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Limited Slip ...

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Innerpiece, Mar 20, 2001.

  1. Innerpiece

    Innerpiece 1/2 ton status

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    I was reading through my Options Codes in the glove box, and it turns out I have a limited slip rear end (who woulda thunk it the way the tires were spinning when I got stuck in the mud not too long ago). I know I have a corporate 10 bolt, so what do I need to know about the limited slip? Special gear oil? Are there any parts that will wear out? how can I check that it's working correctly (other than submerging myself in the mud). Would the front be the same (also corp 10 bolt I think). I've got an 87 silverado blazer, 305, np 208, 32x11.5x16. Thanks

    <P ID="edit"><FONT SIZE=-1>Edited by innerpiece on 03/20/01 11:43 AM (server time).</FONT></P>
     
  2. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    I'm not by any means a LS expert but think that should be a gov-lock which is a clutch type and requires a special friction additive. Also, you have obviously experienced the problem with LS diffs, they do now work well (or at all) if one tire looses traction completely. They work on a principle which requires at least some resistance on each side to force the clutches together. When one wheel breaks completely loose, no torque across the diff and, as a result, no pressure on the clutches. You can often force it to engage by simply tapping the brake for a second. It is also sometimes necessary to maintain some slight pressure on the brake to keep it engaged depending on the condition and type of LS diff. If the LS is worn out, you won't be able to get it to work at all...

    Bad Dog

    85 K30 CUCV, 350 TBI, TH400, NP205, D60/C14, 4.56
    Coming soon: 4" lift, 40" tires, massive cutting, shorter wb and rear overhang.
     
  3. dyeager535

    dyeager535 1 ton status Premium Member

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    Actually limited slip (true limited slip, G80 in the trucks is not true limited slip) is locked together by spring pressure that is OVERCOME when traction exceeds a certain amount on one axle. So turning a corner, limited slip is "locked together" via the srping, and the clutches allow slippage because one wheel is turning slower than the other. With one tire off the ground, unless traction is extremely good on the one tire that has traction, both tire will turn anyways.

    The gov lok is not this way, it acts as an open until a certain RPM is reached before it "locks". Failing, it will stay locked up in corners, or never lock up

    Dorian
    My K5 and Chev/Olds tech/links page: <A target="_blank" HREF=http://www.dorianyeager.com/index2.html>http://www.dorianyeager.com/index2.html</A>
     
  4. Innerpiece

    Innerpiece 1/2 ton status

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    So is there any easy way to test and see if it's working? Would the front end have this too? If I do get bored and pull the diff cover off, what should i look for as far as wear, type, etc?
     
  5. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Ok, sorry, looks like I was flat out wrong on this one. Normally I try to just keep my mouth shut about things I don't know first hand and I should have followed that rule here. I have a pretty good handle on how the lockers work because I have used them and I’m interested in them. I don’t use the LS because my terrain of choice is “on the rocks”. What I know about LS diffs is just stuff I’ve ”picked up” over the years which (as now) often does not lead to a correct understanding. One thing I should have done though is not try to lump them all into one rather vague and lame description. There are lots of different kinds including some that work similar to the way I described. Now that Dorian mentioned it, I also remember hearing about the gov-lok (guess that is why they call it a “gov”-lok) using the weight.

    Oh well, I apologize for jumping in where I didn’t have the goods. Good luck…



    Bad Dog

    85 K30 CUCV, 350 TBI, TH400, NP205, D60/C14, 4.56
    Coming soon: 4" lift, 40" tires, massive cutting, shorter wb and rear overhang.
     
  6. dyeager535

    dyeager535 1 ton status Premium Member

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    I don't think there is an easy way with the Gov-Lok. With my friends S-10 w/Gov-Lok, and smaller tires, I could jack the rear end up off the ground, and spin one tire HARD by hand, and feel the thing lock up. With larger, heavier tires, you may not be able to get the rotation up fast enough to feel it lock...You could jack up the rear end, and spin a tire by hand. If its working correctly, the rear wheels will spin in opposite directions. If it has failed in the locked position, (or someone has swapped it out for a true posi/limited slip unit) it will spin both tires the same direction. If they spin in opposite directions, I would definitely change the diff lube and put the limited slip additive in. And since you have to pull the cover to drain the fluid, I would do this and inspect the internals anyway.

    Look for chunks of metal, not just shiny fluid..wear is gonna happen, flakes of metal are normal, chunks are not. I don't think there is much else to look at, you can inspect the ring gear for chipped teeth also, but if its not making noise when driving, they are probably alright, whether they are chipped or not.

    Front end will not have this unit in it, unless someone added it. You would probably already have broken things like front u-joints etc if it did.


    Dorian
    My K5 and Chev/Olds tech/links page: <A target="_blank" HREF=http://www.dorianyeager.com/index2.html>http://www.dorianyeager.com/index2.html</A>
     
  7. dyeager535

    dyeager535 1 ton status Premium Member

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    Don't worry, I wasn't busting your chops :) No one will ever know everything about these trucks..


    Dorian
    My K5 and Chev/Olds tech/links page: <A target="_blank" HREF=http://www.dorianyeager.com/index2.html>http://www.dorianyeager.com/index2.html</A>
     
  8. Innerpiece

    Innerpiece 1/2 ton status

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    Regarding the special additive for limited slip diff's ... does that stuff just work to quiet the gears, or do I run the risk of hurting something by not having it in there? How can I tell when the diff is going bad (other than noise)?
     
  9. 6.2Blazer

    6.2Blazer 1/2 ton status

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    All of the official literature I have seen, such as GM factory service manuals, say that the Gov-Lock does NOT need any special additive....just plain gear oil.
     
  10. dyeager535

    dyeager535 1 ton status Premium Member

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    Its not to quiet the gears. Its for the clutches. Gov-loks use clutches, hence I can't see why you WOULDN'T need it. I doubt it will hurt anything.

    To the guy posting that you've read/seen/heard that the Gov-Lok does NOT need it, is it specifically stated? I am curious, as I have never officially seen it written one way or the other, but I used it "just in case"

    Dorian
    My K5 and Chev/Olds tech/links page: <A target="_blank" HREF=http://www.dorianyeager.com/index2.html>http://www.dorianyeager.com/index2.html</A>
     

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