Ford 9" under a '67 Coronet

[Brandy]

So I got this 9" rear axle to put under the rear of my '67 coronet. it's 62.25 wide and the stock Coronet one is 59 3/8ths. Can this difference of 7/8ths be made up by backspacing? Or do I have to get out the scissors and whack some off of each side? Keep in mind it will be tubbed to the frame.

 

[terzmo]

check your math first

 

[Cranky]

Are you going to beef up the 9? You know, contrary to popular belief, they are not all that much stronger if any than the 8 3/4 is in stock form.....and yeah, check your math

 

[Brandy]

I see that Cranky. I just read an article from Hemmings about that. So ones as good as the other then. I suppose the best option would be to pick up a surgrip for the one I have.

 

[moparsteve636]

That would be the wisest move!

 

[Cranky]

I see that Cranky. I just read an article from Hemmings about that. So ones as good as the other then. I suppose the best option would be to pick up a surgrip for the one I have.

Plug ins for 9's ain't exactly cheap either. The good things that are good about the 9 is that there are a ton of up grade parts for them plus a ton of different gear ratios. Over all, they are usually more expensive in the long run but man, go ahead and get it anyways. Not sure what they bring these days but someone will probably want it.

 

[mopar12372]

loose hp with a 9 because of pinion location .

 

[terzmo]

9 inch fords are weaker than a 741

 

[Longroof]

The 9" is a stronger axle than the 8 3/4. And the aftermarket support is far better.... Im not going to argue the point, i know its true, I have owned both and only broken one... several times with a small block before I upgraded to the 9" and then never broke anything after that. If you can pick it up for a good deal get it, look for a Nodular case, will have the letter N cast into it on the front side, might be able to find one in an older truck, or there are some pretty cheap aftermarket ones too. With a Nodular case your good to go probably will never have a problem.

 

[Scooby67]

I have 9" behind a 493 stroker in my 65 Belvedere. Strange axles with 4:11's. No sweat!!

 

[Cranky]

What were you breaking with the 8 3/4 and what was the combination? We didn't start breaking them(shaving teeth) until we got down in the very low 11's with a 4 speed and 3200 lbs launching at 6k. A stock Dana 60 went in and problems went away and carried us into the 10.60's and that was even using the stock axles until some tech guy finally noticed they weren't aftermarket.

 

[wannadrag]

X2 but some of these guys with the Mopar Nocar mentality refuse to believe it.

The 9" is a stronger axle than the 8 3/4. And the aftermarket support is far better.... Im not going to argue the point, i know its true, I have owned both and only broken one... several times with a small block before I upgraded to the 9" and then never broke anything after that. If you can pick it up for a good deal get it, look for a Nodular case, will have the letter N cast into it on the front side, might be able to find one in an older truck, or there are some pretty cheap aftermarket ones too. With a Nodular case your good to go probably will never have a problem.

 

[Brandy]

I read that. Something like 12-15 HP.

loose hp with a 9 because of pinion location .

- - - Updated - - -

I saw that too, about the Nodular case being far stronger and the most desirable. Unfortunately the one I have is not the nodular but the next best one that is most common. After sleeping on it I have decided to go with the 9", because i'm not doing a factory resto anyway, and the 9" is 7 years newer, and from what I read here, and on several other forums, the concensis is that the 9" IS stronger than the 8 3/4. I know everyone has their own opinion and experiances with both. I don't. I have to go with the prevailing majority of those who know and my own personal wishes as regards my car. I hope that don't piss anyone off but there it is. peace. OH, and yes, i'll check my math too. Thanks.

The 9" is a stronger axle than the 8 3/4. And the aftermarket support is far better.... Im not going to argue the point, i know its true, I have owned both and only broken one... several times with a small block before I upgraded to the 9" and then never broke anything after that. If you can pick it up for a good deal get it, look for a Nodular case, will have the letter N cast into it on the front side, might be able to find one in an older truck, or there are some pretty cheap aftermarket ones too. With a Nodular case your good to go probably will never have a problem.

 

[Longroof]

What were you breaking with the 8 3/4 and what was the combination? We didn't start breaking them(shaving teeth) until we got down in the very low 11's with a 4 speed and 3200 lbs launching at 6k. A stock Dana 60 went in and problems went away and carried us into the 10.60's and that was even using the stock axles until some tech guy finally noticed they weren't aftermarket.

65 Valiant with a 360. The car went through a few stages of build. When it was a mid 11 - low 12 car it was fine but once I built a new motor 500 ish hp it went in the 10's and was hooking the 8 3/4 just could not hang in there... my uncle who raced mopar's in Stock and super stock for 30+ years warned me but I was a young man who couldn't afford to do it right the first time so I got to do it again and learn my lesson.

If it is just going to be a street car that won't be on slicks and hook the 8 3/4 will live. Put power to it and hook up and it WILL grind teeth off the ring gear..

 

[Cranky]

X2 but some of these guys with the Mopar Nocar mentality refuse to believe it.

I believe the 9" is a good rear end but in stock form, I really don't see it as being that much stronger if any over the 8 3/4. I've seen plenty of failed 9's too but I do see some benefit to the 3rd pinion bearing helping to reduce pinion gear deflection.....

I read that. Something like 12-15 HP.

The 9 does have a fairly low pinion in relation to the ring gear.

 

[mopar12372]

X2 but some of these guys with the Mopar Nocar mentality refuse to believe it.

why do you have a mopar? i sure that whom ever had ever broken a rear end at anytime any make model was using something that wasnt checked out first or not adjusted right .
build engine/transmission install into car do a few burnouts take to track hook break it then blame it on the rear end not thinking why it happened
get a stock 28 or 31 spline with truetrak it will explode behind a mopar . super stock racers use the 8 3/4 , just a bad rep thats all it is. there are plenty of parts to make an 8 3/4 stronger. the cost has come down alot over the years .

you should put a 350 chevy in it too because its less money to build .

 

[Brandy]

I think I'll end up beefing up the 9" with some Currie stuff and also shortening it a little. I expect to have to move the spring mounts as well due to also moving the spring perches in board. I have time, i'm in no hurry. I am taking a lot of notes and studying up. I have a very good friend who lives about 5 miles from me who is a professional welder and fabricator, we ride motorcycle together. He is on alert to do the axle stuff when I get to it. I trust him. I also picked up some great tips from the thread where I think 747 shortened an axle for another FBBO member? That was very instructive on the process.

- - - Updated - - -

"you should put a 350 chevy in it too because its less money to build . "

You should kiss my a**. You have no idea what my situation is, maybe you have wads of cash to throw at YOUR MOPAR but that don't everybody else does. How about you don't take anymore shots from the cheap seats and stick to helping other members make the best of what they have. THAT'S why we are here. MHFO!

 

[mopar12372]

it was a nudge , hope it works out for ya

 

[5.7 hemi]

We can't be friends anymore.....lol!!!

 

[Longroof]

why do you have a mopar? i sure that whom ever had ever broken a rear end at anytime any make model was using something that wasnt checked out first or not adjusted right .
build engine/transmission install into car do a few burnouts take to track hook break it then blame it on the rear end not thinking why it happened
get a stock 28 or 31 spline with truetrak it will explode behind a mopar . super stock racers use the 8 3/4 , just a bad rep thats all it is. there are plenty of parts to make an 8 3/4 stronger. the cost has come down alot over the years .

you should put a 350 chevy in it too because its less money to build .

When you have enough power and traction the 8 3/4 becomes the weak link. I know I had enough of both of those things... ?

Maybe you don't have enough power or traction... and that's ok, they all don't have to be drag cars.

Not any superstockers that run hard use an 8 3/4... stockers do but they also will break them.. I have been around NHRA stock and superstock for over 25 years now have been crewing for a mopar that was #1 qualifer at the US Nationals, several class wins, several time National Record Holder and a National Event win, but if you want an 8 3/4 go ahead, hope it works for you. It is a good rear end if you use it within it's limits.