diff question

Submitted: Sunday, Apr 13, 2008 at 14:57
ThreadID: 56591 Views:2463 Replies:5 FollowUps:7
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Hi All,

A technical question re differential ratios.

I have two 4x4's.

1. 1972 4x4 Falcon Utility. Front ratio 4.10:1 Rear ratio 4.0:1

2. 1986 F100 LWB. Front and Rear ratio 3.50:1

I recently purchased a complete front diff for the F100 with ARB air locker but with 3.54:1 ratio.

My question is given that the 1972 Falcon has .1 difference between the ratios would there be a problem with the .04 difference between the ratios in the F100.

I can see no real issue other than an absolute miniscule amount of wheel slip/spin from the front wheels. Have not noticed this at all in the Falcon with the greater difference in ratios.

Any toughts or comments greatly appreciated.

Just trying to save having to completely disassemble two diff to change over the air locker.

Regards
Ross
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Reply By: kiwicol - Sunday, Apr 13, 2008 at 16:07

Sunday, Apr 13, 2008 at 16:07
i think the falcon has jeep running gear!. col
AnswerID: 298283

Follow Up By: 4x4falcon - Sunday, Apr 13, 2008 at 18:51

Sunday, Apr 13, 2008 at 18:51
Yes the Falcon has Dana 44 diffs same as the Jeep Wagoneer from 1972.
Ross
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Reply By: pop2jocem - Sunday, Apr 13, 2008 at 16:31

Sunday, Apr 13, 2008 at 16:31
Hi Ross

I may be wrong but I think the Falcon 4x4,s had Dana/ Spicer running gear. If it has auto locking front hubs that may be why the diff ratios are slightly different, something to do with not having the front drive dropping out and in too often. Just my very humble opinion.

Cheers Pop
AnswerID: 298288

Follow Up By: 4x4falcon - Sunday, Apr 13, 2008 at 18:54

Sunday, Apr 13, 2008 at 18:54
Thanks but I don't think auto locking hubs were arround in 1972.

I has the original Ford/Dana/Spicer/Jeep manual hubs with two cams on each hub need to engage the hub.

Cheers
Ross
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FollowupID: 564424

Reply By: Bonz (Vic) - Sunday, Apr 13, 2008 at 16:37

Sunday, Apr 13, 2008 at 16:37
I want your Falcon!

And I wouldn't see any problem with the small difference, you could probably get that much difference with new tyres on one end and almost shot tyres on the other end.
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AnswerID: 298289

Follow Up By: 4x4falcon - Sunday, Apr 13, 2008 at 18:58

Sunday, Apr 13, 2008 at 18:58
"I want your Falcon!"

Not on your life :) It took me 25 years to get and it's still undergoing a complete rebuild.

And that was my thought with the diffs just wondering about others thoughts and any experiences.

Cheers
Ross

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Follow Up By: Dunaruna - Sunday, Apr 13, 2008 at 18:59

Sunday, Apr 13, 2008 at 18:59
Me too!
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Follow Up By: Bonz (Vic) - Sunday, Apr 13, 2008 at 20:58

Sunday, Apr 13, 2008 at 20:58
thats fine ross as soon as its finished let me have it hehehehe, I have wanted one since I was 14
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FollowupID: 564452

Follow Up By: 4x4falcon - Friday, Apr 18, 2008 at 11:07

Friday, Apr 18, 2008 at 11:07
Here's one for you:

4x4 Falcon

but probably much more than you'd want to pay ;)

Cheers
Ross
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FollowupID: 565306

Reply By: burnsy - Sunday, Apr 13, 2008 at 19:06

Sunday, Apr 13, 2008 at 19:06
I recall when I was a little boy my dad had a Ford or Chev Blitz & I am pretty sure that the front wheels would drive slightly faster than the rear. Which I believe gave it a lot more steering control especially in slippery conditions.
I do know that Deere road graders fitted with front wheel assist (6 wheel drive] you can vary the speed of the front wheels by 5% (I think) The operators love them in sand.
Well that's my piece of semi useless information for tonight.
Mike
AnswerID: 298313

Reply By: Mick15 - Monday, Apr 14, 2008 at 16:26

Monday, Apr 14, 2008 at 16:26
could it be that the f100 is in fact 3.54 and someone has just rounded that down? after all its only the number of teeth on the crown divided by teeth on the pinion, wouldn't have thought that there would be enough teeth to have a .04:1 difference?
I know that a lot of nissan diffs 4.11 is often reffered to as 4.1:1 and 4.625:1 is often reffered to as 4.6:1 as the compliance plate (gq will sa hg41 or hg46 etc)
Could be wrong tho, sure some googling will find the answer.
AnswerID: 298449

Follow Up By: 4x4falcon - Monday, Apr 14, 2008 at 17:04

Monday, Apr 14, 2008 at 17:04
Ford list two different sets of diffs for the F100.

Ratios:

6 cylinder 3.54:1 Front and Rear
8 cylinder 3.50:1 Front and Rear

Teeth are:

6 cylinder 46/13
8 cylinder 42/12

The front diffs are the same (Dana 44) except for the crown wheel and pinion.

Rear diffs are different 6 cylinder is 8.8 inch and 8 cylinder is 9 inch.

Cheers
Ross
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