Pozzi wont lock on

LightEMup

Registered User
I went out in my SC the other day to do some good ol donuts, and it was really really hard to get my rear end to get both tires to spin and get my car to come around, it use to be she'd come around REALLY quick and REALLY easy....what does this meen if the pozzi isn't locking like it use to?
 
sc's dont have posi-traction, ford calls it a traction lock, same thing really, but if one wheels only spinning, then shes probably getting a little tired back there
 
aplvlydrtybird said:
sc's dont have posi-traction, ford calls it a traction lock, same thing really, but if one wheels only spinning, then shes probably getting a little tired back there
lol they do too have pozzi....i have the pairs of blackmarks to prove it on over 40 streets :D pozzi, limited slip, trac lock..WHATEVER ITS CALLED lol. All i know is it goes from spinning 2 wheels in a straight line, and when i go to whip the *** end around it unlocks a wheel and just spins 1 tire....what do i need to replace to get it back to normal? I'm gonna put 3.27's in it when i go thru it. so what do i need to replace?
 
LightEMup said:
lol they do too have pozzi....i have the pairs of blackmarks to prove it on over 40 streets :D pozzi, limited slip, trac lock..WHATEVER ITS CALLED lol. All i know is it goes from spinning 2 wheels in a straight line, and when i go to whip the *** end around it unlocks a wheel and just spins 1 tire....what do i need to replace to get it back to normal? I'm gonna put 3.27's in it when i go thru it. so what do i need to replace?

When you have it apart, have the TRAC-LOC rebuilt. GM's use "posi-traction".

-Rod
 
LightEMup said:
lol they do too have pozzi....i have the pairs of blackmarks to prove it on over 40 streets :D pozzi, limited slip, trac lock..WHATEVER ITS CALLED lol. All i know is it goes from spinning 2 wheels in a straight line, and when i go to whip the *** end around it unlocks a wheel and just spins 1 tire....what do i need to replace to get it back to normal? I'm gonna put 3.27's in it when i go thru it. so what do i need to replace?

It means your traction loc clutches are worn out. You can get a rebuild kit from Ford or several other places.

David
 
A spool really isn't practical for a daily driver. Not to mention the amount of strain it would put on the halfshafts during turns.

-Rod
 
remove one steel plate and restack them using an extra fiber disk, if this doesnt ring a bell someone can explain or search a mustang site or something, they should have a step by step process somewhere. I always do this and guys that race their cars have never complained of one tire letting go
 
AsScLoWn said:
remove one steel plate and restack them using an extra fiber disk, if this doesnt ring a bell someone can explain or search a mustang site or something, they should have a step by step process somewhere. I always do this and guys that race their cars have never complained of one tire letting go

In addition to the alternate steel and friction stacking mentioned above, you can also add the F-150 "S" spring for more tension on the clutches.

David
 
If you make it stiffer, does it increase tire wear?

:confused: From what I understand of it, the track-loc basically causes the outer wheel in a turn to drag along untill it overcomes the clutch friction, the clutches then start to slip, and this allows the outer wheel to rotate at a different rate. Until the clutch starts to slip, aren't you essentially skidding the outer tire through the turn? So, if you make the clutch pressure greater, won't it cause the outer tire to skid more and wear out even faster?

Well, since you turn in both directions, it would alternate with the net result being increased rear tire wear. However, since a good owner has their tires rotated regularly from front/back, it would seem that overall tire wear would increase. I'd be curious as to just how many more miles you'd get out of a set of tires w/o the track-lock? :confused:

To me, if you can do a burn out on both tires, those clutches are providing a heck of a lot of grab in fact, more grab than the tire-to-road. Is there something else going on that counters this? :confused:
 
AsScLoWn said:
remove one steel plate and restack them using an extra fiber disk, if this doesnt ring a bell someone can explain or search a mustang site or something, they should have a step by step process somewhere. I always do this and guys that race their cars have never complained of one tire letting go
yes this is the same method we used to use in our dirt bikes clutches
and in a few hemi torqueflights back in the day
 
TbirdSCFan said:
:confused: From what I understand of it, the track-loc basically causes the outer wheel in a turn to drag along untill it overcomes the clutch friction, the clutches then start to slip, and this allows the outer wheel to rotate at a different rate. Until the clutch starts to slip, aren't you essentially skidding the outer tire through the turn? So, if you make the clutch pressure greater, won't it cause the outer tire to skid more and wear out even faster?

Well, since you turn in both directions, it would alternate with the net result being increased rear tire wear. However, since a good owner has their tires rotated regularly from front/back, it would seem that overall tire wear would increase. I'd be curious as to just how many more miles you'd get out of a set of tires w/o the track-lock? :confused:

To me, if you can do a burn out on both tires, those clutches are providing a heck of a lot of grab in fact, more grab than the tire-to-road. Is there something else going on that counters this? :confused:

That's not how it works. Rather than try to explain it, I'll try to find an article with some diagrams.

David
 
Simple explanation, from the Eaton web site:
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.
BTW, there is at least one SC with a "posi" - mine. Posi or Positraction is the brand name for Eaton's limited slip diff. It's much better than a Ford Traction-Loss diff, but when I got mine it required some modification to fit. You could search the forum for more info.
 
it takes little force to have both wheels spinning, when turning the clutch packs will allow slip, but if you decide to hammer on the gas you can fish-tail it easier :D . Tire wear is the same

you have to remove both half-shafts and remove the 5/16" bolt retaining the pin, its about 100$ in parts, the trick is installing the spring, you have to intall it at about or close to 90deg. from how its supposed to sit, then rotate it while hammering it in, not fun if you havent done it before :)
 
OK. I think I have this. Based on the Traction-Lok diagram, the friction between the clutches + the force provided by the preload "S" spring provide the total of the grip between each side gear and the differential case. This explains why if you spin 1 wheel with both wheels off the ground they will track together.

In normal circumstances, that force is not all that strong; probably only on the order 100-200 ft-lbs are needed to break the clutch friction and allow the shafts to spin at different rates. During cornering, the tire would stretch a small bit, but not so so much as to cause it to break adhesion with the road surface. Hence, the tires wouldn't wear more from cornering. However, the difference torque would be just enough to give a small bit of push on a slick surface to the non-slick tire.

However, that torque difference depends on the "S" spring tension (springs fatigue and lose strength over time), the clutch thickness (these also wear), and the quality of the friction modifier. So with time, the track-lok will eventually wear out.

But it also means that if you increase the spring tension significantly (stronger spring) or increase the friction between the clutch faces, you could increase the break away torque to the point that it could increase the wear on the tires during cornering. :cool:
 
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I think stock specs call for 25ft/lbs minimum breakaway, thats all thats needed on a flat level surface, you can roughly check this by placing a jack under one lower control arm and turning the wheel by the lugnut(more accurate putting a socket on the axle-shaft nut) using a rod style torque wrench<-----all this means nothing(just for warranty purposes etc), if you feel both wheels turn together when they should its fine :D . Vehicle should be in neutral with the e-brake off and the front tires blocked, if the car rolls and crushes you, too bad, tough lesson learned(keep your shiat away from the bottom of the car) :rolleyes:
 
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