Is a 7.25 rear strong enough?

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I've never tried breaking one, but have still succeeded in doing so... I have not been able to break an 8-1/4 behind a six in anything yet, though...
 
Uncle Tony beats the **** out of his 7.25 so they must be good lol. but his car is VERRRY light weight.
 
It would be an awesome lawn tractor rear axle if it had some 2.2:1 planetary hubs mounted to it.
 
My 7 .25 died behind a mild 318 with a 4 barrel. The 273 never hurt it. After replacing the 7.25 with an 8.75 I took out the 904.
A friend had one with a slant six and a 3 speed. He would roll down a hill backwards dump the clutch with the pedal to the floor in 1st. Did some pretty smoky burnouts this way. He never killed the rear but should have.
I knew a couple other people who's 7.25 s died. I think if they were driven normal they would have lasted longer. But where is the fun in driving normal.
 
You will be fine!!!!! i run one using 255 60 15 tire with a 7 inch rim dumping my clutch all day with a 4 speed, the most H.p you'll get at the fly wheel if luckly is 230/210 and at the wheel your looking at 190/180 H.p, unless your running a super charger or turbo etc

i got a 7.25 with 3.55 gears in it peg leg if your looking for one. Nothing wrong with it just over racing my slant i just drive the damn thing now.
 
let me know if you want the one that came out of my 73 Duster sitting behind my barn. One good thing about 7.25's are they are free.
 
On the earlier topic of what I presume is be a “lunchbox locker””, some of the later FJM 7-1/4s and Ford Grenada and Fox bodies with 7-2:4s started sharing some parts with the Dana 30 and I think the Dana 35. The Dakotas most certainly did but making one fit in an A body would not be worth it. You may be able to find something along those lines, but your best bet may be a Ford Ranger 7.5. The most basic first level upgrade past a later 7-1/4 with more strength this side of an 8-1/4. They’ve got a 4.5 inch bolt circle, and aftermarket support was reasonably good the last time I checked. The hub to hub length was compatible, it just needs perches welded to the bottom of the axle tube. I still cuss ChryCo to this day for not using a Dana 44 instead of the AEM 7-1/4 in base V8 cars.
 
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To me the "fun" in driving normal is making things last so you don't have to spend money and or work to fix them. Maybe that's my white hairs talking.
 
I only have experience with one open 7.25 behind a 380ft lb motor in a 3500lb Duster. It held up to me bashing on it once in a while. I was gathering parts to build a shortened Ford 9 inch.
I've a second 7.25 under a87' 5th Avenue that I'm putting together a 290-300ft lb 318 for a weekly driven town car. If any more torque than that I wouldn't roll the dice and would swap in an 8.25 or bigger from all of the horror stories I've heard about the 7.25 from the old timers.
Just for Future reference, building that shortened 9 inch cost @ $3000 in 2018 dollars with a free housing that my Brother found at work.
It seems that the days of going to the junk yard and finding a 8.75,9 inch or 12 bolt for $50-$100 are gone. At least ,where I live they are.
 
A decent 318 will kill the 7.25 with 205 70r 14s. Been there done that. Know others that have done the same. Takes the spiders out and car needs to be towed.
The 7.25 works for slant six cars and should be discarded In most v8 applications as the factory did.
 
Deltatech said:
It seems that the days of going to the junk yard and finding a 8.75,9 inch or 12 bolt for $50-$100 are gone. At least ,where I live they are.
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long gone, amigo. maybe a local private yard would be better but the corporate yards here in socal are just miserable. a complete 8.8 is almost 300 w/o the brakes and that's before they stick you with the bullshit warranty. and there's no discussion about the price once the cashier has set it, either.

on top of that, good luck finding a half decent 8" or 9" let alone a 8.75
 
junkyardhero said:
a complete 8.8 is almost 300 w/o the brakes and that's before
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I wonder if you bought the brakes and backing plates,

Then the next day or two you bought the axles.

Then a day or two later the housing

Bee any cheaper?
 
Dana67Dart said:
I wonder if you bought the brakes and backing plates,

Then the next day or two you bought the axles.

Then a day or two later the housing

Bee any cheaper?
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nah, no love. they charge for everything... yes, even used brake pads. and then, you have the whole "warranty" debacle, and you're at the mercy of whatever the cashier classifies your parts as. and that's just difficult waters to navigate for such a paltry savings.

my back of the barroom napkin math showed scooping up an axle "complete" and then picking up loaded calipers and rotors from the vato-zone or flea-bay was the more economical play.

i considered picking up 3~4 and going full tilt boogie, figuring if i was shortening and moving spring perches on one, why not just keep the set up and bang out a few? maybe make a few doubloons on the b-side of it. but that just doesn't really pencil out with how cheap fickle buyers are now a days.
 
My thoughts. A 71/4 is stronger then most give it credit for. I ran 3.91 SG 7 1/4 rears for years in my drag and street cars. My 66 Cuda weighed 3250lbs had slicks and a 170 slant six with a nitrous fogger system. It ran low 13's in the 1/4, with that rear. That said, I wouldn't use one today. Parts are hard to find, and expensive when found. The 7 1/4 and "A" body 8 3/4 both also have a problem with finding 10 X 1 3/4 brake parts, and both have the small bolt pattern which limits wheel choice.
I would suggest going with the 5x4 1/2 disc brake kit, and a rear with 5 x 4 1/2 other then the 7 1/4. There are several options for a rear.
 
I couldn't find an 8 3/4 in 2018-2019 for less than $500 that needed rebuilt and shortened, which is why I settled on a Ford 9 inch. I assume prices and availability are even worse today. So now my Duster is Frankensteined with a Ford rear end and GM Metric Disc brakes and wheels. But so far it's easy to find and get parts.
When I'm dead and gone I imagine whoever ends up with this car is going to have a surprise when they go to do the brakes...The last 8 3/4 I ran across for sale in my Area was $1500 for an open dif and highway geared,stock axels and drums.
 
Dana67Dart said:
7 1/4 came stock behind 273 2bbl.

Mine has 322,000 miles on it.

It will hold up just fine
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It’s good to know they will last if treated well. My 68 dart has a 360 in it and the rear end is quiet and seems fine. I drive it gently though,but I never beat on any of my cars.
 
Just a FYI. I got lucky and just happened on a 8 in Ford pumpkin at a swap meet. Had 4.10 gears with a mini spool. $200. Two days later went to a junk yard for some items, and believe it or not, sitting on the ground just inside the gate was a 8 inch housing (drum to drum). it was the correct width for a "A" body. $100. Did a complete brake rebuild (new everything), and have about $550 total, in the rear. The housing is from a 1976 Comet. Spring perches are 43 inches. Don't remember the drum to drum width, but is just a little wider (1 1/2 - 2 inches) then the "A" body (wheels can correct that). 5 on 4 1/2 bolt circle, 10 inch drums. "A" body e-brake cables fit. Easy swap if you can find one, and a lot cheaper then a 8 3/4.
PS: There are other 8 in Ford rears that can work, just have to measure, and make sure you get 5 lug rears. Some were 4 lug.
Ford rear specs. Rear End Widths
 
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In an open diff 7.25 the spiders seem to be the weak link.
What is the weak link in the 7.25 sure grip units? Would it be the ring and pinion or axles?
If someone was teetering on the low HP scale they could possibly gain a little strength with the sure grip.
I have never killed or witnessed the failure of the 7.25 sure grip units as I do not think there were many made.
It is a bummer about the lack of 8 3/4 units around. I am glad I swapped mine out when they were still plentiful. One of my a body 8 3/4 rear ends came from a U pull it wrecking yard. The cost was like $50.00 plus $5. 00 core.
When swapping to another rear finding a donor with disks would be a bonus.
 
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