Differential gear setup advice

[jojothetattooboy]

Everybody seems to want a 8.5. There are people out there having really good luck building the 7.5's on various forums and in shops. Bigger is better sometimes but not always. Any rearend will fail if you abuse it. I'm building a cruiser out of my 81 El Camino. I went with a new diff ,axles and bearings. Along the way I learned these rears(7.5) don't have a long life span with lower gears. The 3:73 ratio was the lowest GM offered factory. GM also had issues with some of these back in the day. By advice it was suggested to go numerically higher than the 3:73 and the rear should live a long time if you drive decent. If you get a deal on a used diff or get one for free pass it up!! This is just what I've learned...some of it the hard way.

[JJLT1]

as said if there setup right,, and you dont abuse it,, 7.5 will last,,
no slicks on a stock 7.5 is what i'v allways heard.. never tryed it..

if the 8.5 is the same price,, or has factory gears for a little more?? i'd go for it..
all new parts,, posi carrier is 4-500$,, gears 200$,, kit 100$,, axles 250$,, setup 2-400$..
a 8.5 posi usually sells for about 1000$ with 3.42 or 3.73s..
as said in other threads 7.5 posi carriers/gears from a s-10 or a camaro will work,,
but axle spline maybe different..
just have to weigh the options.. good deals do come along..

[gmtony55]

forgive me but you confused me. Are you saying I should spend money on the one I have in it? Or are you saying something else? "if I get a good deal pass it up? " I also got lost with the numerically higher than 3:73 which would be low gears, correct? I am looking to have a gear ratio closer to 3:42.

[gmtony55]

Thanks for the info JJ, I have a lot to learn when it comes to rearend housing and such.

[jojothetattooboy]

Originally Posted by gmtony55

forgive me but you confused me. Are you saying I should spend money on the one I have in it? Or are you saying something else? "if I get a good deal pass it up? " I also got lost with the numerically higher than 3:73 which would be low gears, correct? I am looking to have a gear ratio closer to 3:42.

Sorry about the confusion Tony...I meant a numerically lower, a higher gear than 3.73. The reason I said to pass up any used diff .... I put a used diff in mine and had to do the set up and bearings twice. I found a newer complete 7.625 out of a '99 Camaro for the disc brake swap. My internals were worn as well as the axles. I figured since I had to order new axles, why not just swap the Camaro limited slip/gears and all. The diff was bad and filled the housing full of metallic particles in just a few miles. It popped around corners. It was a newer sealed Torson helical gear limited slip. It didn't have a lot of miles on it either! I wouldn't put another used diff in a car again. Even if someone paid me! The 3.42 is a decent gear ratio. I changed from a 3.08 to the 3.42 and it made quite a difference.

[gmtony55]

Thanks JoJo, That is definitely something I will consider..The 2.41 gears I have now to a 3.42 should make quite a difference too..thanks again