead me to believe that it might be my 1-2 shift acculumator spring, but during a recent service I put both new springs and pistons in with no luck. My springs looked OK, but I decided to change everything out in the "accumulator stack" since all the parts were under $30. I changed my fluid at that time as well(all fluid-even torque converter) with fresh Mercon V & added a bottle of Lucas tranny fluid.
All of this, and it doesn't seem to help at all. My 1-2 shift is hard no matter if the truck is under heavy load or not. The accelerator can be all the way in or just a hair in and it still slams into gear. This truck feels like I am being rear-ended by a little car every time this thing shifts. This problem only occurs in the 1-2 range, all others are smooth as silk.
Please offer any suggestions that you may have. I am getting desperate at this point and do not want to ruin my tranny.

Dago

 

I'd suggest getting a pressure guage and testing your line and EPC pressures.

Excessive pressures will cause your symptom (among other things).

Steve

 

If I do in fact have high pressure present, what would cause this? Is there some kind of sensors/solenoids that could be failing?

If I use a standard OBDII scanner (like the loaner @ autozone) would this possibly pull a code from my computer? I don't have any check lights on, but just a thought.

 

The EPC solenoid is computer-controlled to drop the line pressure inside the tranny. Think of it like a pressure regulator, that if it goes bad, allows the internal pressures to rise to the supply pressure. Just an idea at this point.

Check with your auto parts store to see if their scanner can do a KOER self test of your car. Many of the el-cheapos cannot. The better ones can, but the monkeys at the stores usually don't know how to perform this test.

Has your OD light been on or flashing? It is the "MIL" for transmission-related problems.

How do your 2-3 upshifts, your 3-2 downshifts, and 2-1 downshifts feel? Are they also harsh?

Steve

 

My OD light has never flashed for me at all.

My 2-3 up and down shift are as smooth as satin, but the 1-2 upshift is terrble. I can honestly say that the 2-1 downshift is OK, nothing out of the ordinary.

 

worth getting it scanned. Sounds like you have already addressed the mechanicals. Could very well be a selinoid prob. The shift points are computer controlled also so maybe a good place ot look. Otherwise a pressure gauge would be the next step.

 

My old 2000 done the same thing the last week i owned it I was driving along normal and when a slow car got out of my way I puched it the tranny acted up and I done some manul shifting for the next couple days and when i let it do it on its own it started shifting hard at the 1st to 2nd gear change so I took the easy route and traded it in for my new truck and let the dealer or new owner deal with the problem made it to 96k before having a problem.

 

I wish my 4r70w would shift hard from 1st to 2nd. Lucky bastards

 

You probably broke a 1-2 accumulator spring.

 

Did you buy the truck new or used? If you got it used, do you know the previous owner?
Someone may have stuck a shift kit in it or modified the valve body.
Darrin

 

Or the clutches could be bad in the trans....Like mine were...