How To Narrow A 9 Inch Ford Rear End Housing:

After final welding I smash out the wooden plugs with a hammer and punch. Voila!

 

that is the BEST!!!-love the indexing trick too....

 

Thanks patsurf. I really meant to say I smash out the wooden plugs after the initial tack welding, before final welding.

 

I found this series of YouTube videos a good place to get my head around what is involved albeit not a 9 inch diff.

 

Between the above video and this one I felt confident I could now handle such a project.
The template gizmo he uses seems like a good idea if you planned to do a couple of narrowing jobs

Search on eBay - Deluxe Rearend Narrowing Fixture with Rearend Ruler - 9" Ford Rear End

 

I'd hazard a guess that 60% of the guys wouldn't get a perfectly square cut on the tube with a cut off disk plus every axle narrowing setup like that I have seen in the past has some sort of retainer that goes on the shaft to keep the bearing housings located spot on.

 

I have narrowed a couple 9 inch rear ends, one small journal and one large journal, and have one more to do in the coming year. The question I have because the next one I am doing is a 31 spline 9 3/8ths housing , are there any differences I need to be aware of on this unit. BTW, I will be using a 9 inch pumpkin.
Bob

 

I've had a couple of the 9&3/8" housings, cleaned all the Ford bracketry off them but never used them, the third member bolt patterns are the same as the 9 inch so the 9 inch third member will fit in the 9&3/8" housing but to get the bigger ring gear to clear the flange on the smaller housing it needs to be notched.
The common problem with both the 9&3/8" housings and the later large 9 inch housings is the inconsistant size and shape of the axle tubes, the amount being narrowed and the type of bracketry being added will dictate how much custom fitting needs to be done. You won't just slide those 360 degree brackets on like that guy did in the video. See the photo on Frenchtown Flyers post.
Also, I'm sure you know this but for those that don't there is next to zero aftermarket support for the 9&3/8" as far as the third member goes.

 

Yeah, I know there isn't much available for the 9 3/8 ths pumpkin, that is why I decided to buy a 9 inch pumpkin to get the ratio I wanted. I wanted something between a 3.50 and 3.73, and knew that the 9 inch pumpkin would fit in the 9 3/8ths housing that I just happened to have available.
I am really pissed at myself because a couple of years ago, I passed up on a 9 inch nodular rear end that I could have got it cheap because the seller didn't know what it was.
Bob

 

I have one additional comment about using brackets that have a 360 degree wrap so as to minimize tube distortion / warping from welding.
Where possible and when necessary I "skinny down" the brackets in two places 180 degrees apart. Then I saw-cut through one of those skinny places and pry the bracket open - like aligator jaws - at the opposite skinny point. It helps at this point to have drilled a small hole - 1/4" - adjacent to the axle hole so the braxket stretches open without cracking. This way you can make the hole any shape - be it round or "D" shaped as some axle tubes are flattened on one side - and still have a good weld joint.
I prefer to slide all the brackets over the tubes before welding on the ends but sometimes brackets need to be added to housings that already have their ends welded on.
Hope this helps.

Let me add one additional comment and food for thought:
As some may know, I am a retired automotive engineer from Ford. Early in my career when Ford was a presence in Trans Am racing I learned that one Ford team (which shall remain nameless) was modifying their 9" Ford housings under their Mustangs. Trans Am rules forbade the use of independent rear suspension - original axles had to be used. They made a saw cut notch at the top side of each axle tube near the pig. Then they re-welded the housing, intentionally inducing upward warpage into the housing tubes. Thus they caused the wheels to be cambered inwards at the top which significantly improved handling in the twisty road courses. Of course I asked "didn't that induce axle bind?"
"Sure, but the splines allow for some upward movement and we took advantage of it."

I also heard some drag teams induce a little toe-out - maybe 1/8" - on the rears knowing that the thrust during acceleration will tend to pull the tires inward. (Thus the need for back braces commonly seen, where they are legal.)

 

This will be old news to some as I've posted these shots before, others maybe not.
I really like the consistancy of the tubes on the 57 F100 housing, these have the look of the early housings with the larger radius at the third member like the later housings have. These are a one piece housing with only the ends welded, the tubes are 5/16" thick also.

 

DDD,
What are you using for the anti-roll bar? Looks nice.

 

That is a bar that The Deuce Factory offered many years back, not in business anymore.

One of the other Fjastad brothers may do them now.
http://www.deuceframe.com/about.html

You might also give Dennis here a PM for suggestions he has Cornhusker Rod and Custom.
http://cornhuskerrodandcustom.net

 

That wouldn't have been Charlie Kemp on his GT350 TranAm World Champion Mustang would it? I crewed on his CanAm car at the time. That Mustang was about unbeatable back then, Penskie (?) had the Camaro and Donahue had the AMX but that little Mustang would walk the dog on all them.

 

Deuce Frame Company has this



listed here. Looks like a quality system. Of course one would expect nothing less from the Fjastad family.

 

I was told that you always weld all your brackets completely, along with any other welding you need to do. Then weld the ends on last. Have I heard right, or not.

I'm going to shorten mine, myself, and I'm still am gathering info to do it.

Thanks, Pat

 

That's the one (see my post #73).
You don't know how many times I've had to respond to "wow them are expensive, why didn't you just get one out of the wrecking yard".
Hard to argue with logic like that!

 

Yup

In a perfect world that would be the preferred method, using an arbor alignment bar. But we hot rodders being hot rodders are prone to changing things so if you decide to add sway bar mounts, change from a Panhard bar to a Watts linkage, re-weld your brake hose tab to a different location, install bigger tires necessitating moving the spring pads, go from buggy spring to coil-overs, yadda, yadda then sometimes welding has to be done after the fact. That is why I recommend multi-purposing the brackets to minimize the number of welds on the tubes. Maybe in the future additional bracketry can then be bolted on to the existing multi-functional brackets instead of welding to the tubes.