Info on rear ends

[Hack]

I spent a bunch of time in the past year searching for info on the 8.8 and 9 inch rears in order to compare and decide what I wanted to do in my car. I had a lot of trouble finding weight comparisons, actually I never did find the information. I was told repeatedly that the 9 inch was heavier and the gears transferred power less efficiently, but no exact numbers. So, I have a few rear ends at the moment and I decided to weigh and measure them. I have to say the results surprised me.

The weights are with axles but with no fluid or brakes.

Trac-loc 8.8 from Fox Mustang (was in an '85 but the tag gives a build date of April '87) weighs 155 pounds. It measured 59.5 inches from end to end of the axles.

Small bearing 25 spline 9 inch open diff from a '67 Mustang (not original to car but fit properly with original wheels) weighs 149 pounds. It measured 61 inches from end to end of the axles. I did not think the 9 inch would be lighter!

Not a fair comparison, because it's quite a bit longer, but I also have a big bearing 31 spline 9 inch open diff rear from a '79 F150. It weighs 192 pounds. It measured 71.5 inches end to end of the axles. I believe that a big bearing 9 inch rear would be significantly heavier than a small bearing unit, even if the two were the same length.

I have an 8 inch rear end in my convertible currently. When I get around to pulling it, I'll add the info.

I hope this is useful to someone.

 

[SadbutTrue]

interesting,t hanks for the info

 

[dennis112]

I found this site to be interesting and figured it should be added to your "findings."

http://www.ultrastang.com/Rearinfo.asp?Page_ID=1

Near the bottom of this long article he list weights of the indivual components of an 8 and a 9." Interesting read.

 

[stangjunkie]

i could be wrong on this but wont the housing from a nine inch bolt up to the axle shafts from an 8' my freind has the 9 inch housing and i was told i could just use that center section with the 8' i have in my stang now.... true or false??

 

[dennis112]

i could be wrong on this but wont the housing from a nine inch bolt up to the axle shafts from an 8' my freind has the 9 inch housing and i was told i could just use that center section with the 8' i have in my stang now.... true or false??

The center section is definitely not interchangeable so don't expect it to.

About the only thing that is interchangeable are the axles/brakes IF the 9" has the small axle bearing. I could be wrong about the brakes--they may be adaptable to the large bearing housing too(?)

I used my 8" axles/brakes in my 59' 9" standard passenger car housing

 

[Hack]

As long as we're talking about rears, here's some info on installing gears.

http://www.drivetrain.com/ringpinioninstal.html

trac loc rebuild info:

http://projecthp.ford23.com/trackloc.html

more 8.8 gear install info:

http://www.corral.net/tech/drivetrain/gears.html

more 9 inch rear info:

http://www.fordmuscle.com/archives/2002/02/nineinch/index.shtml

 

[stangjunkie]

rear

well in that case what 9' works for our cars i saw a thread about this a while ago but couldn't find it, i have a 65 fb and im curious to know which cars etc had a nine thta can be used with little modification??

 

[65ShelbyClone]

Go to the Ultrastang site that dennis linked. It has a list of donor cars with the right width rear ends. I'm going to use one from a '57 Ford in my '68 even though the housing is one inch narrower on each side compared to the stock '67-68.

 

[dennis112]

Go to the Ultrastang site that dennis linked. It has a list of donor cars with the right width rear ends. I'm going to use one from a '57 Ford in my '68 even though the housing is one inch narrower on each side compared to the stock '67-68.

Yep, the 57-59' Fords are the hot ticket for Mustangs. The normal passenger car rear end is very similar to the Ford 8". Same perch distance and you can reuse your existing axles/bearings/brakes if you want. Been there, done that.

If you search for and find a Ranchero or Station Wagon, you will get the large bearing housing which allows you to add mondo aftermarket axles, while still easily bolting in your stang.

Good Luck,

 

[stangjunkie]

Thanks guys! im not doin anything right away i think im gonna wait to break my 8 first but its good t o know that im better off doing that then dropping a grand for a currie

THanks

 

[65ShelbyClone]

If you search for and find a Ranchero or Station Wagon, you will get the large bearing housing which allows you to add mondo aftermarket axles, while still easily bolting in your stang.

Tempting, but my old man has a '57 parts car w/a 9" he'll let me swap for my car's 8". On top of that, I just bought a 3.50/28spl/T-Lok chunk yesterday .

Stangjunkie-I'll probably do something similar with the 8" just to get the car on the road even though I'll have the 9" ready.