how do i make my rearend a full posi

[MD13ailey]

the 8.5 is a pretty stout rear end and they are a direct bolt in. the 12 bolt if you want to stay GM is the way to go. I'm getting ready to switch to a ford 9. if you are going to change gears often i would say the 9" is the best and I'm gonna change gears for race and for street so thats the route i took. which ever way you go is is pretty much better than a 7.5 but if money is tight throw a spool in the 7.5 or a decent posi if you can find one for cheap. i have yet to break mine and I'm not gentle on it. granted I'm only making about 375 hp and I'm not putting slicks on it but knock on wood its still together.

 

[chicago2tacoma]

So do I want a spool or mini spool what are the differences?......I was going to throw it in the 7.5 till it fails then switch to 8.5 if its a direct bolt in what more do you have to do to put ford 9" in?

 

[MD13ailey]

i run a 3 piece mini spool in mine. the full spool is stronger. and as far as the 9" goes you can either buy a housing with the brackets and such weled on it like i did. or find a 9" and have it narrowed and either put the brackets on it yourself or have a shop do it. i would recommend having a shop to it, because it should be done in a fixture to ensuer it is square and it is goin to fit in the car.

 

[montezuma]

I am getting ready to upgrade to an 8.5 and i have a 3.73 posi 7.5 in the current rear. I would be willing to sell if your interested.

 

[patmckinneyracing]

For those of you guys sticking with the 7.5 rear ends, if you look at the 80's caprices, I've found that a large majority of them use 7.5 POSI rear ends. So an easy junkyard swap for you guys looking for a simple and easy rear end upgrade over the open dog leg gears. I've even found one caprice that had an 8.5 posi rear end, 12 HD brakes, with 3.42 gears.

 

[1983ss454]

#1- posi and limited slip are not the same, my tru-trac in my 9" is the right way to go for the street, #2-yes 8.5 are direct bolt ins, but depends on your HP and torque, it was going to cost me almost as much to build an 8.5 to with stand my power as it did my 9", #3- in my opinion its much easier to call Quick Performance and just order a 9" housing, that a bolt in, with your specs, plus comes with moser axles and GM bolt pattern, plus bearings for $795..... my entire rearend setup cost me $2,400 (9" bolt in housing, hardened moser axles, hardened wheel studs, strange center section with 3.70 gears and tru-trac posi, and disc brakes. Rated to withstand 850hp)

 

[bjohn07]

damn for 2400 i would have just built my own. with better parts and still would have been cheaper. and posi trac, lsd, locker are all the same. just different names due to manufactures and the patents they used. they all do the same. give power to both wheels under a load yet let one wheel spin a different speed for drivability and wear issues. if ur really interested in a posi check out ebay. i found a posi with 3.42 gears for less than 300. it is used of course but still better than paying 500 for a new carrier. i was gonna get it but im just gonna go check out some j/y

 

[bjohn07]

For those of you guys sticking with the 7.5 rear ends, if you look at the 80's caprices, I've found that a large majority of them use 7.5 POSI rear ends. So an easy junkyard swap for you guys looking for a simple and easy rear end upgrade over the open dog leg gears. I've even found one caprice that had an 8.5 posi rear end, 12 HD brakes, with 3.42 gears.

what j/y do u go to. i have checked out u pull it and and pick in pull close to town but had no luck. everything is either pulled or stripped. and i didnt know caprices used the posi. im gonna have to go try to find one.

 

[MD13ailey]

i only have about $1000 in my 9" and I'm happy with it. its only 28 spline for now 4.11 gear (craigslist) and a used center section out of a junk yard. and a light wieght drag race spool. 1/2 x20 hardened 3" studs and disc breaks (81 lincoln continental i believe)

 

[85montemj]

Why would you buy a mini spool just for it to blow up? Whats the point of intentionally wasting money like that? If you're planing on it blowing up weld the damn thing. If you want to do an 8.5" then just wait til you have the money, or get it now if you have it. Or, go with pat's idea. Or, you could even just wait for a posi 7.5" from 85 or 86+ monte SS. It'll handle your 350. I wouldn't make a quick decision just because you want to spin both tires now.