8" Ford rear, how strong is it? - Hot Rod Forum : Hotrodders Bulletin Board
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Old 12-01-2006, 07:02 AM
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8" Ford rear, how strong is it?

I have a 32 Ford Sedan Delivery that came with a Ford 8" rear. I'm installing a SBC 383 stroker / Hilborn injected 500 HP, plus 200 Nitros added on. There is a guy on eBay, in PA. that says he builds 8" rears stronger than 9". It would be a lot easier for me to change out the 8" third member than replacing the whole rear. I've researched Ford rears and understand the basic difference between the two. Is there any truth to his claims or am I getting smoke blown up my tail pipe?
Thanks, Ron

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Old 12-01-2006, 07:55 AM
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There are a lot of factors involved to determine if a rear end is going to live. Generally speaking it's going to be the weak link that breaks first, be it U Joints, third member, axel, clutch etc.

Even with 500HP with a consertative tire and not doing a lot of hole shots chances are an 8" will live (I personally would be concerned the axels a bit more than the third member).

Sticky tires, banging gears, loose convertor or a stick you can break any rear end. I know from personal experience that no rear end is bullet-proof or unbreakable I've even managed to destroy a Dana 60 once.
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Old 12-01-2006, 09:02 AM
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Depends on what you're going to do with it and the gear ratio. At 4.11 and up, the 8" pinion gets really small. The usual figure is about 300HP, but YMMV. FWIW - our Mustang has a 302 that makes about 260HP. The car has a spool and a 4.11 set of Richmond gears in an 8". We run slicks on the car. After 2 seasons (about 1100 passes), the pinion teeth gave it up at the 2006 Thanksgiving race. We'll be going back with a 9". With the equipment you listed, go 9" and get it over with.

In comparison - my Falcon runs a 351C with about 320HP at the rear wheels. Back in about 2000 I built a 9", 4.56 Richmond, 31 spline Mark Williams axles, grade 8 studs, Detroit Locker. This unit has over 1800 passes on it and the parts look nice and new (because I check them every year). Cost was $1650 back then for all the pieces and I did the assembly and install. Zero failures = money saved. Also we'll be going to 350~400HP at the wheels this year - and I don't have to spend a dime on the rear axle. You're a hotrodder, you will always be looking for more oomph.
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Old 12-01-2006, 11:25 AM
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All good input.

Sure a super built 8 is stronger than a "light nine".....

But why waste the money on an 8 ?
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Old 12-01-2006, 05:20 PM
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Just as a side note ...
Whenever Ford was building vehicles that came with either a 8 inch rear or a 9 inch rear ... AND the horsepower got over 250 Horsepower or so ... Ford went ahead and installed the 9 inch ...

Make it stout ... when in doubt ...


9 inch Ford, 31 spline axles and a Detroit Locker ...
Under a 2240 lb. 32 Ford ...
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Old 12-01-2006, 05:30 PM
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I had a friend with a 65 Stang years ago that I street raced with (yeah stupid but hey). His uncle was convinced they could build an 8" that could handle the 289 they were building. They left it at 3.50's and ran short profile slicks... popped the third member after only a couple months. This was a four speed car but I've decided I'm sticking with 9 inchers for anything except a stocker.

-Stephen
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Old 12-02-2006, 05:46 AM
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Thanks for the replies guys. Your input is most helpful. The verdict is to pull the existing 8 inch that came with the car and install a 9. After contacting a professional gearhead, he confirms what everyone has told me. The recommendation is a 9 inch nodular with billit caps and a Daytona pinion support. The billit / nodular carrier Trac - loc will live if I use 12 inch or narrower tires. With 700 HP, I might fudge a little on the tires.
Thanks Again Everyone, Ron
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