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Dan Gruber
GenIII
 
12/18/2001
17:38:58
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 Subject: Computer Recalibration Required?
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Message:
I'm aiming this question at anyone with the 4.7 auto combination that has either changed gearing or gone to larger tires, or both.
Will a gearing and/or tire size change screw up the transmission shift points? I'm asking because I've talked myself into tighter gearing (probably 3.90), larger tires (either 32's or 33's) and a lift to clear the tires. The only thing stopping me right now is a concern that changing the gears will screw up shift points and that larger tires will only complicate it. I'd really hate to spend the money for all that and then find out that I need to have the computer recalibrated or get a custom flash done to bring the shift points to where they need to be. I'm not concerned about the speedometer being accurate, although that would be nice.
Dan
2000 CC SLT 4.7 4X4 Auto 3.55 LSD
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Dan Gruber
GenIII
12/18/2001
17:49:17
|  RE: Computer Recalibration Required?
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Message:
By the way, I think the speedometer might be okay by changing gears...if I'm reading my service manual right the Daks use either an axle or wheel speed sensor for speedometer readings, either of which should be unaffected by a gear change. But the manual doesn't specify exactly what triggers the shift points, just that it takes into account the speed, RPM, temps, etc.
Dan
2000 CC SLT 4.7 4X4 Auto 3.55 LSD
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Hawkeye
*GenIII*
12/18/2001
20:47:26
|  RE: Computer Recalibration Required?
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Message:
Mine is ok with the 33's. Torque converter likes to unlock a bit more often now, especially goin gover bridges, overpasses etc, but nothing major. New gears will put the speedo back closer to normal. Plan on 3.90's (all thats available for 2000 + up right now) myself soon as I have the $$. Not sure how/where shift points are read from but as far as I know, the new gears will make it act more like stock.
But you already know how mine rides. :-)
'00 QC 4x4
4.7 3.55 LSD
33x12.50 Pro Comp X-T's
Urban Warrior
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Dan Gruber
GenIII
12/18/2001
21:23:01
| RE: Computer Recalibration Required?
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Message:
I figured the converter would unlock more often with the taller tires, but I'm not too worried about that. Maybe it's nothing, but here's what concerns me: If the transmission were to depend on speed to know when to do a wide open throttle shift, then a change in tire size would change when that shift occurs because the speedometer would be wrong with the larger tires. But if the transmission depends on engine RPM and load, then the transmission should behave normally. The service manual isn't real clear on that point.
Do you see what I'm saying? Or should I just lay off the crack?
Dan
2000 CC SLT 4.7 4X4 Auto 3.55 LSD
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Hawkeye
*GenIII*
12/18/2001
22:11:48
| RE: Computer Recalibration Required?
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Message:
I know exactly what your saying. From the way mine has performed, I am going to say it is going on RPM and load from the engine.
'00 QC 4x4
4.7 3.55 LSD
33x12.50 Pro Comp X-T's
Urban Warrior
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