350 LSD, how to tell?

[tiger]

Is there any sure-fire way that I can tell if my 350z has an LSD? It's a base model with leather seats and some other options on it.. sometimes it really acts like it has one.. is there any way I can identify from looking underneat the car?

[evildky]

if you have a base modle then it came without a LSD, someone could have added one before you I guess, just jack up the back of the car and put it in neutral with the e-brake off, now turn one wheel, if the other wheel turns backewards it's open and if they both go the same direction it might be LSD, next put the car in gear and try turning the wheel, if you can turn ne wheel with the car in gear then you got an open diff for sure

I'd assume the base model got the 4 spider R200 open diff which is better than the older 2 spider version, even in an open diff the tires try to turn at the same rate, the lsd simply adds resistance to help "lock" the 2 wheels at the same speed, when you have equal amounts of weight and traction on each side you get the same performance out of an open as a LSD it's in the turns that the LSD helps keep the inside tire loaded to prevent wheel spin

[tiger]

ok, when the weather is a little bit warmer, i'll go out and check and post my results. Thanks

[myS13wantsaVQ35]

does your car have VDC?

VDC=LSDLSD=VDC

[evildky]

unless someone opted for an aftermarket, unlikely but possible

[myS13wantsaVQ35]

true, but I just do not see that happing

[johnnyRacer]

are there any identifing marks on the diff as to which it is? letters, numbers?

[evildky]

on a clutch type diff they come with stockers taht say only to use lube with the lsd addetive, on a vlsd they can use standard fluid, do you have traction control? if not then you have a base model with an open diff

[C-Kwik]

I missed this thread teh first time around, but if you want to be more certain about havinf a VLSD or not, raise the rear end and put the car in gear (engine off of course). Then spin a tire. If it's open, it will feel fairly easy to turn. With a VLSD, there will be a good amount of resistance. Locking the driveshaft by engaging a gear will force any movement to go through the VLSD itself. Leaving it in neutral will not and will feel the same. Tere is also potentialthat if something for some reason binds slightly in the spider gears, the opposite wheel may turn in the other direction. Either way, to me, I'd rather feel the results of the VLSD myself.

[tiger]

thanks C-Kwik... my right tire is going bald faster than the left one.. I know that the right one is the one wheel wonder. haha.

[johnnyRacer]

what about if you already have the rearend out of the car and did not what model it came from? What then?

[C-Kwik]

If you're asking what model it came from, I'm not sure how. If you are asking how to tell if it's a VLSD version, simply grab an output flange in each hand and try to turn them in opposite directions. If it turns freely, then it's an open diff. If it takes quite a bit of effort, then it's a VLSD (assuming it wasn't swapped to a clutch type at some point).

[johnnyRacer]

ok I went out in the garage and when I turn one axle the other turns in the same direction. While turning one in one direction I tried forcing by hand the other axle in the opposite direction. It was difficult but it turned slowly in the opposite direction I just had to use some effort. It did not do this easily. So this thing must be a LSD

[evildky]

no, it should take 40 ftlbs or so to turn a lsd oposite directions and vith a viscous it has to have fluid in it to work properly, the old viscous r200's have a washer in the middle that keeps you from inserting equal output shafts, a CLSD wouldn't have this but rather it has clutch packs and shims inside once you crack the carrier open

just to clarify, a VLSD locks the 2 wheels using hydraulic pressure when one wheel spins faster than the other, a CSDL uses frictions disks and ships pressed together to force the 2 outputs together with a specific amount of torque required to break the contack between then, Hellical uses gear and phantim slip is just a piece of crap

[C-Kwik]

no, it should take 40 ftlbs or so to turn a lsd oposite directions and vith a viscous it has to have fluid in it to work properly,

Sorry, but that's incorrect. The gear oil does nothing for a VLSD. The VLSD itself is sealed off from the gear oil and uses a special fluid inside it that is not servicable. No gear oil has to be in the pumpkin for the VLSD to work.

JohnnyRacer: sounds like you have a VLSD.

[johnnyRacer]

Here is a series of letters/numbers off the top of the differential

KN4

3 515 061 383110C000

This is just the way these appear.

[C-Kwik]

Unfortunately, I have no idea what the numbers mean. But as I said, based on your description, it sounds like you have a VLSD.

[evildky]

the 38311 is the gear ratio, should be 38 tooth ring gear and 11 tooth pinion for a 3.46:1 ratio