As a sidebar to the gear oil question:

What is the story on these "earthing" and "4 gauge" grounding kits I see in some of your reply lines?

I followed that thread to some extent over the weekend but I'm not certain what I [or my Z] get out of it.

Point me in the right direction, this seems very interesting

 

anyone know what kind of construction the lsd is? the reason i ask is that torsen's typically take straight 75w90-type hypoid oil, while those using clutch type require a friction modifier. in the case of redline, this means going to the 75w90ns product, as opposed to the std. 75w90.

my specmiata has a torsen, and the differential action is noticeably less smooth than on the z, leading me to believe that perhaps the z's lsd is a clutch type.

ahm

 

From the shop manual, it appears that the "viscous coupling" is a sealed canister within the differential. A friction modifier is not needed, but redline recommends that you use the regular 75w90 anyway. The additive is supposed to reduce wear further; that's what they told me anyway.
mika

 

The fluid inside the viscous coupling LSD is not replaceable. It is the same as used in many of the AWD cars for center diffs. The fluid is non-Newtonian meaning it's viscousity (thickness) increases with temperature. There are interleaved plates attached to each axle. When both sets of plates rotate at the same speed there is no torque transfer. When there is slip on one wheel the plates rotate at different speeds, heating the fluid and increasing torque transfer. Very smooth but there can be a small delay before it kicks in. Torsen is more immediate and seems to be prefered for racing.

 

thanks for the explanation dr_gallup. i think most racers would prefer a clutch-type lsd, cost no object. the torsen more or less needs no maintenance, and lasts a long time. hence - its relatively cheap over its lifetime. the clutch-type all eventually wear out. the clutch-type tends to have a much smoother engagement, causing less drama in the cabin from first hand experience, the torsen is not smooth. it works, but you can feel it tugging this way and that as it engages/disengages. it seems to have minimal impact on a racecourse, but low-speed, high rate of turn corners sure are 'interesting' (autox-type). even with only 300 miles on my Z, i've felt the lsd doing its thing, and it is immeasurably smoother. lets just hope it lasts a long time

ahm

 

dr_gallup, you are corrrect, but I think what you said may be a bit misleading. There is also the housing around the viscous coupling that has replaceable fluid. As you said, this is not part of the differential, but is used for temperature management and lubrication of the external parts. As such, you dont want the stuff with the friction modifier.

As a side note, I changed mine to redline at 1200 miles, and there was a ton of shavings stuck to the magnet on the drain plug. There is no magnet on the transmission drain plug, anyone have any guess why?

 

Anyone have any thoughts (positive or negative) about AMSOil's premium gear lube??
http://www.amsoil.com/products/tgr.html

Since it meets GL-2 through GL-5, it should be fine in both the diff and manual tranny.