What rear-end gears do I have?
#11
07-26-2011, 12:34 AM
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#12
07-26-2011, 06:20 AM
It is. I have had people ask why it pushes you back in the seat a bit. I can wromp on it at 10-11 mph and chirp the tires
#13
07-26-2011, 08:43 AM
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#14
07-26-2011, 09:03 AM
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lift the rear of the truck up...
put a chalk mark on your drive shaft. have a buddy mark the tire on teh top or bottom, and then have him spin the tire slowly. have him count how many times the tire spins around, while you wait to see the drive shaft make one full rotation.
(count how many times the tire goes around, compared to the drive shaft)
if it turns 4.5 times for 1 turn of the drive shaft, you have 4.56s. I am guessing it turns about 4 times. (3.92) if it turns 3.5 then you know its 3.55s
the difference between 4.10 and 3.92 isnt much, so its going to be harder to tell.
You are 4x4. in order to have 4.56s, your front diff needs revers cut gears. they are extremely hard to find.
put a chalk mark on your drive shaft. have a buddy mark the tire on teh top or bottom, and then have him spin the tire slowly. have him count how many times the tire spins around, while you wait to see the drive shaft make one full rotation.
(count how many times the tire goes around, compared to the drive shaft)
if it turns 4.5 times for 1 turn of the drive shaft, you have 4.56s. I am guessing it turns about 4 times. (3.92) if it turns 3.5 then you know its 3.55s
the difference between 4.10 and 3.92 isnt much, so its going to be harder to tell.
You are 4x4. in order to have 4.56s, your front diff needs revers cut gears. they are extremely hard to find.
Last edited by ericemery; 07-26-2011 at 09:06 AM.
#15
07-26-2011, 01:39 PM
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#16
07-26-2011, 03:23 PM
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"My truck has" doesn't really apply here...obviously the previous owner wasn't afraid of unusual mods - the 2500 leaf springs being one example.
If the torque converter is locked and the 4 speed auto is in overdrive, then the driveshaft is spinning exactly 31% slower than the engine. Irrefutable.
Even assuming that Backwoods doesn't have his speed corrected for his 31" tires, here again is a simple calc:
245/70 R16 tires = 684 revolutions per mile (stock tire size = stock speedometer calibration)
58 MPH = 0.967 miles per minute
684*.967= 661 indicated axle revolutions per minute
661*4.56=3014 driveshaft RPM
3014*0.69 (overdrive) = 2079 RPM
Or...almost exactly what his gauges indicate.
Drop the axle ratio to 4.10, and the engine RPM's work out to 1870 RPM. No way his gauges are so innacurate! I'm telling you...4.56:1 in that beast.
If the torque converter is locked and the 4 speed auto is in overdrive, then the driveshaft is spinning exactly 31% slower than the engine. Irrefutable.
Even assuming that Backwoods doesn't have his speed corrected for his 31" tires, here again is a simple calc:
245/70 R16 tires = 684 revolutions per mile (stock tire size = stock speedometer calibration)
58 MPH = 0.967 miles per minute
684*.967= 661 indicated axle revolutions per minute
661*4.56=3014 driveshaft RPM
3014*0.69 (overdrive) = 2079 RPM
Or...almost exactly what his gauges indicate.
Drop the axle ratio to 4.10, and the engine RPM's work out to 1870 RPM. No way his gauges are so innacurate! I'm telling you...4.56:1 in that beast.
#17
07-26-2011, 04:09 PM
Well here is the answer: DSCN0968.jpg
I called masterack. (company in the sticker) They confirmed that it was a fleet vehicle of theirs and was put up for auction because they were going full size. They installed a rear/front end ratio of 4:56.1 and installed 2500 leaf springs along with 265/75/16 highway tires to compensate the load of the truck. It was a sales/service vehicle that installed and sold ladder racks etc. at jobsites and was strictly an in town/ light highway vehicle. I am still in shock
. I have always wondered what this sticker was for and why they had 3/4 ton leafs in it. now I know
I called masterack. (company in the sticker) They confirmed that it was a fleet vehicle of theirs and was put up for auction because they were going full size. They installed a rear/front end ratio of 4:56.1 and installed 2500 leaf springs along with 265/75/16 highway tires to compensate the load of the truck. It was a sales/service vehicle that installed and sold ladder racks etc. at jobsites and was strictly an in town/ light highway vehicle. I am still in shock
. I have always wondered what this sticker was for and why they had 3/4 ton leafs in it. now I know
#19
07-26-2011, 04:12 PM
#20
07-26-2011, 04:15 PM
