So I just followed the steps I found online to check my rear ratio and it comes to 2.05?? What am I missing? rear is a dana 60

I marked wheel and d/s, rotated wheel 10 times, got 20.5 rotations on the d/s. I'm trying to avoid opening it, so what's up??

 

2.5=4.10? I don't know, I never heard of this.

 

Rotate the tire one complete revolution while counting the number of rotations on the drive shaft.

Just slightly over 4 rotations on the d/s = 4.10's

Roughly 3 3/4 rotations on the d/s = 3.73's

etc., etc.

 

ok, so I just went out and did one rotation and the d/s rotated almost exactly 2 times. That didn't help

***Ok, for future reference, spinning one wheel does not work unless it is posi. I just crawled under and spun the driveshaft with both wheels off the ground and got just about 4 rotations to one full rotation of the wheels. 3.73's it is apparently. Thanks for the help

 

^^^yeah...if you have an open carrier, you need to spin twice. 3.73 wouldn't have been in that rear end in that era, it woulda been 3.55's or 4.10's. 4 rotations tells me 4.10s.

 

I'm gonna put new brakes on the rear and at the same time open it up and count the teeth/change the fluid so I'll know more then. Might go get the parts today and get it done.

 

I misread your post and thought you had l/s (limited slip), like dentside man said, with an open diff you rotate the tire twice, not once.

So if you take your results posted above and divide by five you've got 4.10's

 

cool, 4.10's are ok by me. my scab has 3.73s

 

Those are not stock...

 

Dana 60 rear axles from 1966 thru 1979 were available with 4 different ratios at no extra charge: 3.54, 3.73, 4.10 & 4.56. Add 3.07 & 3.23 ratios beginning in 1980 (2WD only).

Ford 9" rear axles installed in 2WD 1973/79 F100's & 1975/79 F150's were available with 6 different ratios at no extra charge: 2.75, 3.00, 3.23, 3.50, 3.70, 4.11.

1973/76 F100 4WD, 1975/79 F150 4WD & 1978/79 Bronco 9" rear axles were available with 3 different ratios at no extra charge: 3.50, 3.70 & 4.11.

The AXLE code is stamped on the Warranty Plate. While not an absolute after 33 + years have passed by, at least peeps will know what axle ratio came with their trucks originally.

1959 thru today: If the AXLE code begins w/a letter: Limited Slip. If w/a number: No Limited Slip.

 

^^^I thought the 4.56's were only available in a C&C truck? And I have never realized a 3.7X was available in a 73-79 4x4. In all of the 73-79 books and manuals I have, I've never stumbled acorss that as being a stock ratio...or never paid attention.

 

Do you have this? The 1973/79 Ford Light Truck Parts Catalog is available on a CD from hipoparts.com

Text, Section 40.1 ~ Parts lists 88 & 91 list the 9" ratios. Part list 93 lists the Dana 60 ratios.

The 1973/79 Ford Passenger Car Parts Catalog is also available on a CD from hipoparts.com

You'll need this if you need Bronco specific parts, cuz 1966/79 Bronco's are only listed in the car parts catalogs.

 

Thanks...I do have it, with all 76-79 shop manuals (partial volumes from other years) and a good chunk of brochures. I read them just to read them. Some people like vampire books, I like Ford truck manuals.

 

My 78 Scab 4x4 has the plates on the axles, and both say it has 3.73 gears (dana 44 front, 9" rear) Also, my 78 Scab 2wd had a 9" rear with tag saying 3.73 gears. I can't read the tag on the dana 60, and haven't looked at the front dana 44 yet.

 

Well I'll be a monkey's uncle...can't find the disc, but sure enough the 1977 manual (engine) showed code 38 for the 60 and 36 for the 70 as having 3.73's. I didn't cross reference, but I assume (yeah I know what assuming does) these are for 2wd trucks???