trans shifts with larger tyres

[Gavin]

Hi Guys
Gav from Australia dont have much info over here on these trucks
i have a 90 7.3 idi with ED04
have put on 35's the trans has never felt to shift propeley
i have replaced the FIPL and adusted as per info link
when crusing at hwy speed my speedo reads 55mph when i apply more throdle it shifts up a gear same when i back off it ***** back a gear
if i really feed it up a hill the speed will drop off then shifs back really hard like dropping into nutral and the rpm goes to 3500,4000 and only gets a gear when i back off the throdle again.

any help will be greaty appeeated

 

[franklin2]

Welcome to running oversized tires. Do you know what gears you are running in the rearends? I am running 4.10's with the zf 5 speed and 35 inch tires and no turbo. Any type of decent hill I run against, if I did not get a running start before I get to the bottom of the hill, halfway up I am shifting out of overdrive to make it to the top. Sounds like your trans is just doing this automatically.

If you are running 3.55 gears it's really going to be bad.

 

[IDIBRONCO]

when crusing at hwy speed my speedo reads 55mph when i apply more throdle it shifts up a gear same when i back off it ***** back a gear

By saying this, do you mean that it downshifts when you push the throttle and then upshifts when you let off? A downshift is going to a lower gear while an upshift is going to a higher gear. Are you certain that it's actually shifting gears and it's not the torque convertor locking and unlocking? A gear shift will have more of a change in engine RPMs than the torque convertor will. I could easily see the torque convertor unlocking at highway speeds with very light throttle. Especially with larger than stock tires. I'm no transmission expert, but the transmission acting like it goes into neutral with heavy throttle sounds like something is wrong in either your transmission or torque convertor. An easy thing to do is to check to make sure that it's not low on transmission fluid.

 

[Slicknik]

@Gavin if its feeling like it’s dropping out of gear then you need to swap your neutral safety switch

This is if you feel the trans is dropping out of gear but will go into drive but drop out of OD

I have 3.55 in the rear and run 33”s , you really only see issues when towing heavy with your setup，you will eventually go through a torque converter

The pic I posted is what I replaced for my issue

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[Thewespaul]

Thats the MLPS, a lot of times they will leak from the shifter shaft and take out the sensor.

 

[trackspeeder]

Hi Guys
Gav from Australia dont have much info over here on these trucks
i have a 90 7.3 idi with ED04
have put on 35's the trans has never felt to shift propeley
i have replaced the FIPL and adusted as per info link
when crusing at hwy speed my speedo reads 55mph when i apply more throdle it shifts up a gear same when i back off it ***** back a gear
if i really feed it up a hill the speed will drop off then shifs back really hard like dropping into nutral and the rpm goes to 3500,4000 and only gets a gear when i back off the throdle again.

any help will be greaty appeeated

At 55 MPH giving it some throttle should unlock the converter. When you let off the throttle the converter will lock again.

At 55MPH ish, if you hit the go pedal hard. The converter will unlock, then drop to third gear. This will give you high RPMs.

Bigger tires will throw the speedometer off. This will throw off the shift points. The TCM uses the speedometer as one of its inputs.

When the tranny randomly goes into neutral when cruising. The TRS is bad.

 

[Gavin]

Thanks guys
Hard to explain
When I slowly put my foot down approx %25 the trans shifts and the revs drop by about 500 rpm
I keep putting my foot down till %100
Then trans drops back the rpm red lines then trans goes to shift up and dose this up down up down until I lift off the gas