I have been told that changing the rear gear ratio on my 99 Lighting will affect the proper shifting of the transmission and other related problems, including speedometer calibration. Has anyone done this successfully ?

 

 

Bill,
Changing ratios, tires sizes, rims size..will affect your tranny shift points. speedometer. i t cost me $100.00 at a frod dealer to re-program the computer. I believe it can be re-calibrated one more time in case i change sizes again or the ratio.
Check this www site out:
https://www.ford-trucks.com/tfts/calc.htm
good luck,
al

 

Bill
it can be done,i assume your 99 came with the 3:55 gears,and you may be looking at 3:73 or 4:10's which are hard to find.You should have little problem with the 3:73's but your speedometer will need to be recalibrated.If you go to 4:10's you may find you hit the rev limiter before the tranny shifts,the same problem exists if you want to go to a better torque converter,it locks up and runs into the rev limiter,also any change in tire or rim size causes problems with correct speedo readings and shift points.do it one step at a time,put in your gears,i think 3:73 as the 2001 have are more than adaquate,drop the extra $250 and put on an aluminun drive shaft,stronger and better balance.
Then to recalibrate,get a diablo super chip,or maybe a flip chip.the chip will give you crisper shifts and a bit of boost in the hp and torque.your 99 has the best computer i think i've heard about it seems to run better than the 2001 or 2000 computers, in other words your truck may be faster already than a 2000,i have a 2000 love it and have loaded it up with mods,but am only running 13.2 at 104 mph,not bad but should be better.If ya wanna drop me a line i can tell you what i know about the gear changes etc.
LIGHTNING GUY (HAMPTONHARLEY@YAHOO.COM)

 

[font size="1" color="#FF0000"]LAST EDITED ON 30-Apr-01 AT 05:26 PM (EST)[/font][p]Actually you only need to recalibrate your speedo if you change tire sizes. Gear ratios don't affect the way the system works.

This is why - the speedos get their signal from an exciter ring (Hall effect sensor) that's attached to the driver's side axle. It reads the rotations of the axle and translates that into mph based on a fixed distance being covered by a single rotation of the axle. Changing things upstream (read diff ration, gear ratios within the transmission, etc) won't effect the ratio of distance to axle rotations, but changing the tire size will.

The '99 computer actually has the most conservative tune of the three years. The '00 trucks run a tenth or two faster in the quarter compared to the '99s, and I'm sure we all know about the '01s. My '00 ran a 13.6 completely stock with 1200 miles on it, and dropped to a 13.36@101.75 with just the addition of a Swanson Performance chip.

Later!
Jeff S.
Lightning #74 in '95 - 11.92@115.2
Lightning #582 in '00 - 13.36@101.75

 

jeff,
come on a 13.6 stock,??????

 

[font size="1" color="#FF0000"]LAST EDITED ON 02-May-01 AT 08:08 PM (EST)[/font][p]Yep, 13.6@99.5. If you have last years issue of MM&FF that covers the World Ford Challenge (I don't remember what month, probably August or September) you can find my name in there as losing in the semi-finals running a 13.9 on a 13.4 dial. For me to have the 13.4 dial, I had to have ran a 13.6 in qualifying (for the Open Comp classes, the event assigns a dial that's two-tenths faster than your best qualifying pass).

The truck had a 1200 miles on it at the time, 700 of them racked up towing a Mustang from Baton Rouge to ##### Louis for the event. I basically drove to the track, unhooked the trailer, raced the truck, hooked back up, and drove home (of course, this was over a 4 day period). I kept joking that it still had stock air in the tires. The only mod was a Jack In The Box antenna ball.

Something I learned about non-chipped Lightnings - the computer pulls TONS of timing when there's a little bit of heat in the engine. I had just ran a 13.7, but had basically hot lapped from the quarter finals to the semis). I treed my opponent (Jarret Bencie, the eventual winner) badly, but the truck wouldn't run the number.

Later!
Jeff S.
Lightning #74 in '95 - 11.92@115.2
Lightning #582 in '00 - 13.36@101.75