Why me? 7.25 diff questions

[62Cometman]

So i decided that i would be nice and replace the fluid in my diff because it was about 5 years old at this point in time. Not much for miles but there on time plus i wanted to add some lucas to basically try to keep the gears from wearing though one another or the bearings from becoming too noisy. I open up the diff and a fair or what i would call reasonable about of metal is coming out in the fluid and the fluid looks very good in color and there is no appearance or smell of burnt diff fluid so i know it hasnt gotten hot. But i was curious as to how my wear pattern on my ring gear looked so i started rotating it around and that was a bad idea. As i was rotating it i immediately noticed that the cross pin was not in the location is should be in had shifted down as if the holding pin wasnt in place. I kept rotating and that when i saw it. The holding pin had sheered somehow and the cross pin had been banging back and forth so much that it had greatly elongated the hole in the carrier assembly, so what started out as just normal maintenance has now turned into a complete overhaul of either this diff or installing a whole new rear end. My question being if i want to only replace the carrier assembly would it have a serious effect on the pinion gear and or are the 3.10 and 3.50 or even the 3.20 using the same pinion gear or do i have to swap both to get the achieved ratio or a working gear set at all? Also if anyone has a carrier they want to send me id happily take it off their hands!!

[62Cometman]

Has anyone heard of a 2.83 ratio 7.25 rear diff? it was my understanding that they were all 3.10,3.20 or 3.50 or am i wrong? cause i found a set online that the seller claims is a 2.83 ratio and since i cant see all the teeth on the pinion could possibly be the case which would be very low and likely kill what little acceleration i have but id like to think that the dagenham thats getting swapped in later this summer would help counter act that.

[mustang6]

2.83 is a common ratio, used in cars with automatic transmissions. Mustangs with a 6 used 2.83 with auto, 3.20 with manual. Seriously, don't try and re-use your existing pinion with a different ring gear, consider them a matched set.

[xctasy]

2.83 is a common ratio, used in cars with automatic transmissions. Mustangs with a 6 used 2.83 with auto, 3.20 with manual. Seriously, don't try and re-use your existing pinion with a different ring gear, consider them a matched set.

And forth time is a charm.


http://falconfaq.dyndns.org/Rear_Axles/RearAxles01.html

The rare 3.50 is only a 7-1/4" axle thing, and not something you can swap into a 6-3/4 or 7" carrier.

7-1/4" axle is a later Roundbody Falcon Comete Fairlane thing.


Not a 144 axle.

Lookes like this









http://falconfaq.dyndns.org/Rear_Axles/RearAxles01.html



Early axles are 6-3/4", for which there are Code 1 and 2 axles of 3.56 or 3.89 ratios. Top picture


Then out came a 144 axle with 7" ring gear, and it was 3.10/3.20/3.50 or 4.00 ratios. Middle picture



Then came a 7-1/4" behind the 170. Bottom picture. Books show ratios of 3:10 or 3:20 with a three speed, They show 3:50 optional, and 3:50 standard with a ford-o-matic, but I haven't seen any.



One code to look for is Axle tag CDD0 or 00004001 AK 504, which is a 3. 50 IJ

Then a 7-1/4" became standard in all 170 and 200's from 1962 onwards.

The later 2.83 ratios from for Mustangs and later Falcons, Cometes, Fairlanes swaps in that.

1 )2.83:1 Automatic 200 six axle
2) 3.20:1 Common Manual 170/200 axle
3) 4.00:1( old Falcon/Ranchero pickups, Econoline trucks and vans, 170/200/possibly 240)


The early 6.75" axle was avaiable with a 3.56 and 3.89 only


The 3.50 is rare in the 7.25", for Falcons, and Falcon autos.


viewtopic.php?f=76&t=77900

x2 if you have found a ring and pinion set only that actually is for the 7.25 ford rears let me know ill definitely be interested 3.50 while performs excellent does not like going much faster than 60-65

Re-read ALL of https://www.fordmuscleforums.com/mustan ... end-1.html

and https://www.fordmuscleforums.com/mustan ... end-2.html


AZCoupe was going to offer the Limited Slip Differential kit, which was a standard factory option in 1966 pickups and vans and trucks. The fact that the Australian drag racers didn't know about it in 1967 was typical of how information wasn't passed around throughout Ford world wide.

The Big o drag raced his 240 rwhp 289 Falcon GT Sedan with the open 7-1/4" 4.00 gear axle, when there was a factory US market limited slip axle around.


Read it again





The USA has the parts you need. You just have to persist with the request, and not get mixed up with other Chinese Whipsers of not true info.

List these down for future reference.

1962-maybee 1972 7-1/4" Factory axle ratios....again.

1 )2.83:1 Automatic 200 six axle
2) 3.20:1 Common Manual 170/200 axle
3) 4.00:1( old Falcon/Ranchero pickups, Econoline trucks and vans, 170/200/possibly 240)


All US made, and also Australian supplied. Ecconlines, Falcons, some Fairlanes, from 1962-1966, then Ford USA went to Brzilian 8 and US 9" axles, with the Auusis upgrading to either B/W 7-7/8", Ford 's Brazilian Sao Palo 8", or US import 9" axles.

No 3.50"s in 7-1/4" axle form. None. Eva. <------I was wrong.


If you want 3.50's, you need a 9". 3.50 wasn't a common 8" ratio, its rare as rare can be


8" were generally 2.79, 3.00, 3.25 3.40, 3.55, 3.80, and a host of other kinds for trucks, vans and pickups.


8" Detroit Locker Positraction, Open Differentials, Trac Loc Positraction, all the same 28 spline axles as the 9"

8" Factory Ratios
1 ) 2.33:1 (250cubic inch 1969/1970 Mustang Economy gearing)
2 ) 2.79:1 (Std 8 cylinder small block Auto gearing)
3 ) 2.80:1 (Rare as rare can be)
4 ) 3.00:1 (Yukon Gear still make new replacements)
5 ) 3.25:1Common Traction Lock)
6 ) 3.40:1 Mustang II and some Pintos)
7 ) 3.50:1 (Rare as rare can be)
8 ) 3.55:1 (Yukon Gear still make new replacements)
9 ) 3.80:1 (Yukon Gear still make new replacements)
10) 4.62:1 ( old Econoline trucks and vans; Yukon Gear still make new replacements )
11) 5.43:1 (Yukon Gear still make new replacements)

IIRC, There was a Pinto listed 5.13 aftermarket axle

Some 9" Factory Ratios
2.47:1
2.75:1
3.00:1
3.25:1
3.50:1
3.55:1
3.70:1
3.80:1
3.89:1
3.91:1
4.11:1
4.30:1

I'm currently running a 3.2 Mustang non slip gears in my local 5 stud commercial diff installed in my round body. The good thing about the US stuff and the local Borg Warner diffs are that they are identical down to the threads on the bolts. The tallest gear set for Australian Falcons in '66 was 3.2, so the US gears of 2.83 will give it longer legs

Picked it up from the post office this afternoon.
I must say the gent I purchased it from in Indiana has been great to deal with. Prompt posting and he didn't ask for any more postage than what USPS charged him. $65 from US to OZ. ^::
You can see the family history of the three carriers. I dropped it into the diff housing to check. All good.
L to Right
'66 Ford OZ utility carrier ( originally 4.00 ratio)
'67 Mustang open carrier (2.83 ratio)
'65/66 Equa-lok carrier ( He supplied the longer bolts that hold the pinion gear than the standard bolts)

The equa lock carrier I have is 24 spline ( like all early 6 cylinder Falcons Comets and Mustangs) with 7.25" gears

[62Cometman]

So how does everyone feel about the 2.83 with a dagenham trans? would it completely kill acceleration or not be too bad?

[bubba22349]

I don't know the gear ratios of the Dagham 4 speed. 2:83 may work depending on the tire diameter you use though I think a 3:20 would be better suited and easier on the clutch. Good luck

[bmbm40]

I continue to be impressed by the detailed and content packed responses from xctasy.