7.25 Rear End Durablity

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7.25 Rear End Durablity

Post #1 by Joey0207 » Sat Sep 23, 2017 12:17 am

I recently within the last few months got my first classic mustang. It's a 66 with a 200 and three speed. Over the next year or two I'm planning a T5 swap and then 2v carb conversion, cam change, and a turbo on an otherwise stock mustang. How far have you guys taken the 7.25 rear end power wise? I don't plan on seeing much track time, mainly just a cruiser so I'm not to worried about snapping axles.

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Re: 7.25 Rear End Durablity

Post #2 by wsa111 » Sun Sep 24, 2017 10:41 am

Joey, the turbo & drag strip will finish off the 7.25 rear.
Go 8" & then you have the luxury of strength & also removable center sections.
67 mustang,C-4, with mod. 80 hd, custom 500 cfm carb with annular boosters, hooker headers, dual exh.-X pipe, flowmaster mufflers, HEI dist. Engine 205" .030" over with offset ground crank & 1.65 roller rockers. 9.5 comp., Isky 262 cam.
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Re: 7.25 Rear End Durablity

Post #3 by bmbm40 » Sun Sep 24, 2017 8:31 pm

66 Mustang is a great car to have and the T5 is the trans I would use. Are you aware of the Falcon Performance Handbook? It has lots of info on the various rear ends.
66 Bronco-1970 250, NV3550, DSII, 4 turn ps, uncut, 1" bl, 2.5" sl, front disc, twin stick D 20, 30 x 9.50
NEXT- direct mount 1.08 on D8 head, power brakes, rear limited slip, 3G, electric fan, electric upgrades, custom curved DSII, header, 31" tires

New guy? Get the Falcon Performance Handbook and Ford six high performance parts from https://vintageinlines.com

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Re: 7.25 Rear End Durablity

Post #4 by bubba22349 » Fri Oct 06, 2017 8:39 pm

Hi Joey, X3 having a Turbo is a grantee that a 7 1/4 isn't going to last long for that matter in my OPIN anything over a very mild 200 build up is going to take out a 7 1/4 axle. Good luck :nod:
A bad day Drag Racing is still better than a good day at work!

I am still hunting for a project car to build but with my current low budget it's not looking so good. My Ex- Fleet of Sixes these are all long gone! :bang: 1954 Customline 223 3 speed with O/D, 1963 Fairlane project drag car with BB6, 1977 Maverick 250 with C4, 1994 F-150 a 300 with 5 speed.

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Re: 7.25 Rear End Durablity

Post #5 by xctasy » Sun Oct 08, 2017 5:51 pm

Don't discredit the 7-1/4". In fact, if you are able to wade through the information, most axles except the 6.7/6.8 came with a limited slip diff "Traction Lok" or "Detriot Locker" option, specially so the 7-1/4".

Everywhere else but America, the old axles and cars are scrapped, and the steel and iron sent to China.

You guys in the USA have the advantage of guys the world over having a go at destroying Ford axles in hopped up Fords, and those 7.25's were pretty dang good. In the USA, everyone just grabs a junked 8" axle, and gos nuts.

The 7.25 ranks as a very underated axle. It existed becasue the 6.8 diff was very weak, and it took Ford 19 years to upgrade that little pip squeek axle to even the level of any 1962-1972 7.25 axle.

Somewhere in my 2500 picture liabary, I have a 1967 XR GT Falcon that used the earlier Round-body and later 7.25" Pickup axles in a drag racing application for 2 years.


In Australia, the Falcon pickups ran a US Import open wheeler 7.25 axle for many years as the 6.7/6.8" wasn't very strong.

That 7-1/4 axle will certainly take a Four speed Toploader, 3000 pound Falcon with 4-bbl 289 which were 225 hp stock.

Then it got modified to 271 hp plus K code 289 spec, the still the open wheeler US import 4:1 ratio 7.25" axle took the pounding. 232 real hpon the chassis dyno, IIRC.

Thats about 240 lb-ft of torque. 13 second 1/4 miles.

Mike W (AzCoupe) back in 2006 was looking at the much stronger Traction Lok option Ford had from 1963 to 1967, and making a New Old Stock kit for it.

The axle housing Ford used back then is a "Salisbury" axle housing.

Its not an 8", but it is very strong, much stronger than the old Sterling made 1956 to 1987 6.7 and 6.8" Mainline/ Falcon to Pinto to Ranger axle they used for years in trucks and Fox bodies and the old 2.3 Rangers.

Ford had access to untold other suppliers for axles the world over...
Sterling Heights, Mich (6.7/6.8/7.25/7.5/8.7/8.8/9/9.25/10.25),
Sao Paulo in Brazil (8"),
ZF Gear Baby 7" and Atlas 7.5"in Cologne, Germany. Zakspeed Capri, Merkur XR4Ti and Scorpio IRS axle center, and the World Group A Mustang "SVO" Racing 5 liter V8 axle

The English Dagenham 6.5" axle used in the 1600 Pinto and early Capri's
The Australian, the Chrysler/Ford compacts cars from 1967 onwards used the Borg Warner 7-1/2" "75" and 7.625 to 7.875" "78" and later BTR G52 and then Dana axles which were then exported to the US for 1984-1989 ish G52 axle code Camaro's, Firebirds.

Fords 7.25 axle was basically very similar to the Chrylser 7.25, and then in the Ford Maverick , the 7.25" got replaced with the very strong and cheap 8" Brazillian axle.

In the Pintos, Bobcats and Mustang II's, the 8" was an option and then the little old 6.7" Sterling Pinto axle was upgraded to supply six cylinder Foxes and Rangers.

The old short and long pinion 6.7's and 6.8's were truly a total piece of crap, but becasue Ford used them in all its sub compacts, it got up graded in 1974, the 7.25 was pensioned off. Eager to keep US production of axles, in 1978, Ford made a brace of stronger Sterling built 7.5, 8.7 and then, in, 1983, the 8.8 axles, all Salisbury types, and they were very strong on a weight/strength basis. with a lot less pinon over lap and darg coapared to the strong but mechanically ineffeicent Tank Fairlane based Pumpkin 8 and 9" diffs. 7.5/8.7/8.8's were Almost as strong as the 8 and 9" Lift out pumpkin axles, and much cheaper to produce.

For more axle info on Ford USA's odd ball non mainstream axles:

6.7-6.8 and 7.5's

http://vb.foureyedpride.com/showthread. ... 5-rear-end
http://vb.foureyedpride.com/showthread. ... -rear-axle

US 6-3/4/6.7 and import 7.5" Atlas axles


8" Sao Paulo and 9" (1957-1986 Ford 9" diffs vary in crown wheel from 8 3/4" to 9 3/8 depending on year and ratio) axle parts sharing


Ford Granada/ Monarch 8.7"

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