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| | | | Joined: Aug 2009 Posts: 25 Apprentice | | Apprentice Joined: Aug 2009 Posts: 25 | Anyone have any idea? Seems to be turning a high rpm out on the highway. Didn't know if that was normal? Thanks. | | | | | Joined: Nov 2008 Posts: 98 Wrench Fetcher | | Wrench Fetcher Joined: Nov 2008 Posts: 98 | it is probably a 4:11...you can go under the truck, wirebrsh the front of the axletube on the passenger side next to the pumpkin,find the code then go on www.americanclassic.com ,they have an axle decoder. hope that helps....mark | | | | | Joined: Aug 2009 Posts: 25 Apprentice | | Apprentice Joined: Aug 2009 Posts: 25 | Thank you very much.
Jason | | | | | Joined: Aug 2009 Posts: 25 Apprentice | | Apprentice Joined: Aug 2009 Posts: 25 | I couldnt get the axle decoder to work? I must be doing something wrong. When I put in 1963 by the axle code column, it doesnt take me anyhere. Any help? Jason | | | | | Joined: Apr 2005 Posts: 2,832 'Bolter | | 'Bolter Joined: Apr 2005 Posts: 2,832 | Jack the rear end up on one side only, leave the other tire touching the floor so it won't turn. Mark the driveshaft and see where the valve stem is pointing (like 1:00 oclock, 8:00 oclock etc.) If your by yourself mark the inside of the tire so you can turn it TWO revolutions while watching the driveshaft. Count the number of times the driveshaft turns in two tire revolutions and that is the gear ratio. A 4.11 will be four turns plus a smidgen, a 3.90 will be not quite four turns, a 3.55 will be three and a half turns, etc.
Evan
| | | | | Joined: Oct 2005 Posts: 1,317 Shop Shark | | Shop Shark Joined: Oct 2005 Posts: 1,317 | Evan hit the nail on the head with his technique for checking out the R&P ratio. However, it's tough to differentiate between that "smidgen." Not much difference between a 3.08, 3.28 or a 3.38. I've found that if you turn the tire 10 times, and then multiple the number of turns of the pinion by 2, then divide by 10, you'll get the first TWO numbers of the R&P ratio. As an example 10 rotations of the tire produces 20-1/2 rotations of the pinion......multiply by 2 which equals 41 and divide by 10 gives you 4.1. That narrows the options appreciably.
Dave
Last edited by Fla54Chevy3100; 12/12/2009 1:12 AM.
| | | | | Joined: Dec 2006 Posts: 1,464 Shop Shark | | Shop Shark Joined: Dec 2006 Posts: 1,464 | Even more accurate, with less math: turn the wheel 20 times, divide the driveshaft rotations by 10.
If it's a posi, jack up both wheels, spin the wheels 10 times and divide the driveshaft rotations by 10. | | | | | Joined: May 2006 Posts: 8,351 'Bolter | | 'Bolter Joined: May 2006 Posts: 8,351 | What's the code numbers? I can check them against that code book for you.
Bill Burmeister
| | | | | Joined: Apr 2005 Posts: 2,832 'Bolter | | 'Bolter Joined: Apr 2005 Posts: 2,832 | Darn, you guys are sharper than tacks but, when it's a 100+ in Texas, your at a junk yard laying in a fire ant mound, and the brakes are dragging then my approach is if it's more than three and a half turns go with a 700R4 and if it's less stick a turbo 350 in it. Sort out the speedo later.
Evan
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