I was thinking of upgrading my differential, but i dunno if i should go with posi or not. I like to do fishtails and donuts etc... so what would a posi do when you tried stuff like that? i like the way my 83 trans am handles it corners good and does nice donuts, should i stay with the limited slip?
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but also when i go to the track a one wheel burnout seems kinda gay, i wish there was a way to unlock it, or is there?

 

Detroit Tru-Trac.

 

Just for your info LIMITED SLIP & posi (Chevys trade name POSITRACTION) are one and the same. One peel that.

 

huh???

 

He's saying you have an open diff now, not a limited slip.

 

ok well i mean unlocked diff vs locked

 

Well like I said Detroit Tru-Trac gives you good streetability with frictionless lockup and there you go for your tire burning enjoyment. My personal opinion only lol.

 

can you get this in a 9bolt? also, what does he mean? so your saying you cant do donuts with a posi? fishtails? like a burnout turn? I understand with a posi both wheel want to go the same speed correct? but im sure you can still do all the above, just have to get used to it..

 

i dunno wouldnt posi donuts and fishtails etc.. be hard on the f body since its a unibody?

 

You'll be lucky if you can find anything for a 9 bolt in North America.

A posi (limited slip) differential uses different methods to control wheel spin. The most common is with clutches and springs.

With an open diff, power is directed to the wheel with the least resistance. That's why you have no traction when one wheel is stuck in the mud or on ice.

A posi feeds power to both wheels but will feed power to the wheel with the most traction. It doesn't lock the differential because the wheels still need to turn at different speeds when going around corners. To do this, a posi will slip the clutches allowing the outside wheel to turn faster than the inside wheel.

Lockers control wheel slip even better but to allow the different wheel speeds around corners, they need to unlock or jump the locks to do this. This normally creates unwanted noise in the diff.

Posi's can and do wear out. The clutches wear out and the springs get weak.

The ultimate in straight line performance is a spool. Mini spools are not recommended unless dirt track racing. A full spool physically locks both axles together so they turn the same speed all the time including going around corners. On dry pavement this mean one tire needs to slide or skip across the pavement to keep up with the other. Spools are not recommended for street use because how they affect traction especially on wet roads.

Cheap factory limited slips differentials use what's called a Gov Lock. It's operates like an open diff until one wheel starts to slip then locks the carrier to allow traction to the other wheel. The locking system is very weak and usually breaks under extreme conditions.

The common "one wheel burnout" created with an open diff is always the passenger side wheel. Under acceleration, the torque produced by the engine twists the car. It forces the left front of the car up but also forces the right rear up. Lifting the right rear takes weight off the tire so it gets less traction and starts to spin.

 

who makes the best diff for the third gen?

 

OMG if i hear someone else call an open rear limited slip ill shoot someone.... na but Ive heard the eaton unit is pretty good.....but i think most people say the 98 up stock lsd is good....

 

You only really have a couple of choices. Eaton and Auburn are the 2 most common. A factory 96-01 is a Torsen LS. www.torsen.com

 

Yeah i dont know much bout diffs, I always thought if it wasnt locked it was just a variation of a limited slip, and if it was locked it was called posi, which i thought was just plymouths patent word for a locked diff. i will edumacate myself better this weekend maybe buy a gear or two

Is there any truth to getting a pin welded in the diff to lock it?

 

your talking bout a miller or lincoln locker....dont do it...thats when they weld the spider gears together, up side its cheap and will make both tire spin, down sides, will not last, will eat up tires, will make it a pita going around corners, will make u instantly grow a ******, will put stress on your drive line, all around not good for a street car... just save up the money and get the eaton unit, its your best bet...welders do not belong inside a rear diff.

 

I heard alot about dana diffs (not sure how to spell it), anyways i heard the dana 60 come up alot , is this a dodge diff or all makes? and is there a good 1 for T/A's?

 

Dana 60 diffs are very big and heavy. Strange offers a bolt in version. Even I don't need one.

GM offered a Dana 44 years ago. It was the best factory diff for a third gen but was never available in a production car except in the SLP Firehawk. Changing out the factory diff to a bolt in 9", 12 bolt or if you can find a Dana 44 that isn't worn out, you can expect to pay $2000+ for a differential.

No matter what you try, there is no cheap diff upgrade for the third gen.

 

Heres the skinny. If you have diff that has no mechanism to lock or send power to the wheel that has grip, then that rear end is called an "open" diff.

If you have any mechanism that will send power to the wheel with traction, but will alow the two wheels to spin at different speeds, by useing either, clutch discs(eaton), cones( borgwarner) or arrangement of worm gears( torsen, truetrac, was originally called mcgleason). Then that is called limited slip. Names like positrac suregrip are brand names of limited slip. For street use and road course racing a torsen style lsd would be your best choice.

If you have a diff that uses interference of parts( splines or cogs) to cause both wheels to spin at the same speed while going straight, and allow them to spin at different speed while turning, that is called a locker or locking real end. Example of brands of lockers detroit locker, powertrax.