Left Rear Locked, Not the Brakes

Discussion in 'Got gears?' started by knucklebusted, May 28, 2022.

  1. knucklebusted

    knucklebusted Well-Known Member

    The issue is with the rear off the ground, both tires in the air and the trans in neutral, the left rear tire is locked but there is the hint of motion when you try to move it, like the trans is in park. It isn't the brakes.

    The right rear wheel will turn against the posi and spin the drive shaft with some resistance but not the left. Once you turn the right wheel, it will usually free up the left one.

    With the tires on the ground, it acts like a trans brake but if you can get it to roll one way or the other, it will free up the left rear and you can move it again.

    We are going to get it on the lift and see what is going on inside the diff on Monday, but I was hoping to get some ideas of what to look for before then.

    I've never seen anything like it. Is a C-clip dropping? Is the center pin falling out? Spider gears broken?
     
    Dano likes this.
  2. FLGS400

    FLGS400 Gold Level Contributor

    My first thought was a bad spider gear in the diff...
     
    knucklebusted likes this.
  3. 12lives

    12lives Control the controllable, let the rest go

    "Is a C-clip dropping?" - what rear is it? Buicks don't use C clips.
     
    knucklebusted likes this.
  4. knucklebusted

    knucklebusted Well-Known Member

    If not a spider gear, definitely something associated with that one axle. My biggest fear is if we get it up on my lift, will it be stranded there once we determine the issue? My Stage 1 lives in the lift bay with no other place to park it inside.

    If it is a side gear, can you replace just that or is it like it ruined the case and/or other spider gears? It has never had slicks on it and, being a truck, it has never had great traction to do any real damage.

    It is in a 93 Chevy 1500 truck 8.5. It was a brand new Powertrax posi he got off ebay. I think it was actually the 8.6 posi with the right type of spider gears for his axles and the hybrid side bearings. I helped him install it and it is quiet with no leaks. It started doing this out of the blue.

    This picture is when we put it together back in May 24, 2017. Hmm, just over 5 years ago.
    [​IMG]
     
  5. BrianTrick

    BrianTrick Brian Trick

    Is that one of those eBay Monkey posis? There are a lot of those showing back up on eBay,broken.
     
    knucklebusted likes this.
  6. knucklebusted

    knucklebusted Well-Known Member

    Don't know. He just told me it was a PowerTrax. Never heard of them but it was cheap. Maybe he will find out why it was so cheap.
     
  7. TrunkMonkey

    TrunkMonkey Well-Known Member

    Made in China.
     
    knucklebusted and 1973gs like this.
  8. 1973gs

    1973gs Well-Known Member

    A few years ago, one of the guys at work purchased an Aeromotive fuel pump on eBay. It failed and when he sent it to Aeromotive for warranty, they said that it wasn't their pump. It was a Chinese knock off. Sometime after that, I believe it was in Hot Rod magazine, there was an article about all of the fake Chinese knock off parts that were being sold online. The example that they showed was an Aeromotive fuel pump. That's why many manufactures won't even accept a return warranty part unless it was purchased from a well known source.
     
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  9. 12lives

    12lives Control the controllable, let the rest go

    Very true - got the same story from ARP about parts sold on Amazon.
     
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  10. monzaz

    monzaz Jim

    rear is a 8.5 you have to spin that case another 90 degrees so we can see the guts. Jim
     
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  11. 1973gs

    1973gs Well-Known Member

    The reason that I buy ARP bolt is for the quality. Imagine ordering ARP bolts and getting generic Chinese crap! The original rusty, worn bolts are probably better than garbage Chinese bolts.
     
    Mark Demko and 70skylark350 like this.
  12. knucklebusted

    knucklebusted Well-Known Member

    That was from the install picture over 5 years ago. He said it was too hot today so he didn't come over to get it on the lift.

    I'm going to steer him toward a TrueTrac if this one is blown. I've loved mine that you built. No issues and quiet.
     
    FLGS400 and TrunkMonkey like this.
  13. PGSS

    PGSS Gold Level Contributor

    Having to worry if something is going to grenade on your car is insane by buying potential china crap. Might as well park it.:eek:
    Maby a metallurgist can make some money on the side testing suspect parts:D:D

    There has to be a way to test at least some so called ARP bolts with torque wrench and socket and vise. Scratch test maby to test the grade level?
    Also does cheap steel pop and sputter when its welded?
     
    Last edited: Jun 1, 2022
  14. 12lives

    12lives Control the controllable, let the rest go

    Sorry to divert the discussion to ARP. Just buy from a reputable dealer!
     
    PGSS likes this.
  15. monzaz

    monzaz Jim

    It is possible the clutches fused together but that usually only happens on extreme driving or one wheel in the water one not deal...etc. :)

    Jim
     
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  16. knucklebusted

    knucklebusted Well-Known Member

    I'm trying to understand. In a straight ahead situation, the clutches do nothing as the spider gears don't turn, correct? They only come into play when wheel speed is unequal.

    With the truck on jack stands, the transmission in neutral, turning one wheel turns the driveshaft while the locked wheels stays motionless. In that situation the spider gears are moving but how could the one side still be locked?

    If the clutches were fused, turning the locked wheel should cause the driveshaft to rotate and the other wheel to move, right?
     
    Dano likes this.
  17. monzaz

    monzaz Jim

    The carrier unit (that has the ring gear on it) is spinning and your one side gear is stationary and the other wheel can spin as the pinion gears spin over the other side gear that is NOT moving BUT DO spin with the CASE and the case will spin the drive shaft.
    Hope you under stand.
    AND if this is doing this...Your Posi unit is NOT working correctly.... :( Jim
     

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