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Technical Positraction vs limited slip?

Discussion in 'The Hokey Ass Message Board' started by Master Brian, May 1, 2019.

  1. Blues4U
    Joined: Oct 1, 2015
    Posts: 3,529

    Blues4U
    Member
    from So Cal

    There's a 3rd type, the torque sensing, or Torsen differentials, which use all gears to accomplish limited slip. Maybe not common in classic cars, but just clarifying that there is a 3rd type of technology. There's actually a 4th technology used in heavy trucks and heavy equipment that's also been picked up by the off-road crowd, the air locker.
     
  2. tb33anda3rd
    Joined: Oct 8, 2010
    Posts: 14,812

    tb33anda3rd
    ALLIANCE MEMBER
    1. Connecticut HAMB'ers

    a friend was telling me about their new car and the fact it was all-wheel drive. later in the conversation I referred to it as "four-wheel drive". he corrected me and said no, it was all-wheel drive........so I asked him how many wheels it had, he said four.
    different name.
     
  3. Deuces
    Joined: Nov 3, 2009
    Posts: 17,243

    Deuces
    Member
    from Michigan

    Need to get a bottle of friction modifier.... ;)
    I think napa sells it....
     
  4. greenie-reddy
    Joined: Nov 23, 2009
    Posts: 537

    greenie-reddy
    Member
    from maryland

    Ok, but my Pontiac has Safe-T-Track !?!
     
  5. Deuces
    Joined: Nov 3, 2009
    Posts: 17,243

    Deuces
    Member
    from Michigan

    It's a limited slip rear end....
     
  6. gene-koning
    Joined: Oct 28, 2016
    Posts: 1,210

    gene-koning
    Member

    Mopar called their version a "Sure Grip". Modern stuff its called a Limited slip. I think the Sure Grip had more spring pressure on the clutches (and better clutches) then the newer stuff has. The Friction modifier allows the clutches to slip more on turns, thus reducing the chatter between the clutches as they are forced apart in a turn. If you get a chatter, snapping, or popping with a positive traction rear, you need to add some friction modifier and do a couple slow figure 8s in a parking lot to work the friction modifier between the clutches.

    I had a 66 Dodge wagon with the old Sure Grip, it was an interesting drive in the winter. Often there wasn't enough traction for the clutches to release on turns, so it was a bear to drive in the snow. I remember having tires with really good tread on the front and nearly bald on the rear so it would turn corners if you stepped on the gas. My 90 with the Limited Slip is much better behaved in the snow. Gene
     
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  7. Ford was still making the 'Equa-Lok' at least through '69 as it's shown in the service manuals for those years.
     
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  8. Limited slip isn't worth a damn on snow or ice, I had a Ranchero with it and took it out as the car was undriveable under those conditions. Wasn't great with an open rear either, but you could at least keep in on the road.

    It should be pointed out that there's 'high bias' and 'low bias' limited slip rears too. High bias is what you want for straight-line acceleration, but for road racing or 'spirited' driving on street tires a low-bias will be less likely to upset the car.
     
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  9. blowby
    Joined: Dec 27, 2012
    Posts: 5,827

    blowby
    Member
    from Nicasio Ca

    0501191919_HDR.jpg
     
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  10. 427 sleeper
    Joined: Mar 8, 2017
    Posts: 444

    427 sleeper
    ALLIANCE MEMBER

    Thank you!!! You saved me a lot of typing!

    Sent from my SM-G892A using The H.A.M.B. mobile app
     
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  11. Boneyard51
    Joined: Dec 10, 2017
    Posts: 2,081

    Boneyard51
    Member

    You are right Blues4U, that’s why I added the word “ main” before types. I’ve been a fan of traction enhancing rear ends for a spell. Those gear types you talk of use the worm gear principle, kinda. Kool gear boxes! The air and electric locker are the absolute best!





    Bones
     
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  12. gimpyshotrods
    Joined: May 20, 2009
    Posts: 15,995

    gimpyshotrods
    Member

    I have a gear-driven torque biasing differential (Quife, Detroit True Trac, Winters Gold Track) in every vehicle I own, with more that 2-wheels.

    There is a subset of that 4th technology, electric lockers, and cable actuated lockers.

    My old 4x4 rig had a hybrid. Gear driven, switch off, locker, switch on, in the rear.
     
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  13. :p
     

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    Last edited: May 2, 2019
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  14. deathrowdave
    Joined: May 27, 2014
    Posts: 1,582

    deathrowdave
    ALLIANCE MEMBER
    from NKy

    Man looks like a can of worms for fishin to me ! I have 2 of the Dana Type that Loudbang , spoke of , and they are clutch type . They can be loaded as tight as you can stand , my old Power Wagon has one front and rear , they work fine when called into use . There is a wedge affair on the spider gears that forces the clutches tighter and tighter together as needed . Call it what you want , I have had Detroit Lockers in my younger days also , for everyday driving , I’ll pass on one today . The banging and tire chirping really aren’t needed the way I drive today .
     
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  15. jnaki
    Joined: Jan 1, 2015
    Posts: 3,383

    jnaki








    Hello,
    Once you figure out which one you have, if it is a Chevy Positraction unit, from 1955 on, the single most unusual thing is to add that required oil. Not just any oil, but Chevy or GM Positraction Oil. We were told by the dealer parts guy, our own expert mechanic in LA, and the local mechanic, that you must add "Positraction" oil. How do you know if it is Postraction Oil if the label is torn or scratched off?

    Our friend who worked at the local Chevy Parts Department opened a can up for us to smell the unusual odor. He told us that if there is no smell, it is not official Positraction Oil. Then because they could not sell the opened can as new, he gave it to us, as we bought several more cans of smelly oil. It smelled like rotten fish or seafood.

    My job as a teenager was to crawl under the 1958 Chevy Impala and change the third member 4:11 Positraction gear set up with a drag strip ready 4:56 Positraction gear set up, almost every single Thursday night. Why Thursday nights? Despite the late hours on Thursday night, it paid dividends on those Bixby Knolls Friday nights and all day at Lions on Saturday. If we were not going to be racing on the following Friday or Saturday, the whole unit was changed back to the 3:55 stock or the 4:11 Positraction. Cruising to San Diego, the local mountains, or Los Angeles areas called for 3:55 gears on the long driving roadways.

    The times were a lot quicker at the drags with the 4:56 gears. But, I used plenty of new oil each time as per requested by my brother. Once we made it to Pomona for the Winternationals and the 4:56 gears were in place from the Friday Night Races. It was a high pitch engine whine because of the 4:56 gears. Everyone thought we were nuts to drive such a long distance with those gears.

    Jnaki
    We did not like the smell floating around the backyard garage between gear exchanges. So, we had to seal up the remaining third member with the either gear set up sitting in the garage. Otherwise, it smelled like a tuna canning factory that did not get its nightly spraying and cleaning. That was awful stuff, but the Positraction worked wonders on the street and dragstrip.


    1958 Impala Lions Dragstrip


























     
    Last edited: May 2, 2019
  16. Well you got me rooting thru the catalogs with that post. :confused: Oddly, only a couple of the RPOs shown in your post were even acknowledged in the GM parts catalogs. G86 was described only as "limited slip" and G87 only specified as a 8.5" ring gear, neither open diff or limited slip. Maybe some of the other codes were SEOs or for fleet equipment, but I've never seen them in our catalogs. o_O

    For later model axles, most, if not all vehicles with G80 will have the Eaton ratcheting style differential. And Eaton is correct in saying that when one of their diffs is used in a GM vehicle it will be designated as a G80 RPO. But as shown below, GM also considers this spring style of limited slip differential to be RPO G80, as listed for 91 to 96 Impala and Caprice, and other models as well.

    G80 DIFF 01.jpg
    I suspect that the best way to identify the specific type of locking differential is by the supplier, either the Eaton style or the GM Corporate design (or Dana, etc.). :rolleyes:
     
    Last edited: May 2, 2019
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  17. dirty old man
    Joined: Feb 2, 2008
    Posts: 8,060

    dirty old man
    ALLIANCE MEMBER

    The "fishy" smell of the old posi additive was because it contained oil from Sperm Whales, and it's now internationally forbidden to kill them. The additives used now are unknown to me, but Blues 4U, who is a lubrication expert, may be able to tell us.
    Interestingly enough, back in the 50s/60s Crane Cams advised adding it to the break in oil on engines with their cams. I mixed the posi oil and STP half and half and used it as an assembly lube, plus adding a can of the posi lube to the crankcase as recommend in Smokey Yunick's writings in HRM. He advised using it only as a break in oil, then draining due to an ash it created causing detonation and preignition..
     
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  18. Boneyard51
    Joined: Dec 10, 2017
    Posts: 2,081

    Boneyard51
    Member

    Just a side note here...... as with most hot rod stuff..... farm tractors had manually operated traction locked rear ends years ago!




    Bones
     
  19. Ned Ludd
    Joined: May 15, 2009
    Posts: 3,840

    Ned Ludd
    Member

    If I remember correctly "all wheel drive" was an American linguistic innovation c. 1985. When the first Audi Quattro appeared in 1980 it was described as "four wheel drive", as had been the Jensen FF before it. It didn't seem to faze the Europeans. It was only when the '80s craze for lowish passenger cars with drive to all four wheels hit the USA that the need was found for a special term to distinguish them from 4x4 Suburbans etc. This despite AMC having already been at it for a while.
     
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  20. KenC
    Joined: Sep 14, 2006
    Posts: 238

    KenC
    Member

    Maybe that's a regional thing, but I my world a 4wd has a transfer case and two ranges in that case. Most cannot be operated on surfaces with good traction while in 4wd.

    An awd does not have such a transfer case.. Their transfer case has one speed front and rear and some have a center differential with variable torque split front to rear.

    There are some full time 4wd that incorporate a center diff for hard surface capability, but retain the hi-low gear set.
     
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  21. Terrible80
    Joined: Oct 1, 2010
    Posts: 691

    Terrible80
    ALLIANCE MEMBER

    My 64 Olds 88 had a sticker in the glove box warning about jacking it up with motor running. Called it Anti- slip or Anti- spin.

    Sent from my LG-TP450 using The H.A.M.B. mobile app
     
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  22. As stated previously by others, G80 is simply one of GM's RPO codes for a limited slip differential in a particular model of car. The specific differential tied to the code will vary depending upon the axle and vehicle in which its used. There are other RPO codes for limited slip differentials, as well.

    For example my 1995 Impala SS has the G80 RPO code, which corresponds to an Auburn limited slip differential. It's not the same as what you've posted.

    If you want into a GM dealership and say, "I need a G80," they're going to ask you, "For what model of vehicle?"
     
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  23. :p
     

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    Last edited: May 2, 2019
  24. squirrel
    Joined: Sep 23, 2004
    Posts: 42,702

    squirrel
    Member

    or slightly more on topic, the RPO codes for 1962 Chevy trucks.

    rop 62 truck.jpg
     
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  25. 427 sleeper
    Joined: Mar 8, 2017
    Posts: 444

    427 sleeper
    ALLIANCE MEMBER

    I'm not trying to start a pissing match here but, when I ORDERD my 2002 Camaro SS, there was no option for a 4.56 gear, because I would have ordered it! The only option was for automatic trans or manual. Autos came with 3.23 and manuals came with 3.42. IIRC. I don't know where these so called experts on the interweb get their info from but, I'm calling bullshit on all of it! G80 has always been the RPO for Posi-Traction. (A limited slip type differential) It ALL depends on what "era" of Posi. you're dealing with. Rant Over!
     
  26. squirrel
    Joined: Sep 23, 2004
    Posts: 42,702

    squirrel
    Member

    I wonder what "maximum traction" was? Huh. This is from the 1970 truck list (seems it used a Dana rear end)

    rpo 70 truck.jpg
     
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  27. Well now it looks like I'm going to have to drag out an old paper truck catalog and see what I can find out about that G87 RPO. But I better not get a paper cut doing it! :mad:
     
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  28. 427 sleeper
    Joined: Mar 8, 2017
    Posts: 444

    427 sleeper
    ALLIANCE MEMBER

    I'm not a betting man but if I had to put money on it I would say it was a Dana axle... with Posi-Traction!

    Sent from my SM-G892A using The H.A.M.B. mobile app
    I've been wrong before though, just ask my wife, she knows EVERYTHING!!!
     
    Last edited: May 2, 2019
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  29. deathrowdave
    Joined: May 27, 2014
    Posts: 1,582

    deathrowdave
    ALLIANCE MEMBER
    from NKy

    My thinking is : all the clutch type of LDS have different names because of “ copy right “ infringements . Posi Trac , Govern Loc , Tru Trac , Power Loc ,Equa Loc all a few of the OEM given names . Detroit Locker , Spool , Lunch Box Locker say what they are a Locker . Each has its place , my 32 has an open 3.00 ratio 9 in Ford . It was an TracLoc when I bought the Bronco rear differential complete . First thing I did was sell the 3.89 gears and Trac Loc . The Mustang crowd went nuts for the stuff . I used the dollars on other stuff that had more meaning to my build . I paid $75.00 for the complete Bronco differential and collected $350.00 for the Pumpkin . It was very cost effective for me to sell and put the funds towards other parts .
     
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  30. 427 sleeper
    Joined: Mar 8, 2017
    Posts: 444

    427 sleeper
    ALLIANCE MEMBER

    The Hilariously Crazy part is that, this WHOLE THING started out as the OP wanting to know what type of lubricant to use in his vehicle's! Squirrel answered it correctly a LONG time ago... use what the manual says!!! Plain and Simple! Although the older stuff really should have the "Whale Oil" added. JMO
     
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