Keep 8" or go 9" rear end?

So I'm considering my options for my '65 coupe...I've yet to get under and check but I'm pretty sure the rear end is the stock, open 8". What I'm wondering is, would it be worth it to keep the 8" and just get a traction lock unit and lower gears, or should I try to find a junkyard 9" and go through the hassle of first finding one, then getting it to fit? I'd likely still need a trac lock unit and gears, since I doubt any that came with those from the factory are long gone or ass expensive by now. I don't have access to a welder or anything like that, and I'm not sure if I'd even need one to put the 9" rear in...Any ideas? The motor is gonna be a 306, Edelbrock RPM heads, Stealth intake, 650 carb, Comp Cam, C-4 possibly with a stall converter. How much power can the 8" take? The car isn't going to see the track or sticky tires or hard launches or anything like that.

Truthfully I don't know that much about the 8", but in my opinion, it's always better to go ahead and maybe do a little more than you think you need to. If you decide you want to take it to a track or you end up with a higher HP build than planned, you will glad that you already have that 9" installed. It may cost a little more and be more of a pain right now, but in the long run it is better than tearing up the rear end you have now. Just my opinion lol

I'm not sure if "ckelly" will chime in on this thread or not. But, I've seen him state (with real life experience) more than once, "the 8 inch will do everything you want it to with small block (289/302 based) power." As for myself I went ahead and bought a 9" out of a Granada with disc brakes. Now, I still haven't hooked up the emergency brakes and that sucker is heavy as heck. There are plenty of vendors around that can hook you up with a new center section (with the traction and gear ratio features that you want).

Step back and think about it, if you keep the existing 8":
1) it is plenty strong...as long as you're not side stepping the clutch at 4K rpm with 10" slicks
2) you don't even have to loosen the u-bolts or remove them
3) you don't have to break the brake lines loose...then, bleed the system
4) you don't have to modify the drive shaft
5) you don't have to fabricate some slick way to hook up the emergency brakes.

With a 9" (small bearing ends), IIRC you can re-use your brake backing plates and drums as long as the off set, center hub hole, and bolt circle are the same. Otherwise you have to deal with 1-5 above.

I'm thinking of switching back to an 8"...and no, the 9" is NOT for sale.

My $0.02.

Robert

imo, you should stay with the 8 since you arnt going to track it. i pretty much have the same setup as you but ill be seeing the track with slicks and i dont want to chance it.
the 8 inch in your 65 has the tapered axle tube ends before the drum brakes. if you are going to build your 8 inch you most likely want one from a 67-68 mustang because the axle tube does not taper and is straight... therefore making it stronger. also if you are going to build it throw in some forged axles and a nice locker or whatever you want back there. with that, it should hold up to 450ish hp. for more references the project 11.99 mustang here is holding up with the 8inch and is making big power.
also, i cant remember which site (eithor mustangandfords.com or mustangmonthly.com) built a full currie 8 inch to make some big power.
goodluck.

The 8" Ford will easily handle the 300 hp that your engine might produce. If you were stroking it and running nitrous then I would say get the 9". The problem is that you are going to have to get the locking rear end with either - most 9" don't come with locking differentials.

Originally Posted by PaulS1950

The 8" Ford will easily handle the 300 hp that your engine might produce. If you were stroking it and running nitrous then I would say get the 9". The problem is that you are going to have to get the locking rear end with either - most 9" don't come with locking differentials.

I'd found a complete trac lock unit with 3.40 gears for a few hundred, that was the only reason I was asking about it

Originally Posted by zpyro

The motor is gonna be a 306, Edelbrock RPM heads, Stealth intake, 650 carb, Comp Cam, C-4 possibly with a stall converter. How much power can the 8" take? The car isn't going to see the track or sticky tires or hard launches or anything like that.

Given all these circumstances, a good 8" will last for years and years. Combine the 8" with the 3.40 gear and you should make it a nice responsive street car.

Originally Posted by beegshot

Step back and think about it, if you keep the existing 8":

4) you don't have to modify the drive shaft
5) you don't have to fabricate some slick way to hook up the emergency brakes.

Info purposes only: A 57-59 Ford 9" rear is a bolt in and the drive shaft doesn't have to be modified. Instead, a "short" pinion yoke can be used on the rear, which were commonly found on some trucks. They can be gotten new for about $60.

Unlike the disc brake Monarch/Granada rears, their is no parking brake problems with the 57-59' swap. Just swap on the 65-66' 8" Mustang axles and drum brakes and life will be good when you need to buy replacement parts.

I've a 331ci stroker engine with a 8" and I drive sometimes hard and my rear axle is still alive.

I put an Auburn locker and 3.55's in my 8" when I redid the car. My stroker puts out 425 hp and 450 foot pounds. I drive the hell out of it and have no trouble.

Cheers,

Gregg
http://www.cardomain.com/ride/2518882

make sure you have the extra ribbed 8inch case.