Hi Gents, What is meant by a Ford 8 or 9 inch rear end and how is it used on a Model A? I realise it is a diff, but what does the 8/9 inch signify, what ratios does it have and is the complete rear end used on an A or only the pumpkin? What about the tourq tube? Regards Chris
It is the diameter of the ring gear. Both the 8 and 9 inch rear ends are swapped in from later model Fords. There is aftermarket support for both, but a 9 inch has more aftermarket support than any other made from any manufacturer, Posted using the Full Custom H.A.M.B. App!
The torque tube will not work, it will need to be swapped with an open driveline. Posted using the Full Custom H.A.M.B. App!
8 inch rear is a smaller version of a 9 inch rear usually found in fords unibody cars, mavericks, mustangs falcons ect 9 inch rears were found in some of these cars such as mustangs in higher HP cars and most 1/2 ton trucks and larger cars from 1957 until early 80s your model A was born with a banjo style rear. nothing swaps with 8 or 9 inch rears 8 inch rears from mavericks usually fit nicely under Model As there is plenty of tech articles here to help if ya do a search good luck
The size also refers to their relative strength. In OEM applications, Ford only installed the 8" behind the smaller V8s (up to 302ci), anything larger got the 9". The 9" was also installed in most small block high performance applications; the 'hipo' 289 Fairlanes and early Shelby Mustangs to name two. Real world performance? If you're running a manual trans with street tires, stick to the above sizes if you plan on any 'spirited' driving, although the 8" can usually take the power of a warmed-over 302 with few issues. You can 'cheat' up to a 350ci if running an automatic trans. Larger than that on motor size, or if racing is planned, go with the 9" for longevity.
This would be a complete swap of the entire rear axle ***embly, end-to-end, all included. On a Model A, other Fords from that era, and numerous other vehicles, the torque tube is essentially part of the rear axle, and acts as a suspension element. The torque tube, combined with two links, form what is essentially a large swingarm, attached to a pivot, which is part of the transmission. In this photo, the gentleman is holding the front of the torque tube, at the pivot that attaches to the transmission: Due to the fact that the torque tube and transmission are linked, you cannot switch one without also doing the other, or converting to a conventional driveline. Also, when removing the original axle and torque tube (or converting to an open driveline), you must recreate the torque tube function, as the outboard two links are not generally sufficient in strength alone. Often, a torque arm is used in its place. Here is an original axle, converted to an open driveline, with a torque arm: A torque arm on a 8" or 9" rear axle would be much the same, except for the attachment to the axle itself
Got to remember you are talking about Ford here, and they didn't always go by the book. I bought a 77 Granada for the engine, it was a 351W with a C4 transmission. Logic would say it had a 9" rear, right? Or maybe a 8"? Nope, it had a 7.5"! While most of what you say is true, with Ford, there is always the exceptions!
That was not a 7.5". It was an 8.7" C-clip unit. They had like a 2.48 gear ratio and no limited-slip. Not a popular rearend at all, but not a 7.5".
OK, it looked like the 7.5". Still a weak, junk rear end. My point still stands, Ford didn't always follow it's own book. You never know on Fords until you look, you might find anything.
the 8.8 is an integral rear, not a drop out like the 8 or 9 inch is. the 8.8 is a fairly stout unit that will take a lot of horse power
8 and 9 in. all load from the front. An easy way looking under the car to figure it out if you can put a socket and ratchet on the bottom 2 nuts its an 8 in. 9in. requires the use of a wrench. Don't for get the 9 3/8 same bolt pattern of a 9 in. All were posi tracs. 2 pinion units with 275 or 300 hi way gears. No aftermarket parts. Came in big Lincoln's ect. Easy way to tell looks like an old war case but has one of the ribs on top turn down making a curve to the parallel rib below. They take the same rear end housing they just put a little v notch in the top of housing for the bigger ring gear. Little bronco 67- 76 make good housings for street rods some time don't need to shorten just get new axles (mosser ) or have them redrilled. The 8.8 is easier to find today and has a ton of after market parts.
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