Why should we change the VLSD fluid?
 

The actual locking mechanism of the VLSD is a fluid sealed inside (and can only be accessed when taken apart), which gets hot very quickly and stops working after about 10 minutes of drifting in my experience. At that point, it acts like an open-diff and needs some time to cool off. It is said that changing the fluid out of the pumpkin would not effect the locking efficiency of the VLSD. I found this to be true in my experience, as well, when i changed the OEM fluid around 15k miles to Redline. No difference.
So to sum it up, if changing the diff fluid makes no difference in performance, why are we doing it at all in the first place?

yah, why bother changing motor oil, tranny oil, blinker oil, etc.

I disagree with you, Mr. KenInfiniteWisdomChan.

I change my blinker oil every 3 months. It's false economy not to do so. Engine, Trans, etc. -- I do not bother.

I had the diff start to bind up with the oem diff fluid after hard track session. Once I put in Redline it never happened again. The diff would still slip more and more throughout a session but at least it didn't bind. Even thought the VLSD is sealed the diff fluid must help in the cooling.

Redline is the way to go. :tup:

:iagree: Also your blinker fluid is definitely the most important maintenance item on your car

Truth.

If cooling of the VLSD were the only function of the diff fluid then, yeah, it wouldn't make much sense to change it often. Since the diff fluid's main function is to lube the gears and all fluids break down (much faster at higher temps), it's a good idea to change it out every now and then. If you are getting the VLSD/diff that hot on a regular basis, it would be a good idea to change the diff fluid quite often.

A cooler might be a good idea.

:tup: okay, i should change my blinker oil more often. thanks!!

I am here to help.

You should skip changing your engine oil as well.

We have already established that... :tup:

It's to ensure functionality, removing the oil ensures that those small shavings don't collect. Upgrading the fluid is just to have peace of mind and longevitity of the pumpkin's use. Otherwise, if you actually do drifting, you are better off with a real LSD. Any 1.5 is WAY better than our stock ones. And, 1.5 is not enough, you'll need an oil diff cooler if your taking drifting seriously. :tiphat: It's like your saying, why clean the toilet if your just gonna sh*t back on it later. lol

engine oil is overrated....just use crisco

I wait until my blinker fluid runs dry. Then refill it. That way, I know that I have fresh fluid through out the blinker system. :tup:

I'm confused as to the purpose of what the OP is asking - I guess the question is more like "what is the reason people change diff fluid?" Rather than if it solely helps VLSD performance.

My testing shows on the highway at 80 mph in the winter for an hour or so my diff fluid reaches 194*. On the track in summer I'm sure it will exceed 300*. I'm hoping my diff cooler will keep the fluid under 250* and allow the VLSD to do its job.

That's the magnets job.

:iagree:

OP does have a point. considering the fluid inside the diff that makes the diff "lock" is sealed we dont have to change it often. i think the reason you should change it is after extended hard driving. oils break down and lose their effectiveness, and thats the reason i change mine out every so often

Thank you.
So basically the diff fluid we put in is just to help cool the vlsd. And as time goes by, the fluid loses it's viscosity and isn't cooling as efficiently, thereby causing the vlsd to overheat quicker and work as an open diff.

It's gear lube. Its in there to lube the gears. If it helps keep the vlsd alive longer that's a bonus.

To the ones who left sarcastic remarks, do you even understand how a VLSD works, or how it differs from other LSD's? My thread was to clarify part of the function and maintenance. I don't believe in blindly following a guide without thoroughly understanding why I should do it at all.

wat?

Thanks for clarifying

I was about to comment, then it occurred to me that I wasn't sure which parts were directly affected by changing the dif oil either...


Here's an exploded view of the 370Z dif

http://img27.imageshack.us/img27/5730/img1xwi.jpg

Which parts are sealed and non-serviceable vs not?

Outer gears are affected by fluid change, whereas inner locking mechanisms are not?

Is that correct?

Ok, looking at that diagram. Part# 38760 is inside the carrier. That would be the VLSD unit that is sealed with silicone fluid. Your gear lube would be seperate from that. The bearings inside the housing is pinion bearing part#38120, and part#38140. 2 carrier bearings, left side and right side, part#38440. Those are lubed with your gear lube.

To clarify - the VLSD uses seperate fluid, that is sealed within the LSD themselves. There is no servicing possible on this device. The diff fluid lubricates the gearing. The VLSD has it's own silicone fluid to act as the coupling.

^^^ Awesome -- thanks for clarifying, guys! Repped :tup:

:tup:

38760 Is the sealed VLSD Unit by the look and shape of it.

http://us1.webpublications.com.au/st...108266_7mg.jpg

uh......that's what I said in my post. ;)

:bowrofl:

Well it's not like people read replies or even use search on this forum.

In summary, the rear differential gears are lubed and serviceable, and should follow an OCI of some sort (30K for street use? 10-15k for track?), but the VLSD mechanism itself is a sealed unit within the pumpkin that is non-serviceable.

Fixed it. ;)

Blinker Fluid?.
 

Well, I guess I'm showing my ignorance, but what the "bl___k" is blinker fluid?

:tup:

If you have to ask...

That's hilarious :bowrofl:

But... booooooooooooo :icon17:

http://kalecoauto.com/index.php?main...tqfn6fh6a2sbu1