9" Ford Rearend Upgrade

[profaqualung]

Have just finished installing a Currie 9" in my 70 Avanti II. The main reason being that Idid not feel comfortable in the ability of the 39 year old Dana 44 [pegleg] to handle the rather large increase in power.

If anyone else out there is contemplating such a swap, here are some measurements that should help. I am not suggesting you rely totally on these measurements - but if there is a major discrepancy between my figures and what you have, a recheck should straighten it out.

AXLE HOUSING 3RD MEMBERS

Style - performance Style - 9-plus round Style - 9" Ford

Type - tapered - T&E End Type - Torino / LB Ratio - 3.50S [the Dana was a 3.54]

Spline - 31 BRKTS - pads see notes Spline - 31

Pattern - 5 on 4.5 inch Hsg Width - 52.78 Diff - True Trac

Stud - 19/32 Dr. Hsg - 21.44 Yoke - 1330 - short 9+ [C]

Reg. Dia. - 2.800 Pass. Hsg - 21.316 Case - Original

Dr. Axle - 27.079 Dr. Tube - 17.417 Pin Supp - Original

Pass. Axle - 29.576 Pass. Tube - 17.289

Brakes - Ford Explorer 10 1/2 Disc

NOTES - Pads 41.25" at 5 degrees down [ weld on universal GM or truck style] - Pinion is Negative - Spring under 2.250 Pads - U-joint strap kit 1 1/8" cup

Overall width - 58.25

Pin Offset - 0.94

Brake space - E 2.5

Drum Rotor - 0.235

U-Bolts - 3 X 6 1/2

A couple of installations hints - if you are using Magnum 500 rims that were manufactured be Specialty Wheels, you will have to grind of a small part of the top of the caliper for the wheels to fit - about .195 - and it is in an area that will not affect the structural integrity. The heavier/stronger welds on the SW rims are the cause of the problem. The remanufactured/restored 500 rims that come from TDW, do not have that problem.

As for the 10 1/2 inch Explorer rear discs - they are perfect - especially if you have already converted to the Turner upgrade on the front. In a couple of 60 MPH 'panic' stops, they tracked as straight as one could hope for, and NO hint of the back brakes trying to lock up before the front. All they did was STOP! ! !

Because of the weight of the new rear end, and the amount of distance it travels when the car is jacked up, there is a possiblity of the driveshaft getting bent where it hits the frame crossmember.

Also, if you are running 2 1/2 inch exhaust pipes, make sure they are as close to the bottom of the car as possible.

The only part we had to make, was the mount for the traction bars - just TOO many variables that figure in to the placement of them. If you need a pattern for them, drop me a note, and I will forward them to you.

As far as performance goes, it is still too early to really know what the difference will be - I did go to a larger rear tire - 235/60R15 -[205/65R15 in front] - 'W' Rated - - - BUT - the added stopping power was a bonus I wasn't expecting and have been extremely satisfied with.

Hope this might help anybody considering this type of swap.

Thomas

[Yobel]

WOW... I love what you have done and thanks for sharing it. I was just talking to a guy last night who has a 9" rear end he wants to get rid of in order to see if it will fit onto my Avanti. I am still in the process of building a high performance 350 engine and ordered a Monster 700R4 tranny so I have some time to look around for rear end stuff.

I am going to use what you have done as a baseline but dont be surprised if I come back later with more questions. Also, would you send your traction bar pattern to my sig line email address? Anything I dont have to re-engineer would be a great time saver. Did you go with an after market traction bar, if so, what type?

thanks again