Help with diff ratios
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New User
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Help with diff ratios
Hi everyone,
I am in Australia and have a 1996 F150 XLT 5.8litre 4 sp auto, 2 x 4.Have changed the gear diff ratios from 3.0 to 1 to 4.1 to 1. It is revving out before shifting gears. Do I need to do anything with the computer ?
Thanks
Tess
I am in Australia and have a 1996 F150 XLT 5.8litre 4 sp auto, 2 x 4.Have changed the gear diff ratios from 3.0 to 1 to 4.1 to 1. It is revving out before shifting gears. Do I need to do anything with the computer ?
Thanks
Tess
Elder User
Joined: Dec 2002
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From: South Carolina
I don't think the computer on your 96 can be reprogrammed, but you can reprogram the speedometer - it has a fixed multiplier stored in it's memory so it knows the vehicles actual speed. It's probably very confused right now, because the speedometer relays this information to the computer and transmission. Ford designed the speedometer to allow for about 7 adustments to this fixed multiplier so people can change gear ratio. So you can only adjust it 7 times without replacing the speedometer - or something like that. Check out this article for resetting the "calibration constant" (the multiplier.
https://www.ford-trucks.com/article/...ND_BRONCO.html
https://www.ford-trucks.com/article/...ND_BRONCO.html
Post Fiend
Joined: Nov 2001
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From: Topsfield, MA
88's use a cable operated speedo - you'll have to change the plastic gears inside the tranny or TC (2wd/4wd).
Isn't it true that since the speedometer sensor on the 92-96's is after the ring and pinion gear - that a gear change does NOT effect speedometer readings, but a change in tire size does...
Isn't it true that since the speedometer sensor on the 92-96's is after the ring and pinion gear - that a gear change does NOT effect speedometer readings, but a change in tire size does...
Post Fiend
Joined: Mar 2002
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From: Bonita Springs FL
Yes, that's true. That's exactly what I was going to say.
My guess is that when the new gears were installed, the tone ring wasn't. So the computer has no idea how fast the vehicle is going and doesn't know when to shift.
My guess is that when the new gears were installed, the tone ring wasn't. So the computer has no idea how fast the vehicle is going and doesn't know when to shift.
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Originally Posted by andym
Yes, that's true. That's exactly what I was going to say.
My guess is that when the new gears were installed, the tone ring wasn't. So the computer has no idea how fast the vehicle is going and doesn't know when to shift.
My guess is that when the new gears were installed, the tone ring wasn't. So the computer has no idea how fast the vehicle is going and doesn't know when to shift.
Elder User
Joined: Dec 2002
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From: South Carolina
The tone ring is a thin toothed ring that sits next to the ring gear in the differential. It works with a sensor to tell the speedometer how fast the rear wheels are turning (using the multiplier to account for differing gear ratio and tire size) If the speedometer is working, it's still there.
