I am thinking about taking out my 9" rearend in farvor of a 8". I was told the 8" is considerably lighter. I am not running a ton of power (about 400hp at the crank) but am wondering if a 8" will hold up? I a lighting the car up were ever I can that is cost effective. My thought is I surley could find someone willing to swap a 8" posi for my 9" posi. So my questions are: 1 will an 8" hold up to a 351W with a 5 speed? 2 How much weight will I be saving? 3 What cars ran a 8" that would bolt into my 69 fastback with out cutting the spring perches, etc?

 

Let me just say this, 289 hipo cars were factory equipped with 9" rears. The advertised BHP was 271. You say you are running about 400. I could be wrong but I doubt if the weight difference is more than 50 lbs.

 

If you are so concerned about weight have the wife or girlfriend go on a diet.

Only kidding. Why do you think 50 pounds will make such a difference. I would rather have the piece of mind my rear end is fine and not on the brink of blowing up. It is very expensive to replace parts back there.

 

It was just a thought. I waslooking to shed as much wieght as possible and still have a comfortable cruiser. The more wieght a guy can get rid of the less power you have to make. I would like to get the weight of the car down to the same weight as the 65-66 coupes.

 

dude its really not worth doing. i believe the 8.8's are also lighter than the 9" rears yet stronger than the 8's

but seriously, keep your rear in there - you'd be a fool to swap something rock solid for something whimpy.... and who cares about a few extra pounds? if your car isnt fast enough just add more HP [8D]

 

yea don't get rid of that 9"

id take that 9" posi over my 8" posi anyday

 

I'd guess a fully built 9" is about 225lbs. Ask my back how I know...

Dunno on the 8"

 

Id just keep the 9 inch taking weight off the back isn't good take it off the front where most of the cars weight is.67-70 mustang and cougar will work.Cheapest place to get a 8 inch id trust is http://www.perogie.com/Rears.htm or trade someone on here and some cash.

 

jaysus. don't exchange for 8". nah i wouldn't
i destroyed 2 7.25" rearends (ya ... i know) so that's why I put in a 9". to never ever have to bother with a rearend anymore
I personally wouldn't even think off running 400CHP on an 8"
grannydriving yes, but i don't think anyone with 400HP wouldn't occasionally floor it ...

 

Well, Im pushing 425 HP at the crank and I have beat on my 8 inch for quite some time(almost 1000 miles)with no problems. Granted, it doesn't have a LSD yet, but it is about to! I don't think you will have any problems on an 8 inch, simply because you aren't going to break it with street tires, no matter what kind of power you have. Remeber, the 8s have the EXACT same axle shafts and spider gears and a 9 inch, and the shafts are the weak point in either axle, so the weakest link is exactly the same in both of them.