viscous lsd - what's inside?
 

Has anybody cut one of the 1.6 viscous lsds open? I'm wondering what's inside, what wears, and if something can be done to improve the lock up. Something comes to mind is draining and then filling the unit with a thicker fluid.

http://www.miata.net/garage/vlsd.html

Here is a description in the second paragraph. I have not seen one cut apart.

That affirms what I've read elsewhere about other OEs, so the Miata's is the same. You would think that if the fluid is doing the lock up and the plates are only for shearing the fluid, then a higher viscosity fluid would improve the lock up. The question is, would the existing fluid actually drain out if you drilled a hole? I've got one, trying to decide to sell or hack. My hope lies on the fact that a lot of the awd cars use viscous as a center diff and upgraded viscous units are offered.

I just tore an open diff and a viscous diff apart and rebuilt one working diff. I'm not that knowledgeable in cars, so I'd have a hard time understand the question and replying... By lock up, do you mean the play between the pinion gear and the ring? These can be adjusted side to side with these little "turny discs" (as I call them :-)) to give it more or less play.

Prob makes no sense what I'm saying, maybe it helped to answer your question. :-)

Lock up - as in how much power is delivered to the wheel with traction. Best case a Miata delivers something like 15% to the wheels with traction. I did just learn that the what's in the viscous is a silicone type gel, so there will be no drilling and draining.

The play between the pinion gear and ring gear is called backlash.

btw- turns out the stuff in the viscous is very similar to silly putty. Though using silly putty in the diff, may turn the putty to a solid given it's starting state.

And liquid towards the end of it's useful life?

you could always drill 2 holes, use one as a drain and send some paint thinner through it at pressure. tap the holes, fill with whatever you wanted to upgrade to and plug them?

I have a spare VLSD if anyone wants to play.