Is This Normal For An Lsd?

[Eug]

my 33 came with the factory lsd as standard.

now this 'problem' has happened to me twice in the time i've owned it (read: 3 years) so i doubt it'll be a common issue.

anyway first time it happened i was reversing up my driveway. it is relatively steep (about a good 30-45º). anyway while reversing i reached a point where the weight of the car was pulling the car down much more than the rear tyres could get traction of. i was pretty much riding the clutch out, and only the rear right tyre would slowly rotate on the spot and eventually the car would gradually slide down hill. i ended up getting my other car tow hooked it and pretty much had my brother assist tow me up the driveway.

second time happened today, we are building a new carport and one section of our front yard is now just dirt. the incline isnt as steep as the driveway (about a 10-20º incline) . and this time while reversing only the rear left tyre was slowly rotating in the dirt. i had to throw a solid plank of wood under to get back onto the driveway.

now i know the problem lies partly with my tyre:surface traction and camber. i am running yokohama c.drive (nice, not cheap and quite grippy tyres) and -1.5º camber at the rear. i think the camber is the issue here.

BUT, what i'm getting at is if it is normal for an LSD to rotate one wheel when in reverse at low speeds?

does it only engage when going forward? does it need a fair bit of speed to engage?

cheers

eug

[MANWHORE]

Yeah, that's pretty standard for a typically worn viscous lsd. What about if you give it more juice? the wheel that is already spinning will spin more, but does it make the other wheel actually turn and move the car?

[Eug]

more stick just fries that one tyre even more, and no the other wheel just stays still and the car wont move.

will a newer viscous lsd spin both wheels in reverse? i was under the impression (from a friend) that an lsd wouldnt engage under reverse load.

under forward load, both rear wheels spin - so no problems there.

just seems to be in reverse. obviously its not something i encounter day in day out - so its not a hassle, but is this a sign that my diff is on its way out?

[MANWHORE]

Oh, I didn't read it carefully enough. I don't know about the lsds in the reverse situation.

Does the same thing happen if you're trying to go up a wonky driveway forward and one wheel almost lifts off the ground? like do you get beached?

My friend's skyline with the viscous lsd will get beached when going forward because of the worn lsd. He has to just reverse back and take a different angle.

[Eug]

yip, i'm primarily asking about in a reversing situation.

when the car is balancing on two wheels (see-sawing) on a driveway it normally just teeters there until the rear wheel touches the ground and it gets some more forward thrust.

i thought that the "beaching" was normal, since there is no actual load on the air borne wheel? and that the only case both wheels would spin 100% of the time is with a locker.

[Kinks]

Beaching is only normal for single spinners and torsen LSDs. Open diffs effectively send all torque to the wheel with the least grip. Torsens act as a torque multiplier so if you have zero grip on one wheel you'll actually spin it up - if however you put your foot on the brake slightly the LSD will function.

Viscous LSDs (standard in skylines) act based on speed differential - ie the faster one wheel is spinning the more torque will be applied to the other. Clutch type LSDs do the same thing but in a more effective way.

My (healthy) VLSD will never beach, but I frequently spin wheels slightly getting up our steep and curvy driveway. However, even though one wheel is spinning the other is still pulling me up the driveway - if I put my foot down harder it'll still launch itself.

[MANWHORE]

Kinks, that is exactly what i was thinking.

But, the thing I wasn't sure about, is how eug was asking about reverse. That is, whether the lsd works the same way in reverse. I'm not sure about that.

[Beer Baron]

it should function the same in reverse as it does going forward.

[Thunderbolt]

I can confirm that diffs do work the same in reverse. Got into a situation in my Pulsar where I had to reverse off some wet grass / mud. One tyre kept spinning and the other dragged me out. I know you can't really compare it to rwd, but the basic concept is the same.

[gun32gtr]

so this is typical with cars with stiff suspension yeh.. i just gerk clutch abit and it shoots forward and is no longer beached...

[MANWHORE]

does a pulsar even have an lsd? I thought fwd cars were just open wheelers?

I can confirm that diffs do work the same in reverse. Got into a situation in my Pulsar where I had to reverse off some wet grass / mud. One tyre kept spinning and the other dragged me out. I know you can't really compare it to rwd, but the basic concept is the same.

[MANWHORE]

Gun, it's a bit different for you, because you have a gaytR. Even if both of your back wheels were off the ground (dunno how that'd happen, but anyways), you still wouldn't be beached. Torque would just kick in at the front.

I think they're more talking about beaching of rwd cars with stiff suspensions.

so this is typical with cars with stiff suspension yeh.. i just gerk clutch abit and it shoots forward and is no longer beached...

[gun32gtr]

Gun, it's a bit different for you, because you have a gaytR. Even if both of your back wheels were off the ground (dunno how that'd happen, but anyways), you still wouldn't be beached. Torque would just kick in at the front.

I think they're more talking about beaching of rwd cars with stiff suspensions.

i gather its gaytr cause u dont have one yeh????

and yeh ur right as front talk kicks it pull it off....

[MANWHORE]

I was only joking about the gaytr bit. i used to call the one we had a gaytr.

But yeah, that's the difference i noticed between the gtr and the gts. I've put the gtr into a mega beach before, so much so that you'd think it was stuck, and it still managed to move.

with the gts, in a similar situation, there'd be a fair bit of wheelspin.

[adikt]

i was wondering about this a bit as well.

33 gtst, one wheel spins a bit when it lifts mostly off the ground going into my driveway.

altho the other still pulls me along fine, and more gas will still send me forward fine.

it seems to be a pretty common problem.

[Kinks]

But, the thing I wasn't sure about, is how eug was asking about reverse. That is, whether the lsd works the same way in reverse. I'm not sure about that.

Some diffs do only act in one direction - they are called "1-way LSDs". You can also get 2-way which act on accel and decel (decel is the same force as reverse). Also there's 1.5 way which has a harder LSD action on accel and mild LSD action on decel.

the standard viscous LSD is basically a bunch of plates sandwiched together, half connected to one axle half connected to the other, and filled with sticky goo. So it doesn't care which way the wheels are spinning, but because the LSD action is provided by a liquid it'll never bite as hard as a mechanical diff.

[GreddyGo]

Ok so what can be done with people that have worn viscous LSD's,

is replacing them with a new VLSD or a mechanical one the only option?

I would have thought you would ba able to shim them up a little to make them tighter?

Cheers

Josh

[Kinks]

no, you can't shim a viscous diff.

[Simon-S14]

oh yes you can

[Eug]

what kinda costs are we looking at re-shiming? is the effort of taking the diff out and bring it somewhere worth it?

or should i be looking into aftermarket 1 or 1.5 ways? (kaaz diffs are ~$1050 delivered)