swapping out the 8" for 9"

Hey Guys, I got a 9" rearend that needs rebuilt and cut to length so it fits better under the 66 but was wondering about the pinion angle. Is the 9" angle the same as the 8" angle? A friend had this setting around and said instead of rebuilding my 8" we could swap them out and rebuild the 9" instead! I almost fell out of my chair on that...I'd be nuts not to take him up on it. The last rearend swap I did was into a 65 Comet and that rearend didn't last 2 months! Any tips would be helpful....such as rear brakes and yokes or whatever you guys might think of.

As far as pinion angle... if you have to cut the rear down to size its very probable that your going to need to re-position the spring perches. Unless the rear came from a similiar chassied car, the spring perches are probably going to be in a completely different position, so you'll have to cut them off and reweld them, at which time you can set the pinion angle.

For rear brakes, it depends on whether or not you want disks, and what type of rear it is. I believe Ford made 2 different types, one with a bigger bearing and one with a smaller bearing. I don't really know too much about this though. Quite possibly the 8" drums and backing plates will even work for an older 9". Somebody on here will know for sure. I know that if you have a big bearing 9" you can get a nice disk brake setup from a newer explorer with a 8.8" rear, which would work really nicely with very minimal modification.

Will

I just got out of small bearing brakes for my 1959 nine inch. I had big bearing ends put on.Go bei bearing way less hassel. Small bearing replacement backing plates are hard to find plus I could not find drums for my set up. Mind U my brakes were out of an edsel.I welded morrso perches on mine and used the same pinion angle as my 8 inch.Drive shaft was the same I cant remember if I swapped the rear ujoint or not.I dont think I did.

I didn't know about big bearing or large bearing ends but that does make since.
I did some reading about the 8" rearend that they're using in the Project Mustang right here on this site and they've said a 8" could handle up to 300 hp easy if it's built with the right parts. I don't plan on going over 300 myself in my 289 so why not just rebuild the 8" with new and stronger parts and call it good? I don't plan on racing much at all if any...this is mostly for the street and 300 hp is more then enough for me. Has anyone built up an 8" around here other then the one for the Mustang?

8 Inch is a good rear end like a little 9inch. Iv heard of lots of guys using them with big HP with no problems. Try a post in the dragracing section.

8 inch backingplates etc will work on a small bearing 9 inch. the big bearing 9 inch's were used in things likes trucks, vans and large cars(not exclusively mind you, remember its fomoco). since your getting the 9 inch sized to your car anyways, if its the big bearing 9 inch you could do what i did to save some cash. i just got them to weld the 8 inch bearing ends onto the shortened 9 inch tubes(leave a bit of the 8 inch tube with the bearing seat, then they can turn it down a tiny bit to fit into the 9 inch tube) works great. also allowed me to use my 8 inch axels in the 9 inch(will work as long as the spline count is the same) and all my old brake stuff.

smblktbolt, That's a great idea....I could do that easy enough but will look around for a small bearing housing before I hack mine up. Thanks!

why swap the 8 for the 9"?

are you racing? putting serious torque to the ground?

trans brake with a big stall?

the 8" is more than strong enough for pretty much whatever you want to do with it.

we have a maverick with a strong 302 that runs 10.12 in the quarter with the stocke 8" axle, and 4.56 gearing.

to me theres no reason to swap the axle, unless of something like your axle is broken, andyou just happen to have a 9" laying around..?

bk2life, your turning 10's with a 302 and you haven't had any trouble with the 8" at all? Sounds like I better rethink this and put the cash into better parts for the 8"...thanks bk2life!

Originally Posted by RickRacer

bk2life, your turning 10's with a 302 and you haven't had any trouble with the 8" at all? Sounds like I better rethink this and put the cash into better parts for the 8"...thanks bk2life!

we might be one of those "it only happens to them" stories, but its true.

4 56 gearing, mini spool, stock prolly 28 spline axles, 10 inch slicks, 4500 rpm no trans brake c4, 250 shot nitrous.

the 8" has many parts available for it, and it is really strong. im sure someone will say go for the 9" swap, and i too would say do it if you really need it, but the truth it, its a strong axle.