Converting a Junk Yard 9"

When I started the build on my 500 Cadillac swap I knew I would need a bit more rear end than the stock 7.5”. I was looking at the available options (8.5, 12 bolt, and 9”).

As far as the 9” go there were only 3 real candidates available that were the right width, the 57-9 Ford station wagon the early Bronco units and the 77-81 Granada and Versailles. These units approximatly measured 58” flange to flange like the G Body rear ends.

These stock rear ends have certain things you will want to be aware of. The 57-9 Wagon rear was only available with a 28 spline axel but from personal experience they will hold up to most HP street use however if you plan on a lot of racing and a set of slicks you would really want to step up to at least a 31 spline axel Additionally the rear brake drums for the wagon rears are almost impossible to find. The bolt pattern on this rear end is 5 on 4 1/2" (the G bodies use a 5 on 4 3/4”). The majority of early Broncos came with the 31 spline axels and are a bit easier to find the common bolt pattern on most of these is 5 on 5”. They are also more likely to have a Posi in them than the earlier wagon rear ends. The Granada/Versailles rear is available with rear disc brakes (a big plus for some people), but normally the rear end ratio in the 2.50-2.75 area, which depending on what you're using your car for may require a gear change. If you decide to use the original Granada/Versailles carrier you will need to do a yolk change to accept a conventional U Joint.

There are a lot of other 9”s out there but most are so wide they would need to be shortened and custom axels made, and by the time that is done chances are you would be just as well off and probably cheaper buying a ready built housing from Currie, Moser or Quick Performance.

The decision for my project was pretty much made when I came across a 59 Ford Wagon rear end at a local wrecking yard for $100 drum to drum. I got very lucky as the axels and brake drums were perfect. It had a 3.50 gear set (which would have been great for a lot of builds.....EXCEPT for what I was planning LOL).

Anyway a long story short, I tore the rear end apart, cut off the leaf spring perches, sand blasted it and added a posi carrier (which I scored from friend and had rebuilt with new bearing, seals and a 2.75 gear set). The drums were turned and I installed new axel bearings and seals. I also added new brakes and wheel cylinders (the 57-9 Fords did not have self adjusters, but were easily retro fitted from a later model).

With the rear end rebuilt I bought a set of brackets off of E Bay for the G body conversion, new set of lower control arm bushings and a set of Lakewood adjustable upper control arms (so I could more easily set the drive line angle).

The adjustable upper control arms are not absolutely necessary provided that the upper control arm brackets are placed and welded on the rear end where the original pinion angle is duplicated......and the original pinion angle was correct in the first place.

I elected to go ahead and buy the set for a couple of reasons. This rear end was going under a project that also included a custom transmission crossmember which could have changed the driveshaft angle resulting in a requirement to change the pinion angle. They are more rigid than the stock control arms allowing for a hard launch. Their smaller size makes it easier to route the tailpipes over the rear end.








The cost break down to this point is:

Rear End $100
Brakes, bearings, seals $200
Third Member and gears $400
Brackets $100
Adjustable control arms $100
L control arm bushings $50

__________

Grand total $950

With all the parts on hand the next step was to set it up for the El Camino. I started by rolling a donor Monte Carlo into the shop so I could get measurements on pinion angle, and ride height.





I then pulled the 7.5 out of the Monte Carlo to get the measurements/angles from lower brackets.



When those were obtained and I was comfortable that I had the lower brackets in the right place I tacked them in place. The bracket kit I picked up did not come with the spring perches, so I built those from a couple pieces of 1/4" flat stock and short sections of pipe the right diameter to fit inside the spring.

Once the lower brackets were tacked in place and spring perches built I rolled the rear end back under the car, connected the lower control arms and installed the upper control arms to the body (after setting them to the length of the original upper control arms). Using the floor jack I set it back at the correct ride height and then using a small adjustable jack stand set the pinion angle to the original measurement. I then trimmed and fitted the upper control arm brackets and tacked them in place.



Prior to removing the rear end for final welding I removed the springs and using the floor jack moved the rear end up and down the full travel to check and make sure I didn’t have any binding issues.

After that the rear end was removed and the final welding on the brackets completed.

A lot of people will tell you that you have to use a jig when doing the welding to prevent warping the housing.......my own experience from doing several rear end swaps over the years is that if you keep your weld short and allow proper cooling time between that the brackets can be installed without the jig.

So anyway here is the 9” ready to install under the El Camino.

Just setting up the rear end is not the whole story, you still need to connect the brakes and get a driveshaft installed. Before I installed the rearend for the final time I boxed the lower control arms and installed the stock rear sway bar form the Monte donor car.

The emergency brakes were plug and play into to Ford backing plates, and little bit of time with a parts book at the local Car Quest store and I was able to come up with a rear brake hose to go from the body to the rear end brake junction. The Centric part number is CNT 150.61006 in case that helps anyone.

The drive shaft itself was more an exercise in research than anything else. The critical part was finding a drive shaft the correct length. I’ve been working on cars for years and have acquired a pretty large stack of old driveshafts in the process. The first step was finding one the right length to go between the TH400 and 9”. Thru the process of trial and error with a couple that were too short, I found one that seated the slip yolk in the transmission and gave the required 1 1/2" of slip to allow for rearend movement. It turned out to be from a 69 Dodge Station wagon LOL



OK now mating a TH400 to a 9” Ford with and Dodge driveshaft may not sound like the easiest thing in the world to do, but all it really takes to accomplish it is the proper U Joints. I ended up using NEAPCOs on line catalog which lists the dimensions and styles for the U joints to come up with a pair that would work with the MOPAR drive shaft.

http://www.neapco.com/n_products-catalogs.php?pdffile=2

At the end of the day my drive shaft turned out to be basically free as my only investment was for the U joints which I needed for the build anyway.






So with the 9” in and all hooked up it cost an additional $25 for the rear brake hose and $50 for the U Joints. The rearend is in and I have a total of $1025 invested in it.

This just leaves the question of the wheels, because as some of you may have noticed I didn’t say anything about redrilling the axels for the Chevy pattern.

I had been quoted “about $200” to redrill the axels and drums for the Chevy bolt pattern, but was really undecided on the wheels I was going to use anyway. The problem I had with re-drilling the drums and axels (or the front rotors to match the Ford pattern which would have actually been cheaper) is that then I have custom pieces that have to be copied if anything breaks or wears out. The decision of the wheels was left till late in the project and the wheel I decided I liked the best were the early Chevy Rally Wheels......which happen to come drilled for both bolt patterns.



I even came across a dual pattern wheel in the local wrecking yard to use as a spare



The rear end has been in a while now, (and even though I initially had some problems with the posi being incorrectly built the first time) it has done great behind the 507 Cadillac engine. There is no rear end noise, it tracks straight and brakes well (there was no need for and adjustable proportioning valve).

All together I have just a bit over $1k in the rear end to include getting it in the car and hooked up. The cheapest bolt in by the time you add shipping is right around $2k and I know several members who have considerably more tied up in theirs. That being said they also have bigger axels that are drilled for the Chevy bolt pattern and possibly a heavier duty carrier than mine. For the price I’m very happy the way mine turned out and for the street car that it’s in it should do very well. For the cost I would definitely do it all over again.

I have in it about the same as an 8.5 (if I could have found one) would have cost, but it is also stronger.

Compared to other 9” bolt in units it is a pretty good alternative if you can find a suitable 9” rearend and are capable of doing the work yourself. If you end up farming the work out or having to spend money on shortening housing and axels you are probably money and time ahead using one of the pre built units.

Quick Performance $715 (housing and axels only)
Currie $1000 (housing and axels only)
Moser $960 (housing and axels only)

Add for a bearings, retainers, studs, carrier, gears, brakes and shipping and you can see where the $2000+ price tag comes in. It’s not for everyone and not as easy as a lot of people think, but it is an alternative if you happen to see an old Bronco sitting somewhere.