31 vs. 28 spline vs. 7.5 vs. 8.8 vs. 9?

[screamin gt]

I know most if not all mustangs are 8.8 rear ends, but who has what for (28 or 31)spline? and just wondering what ever came with a 7.5 rear end? and the advantage of a 9" over the 8.8? and if anything came with a 9" from the factory?

just wondering....

 

[bdcardinal]

v6's had the 7.5". GT's and cobras had the 8.8". they were all 28 spline except for 00 cobra R, 03-04 cobra and 05+ mustang GT.

 

[Mustang92]

9" rears came in older ford trucks and some cars. They are stronger than an 8.8" but honestly there are cars running into the 8's on a built 8.8 so unless you are planning on some really big power they aren't worth it. 9" rears also weigh more so you have more rotating mass.

Bill

 

[StangYellow]

In addition to what Mustang92 said, the ford 9 inch is deemed indestructable. You can find a used one for a few hundred, while upgrading 8.8 will run you double that. If you have some sort of project in the works, a 9 inch is a great rear end. 7.5's are like tits on a bull...

 

[screamin gt]

good info! thanks guys.

like I said though, not starting a project, just getting gears and was wondering more less what vehicles had what.

 

[Mustang92]

In addition to what Mustang92 said, the ford 9 inch is deemed indestructable. You can find a used one for a few hundred, while upgrading 8.8 will run you double that. If you have some sort of project in the works, a 9 inch is a great rear end. 7.5's are like tits on a bull...

Well just to clarify for those that may think that just because it's stated the 9" is cheap it's not as simple as finding a used 9" and tossing it in. Most have to be cut down to fit our cars and have drum brakes, they also do not have the same suspension mounts as the Mustang. So by the time you cut the housing down, add the correct suspension mounting brackets, convert to disk brakes, get custom axles you have far exceeded what it costs to build up an 8.8 rear.

Weld the axle tubes $75-150 depending on the shop.
31 spline axles $200-250.
31 spline differential $250-400 depending on what you go with.
Rear end girdle $150-200.

You can probably even come in under that price if you shop around, go with a ford T-loc built with extra clutches.

Bill

 

[screamin gt]

no one mentioned the difference between 28 and 31 splines? I know the difference but what vehicles came with which? we have 28 spline right?

 

[Mustang92]

Yes we have 28's.

Bill

 

[BurningRubber]

The 8.8 is a very stout axle.

Even stock 28 spline shafts will take alot of abuse. Sure there are some that fall short, but that happens with every part, on every vehicle. In general they are stout.

I have no worries about breaking mine when I romp on my car.

Full bearing kits arent that expensive, so if you take it apart to swap a 31 spine differential and shafts I highly reccomend changing the bearings also.


I know MANY guys from the Jeep world (my other vehicular passion) swap in Ford 8.8's into their offroad rigs that are turning 33, 35, and larger inch tires. They get them from Explorers and Rangers, its a fairly un-involved swap and they RARELY break them... and I garuntee you the stresses off offroading are equal to or exceed what an axle sees making a pass down the drag strip.

 

[Mossberg]

Yeah, I did not have any issues with my 28 spline setup. I swaped to a 31 spline setup though since my car will eventually get blown and make passes down the 1320.