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confusion of what gears i have

P

projectTK

NAXJA Forum User
Location
Swantucky
I was reading the 4wdhardware parts book. I was looking at the tire and gear combo that tells u best rpm for economy. I have 31inch tires, dana 60rear and dana 44 front. The spec sheet i have for these axles say 355's. At 1:1 ratio 4th gear in my nv4500 at 65mph which the tables are rated at says i should be doing 2508rpm at 65mph. Well in my jeep um running at 3grand at that speed which the table indicates i should have 427gear ratio. It makes me think the previous owner put lower gears in. So this makes me confused can someone clear this up please?
 
my guess, and it is purely a guess, is that the D60/44 has factory gears in them of the 4.10 flavor...very common ratio
 
4.27s are fairly uncommon but can be found in older Dana 30 and 44s, and possibly in other axles as well. Usually nowadays people use 4.10s or 4.56s instead.
 
Here's how to check. First, is it open diff or limited slip/ locked? It's easier to tell if both rear tires turn together. Jack up the rear, put a chalk mark at the bottom of a tire. Count how many pinion rotations it takes to do one revolution of the tire. That's the ratio.
 
Open the differential cover and read the gear ratio that is stamped onto the ring gear. There will be two numbers, divide the larger number by the smaller number and that is your gear ratio.
 
projectTK said:
the axles are from currie
So its not like its a junkyard axle setup.
the 427 doesnt add up. Um about to put 33's on it.
Click to expand...
still sounds at least 3 inches too short

pop the cover and look for the stamp on the side of the ring gear, you should have two numbers by themselves, like:
44 9

that would make it 4.56's (divide the big one by the little one)
 
I don't see much point in 44/60 F/R unless you are going over 35" locked F/R. That aside though, do the axles have a serial # that you can use to have currie look them up for you?
 
I think the reason he has those tires is because he bought the Jeep set up like that, and it has a corvette engine in it. More power needs bigger axles.
 
projectTK said:
Well in my jeep um running at 3grand at that speed which the table indicates i should have 427 gear ratio. It makes me think the previous owner put lower gears in. So this makes me confused can someone clear this up please?
Click to expand...
Try putting a tape measure on your tires. Chances are your "31s" were about 30.25"-30.50" new, and may measure less then 30" now.(General rule: The size listed on a tire sidewall is a lie created by the marketing department, and has as much to do with reality as, "It's eight inches, baby, believe me")

If you want to be super- duper accurate, measure from the ground up to the center of the axle, and double it. This measurement is the "true" rolling diameter that the drive train sees.(and varies with air pressure, tire temp, and speed. :D )

Bet when you work it out, you've got 4.10s
 
so you have an xj with a corvette engine and a 44/60 and your on 31's lol?

im not knockin you at all im just a little confused
 
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