Vlsd Question..

[monkey_man]

well I have vlsd in my s13... and it's starting to wear off... what can i do to fix it..is there a way to replace it with a new one or something? or when if i change oil it would be a little better? need help.. let me know.. any suggestions?

[RSP13-Sideways]

I have a vlsd in my s13, it has also worn off. I am getting rid of it and installing a weld locd this week.

I will let you know how it goes.

[ultraDorksGarage]

contrary to common thought, oil breakdown actually makes vlsd engage harder,(although oil breakdown decreases shear resistance, there will be more metal to metal contact, which makes for harsher engagement) the problem is that the plates can wear which can cause permanent damage.

most people say changing diff fluid to new fluid for vlsd's will bring back life to a "burnt" lsd. also most lsd's are designed for use above 70C. like choosing the right MT lube, gear lube with too much lubricity can be a negative for vlsd's...(lubricity, shearing resistance, and weight are not the same)

[orion::S14]

contrary to common thought, oil breakdown actually makes vlsd engage harder,(although oil breakdown decreases shear resistance, there will be more metal to metal contact, which makes for harsher engagement) the problem is that the plates can wear which can cause permanent damage.

most people say changing diff fluid to new fluid for vlsd's will bring back life to a "burnt" lsd. also most lsd's are designed for use above 70C. like choosing the right MT lube, gear lube with too much lubricity can be a negative for vlsd's...(lubricity, shearing resistance, and weight are not the same)

Huh?

None of that applies to a factory VLSD...since the viscous coupler in the center section of the diff is sealed, a change of fluid cannot help or hurt it...and when it wears out, it just does not engage.

I assume you meant that in reference to a clutch-type LSD...??? If so, then BRAVO!

...

To answer your question: The only way to revive a VLSD is to replace the viscous coupler, which was $700 from a dealer last time I checked.

I'd find a low-mileage VLSD form a J30 for cheap, and swap the guts into your stock housing...or install the whole thing, if you like.

- Brian

[ultraDorksGarage]

Huh?

None of that applies to a factory VLSD...since the viscous coupler in the center section of the diff is sealed, a change of fluid cannot help or hurt it...and when it wears out, it just does not engage.

I assume you meant that in reference to a clutch-type LSD...??? If so, then BRAVO!

...

To answer your question: The only way to revive a VLSD is to replace the viscous coupler, which was $700 from a dealer last time I checked.

I'd find a low-mileage VLSD form a J30 for cheap, and swap the guts into your stock housing...or install the whole thing, if you like.

- Brian

actually i meant the factory vlsd, most normal vlsd's are not 100% sealed, they have a flow pattern from outside in, which feeds normal diff fluid into the viscous coupler. i could be wrong,(and often am), but if the factory nissan vlsd is completely sealed from outside oil, thats news to me,(although i \learn new stuff every day). if i remeber correctly nissan vlsd's have no internal gaskets, in fact i remember them having a couple holes where u could see into the (edit:) coupler. the coupler insides look so very near the internals of a clutch type vlsd, with alternating plates being splined for shaft then coupler. vlsds go into "rapid ramp" or hump mode very similar to a clutch type lsd when oil hits breakdown.

Vcoupler is not a pump, rather a "hole and slot" type coupler, which uses diff oils resistance to shear as media to "lock", not a pump like a torque converter that would need a sealed design.

as far as clutch lsd's, spring preload and clutch/cam design have more effect that fluid...

jist of what im trying to say in orig. post was that if plates in vlsd have rubbed, new oil will not help it. if not, some personall friends have said changing it helps.

btw: conventional vlsd's are the whole diff, not just one side of the spider assy(r200 style). and if the vlsd in the r200 is sealed id like to know, i dont have a vlsd sitting around but id like to know if it is totally sealed.

[orion::S14]

It's totally sealed.

Comes only as a full unit (center section), and cannot be repaired or revived.

- Brian

[95zilvia]

ARRRRRRRRRRRRR< VLSDs, SUCK!
Get an illegal garage one, so we can all know how they turn out :P

[ultraDorksGarage]

It's totally sealed.

Comes only as a full unit (center section), and cannot be repaired or revived.

- Brian


i know stock 240 one cant be rebuilt, but honestly remember seeing 2 holes at base(ring gear side of unit, not diff, but that voupler unit)

thanks for the clarification though, i was wondering why se manuls never said anything about silica based fluids, lol.