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posi rearend

Discussion in 'The Hokey Ass Message Board' started by fleetmaster, Feb 16, 2004.

  1. fleetmaster
    Joined: Jan 21, 2004
    Posts: 168

    fleetmaster
    Member

    hey-it's me again. to get some better traction on my 47 coupe-we had been planning to use a posi-traction setup in the rearend. however, lately i have heard of some problems with them going around corners and handling in wet weather. this car is also meant to be both a highway driver and a racer. so-i had heard of other setups like a posi-but a little different.they are supposed to work a little better in some of the situations i mentioned. i was wondering if anyone new of some other options or more about systems like this and what would work well.just so i have some ideas and know what works. i would really appreciate it.
     
  2. briggs&strattonChev
    Joined: Feb 20, 2003
    Posts: 2,233

    briggs&strattonChev
    Member

    the better rear end you are thinking of is called a "limited-slip" I think
     
  3. fleetmaster
    Joined: Jan 21, 2004
    Posts: 168

    fleetmaster
    Member

    is there any more info you can give me on that?
     
  4. briggs&strattonChev
    Joined: Feb 20, 2003
    Posts: 2,233

    briggs&strattonChev
    Member

    im not sure but I think that 80's camaro/firebirds had them and there were a series of discs in the housing that gave it brain-like qualities to distrubute the power to the wheels properly. This is just what ive been told, I dont know for sure, but it wouldnt be hard to find out. BUT, if you are going to run the 496 bbc like you posted, a limited slip probably wouldnt hold up to it very well. I think id run a posi, as long as its not a homeade posi (welding the spider gears together) turning the car shouldnt be a problem. Ford 9 inches and gm 12 bolts are good and strong rear ends. Another thing you have to factor in is the width of the axle do you can get it into the car properly and not have oddly dished/offset rims.

    Briggs
     

  5. metalshapes
    Joined: Nov 18, 2002
    Posts: 10,716

    metalshapes
    Tech Editor

    The one that is suposed to be a little harsh for the street is the Detroit Locker. ( although I have no experience with one )
    The rest are all different types of Limited Slip Diff's, unless its a Torque Biasing Diff like the ones made by Quaife ( GB ).
    Are you worry'd by the diff for rain driving or the 496 Big Block you are planning to use?
     
  6. Sinister
    Joined: Jan 19, 2004
    Posts: 710

    Sinister
    Member
    from Oregon

    I had a posi rear in my *gasp* Camaro, with a 327 (built to DZ302 specs) SBC. making tight turns (like into parking spots) would cause the inside wheel to bind up. On a rainy day, and with a heavy right shoe, I had a hard time keeping it in one lane ( at the time I didn't mind, as I paid taxes for BOTH sides [​IMG]). Forget driving it on the ice.

    The other rear you are thinking of is called a "limited slip" rear. They won't "bind up" when you turn, but will lock up when you need traction from both wheels.

    the only company I can think of off the top of my head for info might be Currie ent.(I don't have the web address, sorry) They build some really strong rear ends.

    Speaking from experience, pitching your car sideways on Sprague ave at 40mph in traffic tends to make people a little freaked out [​IMG].
     
  7. fleetmaster
    Joined: Jan 21, 2004
    Posts: 168

    fleetmaster
    Member

    [ QUOTE ]
    pitching your car sideways on Sprague ave at 40mph in traffic tends to make people a little freaked out [​IMG].

    [/ QUOTE ]

    Hey sinister-r u from spokane?
     
  8. fleetmaster
    Joined: Jan 21, 2004
    Posts: 168

    fleetmaster
    Member

    [ QUOTE ]
    Are you worry'd by the diff for rain driving or the 496 Big Block you are planning to use?

    [/ QUOTE ]

    i am worried about it for rain driving and all around performance-and i a mnot sure if i am even using the 496 yet-some feedback about that would be nice too.
     
  9. Sinister
    Joined: Jan 19, 2004
    Posts: 710

    Sinister
    Member
    from Oregon

    Yes, my friend, I am... [​IMG]

    I sent you a PM with my number, feel free to give me a call anytime. [​IMG]
     
  10. Mutt
    Joined: Feb 6, 2003
    Posts: 3,219

    Mutt
    Member

    Check here...
    http://www.moserengineering.com/moser_interior/products.asp?CatID=24

    "Posi" is GM's positraction rear, the same as a 'limited slip' rear end. The difference in limited slip rears is the method of lockup - either cone type or friction disc. Both accomplish the same thing. I've used a '57 Chev posi (friction disc) in my roadster for 40 yrs.

    Without knowing what rear end you are using it's difficult to give advice. Auburn makes posi's for most cars. The early GM (55-64) are difficult to find and expensive.

    A Detroit Locker is the one that makes noise on turns, and is for serious race type action. It uses spring loaded gears to lock up. It is usable on the street, just noisey, and you can't get squirly in wet weather on turns. I have one to go in my deuce, and it will be street driven.

    Behind a serious big block, I would use a GM 12 bolt, Ford 9in., or Dana 60. My personal preference is a 9in because of cost and ease of maintenance. A "posi" will hold up to a big block.

    Dan
     
  11. wayfarer
    Joined: Oct 17, 2003
    Posts: 1,790

    wayfarer
    Member

    Guys, thanks for helping Emilio out. He sometimes forgets to put details in his posts. He's got a '59 ford 9" housing that he's using and he's got some 4:11 gears a guy gave him. He's concerned about making the car able to hook up at the drag strip, but he doesn't want problems like the rear wheel locking up going around corners because the car will be his daily driver. Wouldn't we all have liked to have a 496 powered daily driver in high school?
     
  12. Past experience tells me if you are worried about rain and other slick conditons, stay away from spools and Detroit lockers.

    I did a customers truck with a Detroit Locker (race locker which is a bit stiffer) and it had some nasty habits. While cornering it is pushing the front wheels untill the Locker "opens" and goes straight to snap oversteer. Just plain freaky!

    Auburn cone style limited slips are pretty good for street driving. If you plan on some track use or have a heavy foot you may wear it out in a couple of years. You will need the friction modifier to keep it from chattering just like the factory plate style limited slips from Ford,GM,Mopar.

    Speaking of those, the Ford Trac-Loc is pretty good as is the GM Limited Slip or Mopar Sure-Grip diffs. They have clutch plates and springs inside to connect each wheel. And in low traction applications they will give up more progressively than will a Detroit Locker.

    As far as I am concerned the gear torque biasing diff that Metalshapes mentioned is the ultimate. Here are a few different choices.

    Quaife America

    Tractech, the makers of Detroit Locker and True Trac

    There are a couple more called Diamond Trac and Gold Trac. Mostly used for racing (9" application only I belive)

    Belive it or not Lenco had a planitary differential for a while. I don't see it on the website but have had the chance to use it before and it worked very well and was very strong.

    Lenco Racing

    Auburn Gear Lots of choices here too!
     
  13. Mutt
    Joined: Feb 6, 2003
    Posts: 3,219

    Mutt
    Member

    wayfarer - I would recommend the Ford Trac-loc then. It's heavy duty, relatively inexpensive, and plentiful. E-bay has a lot of them for sale. I would also recommend 31 spline axles, and use Moser or Currie if he's going to use slicks - aftermarket axles are required by NHRA on any car running 10.99 or quicker. A driveshaft loop is required on all cars running 13.99 or quicker.

    I'll send you any mag. articles on big blocks I can find for him.


    Dan
     
  14. Flatdog
    Joined: Jan 31, 2003
    Posts: 1,285

    Flatdog
    Member Emeritus

    Mutt and Elpolacko nailed it.There are several others but will just confuse the issue.I have run common basic units, cluth type,detroit locker in my car ,elpolacko desribed the feeling pretty good.I have installed many of all types.
     
  15. fleetmaster
    Joined: Jan 21, 2004
    Posts: 168

    fleetmaster
    Member

    thank you everyone for all your advice. that helps a lot. and wayfarer is right- i do forget stuff in my posts some times-sorry-i i will work on that [​IMG] well-thank you guys again!
     
  16. a/fxcomet
    Joined: Mar 31, 2001
    Posts: 554

    a/fxcomet
    Member
    from Eugene, OR

    I have a Auburn Pro (stiffer than the regular version) in my 8". I drive it in the rain all of the time, and it does fine.

    http://ringpinion.com/tech/techind.html . Here is a good rundown of all of the differnt types. I also got all of my parts from these guys- really good to work with.
     
  17. John Copeland
    Joined: Mar 11, 2002
    Posts: 350

    John Copeland
    Member Emeritus

    Fleetmaster,
    Put a posi in the car and forget about it, whoever told you they weren't safe was blowing smoke up your ass! If your lucky enough to find one, and the gear isn't too stiff, your not going to fry the tires anyway, big block or not! What kind of rearend do you have in the car? If this is to be a part time "Racecar", you need a posi.


    Shoe
     

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