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If you are concerned about 8.8 rear end strength, get the 31 spline axles (Explorer and late model Mustang)
The strength of the 9" comes from it's pinion snout bearing. The 8.8 is an excellent rear, and I do not doubt its strength - they are on par with a GM 12-bolt. The 9" is still king when it comes to all-out strength though and why they're used in every form of racing (even if there isn't a single 'Ford' piece in them). If your housing is flexing, you've got bigger issues to fix!
Another huge advantage for many people using the 9" in this particular niche of the hobby is the ability to retain the stock 5 on 5.5" bolt circle...those don't exist with the 8.8.
The strength of the 9" comes from it's pinion snout bearing. ...
I got a chuckle out of that magazine comparison where the pinion shaft diameter of the 8.8 was much larger than the 9", like that was an advantage. In reality it's a testament to the effectiveness of the snout bearing versus the overhung design of most other diff's.
I got a chuckle out of that magazine comparison where the pinion shaft diameter of the 8.8 was much larger than the 9", like that was an advantage. In reality it's a testament to the effectiveness of the snout bearing versus the overhung design of most other diff's.
Just like a bolt in double-shear is stronger than a larger bolt in single shear...those gears are trying to get away from each other and there's a lot of force working it...
When replacing a Dana 44 out of a 1955 f100 the link here says 72 is a direct exchange...some other info indicates 76 works. Does anyone know what the difference is if any?? Thanks for any help!
An unmentioned possible disadvantage of the 8.8 is it is too narrow for our trucks, requiring strongly offset wheels or wheel spacers. That can be an advantage tho if you want a different bolt pattern, you can use all in one spacers and BP converters. Advantage of the 8.9 is they are very available (hence inexpensive) and come in a number of different gear ratios, with/without LSD, with/without disk brakes. I am running 3.70 ratio with my double OD T56 6 speed (.66 5th, .50 6th) and find it a perfect combo, loafs along at 80MPH in 6th while getting 26+ MPG.
That's the ultimate goal is 5spd and larger engine. Right now it is 272 V8 with a Mustang 4spd but the rear diff. needs rework. didn't want to redo it but switch to 9 inch for its advantages. Just found some 73 model up rear assy. and didn't know what the difference from a 72 if a 72 was pretty much a direct bolt in what would be the issues in using later model.
Picked up 72 F100 9" axle assy now to check it out and figure out best way to bolt it down. Shock mtg cradle is cupped for 2.5" tube this is 3" tube. Shocks are mtg to brackets welded to the tube on the frt side of 9" assy and my Dana assy had shocks mtg to the rear of the tube and bolting to the bracket that served as the bottom mtg. Anyone been down this road and have some pics of how they mounted a 9" in place of the Dana 8.8?
Thanks...
Thanks for the info--helped a lot. Cut the brackets for shock mtg off and the bone yard saved the U-bolts but guess I'd better get new ones. Going to call Midfifties Monday and see what they have. Be nice to find a bottom plate like the original made for 3 inch tubes.
If you can find an F-2 or F-3 lower spring plate, they had 3" tubes on their axles. Alternatives are later model F-100 spring plates, and (gasp) Chevy Sierra-class plates. I used the Chev parts because they are mondo heavy duty stampings. As I recall, what MidFifty sells is a flat plat that IMO has no rigidity. These are the Chev parts, note the holes need to be worked a little because the Chev springs are slightly angled.
Anyone have a recommendation on adding a limited slip unit to a 9" rear. Moser shows one but I don't know anything about them. My son and I are cleaning and getting new parts for the 9" and want to add this type unit to the assy. Thanks..
07-17-2015, 09:51 PM
