8 inch rear, how strong?

[65inworks]

How much power can an 8 inch rear handle?

 

[Great68]

More than a chevy 10 bolt

It's more about traction and torque than it is about power, and the 8" usually handles more than people gives it credit.

 

[Blue Thunder]

The 8" looks like a 9" at first glance, just a bit smaller all over. Like the 9", the 8" even has 2 pinion gear support bearings, which keeps gear deflection at a minimum.

I've run 320 hp on street tires through a high mileage stock 8", without trouble.

 

[65inworks]

my setup should be about 325 to the wheels with a stick should this be ok or will it blow

 

[blue66tang]

you should be fine. As somebody said earlyer people dont give the little 8" enough credit.

 

[rbohm]

as long as you are not going to run slicks, you can make as much as 375hp beofre you start to strain the 8" rear. anything over 350 with slicks, you need a 9".

 

[big block 460]

do you have any pic of your 65??

 

[12sec67]

i went through my first 8" with only 250rwhp. then upgraded to another 8" with 3.55 and a locker and blew that one up. most recent set up is 4.11 gears with a locker and drag radials and it doing fine with 300+ at the wheels. i think it all depends on who does that install!

 

[GaPonyFarm]

If you race it, you'll probably break it... Same is true of a 9". If you race long enough, launch hard enough, with tires sticky enough, something is going to break... period.

 

[65inworks]

i plan on having street tires so i know that i wont have to good of traction. If i drive conservatively will i have a problem, i wont be racing often but maybe just from streetlight to streetlight like once a month or so

 

[blue66tang]

You will be fine. I hammar mine pretty dogon hard and i havnt had a problem.

 

[BAD67FUN]

Forget how strong... how fricken heavy are the 8inchers??!!! DANG!! I got mine back together Saturday night. So there I sat with nothing else to do. Should I wait a day or two and get a buddy to come over to help put it back in the car? Yes, but I'm not that patient. So genius here decides to put it on his belly and slide under the car on his creeper (btw, the Sears craftsman creeper is stout! can't believe I didn't break it).

Well luckily I was just strong enough to get it see-sawed in there. But I was worried there for a moment.

Anybody know what the 8" weighs. The 9" must be a friggin pig!!

 

[67GTCOUPE]

I have 410hp at the crank.

I am using under-rider traction bars.

On regular radials 225/60/15's..........I have done many 6000+rpm burnouts a block long.........with ZERO trouble.

If you are using street tires, you will not hurt the rear end........I don't care if you have 2000hp! The limited traction will be your saftey factor......ie/ your smoking tires will cushion the shock to the rear.

Now, you will break a rear end if you have enough traction and enough power. So, if you are drag racing with slicks and 4000+ launches........you need a beffy built-up 9".

My humble opinion.

 

[John Z]

As demonstrated by these threads, people have had a variety of experience with the endurance of the 8". My guideline is that Ford used 8" on 289/302 A and J code engines. For the K code, 271 hp, and bigger blocks they went to the 9". I conclude from this that Ford rates the 8" for more than 220 hp and less than 271 hp.

 

[Edbert]

The folks over at Currie told me (when I inquired about their beefed up 8" components) that the 8" should not be in a car with over 420fwhp. As has been stated here already, traction has more to do with breaking axles/pinions/rings than power. If you are making 400fwhp and get full hookup with a 5K launch you are puting more stress than the 500fwhp guy who spins all the way to 120 feet.

 

[ratio411]

I haven't had good luck with them.
I have broken 3.
2 with 3.00 gears, one with 4.11 gears.
All were open diff.
2 of three shattered the differential, 1 broke the pinion gears.
2 were with an auto tranny, 1 with a wide ratio toploader.
All were running BFG 245/60/14 radials.
All were in my 306 Maverick with no traction.
I lost one 8" to a stock 460/C6 combo in a Ranchero, running 275/60/14 radials when I was a kid. I don't know what broke in it, the rear just locked totally up. It was 3.28/open.
To be fair, none was professionally built and no axles were lost. I think that if you run slicks, the axles would go, but the pumpkin can go anytime.
Good luck
Dave

 

[LMan]

Anybody know what the 8" weighs. The 9" must be a friggin pig!!

...a 9" rear, complete, weighs >100 lbs more than an 8" rear. So you really dont want to go to a 9 unless you really, really, need it.

 

[MustangMatt1966]

I have about 350 h.p to the wheels and my 8 inch holds just fine with a 3.73 gear and posi.

 

[Edbert]

Matt, how sure are you of that 350rwhp number? With that kind of final output and slicks you should be solidly into the 12s and with good traction knocking on the 11s door soon.

 

[MustangMatt1966]

When you are like me and dont know how to shift, it's a posablitily lol. THey call me the granny shifter