Hey guys, I got a '94 F150, with a 351W and an E4OD trans. I'd like to change my rear gears to 4:11's, to get a little more bottom power. Recently I changed my trans fluid and noticed that there is a block off plate where the speed sensor should be. Is there some kind of trick to recalibrate the speedo after gears and tires, or are you just stuck with whatever you have after a gear change?

Thanks

 

The speedo runs off the VSS in the rear differential, the PSOM in the back of the speedo itself can be adjusted for tire size but only 6 times total.

If you want to know the procedure for the change just ask and I'll post it for ya. It is easy to do and only takes a minute or so to adjust for tire size, no need to make any adjustment for gear change, fhe speedo is not effected by gear changes.

 

Hey man, thanks alot!! I appreciate it and would be most greatful if you'd post the procedure for me. The truck has 29" tall tires on it, and 3:55 gears. It turns 1,580 RPMs at around 55 or 60 MPH's in OD, and before I changed the trans fluid, it wanted to kind of surge when I ran it in regular drive. I figure it could really benefit from lower gears.

1 more question though, since it gets its VSS from the rear diff, is it getting it from the ring around the outside of the ring gear? If so, I cant disable the ABS without throwing the computer into a fit can I? On my '89, I bypassed the antilock part under the master cyl, and unpluged it. I hate ABS, and the trucks had some problems with it, I'm told? The truck has decent brakes, but not what I'd call outstanding. On my '89, after I bypassed all that junk, it stopped much better. I dont use it for pulling a trailer or anything anyway, I just hate the ABS junk.


Thanks again and GOD bless

 

<i>since it gets its VSS from the rear diff, is it getting it from the ring around the outside of the ring gear?</i>

Yes, that is why gear changes do not effect the speedo's reading.

1580RPM's is pretty good at 60mph, my 5.8 with 3.55 runs at 1400 at 55mph in O/D. Same as my 7.5L 3.55 gears. Plenty of "roll on power" from there and power to tow with both. I wouldn't want it spinning faster at that speed, no real need to and helps to save a little fuel.

Programing for tire size,

Locate the connector at the bottom of the instrument panel below the center of the glove box. Should be LB/Y, has "PSOM" printed on the connector in white lettering. Held in place with a plastic retainer.

Insert a jumper wire or alligator clip in service wire and clip other end to vehicle ground with the key in the OFF position.

Turn key to RUN while holding down the trip odometer RESET button on the speedometer.
Release RESET button The Speedometer will prove out(sweep across dial and back). The English/Metric and revision levels will be displayed. The last number of the display id the dealer mode lockout count. This count shows the number of allowable conversion constant changes remaining. When the count is zero (0), no additional changes can be made to this instrument cluster. If a revisions required a service instrument cluster must be ordered.
Press and release RESET button again and PSOM conversion constant without the decimal point will be displayed followed by the word CAL.

Press and release the odometer SELECT button as many times as necessary to change the conversion constant to the correct value. The constant will only increase (not decrease) when the SELECT button is pressed so reducing the constant means counting up until the constant jumps to the bottom of the scale and begins counting up from there.

Pressing and releasing the RESET button to lock in the new conversion constant reduces the number of times the PSOM can be reprogrammed by one count. If you change your mind and want to go back to the old conversion constant, turn the key OFF BEFORE you lock in the new constant.

Here is a thread that may be of some help,
https://www.ford-trucks.com/forums/7...tire-size.html

 

You can unplug the ABS module under the dash and the computer will not care.
But the plug on the rear end must remain as it still has to feed the PSOM and Speed Control and the Computer get there information from the PSOM.

When the ABS is disabled the brake system will revert back to old style brakes.

 

My friend just gave me this Ford F-150 XL with the Windsor V8. The previous quote owner had driven it with the tranny and limp mode for who knows how many miles so the second gear is pretty blown out. However after disassembling the PCM and replacing all three 10 Milli farad capacitors, she's up and shifting again just like new. I'm super amazed this truck ran with two blown capacitors. My question is regarding this post... I'm about to recalibrate my truck to run the 31-inch tires that are on it. I can see that the speedometer is off by about 20% and it's shifting way late out of first I'm guessing this is the reason? Is there anything besides the tire adjustment? I'm guessing the previous owner damage the second gear clutch pack or band by leaving it in limp mode for who knows how long... Is there anything else to cause a harsh second gear engagement with all the other gears engaging normally? Thanks again to this forum for helping me get back on the road ..electrical issues to the tranny controller same as my Jeep..