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How do you determine what rear axle gears you have

A

abrahamfh

Active Member
So after some research I found how to determine what rear axle gears you have but I am still confused.

The steps are as follows for a open end rear

1. Raise rear axle
2. Mark the drive shaft or yoke facing the PS tire (to keep track of revolutions)
3. Mark the PS tire at the 3 o'clock position (to keep track of revolutions)
4. Have someone hold the DS tire while you spin the PS tire
5. Spin the tire 10 full revolutions while keeping track of how many revolutions the drive shaft made

Note: I used a video recording device, so I spun the PS tire for 10 full revolutions and then watched the video to count how many revolutions the drive shaft made.

This is where I get totally confused. According to what I read, it said to divide the driveshaft revolutions by the tire revolutions. I counted 14 drive shaft revolutions for the ten tire revolutions, that comes out to 1.4. :wtf

Any enlightenment would be great, the research I did once I calculated my mass confusion states that Ford had a 3.00:1, 3.20:1, 3.25:1, 3.50:1, 2.80:1, 3.80:1, 3.89:1 and 4.11:1 rear axle gear ratios.

Somewhere else, it stated that if you have a open end you lock up the DS tire, spin the PS one full revolution, lock up the PS tire, spin the DS tire one full revolution and determine how many revolutions the drive shaft made. When I did this particular method the drive shaft spun 2.5 revolutions exactly, still scratching my head. :wtf

I'm tired now and have a headache, time for bed.

132a04fc.jpg
 
Re: determining your rear axle gears

Okay, I totally lied, I can't go to sleep with this bothering me. I got back under Fred and started using a wire brush on all the nastyness that the pumpkin is covered in. I think I might have located a ID tag. It is still covered with grime and dirt so I am going to hit it with some lacquer thinner and see what reveals itself.

photo.jpg
 
Re: determining your rear axle gears

So, after some wire brushing and lacquer thinner the tag revealed it's secret.

0bcc659f.jpg


So, according to the tag Fred has 2.80 gears but do the rest of the letters and numbers mean anything else?

Are 2.80 gears any good?
 
They are good on the highway and for fuel mileage. You found the number but for an open rear you don't need to lock a tire. Raise the rear, spin the tire and count the driveshaft rotations for every two tire rotations. This would've given you 28 driveshaft turns for 10 tire turns. (Actually 20 tire turns but it's 1 count for every two turns on an open rear)
 
You almost had it Abe, you got 1.4, you just had to double it. Those are the stock gears for your engine. The 5EB looks like a date code, I'm not sure how to read it.

Frank
 
Thanks everyone for the clarification.

Is there any good websites where I can read up and learn more about this stuff, splines, axles, third members, gears and so on?
 
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