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Rear limited slip in 98 Z71 squeeling

Discussion in 'The Garage' started by AFUFO, Mar 12, 2007.

  1. AFUFO

    AFUFO 1/2 ton status

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    We have a 1998 Chevy Extended cab Pickup, 1500, Z71 option..
    Sometimes when i get on the gas in the mud, when the limited slip engages(never fails me!) it makes the highest pitch squeeling noise iv ever heard.. Echoes a loooong ways and scares the birds to death.

    Im wondering if this is normal and nothing is wrong, or do the clutches need replacing? It only does it occasionally, and im 90% sure its when the locker kicks in.

    All stock, including axles and tires. Very similer to squeeling brakes.

    Im ALWAYS using the locker.. even by accident. In my driveway(muddy multch), offroad, occasionally onroad on wet roads or gravel.. Its got too much power for being an empty truck.. always breaking loose on me (need new tires too). Sometimes i think its a detroit because it will even lockup when turning in gravel(i dont even have to gas it much for it to be digging into the gravel). If i pull the rear diff cover can you guys ID the locker unit?

    Thanks a ton!
    Morgan
     
  2. resurrected_jimmy

    resurrected_jimmy 1/2 ton status

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    The squealing is not normal but then again neither is a gov-bomb working. Look at the RPO codes on the sticker inside your glove box. If one of the says G80 its a gov-bomb (assuming its still stock). While your looking GT4=3.73. gears, GT5=4.10 gears
     
  3. AFUFO

    AFUFO 1/2 ton status

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    Hey thanks!! its 3.73 rearend, and G80.. Its done the squeeling thing i dont know a total of about 5 times? over the past few months.

    Since its a 98 truck is it the same "gov-lock" unit as used in the 80s trucks? Whats the difference between gov lock and posi? My 88 GMC Jimmy has a posi in the rear.. has that metal I between the spider gears... That works, too.

    Anyway...anybody know what would be screeching? Clutch disc(s) i would immagine..if they are the same as the ones in my TH350(in my 88 Jimmy) i would guess the material has worn off. Its time for a rear diff fluid change anyway.


    Where did you find out the codes for this truck? My uncle had some sort of book to decode them all and i keep forgetting every single time to ask him if i could look at it.
    Do they have these codebooks for the 88 Jimmys too?
     
  4. AFUFO

    AFUFO 1/2 ton status

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  5. resurrected_jimmy

    resurrected_jimmy 1/2 ton status

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    The squealing could be the clutches or possibly something more detrimental like stripped gears. Your on the right track with opening it up and having a look. Both of your trucks should be gov-loc units. Posi-traction is a trademark name that commonly gets applied to all limited slip units, which can be misleading. There is a good thread on here I saw yesterday about gov-loc units and how they work. The thread title is something like "does anybody like their gov-bomb" It explains how the governor and flyweights work and what the weaknesses in the unit are as well as what makes them blow up.

    http://coloradok5.com/forums/showthread.php?t=131278
     
  6. AFUFO

    AFUFO 1/2 ton status

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    Just read all that.. thanks

    Also, recently (last month) while pulling out of my muddy driveway into traffic i had to get on the gas rather hard, causing the caked rearend to breakloose and go sideways on me while clearing mud(no weight over the rear axle).. it shifted out of 1st rather hard and then the speedometer went on the fritz from this(probably vibrated loose), causing the tranny not to shift out of 1st..luckily we had cold start 2nd so i was able to go get the speedomter sensor in manual 2nd gear @ 25 mph and replace it.

    Shifts fine and speedo works perfect now. But, you know the normal GM 4wd gear windup *thud*? It seems since the incident there is a VERY small second *thud* after the first thud if you get on the gas a little hard(3k rpm).. and the locker squeel seems to have first started around the same time, or maybe even before the slide.

    Hopefully when i pull the cover in a couple days i wont find any particles in the fluid or on the magnet. If so ill call my uncle and get him to inspect it. Or i may just open it up at his house so he can look with me.

    The Z71 wont be going offroad much longer. When the K5 goes on the road the only wheeling the z71 will see is the Outerbanks of NC on family trips up to a 4wd beach community. Truck has been great to us so far performing very well the couple times its been abused offroad but if i keep wheeling with it something is bound to go at some point.. Can't have that since its the daily driver.
    Oh, and yes...the muddy driveway has been fixed :p:
     
  7. AFUFO

    AFUFO 1/2 ton status

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    Checked the oil at least today.. Gear oil is fine and where it should be..

    Still waiting for uncle to find some free time to look at it with me

    Its driving and wheeling fine cept for that noise.. I think the squeeling is the clutches slipping..i noticed it more on dryer mud..all the weight of the mud+tires and the clutches arnt catching i dont think. if they are the same as the tranny clutches the material is probably gone and the clutches burnt.

    Ill have to ask my uncle about checking the clutch condition too..
     

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