DIY Ford 9" Narrowing and Build for Ford Falcon

With the recent swap to a T5 transmission and soon mini tub/frame notching so I can fit some 315/35/17's up under the Falcon, I am starting to worry about my ford 8" rear end holding up. In the past with my car I try to build it just good enough for my goals, which helps keep the cost down. The problem with that is that goals change and then I have to redo stuff, so it ends up costing more in the long run. I have decided to build a 9" Ford rear end and I plan on making it as bullet proof as possible. I know if you abuse your car parts will always break, but hopefully I can overbuild this 9" rear end so it will give me years of trouble free service no matter what power level I decide to go to next. I will keep a running total to see how much it ends up costing to build a tough 9" Ford rear end.  

The first thing was to buy a 9" rear end. I thought about getting a pre-made housing or a complete 9" from a company, but they cost serious money. I decided I would watch Craigslist and pick up a cheap one to start off with. Here is what I ended up with after about 3 weeks of searching. I got Ford 9" out of a 1970's ford truck for $75.00. I got it so cheap because it came without brakes, which is fine since I want to do a disc brake set up. 

Ford 9" off of Craigslist for $75.00 with out any brakes.

Big pile of dirt after wire wheeling my Ford 9" rear end. 

Since I plan on never having to build another rear end for this car I am going to over build it. I decided that I would install a back brace/truss on my 9" rear end. Everything I have read says that they are not necessary on a car below 650HP, but I plan lots of clutch dumping drag race runs in the future, so I thought I would weld one on while I was building up my rear end. Plus they look cool. I scored this one off of E-bay for $35.00 with free shipping from Quick Performance. This is a great part, but I had one problem. They trim it for a large web 9". The 9" I have is not a large web, so I had to do some extra work to fill in some gaps. My total for my Ford 9" rear end sits at $110.00 so far.

Ford 9" back brace from Quick Performance ordered through E-Bay.

Flat stock cut to weld to Ford 9" Back brace.

I went to Lowe's and bought some 1/8" x 1/2 flat stock for around $5.00 and cut and welded it onto the 9" back brace. After I got everthing welded and ground smooth it was time to start trimming. 

Flat stock welded to 9" brace you can see how much trimming will be needed now.

To make the trimming go a little faster I used some poster board the kid had lieing around and made a template. I then trimmed the template and transferred its markings to the 9" brace. 

Template made out of poster board to make trimming of 9" brace easier.

This is the poster board before trimming. If you look by my thumb you can see the big gap on the 9" rear end.

Now I just need to trim the to the sharpie mark on the brace and I should be ready to weld it to the 9" housing.

Ford 9" back brace all trimmed up and ready to weld.

The next step is to weld on the back brace. You have to take this slow to minimize any warping to the axle tubes. I decided to go a head and buy a Ford 9" housing narrowing set up. I started  looking and think I have found the cheapest solution to this. I purchase this kit of of E-bay. It was $182.00 after paying shipping. The kit comes with everything except a 1 1/4" steel bar. I looked around locally for a bar but ended up getting one online from Stock Car Steel whose price was way lower for the bar at only $40.00, and shipping was only $20.00. So for $242.00 I have the tools need to narrow a 9" Ford housing the proper way.

DIY Ford 9" Narrowing tools

1 1/4" Cold rolled steel bar for DIY Ford 9" Narrowing. 

To see how much my axle tubes move while welding on the back brace on my Ford 9" rear housing I decided to set up the narrowing fixture and check to see how good tubes are aligned now. The first video is the drives side tube and the second is the passengers side tube, which is off by about 1/8".

I got the back brace welded on today. I took my time and let it cool and jumped around while only welding about an inch at a time. All I can say is I am very surprised by how much the axle tubes actually move. I read  about them moving a lot, but just thought people we moving to fast heating up the tubes to much, no I know.

Ford 9" Back brace fully welded on

Close up of 9" back brace welded on

You can see in the videos above how close they were before welding. The drivers side was in alignment. Now look at the video and my axle tubes on my 9" moved about 3/8" to the back. I was hoping to only get about 1/8". I have to cut the ends off for narrowing, so we will see how far offset the ends will be on the tubes. I am hoping since it will be shorter that the warping will not be as bad. 

This is the drivers side axle tube on my 9" after welding on a back brace.

This is the passengers side axle tube on my 9" after welding on a back brace.



Small update. I scored a Nodular Iron center section off of Ebay. It was a Nascar takeout. It is a 3.00:1, Detroit Locker, 31 spline, daytona pinion and cost $475.00 plus shipping of 60.00. I am happy and the 3.00:1 will go well with my tubro 5.3 LS swap I am doing.

Nodular Iron Center Section for Ford 9"

So my grand total so far is:

Housing and brace=$110.00

Narrowing fixture  =$242.00

Center Section      =$535.00

So I was able to mock up my new rims and tires today in the new wheel tubs and measure for the width of the rear end. I will need a 54" wide rear end. You need to do some math to come up with the width of the housing. You need to subtract the brake off-set from this number. So for me it will be 54" -5" with will be 49" wide for the housing.

315/35/17 under my Ford Falcon for measuring DIY rear end width

Once both tires are where you want them you just measure between the mounting flanges and that will be you overall width for your narrowed rear end.

Measure for rear end width

Since I already had a housing I measured it and divided the difference by 2 to know how much to take off of end end. You also needed to remove 2.5" additional off of each side for the ends to be welded back on. I am going to re-use my old ones so I will cut them at 2.5". The most important thing to do is to make sure that you cut the tubes square so you can weld them up easier.

Ford 9" set up in the chop saw for narrowing

I used a small square to make sure everything was set up right before cutting.

Making sure to cut 9" axle tube square for narrowing

One side cut off of my 9" ford rear end

I measured the end I cut off and cut 2.5" to weld it back on

Housing end cut to 2.5" for welding back onto my housing

Here it is all ready to weld back up

I still have to buy axles and brakes. At the beginning of this I said I was building my own Ford 9" rear end because the pre-fabbed ones are so expensive, but by the time you figure $300 for axles and $400 for brakes, I will have about $1600 in this one and lots of hours of working on it. Sometimes it is better just to buy nice stuff from the get go.