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Old 11-19-2015, 08:02 PM
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Default Speedo calibration NP241

So back in my rock crawler days, the Jeeps used np231 tcases. I had a chart with gear (r/p) and speedo gears that you used tire diameter or rev/mi to figure out which gear you needed when altering tire sizes..

Anything like that for the 94-98 style tcases?
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Old 11-19-2015, 08:12 PM
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I found it.. LOL


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SOLD: 96 2500 sclb 4x4, 5spd swap, cam, stack, #10, bhaf, 16.5*, 27mpg
SOLD: 01 2500 qcsb 4x4 HO 6spd, 2" level, 5" exh., Edge Juice, bhaf, 16mpg
SOLD: 97 3500 cc-drw, built 47re, 3 disk, 4" exh., #100, bhaf, gauges
SOLD: 02 QCSB 2500 4x4 5.9-auto
SOLD: 97 ECLB 2500 4x4 V10-auto.. junk..
CURRENT:'06 2500 ThunderRoad QCSB 5.9CTD 4x4, built Auto; '02 Silverado 2500HD 6.0L CrewCab LB 4x4; '14 vw cc r-line 2.0t 6 speed

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Old 11-19-2015, 09:21 PM
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Do those numbers represent gear numbers or tooth count or what?
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Old 11-20-2015, 07:08 AM
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they represent tooth count of the driven gear (the one that is on the end of the speed sensor).
You can increase or decrease the number of [driven gear] teeth depending on tire size to make your speedometer more accurate. The drive gear has 13 teeth and is machined into the output shaft.

So stock, 245/75-16 is 30.5" tall. This should be represented with a stock driven gear of 32 or 33 teeth, if you have a 3.55 axle. Upgrading tires to, say, 35", means you'd now need a 28-tooth driven gear to correct the speedo, or at least, get it more "accurate".
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SOLD: 96 2500 sclb 4x4, 5spd swap, cam, stack, #10, bhaf, 16.5*, 27mpg
SOLD: 01 2500 qcsb 4x4 HO 6spd, 2" level, 5" exh., Edge Juice, bhaf, 16mpg
SOLD: 97 3500 cc-drw, built 47re, 3 disk, 4" exh., #100, bhaf, gauges
SOLD: 02 QCSB 2500 4x4 5.9-auto
SOLD: 97 ECLB 2500 4x4 V10-auto.. junk..
CURRENT:'06 2500 ThunderRoad QCSB 5.9CTD 4x4, built Auto; '02 Silverado 2500HD 6.0L CrewCab LB 4x4; '14 vw cc r-line 2.0t 6 speed

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Old 11-20-2015, 09:14 AM
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My truck says it is supposed to have 245/75R16 tires on in, but it had 265/75R16 on it and the speedometer is pretty close at 60 mph. There is about a 1 mph discrepancy there, but, when the speedometer shows 35 mph the truck is only going 32 mph. That is using a GPS to verify the speed. How would a person go about correcting that problem?
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1996 RAM "Custom Ground" 100 plate 3/4 forward, 300 injectors, 16.5 timing, Goerends Auto = 365HP, 833TQ Third Gen Rims, Aluminum Headache Rack
Duct Tape can't fix stupid, BUT it can muffle the sound
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Old 11-20-2015, 09:32 AM
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What axle is in it?

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SOLD: 96 2500 sclb 4x4, 5spd swap, cam, stack, #10, bhaf, 16.5*, 27mpg
SOLD: 01 2500 qcsb 4x4 HO 6spd, 2" level, 5" exh., Edge Juice, bhaf, 16mpg
SOLD: 97 3500 cc-drw, built 47re, 3 disk, 4" exh., #100, bhaf, gauges
SOLD: 02 QCSB 2500 4x4 5.9-auto
SOLD: 97 ECLB 2500 4x4 V10-auto.. junk..
CURRENT:'06 2500 ThunderRoad QCSB 5.9CTD 4x4, built Auto; '02 Silverado 2500HD 6.0L CrewCab LB 4x4; '14 vw cc r-line 2.0t 6 speed

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Old 11-20-2015, 09:43 AM
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Quote:
Originally Posted by rogan View Post
what axle is in it?

Sent using sprint's invisible microwaves..
3:55
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1996 RAM "Custom Ground" 100 plate 3/4 forward, 300 injectors, 16.5 timing, Goerends Auto = 365HP, 833TQ Third Gen Rims, Aluminum Headache Rack
Duct Tape can't fix stupid, BUT it can muffle the sound
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Old 11-20-2015, 09:47 AM
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265/75 is roughly 31.7" having said that, you should have a 33 tooth gear. Changing to a 31 or 32 would theoretically correct the speedo.

Sent using Sprint's invisible microwaves..
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SOLD: 96 2500 sclb 4x4, 5spd swap, cam, stack, #10, bhaf, 16.5*, 27mpg
SOLD: 01 2500 qcsb 4x4 HO 6spd, 2" level, 5" exh., Edge Juice, bhaf, 16mpg
SOLD: 97 3500 cc-drw, built 47re, 3 disk, 4" exh., #100, bhaf, gauges
SOLD: 02 QCSB 2500 4x4 5.9-auto
SOLD: 97 ECLB 2500 4x4 V10-auto.. junk..
CURRENT:'06 2500 ThunderRoad QCSB 5.9CTD 4x4, built Auto; '02 Silverado 2500HD 6.0L CrewCab LB 4x4; '14 vw cc r-line 2.0t 6 speed

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Old 11-20-2015, 09:52 AM
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Far as the 1 mph at 60 difference, I am happy with that, but how do you correct the mid range?
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1996 RAM "Custom Ground" 100 plate 3/4 forward, 300 injectors, 16.5 timing, Goerends Auto = 365HP, 833TQ Third Gen Rims, Aluminum Headache Rack
Duct Tape can't fix stupid, BUT it can muffle the sound
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  #10  
Old 11-20-2015, 10:33 AM
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It generally isnt linear, from my experience.

Sent using Sprint's invisible microwaves..
__________________
SOLD: 96 2500 sclb 4x4, 5spd swap, cam, stack, #10, bhaf, 16.5*, 27mpg
SOLD: 01 2500 qcsb 4x4 HO 6spd, 2" level, 5" exh., Edge Juice, bhaf, 16mpg
SOLD: 97 3500 cc-drw, built 47re, 3 disk, 4" exh., #100, bhaf, gauges
SOLD: 02 QCSB 2500 4x4 5.9-auto
SOLD: 97 ECLB 2500 4x4 V10-auto.. junk..
CURRENT:'06 2500 ThunderRoad QCSB 5.9CTD 4x4, built Auto; '02 Silverado 2500HD 6.0L CrewCab LB 4x4; '14 vw cc r-line 2.0t 6 speed

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