Front differential
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Freshman User
Joined: Mar 2001
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Front differential
Hi to everyone out there. This is my first post after looking through much of this site. The amount of knowledge all of you posess is amazing. My question is: what is the front diff/gear ratio etc. on my truck?
I've decoded the vin tag on the door and am able to find out everything except info on the ft diff. It is a '72 F-100 4x4, 360ci, 131" wheelbase, New Process 435 and a rear axle showing
limited slip 3.50, 3600lbs WFF. On the door tag, at the bottom
rt is the code 'B6'. This is the only item I cannot find information on. I hope someone can help. I do believe that the ft diff is a Dana 44.
Thanks in advance.
Don
I've decoded the vin tag on the door and am able to find out everything except info on the ft diff. It is a '72 F-100 4x4, 360ci, 131" wheelbase, New Process 435 and a rear axle showing
limited slip 3.50, 3600lbs WFF. On the door tag, at the bottom
rt is the code 'B6'. This is the only item I cannot find information on. I hope someone can help. I do believe that the ft diff is a Dana 44.
Thanks in advance.
Don
Senior User
Joined: Mar 2001
Posts: 379
Likes: 0
Front differential
The front diff ratio is a 3.54:1. A 3.50 ratio isn't available for the Dana 44. This is the same ratio I'm running, although I have a 3.70 3rd member from another 9" that will be swapped in as soon as I can afford a 3.73 swap for the front. I know the front and rear does not match. Ford does this frequently. i've heard that as long as there within 1% of each other it's OK. I would really prefer them to be a little closer personally.
New User
Joined: Mar 2001
Posts: 9
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Front differential
How can the front ratio be different than the rear? This would cause the front and rear end to spin at different speeds. I have read articles saying that you MUST have the same ratio front and rear. Anyone else heard different.
79 Crewcab 4x4
79 Crewcab 4x4
Senior User
Joined: Dec 2000
Posts: 358
Likes: 1
From: Northwest Iowa
Front differential
I have 3 different 1/2 ton 4x4's and all have 3.50 gear ratio front and rear. My 3/4 ton 4x4 has 3.54 front and 3.54 rear. I cant see how you could run different ratios without ripping the bahazuess out of things.
Kevin
Kevin
Laughing Gas
Joined: Jul 1999
Posts: 1,048
Likes: 22
From: Lacey, WA
Front differential
Don,
I have read that there is a small difference in ratio's engineered into the drive line to maintain moderate tension on the gears in the transfer case. This is to prevent "gear rattleing". Some folks call it gear banging. My 1970 F250 has a 4.10 rear and a 4.09 front.
Your front diff should have cast into the housing "44 6CF" or simular. Also there should be a small metal tag attached with info on it.
You can also figure out pretty close what your ratio is by rotating a tire and counting drive shaft rotations. If tire rotates once and shaft completes about 3.5 rotations then there's your ratio.
Good luck
Lee
I have read that there is a small difference in ratio's engineered into the drive line to maintain moderate tension on the gears in the transfer case. This is to prevent "gear rattleing". Some folks call it gear banging. My 1970 F250 has a 4.10 rear and a 4.09 front.
Your front diff should have cast into the housing "44 6CF" or simular. Also there should be a small metal tag attached with info on it.
You can also figure out pretty close what your ratio is by rotating a tire and counting drive shaft rotations. If tire rotates once and shaft completes about 3.5 rotations then there's your ratio.
Good luck
Lee
Moderator
Joined: Jan 2001
Posts: 56,995
Likes: 2,741
From: Virginia
Front differential
As far as I know, Dana never made a 44 with a 3.50 ratio. When Ford used a Dana, the closest ratio was a 3.54. Just like the 8.8. Ford doesn't make a 8.8 with a 3.50 ratio. Closest is a 3.55. I would guess that it is physically impossible to get any ratio you want for a certain design rear, because of ring diameter and tooth pitch. If you keep the same tooth pitch, you can only go plus or minus one whole tooth to get the ratio you want.
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Freshman User
Joined: Mar 2001
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Front differential
Thanks for all the insight. I've checked the diff
and it has a casting number along the rt flange C35832 and also
has the number 46 cast onto the top, No letters here.
The metal tag has:
3 50 D4TA-AJA
603482 3
Are these decipherable???
Thanks,
Don
and it has a casting number along the rt flange C35832 and also
has the number 46 cast onto the top, No letters here.
The metal tag has:
3 50 D4TA-AJA
603482 3
Are these decipherable???
Thanks,
Don
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Joe Kucinski
Cargo Master
Joined: Aug 2000
Posts: 2,931
Likes: 12
From: SW Michigan
Front differential
Don, your truck has a Dana 44 front axle made in 1974 and you have the 3.50 ratio. I don't know where some of the guys got the idea that D44s didnt come with 3.50s, I purchased a 76 axle to take the disk brakes from and it has the 3.50s, I'm positive because I counted 12 teeth on the pinion and 42 on the ring gear. It would be ideal if the front and rear ratios matched, but even from the factory this is not always the case. Like one of our men said his truck has 4.09 and 4.10 gears, not exact but damn close. DF
Post Fiend
Joined: Sep 2000
Posts: 8,238
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From: Oregon
Front differential
[font size="1" color="#FF0000"]LAST EDITED ON 29-Mar-01 AT 08:01 PM (EST)[/font][p]Just to support what DF & Lee mentioned, I have the original diffs in my rig and have 4.09s up front and 4.10s in back too. Close enough for military work. Hadn't heard that this was to maintain tension and prevent gear ratteling...guess you learn something new every day.
If your knuckles ain't bleeding you did something wrong.
'72 F-250 "Hi-Boy" 4x4, Dana 60/HD44, FE390 @ 400hp(purt near!), 4-speed, custom suspension w 4" lift, mud on black.
If your knuckles ain't bleeding you did something wrong.
'72 F-250 "Hi-Boy" 4x4, Dana 60/HD44, FE390 @ 400hp(purt near!), 4-speed, custom suspension w 4" lift, mud on black.
New User
Joined: Mar 2001
Posts: 14
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Front differential
I have a 77 Dana 44 with 3.50 gears. I was also told that as long as the difference is within 1% it should be O.K. All you do is divide the rear by the front and see if it is within 1% . I run a 3.50 front and a 3.54 rear. Not a seconds trouble. If you will look at randy's ring and pinion's web site and look at the tech section it tells about this theory.
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