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Posi front and rear differentials

Discussion in 'Chevy Trucks' started by Northman, Feb 3, 2009.

  1. Northman

    Northman Senior Member
    from Ohio
    Messages: 201

    Just wondering how many of you guys have posi front and rear differentials on your plow trucks?

    I know I am getting sick and tired of my open differentials on my truck K1500 and getting hung up in my lane 700' in the bigger drifts etc and even my other 2 winter vehicles with their open differentials.

    Why in the world dont they add the $100 per unit installed at the factory to the cost for a front and rear posi for 4x4's $200 total. Just seems to make since to me.

    I know my next plow truck I will look hard for posi in both ends.
     
  2. Mark13

    Mark13 PlowSite Fanatic
    Messages: 5,734

    What year truck are you plowing with?

    GM posi's in the 1/2ton 10bolt axles have a bad rap, I've seen several that blow up wrecking the whole differential just because someone slid a corner or got a heavy foot. They seem to be much better in the 3/4 and 1 ton,s but still not perfect.

    And I wouldn't posi an 88+ 1/2ton 8.25" front differential. I can't see it lasting to long. Some of the dmax pullers put them in their trucks (9.25" front diff) but most arn't daily drivers, they are made for 1320ft or 300-350ft at a time under power.

    If you want to posi your 1/2ton I'd go with a detroit tru trac and if you can., find a 14 bolt semi floater out of a f44 package equipt 1/2ton or 2500ld truck, then it will have 6 lugs.
     
  3. aeronutt

    aeronutt Senior Member
    Messages: 262

    Be careful of naming conventions with "posi" axles. Detroit Tru-Trac is not a "posi", it's a locker. Posi generally refers to a friction biased limited slip system that is prone to wearing out clutches and reverting to normal "open" operation after a while. They also don't help much when one tire is extremely low on traction because they need torque feedback to work. Lockers don't have these problems, but they tend to be clunky and noisier. GM late model axles with traction assistance are almost exclusively lockers, not posi and they are electronically engaged to avoid the ratcheting, clunking problems of fully mechanical lockers.

    The 8.25 front IFS axles have no aftermarket posi or locker upgrades available that I'm aware of. The 3/4 & 1-ton 9.25 IFS is a whole different story.

    Rear 10-bolt 8.5 axles have some aftermarket support and you basically get what you pay for. They aren't automatically junk, but they will break faster than the 3/4 ton axles if you flog them.

    See http://www.ringpinion.com for some ideas of what's available.
     
  4. Mark13

    Mark13 PlowSite Fanatic
    Messages: 5,734

    I thought the tru trac was a gear driven posi traction?


    Or if you want to be fancy about it. get a 14bolt semi floating axle with 6 lugs, and put an electronic locker out of an h2 in it.
     
  5. flakesmeangreen

    flakesmeangreen Senior Member
    Messages: 217

    I'd like to know too. Was just thinking about this the other day.

    My old truck had open, new truck has posi rear and what a difference. Posi front and rear would be great. Do any make/models offer a front posi as an option? Besides the like of a Jeep Rubicon or a Power Wagon, or do they have lockers? But either way, who offers anything in the front as an option?.[/QUOTE]
     
  6. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    It is Mark. I believe aeronutt is thinking of a Detroit LOCKER...not the gear biasing Tru-Trac. Two different units....
     
  7. Northman

    Northman Senior Member
    from Ohio
    Messages: 201

    I would like to know too.

    I am leaving the 89 K1500 alone. Not worth sinking money into, even though the 88 motor in it now only has 38K, Body 160K.

    So the newer half tons dont have the posi or locker traction control options either?

    Learning the new stuff, so bare with me.

    I am more interested in the GM trucks myself.
    So I am looking at 3/4 tons to get the traction I am looking for then. Can you still check these new systems out the way you would the old posi systems to see if a rear or front was posi? How would you know on a used truck now days and check it out to make sure it had traction control etc for plowing.

    When the newer trucks are listed snow prep package, is that a indicator it might have the traction control fronts and rears?

    Thanks for the info.
     
  8. aeronutt

    aeronutt Senior Member
    Messages: 262

    As far as I know, the only front axles that got traction devices from the factory are Jeep Rubicons and Dodge PowerWagons. There may be others, but I'm reasonably certain they were not made by General Motors. In the GM realm, it's fairly easy to upgrade the axles with aftermarket devices, but it costs several hundred dollars! You need to either get an old 1/2 ton that had a solid front axle or go with a 3/4 ton (possibly a heavy half? 1500HD?) that has a 9.25" front IFS if you want both axles to have a posi/locker due to lack of aftermarket support for 8.25" IFS.

    The build code to look for on later model trucks for the factory locker is "G80". This will be one of the codes printed on the sticker in the glovebox. Here's a video that shows what the G80 does for you: http://www.youtube.com/watch?v=rGlacQlBGcQ&NR=1
     
  9. Mark13

    Mark13 PlowSite Fanatic
    Messages: 5,734

    And this is what happens if you have a 1/2ton with a g80 that you abuse:
    [​IMG]

    One of the kids in my autoshop class blew the rear diff in his 96 yukon equipt with a g80 by going around a corner and getting a little throttle happy. The whole "truck" was stock, all the way down to the 245 all season tires that were 98% bald.
     
    Last edited: Feb 4, 2009
  10. aeronutt

    aeronutt Senior Member
    Messages: 262

    Awsome carnage pic Mark! That's a confirmation of my previous post that 1/2 ton stuff tends to break when you flog it. You also make the case to stick with 3/4 ton stuff when doing heavy duty work. The G80 in my AAM1150 axle works very smooth and lays rubber with one tire while the other is on glaze ice. I might add an Eaton E-Locker to my front IFS someday, but I've never been stuck with what I have now so why spend the money? A good set of Blizzak W965 tires makes more difference in the snow and ice than a locker under most normal conditions. Having both would be sweet!
     
  11. Mark13

    Mark13 PlowSite Fanatic
    Messages: 5,734

    It seems that any gm with the 10.5" 14 bolt full floating axle or the AAM 11.5 are fine if they have the g80 rpo code. I believe the posi traction units in the 1/2ton axles are the only ones suspect to randomly blowing pretty much whenever they feel like it. Some don't last long and break easily, others seem to go forever and endure major abuse. They seem to be quite hit or miss.
     
  12. IMAGE

    IMAGE Sponsor
    Messages: 1,741

    I have an Aurburn limited slip NIB for a 30 spine 10 bolt gm rear. If anyones interested PM me.

    It's probally the best limited slip you can get. And its much safer for many reasons then a locker in a C clip rear end. Lockers like to break axles, axles will slide out and roll down the road with the tire on head on into traffic, while your on 3 wheels and a backing plate. Not really fun. Limited Slips are much less likely to break an axle. Lockers also like to put you in the ditch when they lock up on icey corners. Again, Limited Slip is the way to go for anything other than a dedicated Off Road vehicle.
     
  13. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    28 or 30 spline Steve?
     
  14. IMAGE

    IMAGE Sponsor
    Messages: 1,741

    30 spline. I actually have 2 of them. New in the box.

    I have a detroit locker for a 14 bolt also. I'd have to pull it though. Used 1 summer in a mud truck. I think it was a 9.5" if I remember right.
     
    Last edited: Feb 5, 2009
  15. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    PM me a price...
     
  16. IMAGE

    IMAGE Sponsor
    Messages: 1,741

    pm sent

    and my message is to short...
     
  17. KentuckyPlow

    KentuckyPlow Member
    Messages: 64



    You wouldn't want a posi in the front unless it was an e-locker or something selectable like that. You would never be able to steer the truck. It would be fine for a long straight road, but that's it.
     
  18. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    How many LS diffs have you run in the front of a truck?

    Limited slips aren't that tight that they grossly effect turning capability.

    Just one of the many examples... I ran a clutch type LS in the front of my own truck for 12 years. Not once did it prevent me from turning, their just not tight enough.

    Now a spool is another matter entirely. ;)
     
  19. Northman

    Northman Senior Member
    from Ohio
    Messages: 201

    Thanks guys I am learning the differences etc.

    Also Thanks on the reminder on the G80. My 87 IROC had that when I bought it new and was a $100 option back then.