Thread: 9" Ford Rear Center Section - 31 Spline

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So, I call the auto salvage yard to get a 9" Ford Rear Center section for 31 spline axles ... what Fords did this rear come in?

(Dumb question, I know; but I'm learning.)

73-82 Ford full size trucks (not Bronco) F150-F250 should have the 31 spline center carrier, 70-78 Lincoln Towncar, 69-75 Drag pack or big block equipped Mustang, Cougar, Torino, LTD should all have the 31 spline center section as well. I know I might have missed one or two, but the rest of the regulars here should be able to fill you in on them.


Bill S.

Actually, they can show up anywhere. I've had 31 spline rears in 6-cyl. pickups and 302 cars, and 28's in hi-po big blocks. They're where ya find 'em!

Thanks, guys. Looks like they won't be hard to find.

This is probably more rant than rave.
I got a complete 9" as part of a rod parts package. It had some big drum brakes on it and was very oily and full of dirt. a mess. It had 31 splines ok, open carrier.
First was taking it apart. Every bolt and nut was rusted tight. I had to heat every one of the carrier nuts to get them off and all 8 of the backing plate nuts/bolts. You would not believe what this thing smelled like.
Next both axel bearing were totally worn. A 40 ton press wouldn't even budge them so I had to cut them off. The housing bearing rings popped out with a good puller.
The pinion nut took a special bolt-on bar and my big truck lug nut cross to bust loose. Then it took another puller to get the bearings out. These were also fully spalled. It must have made a big howl going down the road. then the carrier bearing races had to be cut off and they were galled up. What a mess. I didn't plan on reusing any of them but this thing had to have the crap beat out of it.

Then I find out it has the small carrier bearings typical of a 28 spline and the 31 spline spider gears. These are not availabe for this combination anymore so I'm told. Just great and orphan. At least it had the new style housing ends.

Then I go over to the car wash to clean it up. haha I'm right in the middle of engine cleaning it and who shows up?? The owner. Well he runs me out of there on a rail. Says that the inspectors don't want grease and oil in the drains. I asked him what he has engine cleaner for then. Well I got the boot anyway.

Off to the sand blaster. The going rate was $50-70 but I managed to get it done with some other stuff for $30.

Now back home I get ready to narrow the thing and behold it's a truck rear end with the 3 1/4 " tubes tapered to 3" right at the end. Well with some carefull measurement I was able to make the cuts right on the taper and weld it back together. I have a pretty stout line up bar and pucks so even if it is a bit out of line with the housing after welding the bearing housing are in perfect alignment.

But now my nicely made 4 link plates don't fit the tubes so I have to cut the plates for the 3 1/4 tubes. the disc brake brackets also had to be reworked. PIA again.

About the only thing that went well was setting up the new ring and pinion. BTW I used the pinion spacer and shims instead of the crush sleeve. Great item.

Not done yet. I tried to put the axel bearings on but they were locked up tight. took them to the drive line shop and they busted one with a 50 ton press. Turns out the bearing is China made and undersize a little. So another $65 for new bearings and these also are on the small side and the axels are on the very larger side. We had to grind down the axel a few thousandths to fit. PIA. So homeward we go. Only to have buddy mess up one of the axel seals. Dang. I need to lose this thing before it drives me crazier than I am.

As it turns out up untill recetly there was a ball bearing that exactly fit instead of the tapered rollers. No such luck now they don't make them anymore. These really made the seal problem go away.

Anyway the bottom line is avoid the truck stuff if you are narrowing it. Actually looking at what these go for now in the junk yards you can build one out of brand new stuff for a net of less and have mor fun doing it..

Edited today:
Well another thing. I just got the long awaited rear disc brake set. More truck rear end troubles. Dang when is it going to stop. Now the blasted axel flanges are too big to fit inside the rotor hats. Like by about 1/2 inch or better on diameter. Well the axels go off to the machine shop tomorrow at 0700. Looks like another $75
I learned something about this thing, Give me a Dana any day. Otherwise just order new parts no more junk yard stuff. They are getting way past $200 for these things now. If they have one.

i used to get 28 spine 9s with limited slip s for $75. a rear end and 31 where the same price .god i miss them days. i only found 31 s in a four wheel drive truck and a 390 ford truck . the big tube rear ends i have cut down at the center where it get pushed in and welded from ford. i have used this truck rear end in car where you can not see them the older 9s look better and the older 59 look the best in old street rods but the trucks are beefer for race and hot street car and have the big truck brakes that i like they work great to stop a heavy car and easy to redrill for the chevy 4.3/4 bolt pattern and brake parts are cheap to. i have one i made for my up for my gto and did other.s gm A and g body cars and a had made up a jig to weld all gm brackets to the ford 9. for heavy use i like to use a shim pack and not use a crush sleeve with all stock ford parts but a shim pack and set up the new clutchs pack with very good luck have put alot of power thru them

TM,

What are you working on?


Bill S.

Bill, in the "thinking" stages of building either a '34 Chevy Tudor or a '41 Willys. Many of the body/chassis combos come with the 9" Ford rear end less the center section. I'm working up the budgets now.

not 100 % , didn`t the outside end of the axles on the 31 spline have sort of an " 8 " cut into the center and the 28 spline where solid ? or maybe the other way around .......... I have quick performance in ohio do the work on mine and all of my customers needs , these guys rock , are way fast and you actually get ......customer service !!!

Ratso, Alamosa, CO! Many years ago (like 50!) my Uncle worked at the A&P in Alamosa, then opened Barrett's Men's Store in Alamosa. No idea if either is still there.

Anyway, what I'm currently looking at is the body/chassis combination of the '40/41 Willys from Outlaw Performance. The chassis comes with the narrowed 9" Ford rear with axles and no center section. I'm working through the budget and trying to figure out how much it would cost and whether to go pick and pull or something new from a vendor.

All comments, suggestions, ideas, thoughts, or experiences are VERY helpful.

Turkey master,
I see you are working on a Willys. Me too. When it comes to a 9 in ford read my post above. If you already got the housing and axels you getting close. haha.
The saga continues.....I started installing the new metric e-brake calipers only to find that they interfer with the coil overs as they are supposed to be installed. Just Great. So I'm looking at the mess trying to get the calipers to fit in some other position. No luck. So I spend about 2 hours drawing up a new e-brake arm rotated 90 deg so I can reposition the calipers. I'm about ready to start making chips when I make one last attempt to move things around. I take the e-brake arms off and reverse them side for side then discover that the brackets can be flipped too. We're making progress. Now I see that it only takes a small extention welded on the arms for a stop and we are home. Finally a break. so the caliper now fit with the bleeders up besides. I quickly TIG welded them on before they changed their mind. Even the springs fit. Now all I need ar some cables but they are not hard. So today I got the fill and drain plugs made and welded on. Then I got the rattle cans out and primed and painted the thing. Ready to final assemble.

You are lucky you only have get the "pig" completed. Here is a tip....go to Currie or Moser and if you can set it up yourself (not hard) just buy the parts needed. forget the junkyard stuff. You can even do a locker right out of the catalog.

good luck. Let's hear some more about the Willys.

Went to the GoodGuys Show in Hershey last weekend. I met a number of firendly Willys owners. I want to stress that I am still in the thinking stage. I have a couple of different things boiling around in my head.

Thanks for the thoughts, everyone. I really appreciate the help. I have a lot to learn before I make the leap. I continue to watch this post, so feel free to pile on.

i'm glad i i dont pay $200 for a 9" from the junkyard.... i paid $68 for a 28 spline 9" ended up having a detroit locker inside of it..... i narrowed it, and rebuilt it for about $600 and that included everything

hehe, all of the 9" horror stories are kinda nostalgic.....I switched to the 8.8 rear 10 years ago and never looked back. It is lighter, simpler, cheaper and I've never broken one. Parts are on every street corner too.

Example: got a housing, sans axles and drums from the local junkyard=$140.

Found a pair of 31 spline, 5 lug axles from a Mustang guy at the swapmeet for $100.

repacked the stock posi for $25 worth of parts (lockers are $300)

Found new 5 lug drums at NAPA for $25 ea.

So, under $500, I have a nice rear axle narrow enough for an A model.

D.B.

It's in...finally. i just finished installing the dam 9" in the Willys for the 10th + time. Dang the pig is heavy. The rest of the story....haha. seems Ford in their great wisdom chose to retain the backing plate with a tin retainer. Well since I replaced the drums with discs there is no backing plate so I'm short 1/8 space between the retainer and the end of the housing. I had the backing plates all stripped down ready to Plasma cut out the centers for the spacer. I made one last search of the shop for some 1/8 material. Ahaa I found just enough to make 2 spacers. 1 hour later they were done. Now I got a complete 9" with everything. An hour later it's installed in the Willys.

Well at least MY 4 link fits and works right. A quick pass thru on the 4-link simulator and I have the right length adjusted and holes selected. Viola!! it bolts right in and about 2 turns here and there and it is lined up and ready to rock and roll. Hate to look at the spread sheet for the hours and $$$$ . Why do I even have the thing... just throw lots of $$$ and hours at it untill it is done.

I see on the news that scientists have discovered a new black matter ...can't see it but they know it's there and it sucks up everthing....my Willys must be a space invader because it's black, sucks up $$$, time and energy like no tomorrow. They say you can neither create nor destroy matter....hahaha. I can take 10 $100 bills and throw them at the Willys and they disappear never to return and nothing changes.

rant rant. haha

Oh yeah someone said there are cast in drive dogs on the 28 spline ..that's right most of the time and 2 drilled holes plus a center drilled center on 31 splines..that's right most of the time except trucks have 4 holes and a center drilled one.... notice the most.haha