The Stovebolt Site Forums The Shop Area General Truck Talk Ford 9" rear end question

I am doing a frame off restoration on a 57 chevy truck and have decided to use the Ford 9" rear end on it. A friend has a used Ford 9" rear for sale for $150. Unknown what it came off of or what kind of shape it's in. My Chevy rear end measures 61" from outside hub to outside hub. This Ford rear measures 59" hub to hub. Will this work for my truck? Is $150 a descent price? I plan to put a 350 Crate motor in the truck, what would be a good gear ratio? What can I expect to spend to rebuild this Ford 9"?
Thanks!!!

you might have to do spacers, but it really depends on what wheels you are planing to use. Also means the wheels probably can't rotate front to rear. I have heard of ford 9" being used a great deal. Prices is ok if its in good shape. Are you planing to rebuild and change ratios? You might post over in the hi-perf forum.

most nine inch rears ive bought just needed cleaning and painting and axle seals.most aftermarket wheels stick out more than stock.

Ford 9".Im running one in my 51.The gears are 333's with a 700r4 tranny.There cruising gears for gas mileage.Do as Zenish said.There a strong rearend.Mine is from a 64 galaxie.355 gears are good.Depends on what your going to do with the truck.You'll have too cut the saddles off and move then over and weld them in place.Set the rearend pinion angle at 5deg Then weld saddles..Weld a piece of channel on frame between frame over rearend for shocks.Use Ford u-bolt plates from ford for shocks.You can have the axles redrilled for a chevy bolt pattern 4 1/2" .. or carry a unilug rig.NAPA parts store sells a U-joint thats call a set up or set down U-joint.It goes from the ford rearend to a gm drive shaft.Make sure the rearend is not tooo far forward in to the rear fender well.I welded a lug nut about 1" from the original center bolt on the springs.This made the tires set center in the fender.The last thing you want too do is the driveshaft after everthing is bolted up That's a very good buy on the 9". Most are $400 +

Shouldn't that be 4 3/4" for Chevy??

5 lug ford vs 6 lug chevy ??
so you will have to change your front end to match 5 lugs
or drill the 5 lug to 6 ??$$$

cause it sounds like you are intent on the 9''

good luck

Two or three issues with a ford 9" rear end.

First: Width- Since you are going to a new bolt pattern, you are going to have to switch rims too. More modern rims are 'backspaced' differently than the original rims, usually moving the tires closer together. So, when you replace the axel and rims you usually go with 2" + wider than the original, not narrower. Trying to space your rims out 2" on either side by adding a spacer that'll cost you $100-$200 and compromise the strength of the differential might not be the best use of your money.

Second: Bolt pattern- When you change the rear differential you'll get a new bolt pattern for the rims, probably Ford '5 on 5,' which is 5 bolts on a 5" circle. Chevy made a 5 on 5 bolt pattern too. Your real issue is going to be that your front tires and back tires need two different sets of rims, requiring two spares... If you are doing a frame off restoration and upgrading to disc brakes in the front you should try to get a rear axel that matches to bolt pattern on your brake upgrade. Now, you could upgrade the front brakes to match the rear axel, but not in a standard kit. All of the kits I found for my front disc brake up-grade were '4 3/4 on 5.' DOing your own front brake upgrade isn't that hard, all you really need are the brakets, you can buy rotors with a bolt pattern that matches your rear axel and then buy some standard calipers, but that'll require more work by you. If you ain't up to the work, don't get the rear diff.

Third- Cost of rear diff. A ford 9" for $150, if the brakes are in good shape and the pumpkin is in good shape is a pretty good price! At the local junk yard I can pull them myself for $100.

Fourth- Convenience- Racers love the ford 9" 'cause you can swap the pumpkin pretty easily. The pumpkin from almost every ford 9" will swap with every other, so if you want to change the gear ratio its easy to do.

If the axel were the right width and you could make your front bolt pattern match, it would be a good deal. But since its gonna cause you lots of headaches to get the width right and the bolt patterns to match, why not hold out for something that'll work better for the same price?

PS-

The ford 9" is a popular rear end with racers and hotrodders alike for several reasons-

You can change the pumpkins cheaper and easier than swapping the ring and pinion in a chevy differential.

The ford 9" is everywhere, so parts are easy to find.

The ford 9" is easier to 'set up' than chevy differentials, ie adjust the pre-load and lash.

The ford 9" does not use the chevy 'c' clip desigh to keep the axels connected to the ring and pinion and otherwise in the car. Occasionally the c clip on an chevy diff will break or come off and the axel will come off the car along with the tire. I've never seen it, but I've heard about it. It is for this reason that NASCAR requires either a ford 9" or 'c=clip eliminators' in a chevy diff.

GEAR RATIO- Try the search function here for more information on this point. Basically, your rear diff gear ratio is determined by your planned use for the truck, tire diameter, gear ratios on your tranny and the torque range/power band of your engine. So, if you are planning on hauling a trailer and have the original 4 speed you'll want something different than if you are using an automatic and planning on just zipping around town.

I'm running the same width 9" in my 55 with the 3:50 gears and a 327 T350 combo.

Another thing to consider is the axle offset from the backing plate flange. Early 9"'s had an offset of about 2 3/8" and used a narrow brake shoe without self adjusters. Later 9"'s had an axle offset of 2 1/2" and used a wider brake shoe. I can't remember the exact shoe width, but offset #'s are accurate. The reason this may be a concern is there are lot's of aftermarket brake upgrades for the later axle, but very few for the early axle. Even a lot of the late model factory disc brake setups will bolt on to the 2 1/2" offset axle. The change I think happened around 1963 / 65.

Thanks guys for all the great information! I went to the Portland Oregon swap meet yesterday and looked at several Ford 9" rear ends, but didn't find one with the right width. I found one from a Lincoln that had disc brakes and thought that it would be nice to have disc all the way around, but it was 3" wider than my chevy axle so I'm not sure if that would work. I forgot to mention I have a Mustang II kit on the front with Ford bolt pattern. Question, is the Mustang II Ford bolt pattern the same as the pattern on the Ford 9" rear end? I'll be using a 350 turbo tranny with my 350 motor, I've been told that a good gear ratio to have would be 355 for good street and freeway driving. Any thoughts? Thanks again for all the help, you guys are great!! David

Ford used various different bolt patterns. I think it makes sense to have your front and rear rims and bolts match.

There are three things that need to match:

1: The number of bolts (probably 5 on the M-II)

2: Bolt circle diameter- 5", 4 3/4", 4 1/2"...

3: Bolt size- 1/2", 7/16"...

For a Chevy rear differential you might find "5 on 5" with 1/2 bolts or 5 on 4 3/4 with 7/16 bolts, etc...

It took me alot of work to find a rear differential of the right width with the right bolt pattern and gear ratio, and I think it was worth it!

Width was the hardest part, after that the other stuff is easier to change. To figure out the width I needed I figured out the tires I wanted to use, then the minimum width rim they required, then got the rims and figured out what the difference in backspacing was from the inside edge of the stock rim to the mount plate on the stock rims compared to the new rims and discovered I needed 1 1/2 inches more on either side of the axel and ended up with an axel 3" wider than my stock one. The main difference was the backspacing.

best of luck!

What John 1 says is important too. The brakes on your new axel can come in different shapes and sizes- Disc or Drum? If Drum, what size? 9", 10", 11", 12"... Will they fit inside your rims? What do the rotors/drums look like on your prospective axel? How about the piston/caliper? Is all the brake hardware intact?

If two axels meet your width/ratio/bolt pattern requirements, don't forget to check out the brakes. Finding an axel with larger drums is better, and if the hardware is in good shape you'll save yourself alot of money from the git go.

'most'ford CAR rears will match your front end.some lincolns are 5x5,full size ford trucks are 5x5.5.