what posi for my 9"? - Third Generation F-Body Message Boards

mw66nova · 10-07-2009, 11:23 PM

ok, obviously a spool is the best bet for drag racing, but i HATE driving my car on the street with the spool. it's really really tough to manuevor around a parking lot.

i've mulled this over alot, and i've decided that i'd rather give up a small amount at the track so i can have the pleasure of street driving back.

so what's the best thing for my ford 9"? i want the best straight line performance out of it as possible, but still be able to drive it down to the cruise in without feeling like i'm going to rip the rearend out from under the car when i turn into the parking spot.

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radical82 · 10-08-2009, 12:03 AM

IMO, a Detroit Locker is hard to beat.... A bit noisy, but they sure do work good!!!!!!

ZONES89RS · 10-08-2009, 01:34 AM

Might wanna look into the detriot tru trac as well. I have one and i like it.

mw66nova · 10-08-2009, 06:48 AM

yeah, i was thinking a locker might be a good idea, as it'll "lock" into place when torque is applied (based on what i know about how lockers work anyhow...) i'm a little afraid of using a clutch type posi as clutches almost always wear out, and when big power is applied to worn clutches, you end up with a car that won't leave straight, which is what i don't want.

i'll look harder into the detroit stuff, i just haven't had the opportunity to do the research like i used to be able to do...

five7kid · 10-08-2009, 10:40 AM

I'm totally disappointed in Eaton and Auburn because their posi disks can't handle synthetic gear lube. Come on, guys. . .

I loved my Power Trax, never failed to lock. However, you have to use a factory non-posi carrier, which in the case of my 8.2" 10-bolt, turns out to be weak in the bearing carrier area.

I'm seriously considering a Tru Trac for next season.

xpndbl3 · 10-08-2009, 12:36 PM

i HATE lockers, getting on and off the gas can cause one wheel to get power before the other and wants to jerk a car into the other lane. Personally at the power level you're at a spool is the name of the game. If you have 35 spline axles there aren't any posi's available anyways. If you have a 31 spline axle then I'd go true trac but realize that they DO break at the track. If for a bit one tire spins and the other doesn't that'll be the end of the posi after the burnout box.

mw66nova · 10-08-2009, 02:20 PM

i'm running 31 splines, so i guess i'm good there.

the 305 ripped a powertrax lockright locker up at the track years ago...i don't trust them one bit.

well, for the moment, power steering is cheaper than a new carrier, so i'll put that in, if after that i still don't like the way it drives, i'll swap out the carrier.

five7kid · 10-08-2009, 07:09 PM

Quote:

Originally Posted by xpndbl3

If you have a 31 spline axle then I'd go true trac but realize that they DO break at the track. If for a bit one tire spins and the other doesn't that'll be the end of the posi after the burnout box.

From what I've been able to gather about Tru Tracs and drag racing, you have to hit them immediately and hard for the burnout to get them to lock, and then you'll be fine.

Quote:

Originally Posted by mw66nova

the 305 ripped a powertrax lockright locker up at the track years ago...i don't trust them one bit.

I remember that now. The difference between your experience and mine is probably 7.5" vs. 8.2". Even after the carrier bearing support broke off of mine last year and committed pumpkin carnage, the PowerTrax looked practically brand new - just a little burnishing at the engage points. I sold it on eBay and the buyer couldn't be happier.

greezemonkey · 10-08-2009, 07:54 PM

Tru Trac Matt, best choice hands down....you do need to "stun it" in the burnout box too but aside from that no noise and works good at the track.

ziggy89 · 10-08-2009, 07:56 PM

ive got a locker in mine and it works great. it can be a little goofy when cornering but its not bad and im running a low 13 with a dead hook at the track on street tires

EvilCartman · 10-08-2009, 08:02 PM

I just burned up the clutches for the 2nd time in the factory 9" posi I'm running. One tire got a bit more wet in the burnout box than the other and poof, it was toast. Switching to a spool for the 4.56 gear set and rebuilding the posi to use with the 3.50 gear set to drive around on. Also broke a PowerTrax unit in the 10 bolt, it was the no-slip version and one of the little "ears" busted off. It ended up jamming the one side gear open so it was true 1 wheel drive while the other just freewheeled.

Stephen 87 IROC · 10-08-2009, 08:14 PM

Based on your first post, my first response would be a Detroit Locker. Some people don't like the noise they produce while driving on the street but you don't buy such a thing for quiet or comfort.

I'd like to install a Power Trax in my daily driver since I broke the original gov lock and currently have an open carrier installed. I really miss having a locking diff even if it was just a gov lock. This is a GM 14 bolt, 9.5" ring gear diff in my 91 454SS.

My race car however runs a full spool.

ross · 10-08-2009, 09:03 PM

My vote is for a Detroit locker also. It will be noise and some times it does jerk the car around when it unlocks but all in all I was happier with the Detroit locker over the spool on the street and in parking lots. And at the track it is just as good as a spool.

mw66nova · 10-08-2009, 09:20 PM

that's what i'm thinking, and even eaton's website says the locker is better over the true trac. now to find an additional $500 on top of all the other crap i'm trying to do right now, lol!

has anyone bought any of the lockers off ebay that are supposedly "used NASCAR parts"? some of the stuff is decently priced and is either dyno time, or practice runs only.

radical82 · 10-08-2009, 09:26 PM

Good luck on the eBay thing with the used NASCAR stuff---I bought a set of titanium exhaust valves that were "dyno use only" parts---they make great paperweights.....

Not saying all the sellers are peddling worn out junk, just letting you know that some do.....

Stephen 87 IROC · 10-08-2009, 09:45 PM

My current gear set is a used oval track set purchased off Ebay. Lightened, polished debured and a pro gear set. Got them for a good price and they're performed well. I think the aluminum spool I also use was also used but don't know to what extent.

Typically the NASCAR stuff is flogged off after one race because they want new parts for the next race. When you're racing for the big money that they compete for, you don't want used parts that can be easily and cheaply replaced to fail. For the rest of us, the used parts are fine.

As for titanium valves, if they were used in any way, there's a reason they're on Ebay. At around $80-$100 each new, you won't find a good set for a cheap price. When I bought my current heads, a set of used titaniun intakes were included. Every one of them was worn out. Right around the notch where the keeper holds the valve was chipped from hard usage. Unlike normal valves, titanium valves are not really designed to be reground and reused. I had new guides installed in the heads and bought new SS valves with a 5/16" stem to help reduce the weight. Still not as light as a titanium valve but a lot more affordable.

gtpro700 · 10-08-2009, 10:20 PM

Quote:

Originally Posted by greezemonkey

Tru Trac Matt, best choice hands down....you do need to "stun it" in the burnout box too but aside from that no noise and works good at the track.

What do you mean by "stun it"? Just wonderign because I have a tru trac and yet to get the car done so just curious on how to stun it and what it means when i finally run the car. Thanks for the help.

madmax · 10-08-2009, 10:45 PM

Since you're already running a spool, a detroit locker is probably the best choice for what you want.

greezemonkey · 10-11-2009, 10:00 AM

Well, if you roll into the pedal it would one wheel for a while before locking (kicking you side ways in the burn out box) opposed to if you nailed the pedal right off the bat it was instant "posi" Most all of the limited slip diffs work this way.

scamaro355 · 10-11-2009, 03:28 PM

hey man for quality used "Nascar and dirt track parts" look into www.musclemotorsports.com they are around charlotte nc

mw66nova · 10-11-2009, 08:18 PM

Quote:

Originally Posted by scamaro355

hey man for quality used "Nascar and dirt track parts" look into www.musclemotorsports.com they are around charlotte nc

it's funny that you post that link as one of my co-workers just gave the url to me tonight. i'm going to check it out and see what i can come up with for a locker. those lockers are completely rebuidable, so if i can get a good deal on the unit, and there is one or two worn parts, then i'm still ahead.

mw66nova · Yesterday, 08:03 AM

just a quick fyi, i haven't really driven the car much as the spare 5.3L is not really in as good of shape as i thought it was (low oil pressure, bottom end noises) but i did drive the car down the street just to see how it acted with the newly added power steering. i'm impressed to say the least. i can feel the spool at slower speeds but it's not really an issue at all at normal cruise now...so i may just leave it alone for now.

i'm thinking of making my little bro give me his garbage 10 bolt to build up for a street rear...something that'll be easier on the car for the street, and swap out stuff for the track later...could become combersome for track prep...eh, we'll see.

ZONES89RS · Yesterday, 07:35 PM

Well, hope you can just end up with the unit you want, i would hate to see you swapping rears for nothing, not to mention the 10 bolt might just crap on you..

I am selling all my BBC stuff and my T56 for the BBC and going with a LS T56 and a 5.3/LS1/6.0, whichever i find and use the carb setup from edelbrock. I just dont have enough money to do the BB right so i can budget a LS and beat on it with nitrous till i get a procharger.