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Telling the difference between a limited-slip/Posi-traction vs. locker

Discussion in 'The Hokey Ass Message Board' started by Flynn's_57, Aug 24, 2009.

  1. Flynn's_57
    Joined: May 10, 2002
    Posts: 932

    Flynn's_57
    Member
    from Nor*Cal

    So, just to clear things up, a person can tell the difference between a limited-slip/Posi-traction rear-end and a locked rear-end that is off the ground by spinning the wheels?
    If both wheels spin backward together it's locked, correct...?
    And a posi-rear-end will only spin forward together???

    I've had Datsuns with locked rears, and I know plenty of 'wheelers' rigs that are locked, but how shitty does the drive become in a hot rod/custom?

    Any horror stories....?

    I understand the math (the outside tire squeals because it needs to be spinning faster than the inside tire and "locking it" spins them at the same rate); I just don't get the whole "you don't want a daily-driver with a locked rear" mentality...




    Fucking Lincoln-locker....
    guess I need to practice drifting.....
     
  2. Flynn's_57
    Joined: May 10, 2002
    Posts: 932

    Flynn's_57
    Member
    from Nor*Cal

    guess I'm right?
     
  3. loudpedal
    Joined: Mar 23, 2004
    Posts: 2,200

    loudpedal
    Member
    from SLC Utah

    You will only find a "Posi" under a GM vehicle.
     
  4. bulletproof1
    Joined: Feb 23, 2004
    Posts: 2,080

    bulletproof1
    Member
    from tulsa okla

    posi /limited slip are the same thing ,ford called it one thing and gm called it something else. even what most call a locker arent ,ie gov-lock.really just a clutch type posi.if it has a friction clutch beside a spidergear ,its a posi/limited slip.truetrac also a posi/limited slip.has gears that work together to preload the side gears .but its NOT a locker.detroit locker is a mechanical locker.lockers the (side gears ) together..air locker ,uses air presure to lock the side gears together but it becomes a spool.will not ratchet like a detroit locker....i have a detroit in my 53 ford car..run it daily ....alot of import axles are pretty tight and feel like a posi but arent....
     

  5. bulletproof1
    Joined: Feb 23, 2004
    Posts: 2,080

    bulletproof1
    Member
    from tulsa okla

    big diff between welded and locker.when coasting the locker will ratchet letting the inside tire turn slower then the outside.with a spool/weld the tires turn the same speed all the time no matter what.wears tires, rough on drive line parts and no fun on wet roads
     
  6. squirrel
    Joined: Sep 23, 2004
    Posts: 50,298

    squirrel
    Member

    The Detroit Locker in my 55 is pretty easy to tell from a spool/posi/open rear...it ratchets. Jack up one wheel, take it out of park, you can turn the wheel and feel the ratcheting.

    A LSD with moderate springs or worn clutches will let you turn one wheel also. A guv lock may grab if you spin one wheel fast enough in neutral.

    A tight LSD acts like a spool when turning wheels by hand.

    The limited slip Dana 40 that was in my old truck has no springs, just clutches, and spins freely by hand, but it's a posi.

    I guess you can generalize, but you might come up with the wrong answer in some situations if you do.
     
  7. squirrel
    Joined: Sep 23, 2004
    Posts: 50,298

    squirrel
    Member

    Built that way. I guess the cross shafts move up the ramps to engage the clutches....strange...
     

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  8. seret
    Joined: Apr 28, 2008
    Posts: 539

    seret
    Member

    I have a rear end being built right now, and Im using a True Track brand posi, the builder told me on jackstands it will spin like a non-posi. I guess its what nascar is running.
     
  9. squirrel
    Joined: Sep 23, 2004
    Posts: 50,298

    squirrel
    Member

    Yeah, the true track has worm gears in it...easy to turn one wheel by hand, but hard for it to spin only one wheel by turning the driveshaft
     
  10. Flynn's_57
    Joined: May 10, 2002
    Posts: 932

    Flynn's_57
    Member
    from Nor*Cal

    so both wheels spin whatever way I toss the wheel....
    What am I dealing with here fellas?
     
  11. I agree with squirrel. 440, your experience may have been in LWB cars, so it would be harder to tell, but in a SWB car in a tight turn it's pretty easy to feel it and if they bind a little, you can hear the tire chirp a little before it rachets. As for a spool, I'm not sure how you wouldn't feel it, even in a LWB car. Also, as 440 suggests, do not run a welded (or even a spooled) axle in a street car. Makes no sense at all.

    I don't see a problem in running a detroit in street car and will be in my '33. It takes some getting used to, but if you know what to expect, it's no problem. Having said that, 90% of the people out there just need LSD (not the drug! :D )

    greaseball, raise the rear wheels off the ground. Place the transmission in low gear and see if you can turn the drive axle wheel by hand. If the drive axle is a LSD, it will be hard to turn the wheel-or maybe not turn at all. If it's an open diff, the wheel will turn easily, and the opposing wheel will rotate in the opposite direction.

    Next, put the transmission in neutral and turn the rear wheel. If the axle is a LSD the opposite wheel will rotate in the same direction. If the diff is an open type, the opposite wheel will rotate in the opposite direction-or not at all.
     
    Last edited: Sep 22, 2011
  12. Warpspeed
    Joined: Nov 4, 2008
    Posts: 532

    Warpspeed
    Member

    Yup......

    About the only thing you can be sure of is that if the opposite wheel easily turns backwards, it is a fully open diff. If in the same direction it is "something else".

    It is the "something else" that is the problem.
    It could be just about any type of locked, locking or limited slip type of diff.

    The only way you are going to know for sure is to pull the diff and see what is actually in there.

    Some genius that says it has an LSD may be quite right, but it could also be be a spool, viscous LSD, clutch pack LSD (posi) or something really wild like a Detroit Locker, or a Torsen.

    They all have advantages and disadvantages depending on the vehicle and what it is going to be used for. There is no "best" type of diff.

    If one type was vastly superior, everyone would be using it, and all the other types would quickly become obsolete. But you get to choose. And what is best for you depends on what you want your vehicle to do, and on what kind of surface.
     
  13. loudpedal
    Joined: Mar 23, 2004
    Posts: 2,200

    loudpedal
    Member
    from SLC Utah

    That's correct ...and I'll make the statement again:

    Posi-Traction is a GM product.
     
  14. carcrazyjohn
    Joined: Apr 16, 2008
    Posts: 4,844

    carcrazyjohn
    Member
    from trevose pa

    Stay away from Spools and locked rears .They suck I had a 410 in my elcamino It would hop on turns Going straight was fine. I didn't drive car much do to it was not very enjoyable .Traded a guy straight up .This rear was brand new with a few miles Traded for a used 3.31 posi Best decision I ever made
     
  15. squirrel
    Joined: Sep 23, 2004
    Posts: 50,298

    squirrel
    Member

    What type of rearend is it? what's it in? you're not giving us much to go on....and one wild guess is as good as another
     
  16. Larry T
    Joined: Nov 24, 2004
    Posts: 7,690

    Larry T
    Member

    Should be pretty easy to tell an open (wheels turn opposite directions), from a Detroit Locker (ratchets and clicks), from a locked/clutch type limited slip (wheels turn same direction) You're gonna have to pull the cover or drop out section to tell a rearend with welded spiders/spool/minispool from a good clutch type limited slip.
    I don't have any idea about the worm gear and dual pinion type rearends.
    Larry T
     
  17. autotec
    Joined: Sep 22, 2011
    Posts: 1

    autotec
    Member
    from phila

    A limited slip dif will only spin on wheel at a time, this is made by ford. A positive dif will spin both wheels at the same time, this is made by GM. As we all know GM is located in Detroit, thus it became known as the Detroit locker.
     
  18. bulletproof1
    Joined: Feb 23, 2004
    Posts: 2,080

    bulletproof1
    Member
    from tulsa okla

    sorry ..you are wrong....
     
  19. Both back wheels propel the car with the standard peg leg rear end, it's just when one wheel brakes loose most of the power it transmitted to that wheel..

    NASCAR used peg legs in the 50s and 60s...... Checkout the video, notice the Miller 62 Pontiac throwing sand... http://www.youtube.com/watch?v=Ly2vuzs1-As
     
  20. partsdawg
    Joined: Feb 12, 2006
    Posts: 3,056

    partsdawg
    ALLIANCE MEMBER
    from Minnesota

    If it's a Mopar it could have a sure-grip.
     
  21. Lots of info already so I won't go into it.

    I have run lockers on the street since i was a kid, not spools but lockers. A spool is a locked rear for sure but most folks don't call them a locker. I have run spools also but I don't care for them the only way to actually corner with a spool is to do it dirt track style.

    I do like a detriot locker, it isn't like driving an open rear but it isn't bad to drive. Some of them are a little rough when you corner but it only takes a little getting used to, once you realize that it may be a little jerky you adjust and you are fine. I prefer a locker to a posi, but I think it is just a personal preference.

    they do not drive like an old caddy with an open rear it is a performance option. Performance cars are not designed for comfort and you have to make some concessions for going fast.
     
  22. edgeabilly
    Joined: Dec 10, 2006
    Posts: 735

    edgeabilly
    Member

    So posi and limited slip are the same thing?
     
  23. HEATHEN
    Joined: Nov 22, 2005
    Posts: 7,591

    HEATHEN
    Member
    from SIDNEY, NY

    Yes. "Positraction" is just a brand name that has come to be used for every type of limited slip differential, much like every facial tissue is a "Kleenex". Not even all of the G.M. makes used the term; if you ordered it for your new Pontiac, it was "Safe-T-Track".
     
  24. edgeabilly
    Joined: Dec 10, 2006
    Posts: 735

    edgeabilly
    Member

  25. yellow dog
    Joined: Oct 15, 2011
    Posts: 474

    yellow dog
    Member
    from san diego

    Detroit Lockers are now produced under Eaton's name. We Just put one in an early Falcon....fantastic. Lockers drive the inside tire until the inside speed matches the outer. This could drive the vehicle toward the outside @ partial power. Haven't noticed anything on this particular installation, they are even quieter (fuel pump is much louder) than old ones w/ a variety of spring tensions available. Eaton also makes Trutrac and Posi LSD under those names
    http://www.eaton.com/Eaton/Products...AutomotiveAftermarket/Differentials/index.htm
     
  26. bulletproof1
    Joined: Feb 23, 2004
    Posts: 2,080

    bulletproof1
    Member
    from tulsa okla

    another thing about running detroit lockers ,,, with a automatic trans you dont notice the locking and unlocking as much,, every now and then i hear mine or it might " clunk" ....
     
  27. 52lomofo
    Joined: Jan 29, 2005
    Posts: 706

    52lomofo

    so the newer styled jimmy's bakzer should have a posi under them???
     
  28. 52lomofo
    Joined: Jan 29, 2005
    Posts: 706

    52lomofo

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