posi in auto x

[Keddy_StangGT4.6]

hey this is a dumb ? but would a posi diffentral be bad for auto x

[Neutrino]

quik question will a posi tend to lock your wheels for 50:50 under power if yes...then its bad for autox since it will cause severe understeer

btw its a posi rear a cluch type diff?

[MustangRoadRacer]

Posi is good.
I have an Eaton Posi in my car and it runs fine.

[Neutrino]

Originally Posted by MustangRoadRacer

Posi is good.
I have an Eaton Posi in my car and it runs fine.

again question...posi its more of an old school name....so...

when you refer to a posi...do you refer to all limited slips or only certain types?

[Keddy_StangGT4.6]

i mean the type that both tires spin at the same rate. as in the power is distruated to both rear tires instead of one.

[Neutrino]

well all LSD's are meant to transfer power to both wheels but some (like a clutch type) tend to lock up the wheels togheter and get close to a 50:50 transfer....this is very good for drag racing however if your rear wheels do this 50:50 lock during a turn it will cause severe understeer


so basically for autox you are much better off with something like a helical LSD(quaife is my fav) which in a turn will bias power to the outside wheel and help you turn...it will be however much less efficient at the drag strip however

[MustangRoadRacer]

yeah, my posi is a limited slip.
a locking differential is what is used at the strip.
that's a NOGO in cornering though.

[Neutrino]

Originally Posted by MustangRoadRacer

yeah, my posi is a limited slip.
a locking differential is what is used at the strip.
that's a NOGO in cornering though.

ok gotcha...i was always confused about this....posi its a term used mainly by muscle car guys and i was laways confused if they meant lockable diffs or LSDs

[MustangRoadRacer]

yeah posi was old like posi trac they had on firebirds and crap like that back in the day.
now they mainly use limited slip. they probably held on to the posi name for marketing reasons or something.

[MustangRoadRacer]

here is what eaton says:
Basically, the difference between the two is this: A limited slip differential sends power to the non-drive wheel based on input torque; that is, power coming to the axle from the engine.

So, when high torque comes to the differential and both wheels are on a high traction surface, like a drag strip or country road, and high torque is delivered to the axle, the clutch pack clamps the gears to the differential case. This clamping action is in proportion to the torque delivered. The higher the torque, the higher the clamping load.

The idea here is to prevent wheel slip -- at either wheel -- in the first place. If one wheel starts slipping before the other, the clamping force drops in proportion to the torque delivered to the slipping wheel.

The whole point of the torque sensing limited slip differential is to reduce the likelihood of wheel slip.

The locking rear differential locks the drive and non-drive wheels together based on wheel slip at the drive wheel, regardless of engine power input.

that should help.
for diagrams, go to http://www.torquecontrol.eaton.com/prod2.htm
that is for the locking dif.
for LSD check out
http://www.torquecontrol.eaton.com/prod3.htm