LSD on Sport Package

Jimc

Curious, why does everyone knock the LSD on the 370?

Thanks

Tigger

Here's a nice write-up from wiki. Read the whole thing and you'll understand why. For true enthusiasts, like us, viscous couplings suck. In a way, in a very simply put way, it is like taking a torque converter and putting it in the rear. I'll keep my open diff over the stock LSD any day. Clutch-types are for the most part the best, depending on manufacturer of course.

"The viscous type is generally simpler because it relies on hydrodynamic friction from fluids with high viscosity. Silicone-based oils are often used. Here, a cylindrical chamber of fluid filled with a stack of perforated discs rotates with the normal motion of the output shafts. The inside surface of the chamber is coupled to one of the driveshafts, and the outside coupled to the differential carrier. Half of the discs are connected to the inner, the other half to the outer, alternating inner/outer in the stack. Differential motion forces the interleaved discs to move through the fluid against each other. In some viscous couplings when speed is maintained the fluid will accumulate heat due to friction. This heat will cause the fluid to expand, and expand the coupler causing the discs to be pulled together resulting in a non-viscous plate to plate friction and a dramatic drop in speed difference. This is known as the hump phenomenon and it allows the side of the coupler to gently lock. In contrast to the mechanical type, the limiting action is much softer and more proportional to the slip, and so is easier to cope with for the average driver. New Process Gear used a viscous coupling of the Ferguson style in several of their transfer cases including those used in the AMC Eagle.
Viscous LSDs are less efficient than mechanical types, that is, they "lose" some power. In particular, any sustained load which overheats the silicone results in sudden permanent loss of the differential effect.[6] They do have the virtue of failing gracefully, reverting to semi-open differential behavior. Typically a visco-differential that has covered 60,000 miles (97,000 km) or more will be functioning largely as an open differential;[citation needed] this is a known weakness of the original Mazda MX-5 (a.k.a. Miata) sports car. The silicone oil is factory sealed in a separate chamber from the gear oil surrounding the rest of the differential. This is not serviceable; when the differential's behavior deteriorates, the VLSD center must be replaced." - wikipedia

TerribleONE

Even though it is leaps and bounds better than the open diff, it is still not a great unit.. I know on my G37 (I have a non-sport Z with a OSG LSD) I would still get the inside tire to slip while pushing it really hard, and occasionally get engagement. For the average driver though the stock VLSD is pretty good..

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Felix 808

The only way an open diff is better, is that it might be easier to swap in another unit & don't kid yourself, those super tight clutch packed units burn out too. I know when mine starts going, I'll be looking for a torsion type unit (Quaife)

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Mozen

Thats the problem i am having with my Carbonetics, constant need of rebuild. Ive had it on the car for 30k miles, id say 200 of which are track/hard use. I have had to get it reshimmed twice and now im fairly sure it needs a full rebuild. Mind you this is with me changing fluid religiously every 3k miles or After a track/race event. Install and work was done by SSA in Houston so i know it wasnt me f-in anything up.

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Chan Chee Hoe

The last service,my service centre changed the rear Diff oil,i think they used the wrong type of oil,it became an "Open Diff",just last week,i changed to "Cusco VLSD" Gear oil.....the feeling are not the same,esp power during conering..

kenchan

because most people do more car forum driving vs real world driving.

the VLSD is fine for me. works great.

SPOHN

Great till it gets hot.

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kenchan

you track your car, you should get a LSD to begin with.

Chan Chee Hoe

My daily driving about 25 km....just nice...

SPOHN

I do. OS Giken baby

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kenchan

so i still dont get your point spohn. go work on your turbo or something.

Mike

I think he is saying that for the street, the VLSD is fine.

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Tigger

Let's play the other side of the coin, shall we? I'm not trying to advocate an open diff (just because I have a base model) but for the street, even an open diff is fine because if you are driving hard enough on the street to really get any use out of a VLSD, ELSD, Clutch-type LSD or any other variant, you probably belong in jail.

If you plan on a track day here or there then sure, the VLSD will help. I planned on the OSG myself which is why I got the base model to begin with. To each their own. But for daily driving even the VLSD is nearly pointless.

kenchan

thanks for the translation, mike. .. we just kidding around.


ive not driven the open diff Z so can't say for sure, but as long as your suspension is tuned to your car and your tires, it should be able to compensate for the limitation for street use.

ive had cars in the past where open diff was very obvious and problematic when driving out of a sharp quick turn. but i was able to reduce it considerably by planting the car better using swaybars and some suspension tuning, offset changes.

that said, some folks go all out with suspension mods without considering the VLSD, VDC, ABS program. they all work with the dynamics of the car so if you do dramatic changes without much thought, it will make the car drive worse and slower...

another reason why ive not changed much of the car this time around.