just wanted to get some input from anyone running a 9" ford rear end and what type of diff. setup you have, i'm also curious about how the mod of the rear end went or where you had it done.. i think i have decided to go with a full spool 4.11 setup, but i am just learning about rear ends so any and all tips and suggestions would be helpfull thanks....

 

is this gonna be a street driven vehicle? I'm guessing not since you said spool and 4.11 with a T350 trans. Full-on race, the gearing sounds good, but that all depends on your engine's power band and tire height. As far as a spool and a 9", well, it won't do street, but as long as you're running decent axles, you can't beat a 9".

 

I just finished the install and there was some choice words before it was all done. Especialy with retaining the OEM rear brake setup, which by the way the
"trained monkeys" or Moser Techs to you say can't be done but in the end we got it done and let me tell you, it looks sweet sittin there with the Spohn Torque arm and Custom 3.5" Aluminum Shaft.

 

There's nothing wrong with using a spool if it's race only but you're going to want a limited slip diff if you intend to use it on the street.

My diff housing is from a 1970 F100. I use ladder bars to eliminate the torque arm attachment problems. All the other mount hardware for the springs, shocks etc were cut off a 10 bolt housing and welded onto the 9" housing. I have a Strange 31 spline steel spool with 4.56 gears. Strange axles with 1/2" studs in the Ford 5 on 4-1/2" bolt pattern because I use the Ford large 11" drum brakes. My rims are dual bolt pattern so that was the easiest way to go to get rear brakes. There is no parking brake assembly installed. Current tire height is 29.5" tall and I cross the finish line at just over 7000 rpm.

Chosing the gear ratio depends a lot on how you're going to use the car. For strip only, you pick the tallest tires you can stuff under the fenders then calculate the best gearing for those tires in your engine's rpm range. For street use, it's a trade off between performance and economy. 4.11 gears with a 26" tall tire would be fun stop light to stoplight but isn't suitable for highway use even with an overdrive.

 

thanks alot, i guess i have some more things to take into consideration at this point, i know there will be some wheel hop while cornering if i go with a spool setup but it will only be when i take the car around the block on nice days.... also does anyone know how an all gear tru trac diff would hold up in a street/strip application?

 

I heard, but don't quote me on this. That they are good for street use up to 600hp anything more and your wasting your money.

 

mine's taking 11.7's and 1.6X 60fts no-problems.
wheel hop, broken axles, etc.....