View Full Version : Metal manipulation on a Ford 9" rear diff

08-05-2005, 12:22 AM
I narrow quite a few rear diffs for hot rods etc. Here's a trick I use that may interest some here. After cutting and trimming, boring the ends etc. this is what you often end up with after the jig is installed
The end is a bit more than 3/16" out. The housing has tweaked over the years. Here's how I get rid of that.
I run a heavy weld bead on one side and then decide where I want to apply heat to help pull it. The circled areas are where I want it to pull. It's heated to a dull red and allowed to cool. Here's what I get after this....perfect alignment! The whole thing done with out a grunt and usually with a cup of coffee in one hand...lol!
An old fabricators trick. We use this to pull/move some really big steel....20"XXX wall pipe...thick plate etc. I still marvel at the power you have in your hand!

3 Phase Lightbulb
08-05-2005, 12:35 AM
Cool.. How did you decide where you wanted to distort it back to running true? It also kind of looks like axle housing is tapered at the end?


08-05-2005, 12:42 AM
Adrian...it's sort of an aquired knack...mostly from screwing up til you learn how to do it.
You're right...the housing is tapered. This is a terrible housing to work with. They smash it flat on the top and it is double tapered. It's from a mid 70's T-Bird...not my favourite.
The truck housings are far easier to work with. This rearend is going in my ol' Willys pick up.
I have another on the go that's going into a Cherokee.

[This message has been edited by torker (edited 08-05-2005).]

08-05-2005, 12:43 AM
Good deal,I know what you mean about pulling.Ever notice the weld beads top and bottom on house trailer frames?They weld beads on them down the center of the flanges to pull a reverse crown on the neked frame before they start adding wieght building the house on top.Some I have seen actually have 4" of crown pulled in them.

08-05-2005, 12:51 AM
Darin...yup..I've seen lots of that. A place I worked we built big 40 foot long log decks from 8X10 1/2" wall HSS. A lot of crap got welded to these and some would bow up over 6". This was with two, back to back and a 6" block in the middle, and the ends pulled together with a crane and come alongs. Man did they pop when you cut them apart. There used to be two of us that could straighten these with a rosebud. Took about an hour to pull them big buggers back. The other guy is the one who taught me how to this. That was many moons ago.

Duct Taper
08-05-2005, 03:50 PM
When you weld spring mounting pads on the axle housing, what do you do about shrinkage and bowing?

3 Phase Lightbulb
08-05-2005, 04:16 PM
<font face="Verdana, Arial" size="2">Originally posted by Duct Taper:
When you weld spring mounting pads on the axle housing, what do you do about shrinkage and bowing?</font>

Personally, I'd bolt up the axle to whatever suspension you plan on using with the correct diameter U-bolts:



08-05-2005, 05:32 PM
duct taper, Good question. Think about a spring perch and how it's made. Looking at the front view, it's an upside down U. You weld the sides of this. If there is any pulling the perch itself will absorb the little bit you'll get with a weld around the diameter. This has never been a problem. Of course you could make it a problem if you slop a real heavy bead on it like I did where the tube enters the housing. But why would you? A 1/2" weld on all four corners will hold a spring perch.
The big problems lie with some of the heavy bracing we do to these housings for extreme competition vehicles. You have to brace the dickens out of the housing before welding and often have to use the torch to relieve the welded areas after the fact.
Adrian...that's how I prefer to weld perches on if I can. Most housings I do are sent out so I don't have the vehicle to bolt them to.

08-05-2005, 06:12 PM
I would never use the springs as a guide for the spring perches - is that what is being suggested? The springs are seldom that true with one another.

08-05-2005, 06:32 PM
GregC...have you ever actually checked the spring perches from a factory rear end? There are some I've seen that are canted in two totally different directions. Besides... this is how it is normally done to set the pinion angle on a rear diff. How are you going to do that before hand if the (as you say) springs are so far out of whack? To get the angle set true you need the weight of the vehicle and the "difference" in the springs all in place beforehand.
I'm often asked to weld these on for out of town orders. I always recommend not doing this but guys who don't fabricate or weld will use shims instead.

08-05-2005, 07:42 PM
Nice post!

I've had the same problem with Dana 60 rears when I weld 9" ends on them. Always bent. I've just jigged it up straight and butt welded the ends on. There's plenty of meat in a D60 tube, so the misalignment didn't hurt. I figured that it would be OK as long as the end was aligned properly with the carrier bearings. I will have to try to straighten the tube next time just to see if I can make it work.

[This message has been edited by Nutter (edited 08-05-2005).]

08-05-2005, 08:31 PM
Nutter... Bears (in Canada), a division now of Strange...sell the Ford style ends that are meant to be butt welded on all tubes. Thats what I used for the 60's in my mudrails.
You are right. They are easy to line up even if the tubes are out of whack. Here's what I do...
Cut the end and make sure it's square. Easy with a 60!
Stand it up, drop in the axle, ends and dummy bearings. Swing the axle around and measure the quadrant distances. Calculate the center and tack it in place. Tack it some more until you are sure it won't pull off to one side. Remove innards and weld away.
Sound right?
I like doing them that way. The ends up here are $70 so I use the Ford factory ends for stuff like this. Not as much meat to work with though.

08-05-2005, 09:59 PM
I've used similar ends from Dutchman and Moser.

Your method of alignment sounds like it should work perfectly. You just made me wonder if I really need the pucks and rod that I use http://bbs.homeshopmachinist.net//smile.gif

08-05-2005, 10:13 PM
Hey,, Howdy..

Another machinist with a coal scoop, I won't be the only one here now.. I make some heavy duty chips here.. About five gallons is a good day here.

Nice dealie on the 9incher.. do you spline them too? I tried to heat treat the last ones and had to file for hours..


08-05-2005, 11:03 PM
Hey,the handiest tool I have found for this type work are those torpedo levels with the magnet base and the adjustable level.

That 44 special frontend I did I had no less than two hanging on it before I cut/welded anything.

Oh I did notice one difference between the Dana 44 Ford end and the Dana 44 Chevy.The Chevy has a smaller diameter tube,but one that's a lot thicker,like 5/8" wall,the Ford has a larger od with a 1/4" wall.

Hey,ever use a section of retangular tubing and a soapstone compass to layout a back brace for the 9"?

08-06-2005, 01:43 PM
<font face="Verdana, Arial" size="2">
Oh I did notice one difference between the Dana 44 Ford end and the Dana 44 Chevy.The Chevy has a smaller diameter tube,but one that's a lot thicker,like 5/8" wall,the Ford has a larger od with a 1/4" wall.

Depends on which Ford front end you use. Sounds like you have a '78-79 F150 or bronco housing. The F250 housings have 1/2 thick tube.


I know you weren't asking me specifically, but I spline my own D44 front shafts. I turn the sealing surface and cut the splines hard, no need to re-heat treat and no filing.

I haven't done any 9" rear shafts yet. I'd need a 31 slot plate for my super spacer and some tye of a cutter that uses something like SPG inserts held at a 45 degree angle. There isn't too much call for that from my Jeeping buddies. They tend to go for aftermarket 1541H shafts from Moser or Dutchman.

Splining shafts was really what led me into my amateur machining hobby. I was told by several people that couldn't do it, so I did it.

08-06-2005, 09:52 PM
Hey Russ,

What does the jig in the housing look like?

Rob http://bbs.homeshopmachinist.net//smile.gif

08-06-2005, 10:02 PM
<font face="Verdana, Arial" size="2">Originally posted by Nutter:
Depends on which Ford front end you use. Sounds like you have a '78-79 F150 or bronco housing. The F250 housings have 1/2 thick tube.

it. </font>

F-150 actually.It was being built to go in a Jeep,the guy wanted the top running pinion Ford chunck with the Chevy ball joint ends.I had to drill&tap the tie rod arm holes in both too.

08-07-2005, 12:55 AM
weird...that frontend you built is cool. I reckon I'd better try one of those myself. I haven't done a front yet.
Yes..I've used the compass trick but made a pattern some time ago that works really well.
David....no, I don't respline axles. Most Ford 9" axles don't have enough meat left on them to respline. They cut them down right after the spline to get rid of the stress risers. There are SOME 9" axles that where made that can be easily resplined. They are the same diameter along the whole length. I haven't see any of these for years and can't even remember which year of 1/2 ton they came in. Some of the big ol' T-Birds used these axles as well but they are mostly crushed and in China by now.
Rob...It is a standard type of jig that uses metal pucks and a heavy rod in place of the bearings and axles. I just got finished welding the ends on. I leave the jig in place til it's cool. I'll take a pic of the jig for you in the morning.

08-07-2005, 07:47 AM
Interesting topic. Everything in life's a compromise,and rear axle housings are no different.
I've fixed quite a few tube ends on farm truck rear axles over the years, and one thing I found out is that they really don't 'tweak' over the years in most cases, but are purposely made that way, right from the factory, with a bit of postive camber in them. I know that sounds dumb, but if you ever happen to chuck up a brand new housing that's been dropped and had the threads damaged, you'll see this for yourself. The tube ends do not run true with each other, not even close, and the runout is always to the same side,new or used, so it's no accident.
My take on it is that like any steel fabrication, they flex under load, and the factory figures in a certain amount of flex,and machines the housings appropriately.
Normally, when setting up to bore out a tube end for a shop made replacement,such as when the bearing seats and threads have been ruined from losing a wheel etc, I find that in order to get the tailstock side tube end to run true, the end at the headstock will have to be set up with quite a bit of runout. 1/4" or more is very common.
I have seen people try to machine these straight,or straighten them, with the result being that you can't keep a spline in them anywhere. YMMV, and I'm sure a car or light truck rear end differs.

[This message has been edited by pete913 (edited 08-07-2005).]

08-07-2005, 10:25 AM
Pete,yep your right on the bigger trucks,they are cambered.That's why when you rotate tires on one,the inside dual becomes the opposite side front while the outside dual becomes the opposite side inner and the front becomes the outside dual.The inner dual is loaded light when the truck is empty,but the situation reverses or balances out when loaded.Real fun was suspension work on one,try explaining the need for right and lefthand leaf springs to an owner that knows nothing about trucks http://bbs.homeshopmachinist.net//biggrin.gif

My brother used to haul steel down to Larado,Tx,they would transfer 48,000 lbs of 20' sections off a semi trailer rig and load it all on a Mexican Ford tandem axle straight truck that would take it on across the boarder.He said it was common for them to overload one of those trucks till you could see the housings bow in the opposite direction.It's said that God watches over children and fools and I believe it http://bbs.homeshopmachinist.net//biggrin.gif

Russ,the best 9" axle supply I have found are 1975-84' 150 vans(long wheelbase) and oddly enough the old Ranchero's,there are lots of them with the big axles that have the fat neck.

08-09-2005, 11:36 PM
A little confused here. I see what is being done here as far as narrowing the differential housing. The axles would seem to be the challenge. Can the original axles be cut and then welded back together successfully? If so how is it done?

08-10-2005, 12:37 AM
Pete...that may be true for the bigger trucks and was maybe done on the lighter ones but I've seen no regularity in the way the housings are "tweaked with the 9" or the 60's I work on.
The worse Ford 9" (for bent housings) are the ones out or the late 70's Supercabs that a lot of people hauled large campers on. The next worse I've seen are farm trucks that have been loaded down with god knows what.
A good indication that the housing may be bent is if the third is really stuck on the housing bolts. Almost every time...If you have to really fight to get the third out...the housing will likely be tweaked.
Darin...I've only seen a couple of the vans you speak of up here. Have to keep an eye out though, there has to be some around. The Rancheros...have only ever seen a couple of them here period.
The guy I talked to (who resplines the axles)said the ones he like came out of one certain truck but I can't remember which one he said.
I looked again in my pile of stock axles. Most prolly couls be resplined IF you where making a really narrow rear. Most I do are only narrowed enough that the resplines wouldn't work. They'd have to be narrowed 10 to 12 inches before The stock axles could be resplined.
Bruce...the axles are really the easy part...LOL!
First you draw a picture with measurements of the required axles....then you load the pic in the fax machine, fax it off to Bears and POOF...You have new Pro Street axles with a limited warranty, your choice of splines, lengths, studs, bolt pattern and brand new Green "O" ring bearings and retainers for $300 USD. Up here the bearings alone are worth over $100.
My mill table isn't really long enough to fit axles on anyway. I could make up a fixture but it's easier to load up the fax machine.

08-10-2005, 11:45 PM
weird...you meant likey this....
Put a brace across the front and welded it down with a buch of big sloppy welds that will pull like the dickens...then pre-heat the back brace and housing...then stitch weld it in a random pattern
The finished product...note the little filler neck I added, there's even a dipstick to check the oil level!

08-11-2005, 08:26 AM
welding axles back together is a risk at best. not worth the bother.

back in the old days we used to use the axles out of 57-62 buicks. they were big enough to trun down and use in the narrowed rears dodge and ford.

08-11-2005, 08:46 PM
Yup,that's pretty much it,I never seal weld one thou,just a series of 1" long tacks spaced out 3" apart.

I have toyed with the idea of using a single 1/4" thick rib down the back,should cut down on the welding.

Cutting axles,you might try this on a home project.Guy near here cut and welded a set of Ford axles,only he didn't cut them straight across he cut a scarf joint into them on about a 60* angle,gapped them out 5/16" apart and tacked the root.He chucked them in the lathe and gave them a spin to check for straight,once he was set he pre-heated to 350F and welded them in 100% with 7018 low high.He knocked off the high spots and ran the axles......for about three years!Until he wrecked it at a dirt lap that turned into a demolition derby http://bbs.homeshopmachinist.net//biggrin.gif

The reason he got away with it I believe was the scarfed weld.I'm thinking that by spreading out the stresses over a larger area it was able to handle the torque.

I do something similar when a customer wants to use an automotive engine as a power unit.I get a standard tranny input shaft,machine it round between the splines and the gear,then chop the gear off.I take my new shaft and bore a hole in the end to press the end of the input shaft I turned round into,but before I press it in I mill four or six 3/8" wide slots through the side of the bored section.After the two pieces are pressed together I preheat and weld through the slots filling them up with weld.It has worked great so far,last one I did was a customer who wanted to put a Ford 5.0L TFI on a stump grinder,but also wanted a clutch.

I made up a steel bearing housing to handle the side load,then made it to fit a standard shift bell housing so I could use a pickup flywheel,clutch and pressure plate along with the throwout bearing and shaft support tube.

He wound up with a stump grinder that would vaporize a 24" pine stump in 4 minutes flat http://bbs.homeshopmachinist.net//biggrin.gif

I did have to knock the springs out of the clutch disc center and weld the hub in solid,darn springs couldn't handle the shock loading from the cutter wheel http://bbs.homeshopmachinist.net//biggrin.gif

08-11-2005, 09:31 PM
Darin...LOL! Thanks for that! That's what Dishonest Man didn't know...you're a genius http://bbs.homeshopmachinist.net//biggrin.gif
About seal welding...normally I wouldn't but I own this truck and I know where it will end up. In da MUD! If I only stitch it, sooner or later it will fill with wet mud. Then it will freeze in the winter and swell the brace and then rust it out. Stitched is definately easier with little chance of warping.
The scarf joint on the axle...I've done this on a few things but have never done it on an axle...hmmm...I can see the AWD four wheel steer, Suzuki 3 banger powered snow plow I've always wanted to build!
I like your idea about welding on the gear also. Thanks bud!