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Shim your VLSD?

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  • Shim your VLSD?

    I didn't think this was possible with a viscous unit. I thought it had to be replaced. Are the thicker shims to bring the gap into spec as the VLSD wears out?
    Addicted to Motorsports

  • #2
    It is the same as replacing clutches in a clutch diff. Things wear out and they have to make it serviceable otherwise it would be a really bad design. That being said, they said you COULD add 2 extra shims in there but you may have to weld the whole unit back together. I'd just buy 2 new ones and take out the old one, so you have 2 fresh ones, it should lock better that way.

    Or don't waste time with it and buy a new VLSD, haha.


    • #3
      ah hahaha. What they're doing is F-ing up the meshing of the spider gears, making them a lot tighter. Now they can't really spin freely without rubbing together really hard. Being that the only time they spin is when one is going faster than the other, you've basically increased the locking power of the diff. I'll bet you could fill up the diff with metal shavings with one grip trackday.

      Changing the plates in a clutch diff is different. Those plates are designed to wear, and adding/subtracting plates is usually compensated for by a spring plate.
      She's built like a Steakhouse, but she handles like a Bistro.


      • #4
        Yea - not the smartest idea I've ever seen.

        For the price people are paying to have this done you can almost buy an S15 HLSD.
        '18 Chevrolet Volt - Electric fun hatch for DD duty!

        DefSport Koni Sleeve and Spring Perch Buy!!!


        • #5
          All they're doing is binding up the spider gears. The VLSD is a completely encapsulated item that's not adjustable or rebuildable.

          You can scr*w with it a little however ;-)
          I took one and drilled out the original fill and vent holes. The OEM method is a countersunk hole with a ball bearing dropped in and staked into place to plug the holes (that means you need a carbide burr). I tapped the holes 1/8" NPT and attached some fittings so I could flush out the old fluid. I then filled it with Prothane Supergrease, which is a silicone based grease, then plugged the holes. It made for a significantly tighter VLSD, but when it gets real hot it turns into a spool!. The theory is that when the plates get hot enough and expand, they get wavy and bind up against each other.
          Don Johnson (really!)
          Just so you know.