1951 F1 Rear Diff
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New User
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From: Seaford East Sussex UK
1951 F1 Rear Diff
Hi Again,
We are currently awaiting our 1951 F1 to get shipped here (UK) from The USA (arrives end of month) previous owner has told us that it is a low ratio diff & only does 45mph (flat out) and is no good for our roads over here, but i would desperatley like to keep the original axel, and not go for the usual 9inch rear end, is there any diff known of a much higher ratio that would go staright in to original axel.
Many thanks
Trev.
We are currently awaiting our 1951 F1 to get shipped here (UK) from The USA (arrives end of month) previous owner has told us that it is a low ratio diff & only does 45mph (flat out) and is no good for our roads over here, but i would desperatley like to keep the original axel, and not go for the usual 9inch rear end, is there any diff known of a much higher ratio that would go staright in to original axel.
Many thanks
Trev.
Ford Parts Specialist
Joined: Nov 2006
Posts: 88,826
Likes: 785
From: Simi Valley, CA
Parts catalog sez for 1951 F1: 392-1 & 4.27-1.
The actual rear axle ratio is stamped on the Rating Plate.
What some ppl that own these old trucks don't realize is...there were no Freeways/Interstate Highways in the US back then.
Most ppl didn't drive much over 45 MPH. Trucks in many states were restricted to 35 MPH...top speed.
President Eisenhower, when he was General Eisenhower, Supreme Commander of the Allied Expeditionary Forces in Europe during WWII, was very impressed with the German Autobahn System.
When he was elected President, he championed a similar system for the US.
In 1955, he signed the Interstate Highway Act. Then work began on the Interstate Highway System we all use today.
The actual rear axle ratio is stamped on the Rating Plate.
What some ppl that own these old trucks don't realize is...there were no Freeways/Interstate Highways in the US back then.
Most ppl didn't drive much over 45 MPH. Trucks in many states were restricted to 35 MPH...top speed.
President Eisenhower, when he was General Eisenhower, Supreme Commander of the Allied Expeditionary Forces in Europe during WWII, was very impressed with the German Autobahn System.
When he was elected President, he championed a similar system for the US.
In 1955, he signed the Interstate Highway Act. Then work began on the Interstate Highway System we all use today.
Post Fiend
Joined: Jun 2001
Posts: 7,493
Likes: 7
From: Erie, pa
Randy's Ring & Pinion. The Differential Experts. Auto Parts & Services.
Randy's has a ring and pinion for the Dana 44 that will do what you want.
Randy's has a ring and pinion for the Dana 44 that will do what you want.
Lead Driver
Joined: Oct 1999
Posts: 6,776
Likes: 553
From: Kalispell, MT
Bill, could you check this out for us, please? Ross and I have sorted thru this before and came to the conclusion that the ratio must have been 3.73.
The shop manual states 3.92 in the specs, but contradicts itself on p. 166 where it clearly lists the F1 ratio as 3.73
Were the r/p ratios 47/12 or 41/11 for the F1? I've seen both reported on the internet, but no hard proof.
Anybody else have a tag on your stock F1? Mine was 4.27 so I'm no help.
The shop manual states 3.92 in the specs, but contradicts itself on p. 166 where it clearly lists the F1 ratio as 3.73
Were the r/p ratios 47/12 or 41/11 for the F1? I've seen both reported on the internet, but no hard proof.
Anybody else have a tag on your stock F1? Mine was 4.27 so I'm no help.
Marmon-Herrington Man
Joined: Jul 2005
Posts: 11,986
Likes: 444
From: Central Illinois
The Jan '52 edition of the Chassis Manual says 48-50 was 3.73 (#8C 4209) and 4.27 (#8M 4209-B). Then it lists '50 alone having a 3.92 (#OM-4209), so guessing it must have been a mid year change. But then it shows '50 through '52 having the 3.92 (#1M 4209-A) and 4.27 (#1M 4209-B). Why it lists two different numbers for the 1950 3.92 gear is a puzzle. Stu
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Freshman User
Joined: Nov 2003
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The F1s used a Dana 41 which is very similar to the Dana 44. The gears are the same and Dana 44s have a large following in the Jeep community. This means getting almost any gear ratio for them is possible.
They use two carriers - one for 3.92 ratio and up and another for below 3.92. This means if you want to go below 3.92:1 you will need to change out the carrier with the new gear set. Fortuanately Dana 44 parts are widely available and fairly cheap. With that said make sure you get parts from a Iron center section 44 and not a D44A which is aluminum center sections and the carriers are different. The D44As are found in Grand Cherokees, some corvette centers, vipers and some Dodge based SUVs.
Good luck.
They use two carriers - one for 3.92 ratio and up and another for below 3.92. This means if you want to go below 3.92:1 you will need to change out the carrier with the new gear set. Fortuanately Dana 44 parts are widely available and fairly cheap. With that said make sure you get parts from a Iron center section 44 and not a D44A which is aluminum center sections and the carriers are different. The D44As are found in Grand Cherokees, some corvette centers, vipers and some Dodge based SUVs.
Good luck.
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Ford Parts Specialist
Joined: Nov 2006
Posts: 88,826
Likes: 785
From: Simi Valley, CA
Bill, could you check this out for us, please? Ross and I have sorted thru this before and came to the conclusion that the ratio must have been 3.73.
The shop manual states 3.92 in the specs, but contradicts itself on p. 166 where it clearly lists the F1 ratio as 3.73
Were the r/p ratios 47/12 or 41/11 for the F1? I've seen both reported on the internet, but no hard proof.
The shop manual states 3.92 in the specs, but contradicts itself on p. 166 where it clearly lists the F1 ratio as 3.73
Were the r/p ratios 47/12 or 41/11 for the F1? I've seen both reported on the internet, but no hard proof.
Volume I / TEXT / Rear Axle ID Chart, Page 145.
----------------------------------------------
1948/50 F1: Rear Axle Parts List # 59, listed on page 177.
8C-4209 .. Ring & Pinion: 3.73-1
8M-4209-B ..Ring & Pinion: 4.27-1
OM-4209 .. Ring & Pinion: 3.92-1
----------------------------------
1950 F1 & 1951/52 F1: Rear Axle Parts List # 60, listed on page 177.
IM-4209-A .. Ring & Pinion: 3.92-1
1M-4209-B .. Ring & Pinion: 4.27-1
It appears to me that Ford changed the rear axle type sometime in 1950.
I was around then, but Ford Cars/Trucks were the furthest thing from my mind, cuz my dad was an Olds Dealer.
How I ended up working...originally as a Studebaker/Packard partsman...then as a Ford partsman is another story.
Studebaker used Spicer-Dana 44's in Passenger Cars thru 1966. Half ton pickups thru 1963.
The Nissan Titan Pickup, Armada SUV and the Infiniti QX56 SUV also use Dana 44's rear axles, Dana 44 front axles on 4WD's.
It's a weak sister of an axle in these vehicles, the biggest complaint from owners. It seems Dana 44's don't hold up too well with a 317 HP DOHC V8...and leadfooted drivers.
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New User
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From: Seaford East Sussex UK
Thanks
Just wanted to say thanks for all the warm welcomes you have sent to me i am very new to this forum stuff so excuse any mistakes i might make.
the Ford F1 is as rare as rocking horse poo over here in the UK so any help you guys & gals can offer is great.
once again many thanks for now
Trev F1
the Ford F1 is as rare as rocking horse poo over here in the UK so any help you guys & gals can offer is great.
once again many thanks for now
Trev F1
Fleet Owner
Joined: Jul 2004
Posts: 27,294
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From: NM
The F1s used a Dana 41 which is very similar to the Dana 44. The gears are the same and Dana 44s have a large following in the Jeep community. This means getting almost any gear ratio for them is possible.
They use two carriers - one for 3.92 ratio and up and another for below 3.92. This means if you want to go below 3.92:1 you will need to change out the carrier with the new gear set. Fortuanately Dana 44 parts are widely available and fairly cheap. With that said make sure you get parts from a Iron center section 44 and not a D44A which is aluminum center sections and the carriers are different. The D44As are found in Grand Cherokees, some corvette centers, vipers and some Dodge based SUVs.
Good luck.
They use two carriers - one for 3.92 ratio and up and another for below 3.92. This means if you want to go below 3.92:1 you will need to change out the carrier with the new gear set. Fortuanately Dana 44 parts are widely available and fairly cheap. With that said make sure you get parts from a Iron center section 44 and not a D44A which is aluminum center sections and the carriers are different. The D44As are found in Grand Cherokees, some corvette centers, vipers and some Dodge based SUVs.
Good luck.
Freshman User
Joined: Nov 2003
Posts: 34
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Well in the case of the 41 and 44 they were used in Jeeps since the 50s and honestly parts are fairly cheap. But it will alway be cheaper to with a 9 inch or 8.8 swap. They are so plentiful and labor is pretty high too these days on diff work. If you dont set up gears yourself it best to find a local mechanic that does gear work on the side. Cool part about being into Jeeps there are a lot of guys that do diff work on the side. I do almost everything but Gears.
Fleet Owner
Joined: Jul 2004
Posts: 27,294
Likes: 1,055
From: NM
Yep, there's a guy down the street, professional mechanic, who will do gear changes on the side for 8", 9", or 8.8's with factory or Ford Motorsport gear sets for $150. For a D44 he wants $450, no parts included.
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