LSD question

[alex_77]

how to diffend 1 way, 1.5 way n 2 way lsd ???

have some sifu can help me here?

 

[Zeroed]

1way: Limited slip effect only during acceleration
1.5way: effect during acceleration, partially during deceleration
2way: full effect on both acceleration and deceleration

Im no sifu, just sharing what I have learned...

 

[alex_77]

thx bro,,,
then how to diffren when it alreadly put it in the car d??
i had hear some of my fren said that
1 way-when u turn 1 side of the rim by 1 round then another 1 move with same way.
1.5 way-when u turn 1 side of the rim by 1/2 round then another 1 move with same also
2 way-when u turn 1 side of the rim another will move together n didnt have free space.
ittz it true??

 

[si|verfish]

thx bro,,,
then how to diffren when it alreadly put it in the car d??
i had hear some of my fren said that
1 way-when u turn 1 side of the rim by 1 round then another 1 move with same way.
1.5 way-when u turn 1 side of the rim by 1/2 round then another 1 move with same also
2 way-when u turn 1 side of the rim another will move together n didnt have free space.
ittz it true??

???

About Differentials: http://en.wikipedia.org/wiki/Differential_%28mechanics%29
About Limited Slip Differentials: http://en.wikipedia.org/wiki/Limited_slip_differential

All cars have differentials. That's because when you are turning/cornering, the wheel on the outside (relative to the corner) need to travel further than the inside wheel. If they both rotate at similar speeds, the inner wheel will just spin around uselessly. Therefore, diffs allow them to move at different speeds. I still don't understand how the mechanism works though.

The problem with a normal diff is that if one wheel loses grip, more or all torque will go to that wheel and none to the wheel with grip. So you end up with a wheel spinning uselessly and not moving.

Limited Slip Differentials solve this by moving the torque transfer away from the spinning wheel to the wheel that actually has grip. Therefore you maintain traction and propulsion.

 

[Zeroed]

Well LSDs dont only work during wheelspins... even when youre making a turn at 10km/h, it tries to stop the outside wheel from spinning faster than the inside thus causing stiff steering.

I dont know how to test 1.5 or 2 way LSDs (maybe slowdown a spinning wheel?) , but the 1-way one is correct.

 

[si|verfish]

Well LSDs dont only work during wheelspins... even when youre making a turn at 10km/h, it tries to stop the outside wheel from spinning faster than the inside thus causing stiff steering.

That's not right? Is it?

That goes against the whole idea of having a differential (the outer wheel needing to travel faster because it travels further). And if it goes against the idea of having a differential in the first place, then there wouldn't be a need for a limited slip differential.

 

[Zeroed]

It does work that way as far as I know. A differential is there for both tyres to propel independantly depending on steering angle, but when power overcomes one tyre's grip the differential may transfer too much power to the slipping tyre. A limited slip differential would stop that from happening depending on the locking degree... I think. Its a differential which doesnt allow too much difference between both tyre speeds.

The grip level of the tyres normally overcomes the LSD's effect, but this transfers the forces towards the steering which makes it straighten itself (or 'fightback', hence a stiffer steering). But wheelspin is a different story, LSDs should still be strong enough to limit wheelspin to a certain degree depending on its locking strength when one of the wheels loses its grip marginally. In that sense having too strong a LSD would make cornering worse (and steering a bitch), but very effective for straight line drags.

I've observed this case on a FR machine running in tight circles at slow speeds,which on rough sand and rock grounds with very little grip had its inside rear tyre spinning slightly faster than it should be, trying to catch up with the outer tyre which was the one gripping the ground. Both tyres should have gripped the ground normally, but apparantly the LSD's strength was enough to overcome the inner tyre's weak grip on the sand and sped it up to the outer tyre's speed.


Sifus correct me if im wrong. :)

 

[si|verfish]

It does work that way as far as I know. A differential is there for both tyres to propel independantly depending on steering angle, but when power overcomes one tyre's grip the differential may transfer too much power to the slipping tyre. A limited slip differential would stop that from happening depending on the locking degree... I think. Its a differential which doesnt allow too much difference between both tyre speeds.

The grip level of the tyres normally overcomes the LSD's effect, but this transfers the forces towards the steering which makes it straighten itself (or 'fightback', hence a stiffer steering). But wheelspin is a different story, LSDs should still be strong enough to limit wheelspin to a certain degree depending on its locking strength when one of the wheels loses its grip marginally. In that sense having too strong a LSD would make cornering worse (and steering a bitch), but very effective for straight line drags.

This sort of makes sense but I still don't quite get it, hehehe, if that's possible. I think it may have something to do with the type of LSD you have; clutch, viscous, electronic, etc.

I've observed this case on a FR machine running in tight circles at slow speeds,which on rough sand and rock grounds with very little grip had its inside rear tyre spinning slightly faster than it should be, trying to catch up with the outer tyre which was the one gripping the ground. Both tyres should have gripped the ground normally, but apparantly the LSD's strength was enough to overcome the inner tyre's weak grip on the sand and sped it up to the outer tyre's speed.

Again this doesn't sound right, in a physics and mechanical sense. The LSD should be limiting the slip of the inner wheel, not speed it up, right?

Ah, fuck it. Whoever's got a degree in mechanical or automotive engineering, please stand up. Qualified mechanics or people with similar knowledge also. Need your clarification on this issue.

 

[Zeroed]

This sort of makes sense but I still don't quite get it, hehehe, if that's possible. I think it may have something to do with the type of LSD you have; clutch, viscous, electronic, etc.

Heheh that is true. What I said probably doesnt apply to modern differentials used in Active YAW or ATESSA or whatever.

Again this doesn't sound right, in a physics and mechanical sense. The LSD should be limiting the slip of the inner wheel, not speed it up, right?

Ah, fuck it. Whoever's got a degree in mechanical or automotive engineering, please stand up. Qualified mechanics or people with similar knowledge also. Need your clarification on this issue.

Thing is the LSD is trying to match the speed on both wheels. The faster wheel probably had forces from the LSD trying to slow it down, but since it had the car's weight on it and hence more traction it kept on going at a faster rate,
while since there were very little grip on the innerwheel the strength of the LSD overcame its grip and did the opposite of its purpose, hence speeding it up towards the outer wheel's speed. That is atleast what I have concluded...

In the case of serious cornering, the LSD would stop the wheel without traction from frantically spinning, while transferring power to the wheel with traction. I would say that this would also be a form of equating speed on both wheels, neh?
If the wheel with traction also loses its grip then after the LSD transfers the torque then both wheels would spin and it would be a sign for the driver to stop screwing around.


One of these days I ought to confirm this with my mechanic...

 

[si|verfish]

Ok...after reading that, my brain is officially fried...


mmmggghhdddaaaggghhh...

 

[koolspyda]

wha kena LSD. hayal now is it? bro dont loose hope la. hannah still single la

heheehe

j/k aside ;

something to drool on LSD (legal); quaife type
http://www.cattman.com/img/prod/quaife.jpg

http://www.forwardmotioninc.com/html/linked_photos/quaife.jpg

 

[Zeroed]

Ok...after reading that, my brain is officially fried...


mmmggghhdddaaaggghhh...

Ahahahah. Basically LSDs are also in effect other than times of wheelspin, but the effect is minimal la.
I just read up that apparantly good LSDs have its effect kick in stronger during during wheelspins, but less during normal conditions.

Now how about a bottle of brainjuice?

 

[dean75]

Can anyone tell me about how the lsd work during heavy rain? Does it help a lot?

 

[si|verfish]

Ahahahah. Basically LSDs are also in effect other than times of wheelspin, but the effect is minimal la.
I just read up that apparantly good LSDs have its effect kick in stronger during during wheelspins, but less during normal conditions.

Now how about a bottle of brainjuice?

Cannot compute...cannot compute...cannot compute...shutdown imminent...

Nah, I should be fine. Sort of get it now. Sort of anyway...