rear end ???


tmaxxman

tmaxxman

10+ Year Member

Joined
Oct 17, 2010
Messages
408
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1,601
City
PA
Vehicle Year
1988
Transmission
Manual
I'm just wondering what is the difference between a posi-traction rearend and a rearend with a locker? :icon_confused:
 
Posi is the GM version of a Limited Slip, which is generally a standard open differential with clutches to limit the "slip" of one shaft in relation to the other. A locker on the other hand locks each axle shaft to the carrier, an automatic locker will ratchet around corners but will generally lock the tires together when only one tire has traction. A selectable locker is normally an open differential but when activated becomes solid.
 
For what you are asking, there are three types--Locked, limited slip, and open.

An open axle is torque controlled. Which ever axle has the most torque, loses the power. It's like socialism--the squeaky wheel gets no grease.

Limted slip (posi, Gov-Lock etc) is the same as an open axle--it has all the same gears that make an open axle brilliant, but suck. The difference is that there are clutches that are supposed to pinch together under load and force the diff to send power to the tire that has traction available. It's better than nothing, but still bad.

An automatic locker like a Detroit No-Spin or a LockRight or an Aussie, is speed controlled. When it goes around a corner, the outside tire is driven by the road and is going faster than the inside tire. This causes the outside tire to unlock. If you want it to herk and jerk, acclerate hard enough to bust the inside tire loose and you can have a nasty axle.

You have to drive it easy, but you can forget about a Lockright after a while. The No-Spin in my bigger truck is constantly making horrible noises, even though I know the axle is set up perfectly.

One bad thing about a locking axle--where I live, I'm often facing a steep turn onto a road with a 10,000# trailer and a heavy grade. You have to remember that with a Detroit Locker, you can't just floor the pedal. You have to nurse the trailer out flat, and then feed in the throttle so you don't risk breaking an axle. Only one axle is carrying the thrust in turns.
 
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"Posi-trac" is GM crap that should never be put in a Ford. A locker is aftermarket crap that is ok when the truck is being used in situations like rock crawling or deep mud.
 
That's punishing it right there. I can feel the heat from the torque converter through my computer screen.

I can't answer your question without seeing the truck. Either it has a LS or holding the brakes is making both sides see the same resistance. Jack it up under the pumpkin and with the truck in park, turn a tire by hand. If the other one rolls the other way with very little effort, it's got a functioning differential. A limited slip looks like an open, but has this S-spring thing between the side gears.
 
Ford has called a limited slip a "locking differential" in the past to add to the confusion.

Dunno when they started, but the newer 31spline 8.8's are set up like a 9.75 without the big S spring.

If the weight is balanced and traction equally crappy it is possible to spin both tires, I have done it before.
 
Will said:
That's punishing it right there. I can feel the heat from the torque converter through my computer screen.

I can't answer your question without seeing the truck. Either it has a LS or holding the brakes is making both sides see the same resistance. Jack it up under the pumpkin and with the truck in park, turn a tire by hand. If the other one rolls the other way with very little effort, it's got a functioning differential. A limited slip looks like an open, but has this S-spring thing between the side gears.
Click to expand...

it has no torque converter now it a 5 speed . and i dont need to be hiting the brakes for them to both spin. ok i will try that tomorrow
 
85_Ranger4x4 said:
Ford has called a limited slip a "locking differential" in the past to add to the confusion.

Dunno when they started, but the newer 31spline 8.8's are set up like a 9.75 without the big S spring.

If the weight is balanced and traction equally crappy it is possible to spin both tires, I have done it before.
Click to expand...

like i sed it dose it all the time it don't matter what i do i have tryed to get it not to and i cant im glad both spin but i dono why lol
 
ok got a quick question would it hurt to weld the front differential on my truck
 
if you run tight trails, it can make it more difficult to manuver, that's why most people that just trail ride run a rear locker and open front.
 
ok but if i dont have it in 4 wheeldrive and the hubs locked it wont make a difference in how it drives on the road right may be a dumb question but i just want to make sure before i do it lol
 
tmaxxman said:
I'm just wondering what is the difference between a posi-traction rearend and a rearend with a locker? :icon_confused:
Click to expand...

Posi is a worthless POSi GM product that needs to be kept out of this forum.

Lockers are good for traction.

And just leave the front end be.
 
one more question.what dose takeing the front swaybar off get you. is it worth it to do it ???
 
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