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Are factory 14 bolt posi's any good???

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Tommy, Jun 11, 2000.

  1. Tommy

    Tommy 1/2 ton status

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    Are factory 14 bolt posi\'s any good???

    Got my axles home the other day I swapped for, the guy said they were both open diff's, Little did he know the rear has a posi in it. Just wondering if they are any good, as in pulling both wheels when you need them?? Only thing I se I'm gonna have to do is move the spring perches in.
     
  2. ken

    ken 1/2 ton status

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    Re: Are factory 14 bolt posi\'s any good???

    No, not really!!

    ken
     
  3. laketex

    laketex 3/4 ton status

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    Re: Are factory 14 bolt posi\'s any good???

    probably worn out. The only other problem is if you ever want to put in a rear locker, you're going to need a 4 pinion carrier which only came in open versions. I just did this, picked up a used carrier from a guy for 60 bones. Good luck

    [​IMG][​IMG]
    Durant, Ok
    '79 Blazer in progress
     
  4. HarryH3

    HarryH3 1 ton status Author

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    Re: Are factory 14 bolt posi\'s any good???

    As far as I know, there are only 2 non-open diffs available for the 14-bolt FF's. The factory used the Eaton Gov-Lok, which uses what look like watch gears to spin a spring-loaded flyweight when the two wheels are spinning at different speeds.

    When the speed difference gets to about 100 RPM, the flyweight causes the "locker" to engage. It isn't really a locker though. If you look closely, you'll see that it just engages a set of clutches, similar to many other limited slip devices.

    The other option is the Detroit Locker. To install this, you first need to have the open, non-posi diff carrier. You remove the guts from the carrier and replace them with the Detroit (Their documentation calls it a "NoSpin", since it doesn't include the carrier, but it consists of the same parts that you'll find in the guts of a Detroit Locker for other axles. As far as I've seen, the 14-bolt FF is the only light-truck rear end that reuses the existing diff case).

    It's easy to install, if you already have an open diff. Since your axle has the Eaton in it already, you'll need to find an open diff carrier to be able to install the Detroit. This will require someone that really knows how to set up diffs properly as there is usually a few thousands of difference between any 2 carriers. [​IMG]

    As stated earlier, it's very unlikely that your Gov-Lok still functions as the clutches wear out in 50K miles or less.

    <font color=black>HarryH3 - '75 K5</font color=black>
    http://ThunderTruck.ColoradoK5.com
     
  5. Tommy

    Tommy 1/2 ton status

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    Re: Are factory 14 bolt posi\'s any good???

    So you guys are saying I'd be better off with an open than the gov-loc? I don't really need a locker, I just want the brake the 3/4 ton stuff has to offer, however I do want to be able to get out of a tight if I do go play a little. I tore into the unit, the clutches looked good, compared to what I've seen in the past. I just wondered if they did work decent enough to get out of a tight if both wheels are needed?
     
  6. HarryH3

    HarryH3 1 ton status Author

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    Re: Are factory 14 bolt posi\'s any good???

    If you're playing in mud and the keeping both tires on the ground, a Gov-Lok that's in good condition will work pretty well. If you're playing in the rocks, where one tire on the axle is getting air from time to time, it doesn't work so well. The tire in the air will spin while the one on the ground won't. Riding the brake pedal will help as it loads up the differential a bit and keeps the clutches from slipping.

    The real weak spot in the Gov-Lok is that it has to spin up to the 100 RPM difference in wheel speeds before it engages. Lots of them have exploded because of drivers that are sitting in a mud hole, rocking back and forth at full throttle. Think of this scenario, dead-stop to full throttle forward, one wheel spins up and BAM! the Gov-Lok engages with lots of engine torque coming at it. Then let off the loud pedal and drop it in reverse, floor it again, one wheel spins and BAM! there goes the Gov-Lok engaging again.

    If you're running big tires it's only a matter of time until you get one BAM! too many and the Gov-Lok is laying in pieces inside your rear end. [​IMG]

    Don't abuse it and it could last for years. If you know you're going to abuse it go ahead and install the Detroit Locker now. It'll save you money and hassle in the long run.[​IMG]

    My '91 S-Jimmy has the Gov-Lok rear end in the wimpy 7.5-inch axle. It worked well for a long time, as long as I remembered to use the gas the brake together to keep it engaging when I needed it. At 116K miles, it's pretty much useless. The clutches are apparently worn out (too many Colorado trails!) as it barely makes any difference at all these days. [​IMG]

    <font color=black>HarryH3 - '75 K5</font color=black>
    http://ThunderTruck.ColoradoK5.com
     
  7. Tommy

    Tommy 1/2 ton status

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    Re: Are factory 14 bolt posi\'s any good???

    What if you removed the spring loaded weight, would this let it grab sooner?
     
  8. HarryH3

    HarryH3 1 ton status Author

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    Re: Are factory 14 bolt posi\'s any good???

    I think that removing the weight would disable the posi funtion entirely. You might be able to play with the spring tension to make it engage earlier, but I've never heard of anyone doing this. Having it engaged all the time would wear out the clutches much faster. Most folks live with it until it dies and then replace it with a Detroit Locker. [​IMG]

    <font color=black>HarryH3 - '75 K5</font color=black>
    http://ThunderTruck.ColoradoK5.com
     

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