Is my Ford 9" right for me?

Hey Everybody, I picked up a 9" to put in a '31 Model A (350hp, 327 SB Chev). The width seems like it will work, but is this model going to work for me from a durability standpoint? From what I've read, it sounds like the rear end was from an early Mustang. Below are the casting numbers on the case, and measurements. All opinion are welcome. Thanks

Flange to Flange - 59 1/4"
Inner Backing Plate to Inner Backing Plate - 51 3/4

No oil plug in rear cover

10 housing bolts

5 pinion bolts

Casting numbers on case:
7H8
DIF58
7F19
24
DIF
07AW or C7AW or MYLO (depending on which direction you look from as well as some rust making it difficult to decipher)

 

'67 to '70 Mustang, , Fairlane , Comet and Cougar. If you're building coupe or roadster it might be a little wide but perfect for a sedan.

 

It's a roadster, full fenders..

 

'Durability standpoint'? If that rear is a 9", it will outlast your Chevy engine 3 to 1.

 

It is A 9", HOWEVER it's the model of 9" that I'm questioning. Some people have these massive Currie built rear ends with 31 spline posi's.. and mine is the said to be the weakest of the 9" familly (at least that's what one article said). So I was wondering what kind of power would be reliable, if I need to beef anything up, if I have the wrong style all together, etc etc.

 

doubt you would break it unless you were mercelessly thrashing on it..dumping the clutch at 6Grand all the time etc..or if it wasnt put together right
Roaster isnt very heavy, probably not going to hook up real hard, or at least not hard enough to snap it...but its just like anything else ..punish the shit out of it, soon enough it will shit and punish you

 

Is the pinion centered on that rear end? Could you post some pics

 

It's not a centered pinion, the pinion is off to one side slightly I believe. I will post pics asap tomorrow

 

It's about 2 1/2 inches wider than you really want for a fendered roadster. You can get it narrowed just on the long side and leave the other side alone.

 

Get the wheels and tires you'll use before you do anything to the rear .

 

The rear end should be able to handle the motor that you intend to use unless like someone else mentioned on hear about doing the 6 grand hole shots !

The rear end housing is just as strong as any stock Ford 9in housing and ford had a lot of peppy engines in their day.

The axles should be inspected to make sure that they are not twisted and sometimes when having an axle cut it could weaken it but in most cases it will be fine.

The center section/gears is the weakest link on this rear end but that does not mean that it will not hold up. I would use if it were mine. I did not see if you said that it was posi or non-posi ? a non posi tends to handle more HP as only one wheel spins saving the axles and gears a lot of stress.

As far as the width you have to decide if you can get wheels with the offset to make you happy or would you like to have it cut for wheels that you might already have.

I would use it and if you make more HP in the engine later you can upgrade the axles and gears etc etc... Good luck with whatever you decide and post up some pictures. Pictures would not change my mind but I like to look at things.

 

Thanks for the replies. The rear end isn't a posi, at least not yet. I was interested in opinions on that as well.. a 1 wheel peel kind is pretty lame.. Is it worth getting an aftermarket internal setup with posi or sourcing a new rear end that has it built in? Also, should I be considering any bracing for the housing?

 

Murdered one 9 inch in my life, with a bone stock 300i6 of all things! 'course shifting from the granny first into second with the 35x12.50's smoking might have had something to do with it... Never killed another and I drive like a total asshole!

 

i ran a standard 9 inch housing with 28 spline stock axles for years and clutch type limited slip diff. i beat the crap out of that thing at the drag strip and on the street for years without any failures. i upgraded the internals and axle shafts after i burned up my 2nd set of clutches. i installed a detroit locker and moser 28 spline axles and resumed beating the crap out if it. i run a stick trans and dump the clutch at 4500rpms on a sticky track and never worry about the rear axle breaking. i have a stock housing and stock center housing, no nodular case or aftermarket pinion support. i have an est 400+ hp small block.

 

You didn't state whether it's an auto or stick? I think you are over thinking it, that stock rear, even used will hold up. If manual are you dumping the clutch at every light? Open dif is fine unless you are racing it. You should do as Metal Man suggests get your rolling stock first, measure and see what width you need and then go from there.

In my opinion an 8" is a better choice as it is smaller overall size and has less drag, 9" is overkill in many applications.

 

I plan on going with a manual trans, and as for dumping the clutch that's really not going to happen to often. Even is a 9" (in any form) is a bit overkill for that kind of power, I'd rather build it stronger and never worry about repairs then to build it "just enough" now, and upgrade later. Here is some pictures of the rear end.

 

To be honest the 9" is overkill and when you have to spend money to get the rear cut down , have the axles cut and re splined , why don't you just get a Ford 8" rear that will fit in just fine without any cutting and you can still dump all the HP you want behind that rear . The Ford 8" is a very strong rear and is a lot cheaper too . A early Mustang , Cougar , Maverick , Comet rear will be the one to get and with no cutting to be down for way less than $300 ! I have put 400 HP to a Ford 8" rear and hasn't broken yet ! Think of all the Mustangs that guys beefed up and took that clutch and dumped it smoking the tires clean off the rims !
So it's your money and your project and I know you can use the extra money someplace else also !
Just my Ford opinion !

Retro Jim

 

Ford has different length axles in each side for MOST of their 9 inch models.
A long and a short. It is very easy to find another axle 2 to 3 inches more narrow than the long one in your rear end. Just shortened the housing and you are GOOD.

Or Moser can shorten the housing and the axle for reasonable money.

They respline a axle for $65 and the housing for $85

http://www.moserengineering.com/moser/shop-services/

Most Model A coupes and roadsters ... need a rear end with the width at 56 inches. Measured from the Wheel mounting surface to the wheel mounting surface.

I have a 56 inch unit my 32 3W



I used a original 57 Ford 9 inch and a stock 65 Galaxie axle to get to 56 inches ...

 

Thanks for the replies. The main reason that I chose a 9" is because I ended up with it for free.. long story short, I did a bunch of swapping and trading one weekend and made out with a free 9" and engine stand. Pretty sweet deal if you ask me! As for narrowing my long axle tube, I think that is a viable option. Sourcing out a new or used axle is probably not to difficult and likely a reasonable price. I'll also leave the rear end non-posi for now as it can always be upgraded later if need be. How involved is narrowing the long axle tube? Is 56" a conservative estimate or a bang on number to shoot for?

Thanks!

 

"Weakest one in the 9-inch family" does not mean that it is weak. Narrowing requires a jig, which a lot of shops have. Most do not charge a whole lot for this process. In your case, one flange, along with the right amount of axle tube would be cut off, and a new, same design axle flange welded back on. In order to make sure that that new flange is lined up properly, a solid round bar is passed through the axle housing, passing through metal pucks, one in the axle flange on the far side, two where the carrier bearings go, and another puck in the hole of the new axle flange. This assures the whole deal is lined up while the flange is welded on.

 

85 dollars is pretty cheap ... to narrow a housing ( one side )

Then 65 dollars to respline the axle ...

150 dollars plus the freight

The best 8 inch axle is a 5 lug Maverick. It is the most narrow 8 inch. It is 56 inches from the factory. The most narrow 9 inch is the Bronco and the 57/58/59 Ford car.

This came of the internet

67-70 Mustang 59.25 inches
71-73 Mustang 61.25 inches
77-81 Versailles 58.50 inches
74 Maverick 8" 56.50 inches
75 Mustang II 8" 57.00 inches
67-73 Mustang, Torino, Ranchero, Fairlane 9" 59.25 inches to 61.25 inches
57-59 Ranchero and station wagon rears, 57.25 inches
66-77 Bronco 9", 58 inches
77-81 Granada/Versailles, 58 inches
67-71 Comet, Cougar, Mustang, Fairlane, 59.25 inches
71-73 Mustang, 61.25 inches
67 Cougar 60 inches
67 Fairlane 63.50 inches (coil springs)
72 Ford Van 3/4 ton 68 inches
73-86 65.25 inches
57-59 Ford 57.25 iches (narrowest 9" housing)
66-77 Bronco 58 inches but has 5-on-5 1/2 inch diameter bolt circle
67-73 Torinos, Rancheros, Fairlanes 59.25 inches or 61.25 inches
67-71 Comets, Cougars, Fairlanes 59.25 inches

 

I've been running a 8 inch behind my nailhead and a 5 speed for five years... no troubles at all.

 

If it's already got the gears in it you're gonna run - heck just run it as is and go from there. OTOH IF you are changing the gears then if it were me - I'd go ahead and add the daytona pinion support in it and call it a day. The daytona support is probably the biggest bang (strength-wise) for your buck. If OTOH you intend to do some serious racing with some sticky slicks, steep gears then by all means - put the nodular case and the rest of the goodies.
You already have the 9" - narrowing it isn't all that much - I did the one in my truck myself - including resplining the axle - just to see if I could, but heck for the money they get - it's a heck of a bargain!!!!

 

So far, a 1958 9" cost me 2 swaps (and over $500):

1) Cracked Housing.

2) "Blown" Posi

Albeit it is behind a 454 BBC w/400 Hp & 4sp Muncie.

 

I guess you can't turn down a FREE Ford 9" truck rear . Do one axle/side and you will be fine ! Good price for the work !
The Ford 8" I am referring to is the early Mustangs mostly . They fit under the 1950,s Fords real well with no cutting which is about the same on a roadster .
Anyway you look at it Ford made the best rears !

Retro Jim

 

When Ford first made the V8 Mustangs ... they installed the 8 inch behind 260's and low horsepower 289's. When the 289 got to be High Performance ( only 271 HP ) Ford quit with the 8 inch and upgraded to a 9 inch. A 9 inch for a High Performance Mustang ... is pretty rare.

Later ... when the Fairlanes and other Fords got past 250/260 HP ... Ford installed the 9 inch from the factory. Why install a 8 inch behind 300 HP or so when Ford would not past 250/260 HP ???

In the late 60's, almost every decent running Mustang around my area had upgraded to a 57/58/59 Ford 9 inch ... BECAUSE ... the 8 inch had given up and broke and the 57/58/59 9 inch was almost a direct bolt in.

 

I agree, a free 9" is an excellent, excellent deal! I'm unsure of the ratio in the housing right now, but I do believe they are 28 spline. So it's set, the 9" wins. The car is a street car and will never, ever have racing slicks on it. Street radials are probably what it will end up with. Again regarding the width, is 56" a conservative estimate or a number that I should shoot for, give or take my rim offset?

Thanks for all the help!

 

You might also look at the ford 8.8 out of an explorer. they are 31 spline, choice of 3.55 3.73 or 4.10 gears. Limited slip and pre 95 had drums. 95-01 has discs. I am going this route with my 36 chevy. I bought a 4.10 L/S with discs for $200 and a spare open rear end for $100, yanked the short axle out and kept the disc brake set up. The long side is getting chopped as we speak. I think it would be close to what you need. They claim its very similar to the chevy 12 bolt and would hold up to your engine. You could sell the 9" for some $

 

One thing to put into consideration is how weight and torque work. Heavier wight takes more torque to make it move from stationary.
Sticky tires and shock load from sudden torque application will splatter rearends and transmissions in the right conditions.
Light street car, street tire limited traction=most likely you will break traction before parts unless you really mean to hurt something.
I have learned this from dump trucks, log trucks, severe duty heavy haul trucks in off road conditions. Splattered locking two speed differential carriers, driveshafts with 3/16" thick tubing twisted, opened like a book, or shattered with pieces missing.
Torque talks.