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I launched my car today for fun after work. I reved up to 3K and dropped the clutch while watching the speedo. Felt like it jumped but the tires were screaching for a second and a half until if finally caught. The car was moving as it was screaching and the speedo jumped up to 20mph and then when the tires caught it started climbing. Now is the LSD working? or am I the idiot and not really using our style LSD correctly? I know LSD is also for steering performance. And I do know our G20t are equipped with viscous lsd. I read alittle about it and viscous uses fluids to transfer the power so its limited by power. Does it work for launching in our G20t? I have been wondering this for awhile now...wish I can get a G20 and G20t with same setup to do 60' times....I want some comparison so I can feel better about my G....I also remember someone mentioning they drove a G20 and G20t with the same suspension and engine setup on the track and the LSD made a world of a difference on cornering and overall track time. TIA
 

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I've always thought of an LSD (helical OR viscous) as a help-you-out-when-you're-turning kinda thing. Drag racing = mastery of the art of going straight. ;)
 

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I know what you are saying but also if you think about it it also applies to drag racing. Have you seen Honduhs do burn outs? They usually spin only one wheel I think it was the passenger side because the normal Honduh differentials only really puts power to one wheel or something like that....but with LSD it transfers the power to the tire with the most traction or something like that...so when you launch your car it would be balancing out the power evenly giving you better traction for both wheels. I'm just shooting this out of what I know and read. I know there are some things about LSD that are more complicated than that, but I'm no rocket scientist.

Also from what I remember it was somewhere around 250~300whp where the stock viscous LSD don't do shit for drag racing or can't handle the power or something...need to get something better like Kaaz or something. Don't ask me why but you do...
 

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The LSD was probably working for your burn out. I'm assuming you have a touring model now. ;)

If you get both wheels to lose traction the LSD is not going to really do anything except keep one wheel from dogging it. Cars without LSD's can still get both tires spinning in a burnout also.

You probably dont want to try this but put one wheel on tarmac and the other on a sandy/gravely surface then try and burn out. You should feel your car pulsing along as the LSD locks up from the wheel spinning in the dirt. You wont move as fast as both wheels on the pavement but you won't move as slow as both wheels on dirt. :-\
 

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Go to "How Stuff Works" (howstuffworks.com) and look up LSD. They have a pretty interesting article there about it.

However, I'll try to sum it up quickly in response to this particular thread.

What your VLSD does is make sure that if ONE of your front wheels loses traction, that the car doesn't shift all the power to it. Normal differentials do this. Imagine if half of your car was on concrete, and the other half was in mud (or on ice, or etc.) If you had a normal non LSD car, the wheel with no traction (mud, ice, so on) would just spin and spin, and the other wheel would just sit there. Doing nothing, because all the power of your car was going to the tractionless wheel. Now, with the VLSD that we got lucky with, the wheel that is in the mud will be spinning, but because one wheel cannot turn much farther than the other, the other wheel will be going too, therefore pulling your car out of the mud (hopefully) and sending you along on your merry way.

As for turning, I'm not exactly sure how it helps there. I used to think that the VLSD was going to be on the back wheels (working against fishtailing and the like) but because it's on the front, I'm not exactly sure how it would help that much, except in the ways that I already detailed.

Hope this helps, check that website for more info. They have a lot of cool stuff there.
 

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Well when you turn, the wheel on the outside is moving much faster than the wheel on the inside. In certain circumstances; such as a really tight turn, or drifting, etc.... the wheels will spin at rates different enough that the LSD would help. Just...yeah. LSDs are cool. They be good. tHeY r tIgHt hOmEz.
 

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FF Drifter said:
Well when you turn, the wheel on the outside is moving much faster than the wheel on the inside. In certain circumstances; such as a really tight turn, or drifting, etc.... the wheels will spin at rates different enough that the LSD would help. Just...yeah. LSDs are cool. They be good. tHeY r tIgHt hOmEz.

That's a differential - it allows the wheels to turn at different speeds.

A limited slip does just what it sounds like - it limits the speed differential between the wheels. Typically, this is a matter of traction. One wheel will not have traction and a differential will strangely enough send all the torque to the wheel that is spinning. This means you put no power to the ground.

A viscous LSD uses a fluid that surrounds two plates attached to either halfshaft. When the speed differential reaches a certain point, this special fluid will thicken up nearly solid and make both axles turn at or near the same speed. It allows speed differential, but it limits it.

A clutch type LSD uses multiple clutch plates that can be preloaded for the amount of lock-up. As speed goes up, the clutch plates start to lock down and while they do allow speed differential between the halfshafts, it limits it.

An automatic torque biasing LSD (aka: ATB, Torsen, Quaife, etc) uses gears cut to a specific pitch that allows speed differential, but the gears bind up when the speed differential becomes too great. When the gears bind up, they limit the differential action.

Each has advantages and disadvantages.

A little history of the Torsen (ATB). Torsen stands for torque sensing. It was invented in the late 70s by father and son inventors in Pittsford, NY, a suburb of my hometown of Rochester. They sold it to the Gleason Corp (no relation), a company that manufacturs large gear cutting machines. Gleason had initial success with the Torsen in racing with the McLaren F1 team, the Audi rally team, and Newman-Hass racing in CART. I actually met an engineer who worked with these teams for Gleason. Gleason tried to market the Torsen to OEMs but had littel success. They eventually sold the tooling and rights to a Japanese company. They set up the Torsen company in Rochester, where it still is based. All ATB differentials are Torsen designs or derivations of the Torsen.
 

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LSD was most popular back in the 60's.

You could almost always find it in any VW Microbus, Volvo Amazon, or Citroen 2CV. Unlike on the G20t's, the LSD was usually located in a safe spot in the engine compartment, or for more convenience, in the glovebox.

Having LSD in a car made the trips far more fascinating, apparently.

:cheeky:
 

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Geo said:





A viscous LSD uses a fluid that surrounds two plates attached to either halfshaft. When the speed differential reaches a certain point, this special fluid will thicken up nearly solid and make both axles turn at or near the same speed. It allows speed differential, but it limits it.


I'm glad I dug up this nice informational post. I've been thinking about getting a G20t so I've been doing some reading. I saw that the VLSD may eventually "wear out". Would this be caused by the fluid losing it's thickening properties? And if so, can you change the fluid like tranny fluid or is the VLSD a sealed unit?

Thanks,
Jacob
 

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jdircksen said:



I'm glad I dug up this nice informational post. I've been thinking about getting a G20t so I've been doing some reading. I saw that the VLSD may eventually "wear out". Would this be caused by the fluid losing it's thickening properties? And if so, can you change the fluid like tranny fluid or is the VLSD a sealed unit?

Thanks,
Jacob

No the unit just has to be replaced when it goes bad. There are several options like, Quaife, Phantom Grip Nismo. These are clutch type I think which is probably more reliable.

I have a '95 G20t and my VLSD doesn't work. Still people always say "oh yeah you have the VLSD in that, that's cool" and I'm like yeah I do have one! Sssshh...it doesn't work. ;)
 

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Another difference is that LSD is just that.... 'limited slip'.... one wheel will ALWAYS turn faster than the other..... but both will always have an amount of power to them to turn both (in case of that mud/pavement situation).

The other one would be GMs Locking Differential.... still the only company to have a true Locking differential..... Where both wheels will turn the same rate. However, both Locking Diff and Limited Slip are usually only good up to around the 30-60kmh range... then after that have no effect.

All differentials naturally do a transfer of 50/50 power to left and right.... the reason why Hondas spin the left wheel easier is for a couple reasons..... 1 - less weight on the passenger side of a honda, equals easier to lose traction.... and it comes down to the axles too..... too much engineering for me..... its usually the weight issue....

Go around a corner and pin it.... the wheel that spins is the one with the least amount of weight on it.....

I think Honda had a neat differential that transfered power to the wheel that had the most traction.... GM has a similar one, but it applies brakes to the spinning wheel to do the transfer....
 

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Mike.Com said:



"No the unit just has to be replaced when it goes bad."

I know these are sealed units but has anyone actually tried opening one to replace the fluid? I have heard that what goes bad is the silicone fluid inside breaks down from shearing action.

CraigM3 said:
)

"The other one would be GMs Locking Differential.... still the only company to have a true Locking differential..... Where both wheels will turn the same rate."

The infamous "Detroit Locker". I have heard that these make a lot of tire squal in a turn.
 

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TY423 said:
I launched my car today for fun after work. I reved up to 3K and dropped the clutch while watching the speedo. Felt like it jumped but the tires were screaching for a second and a half until if finally caught. The car was moving as it was screaching and the speedo jumped up to 20mph and then when the tires caught it started climbing. Now is the LSD working? or am I the idiot and not really using our style LSD correctly? I know LSD is also for steering performance. And I do know our G20t are equipped with viscous lsd. I read alittle about it and viscous uses fluids to transfer the power so its limited by power. Does it work for launching in our G20t? I have been wondering this for awhile now...wish I can get a G20 and G20t with same setup to do 60' times....I want some comparison so I can feel better about my G....I also remember someone mentioning they drove a G20 and G20t with the same suspension and engine setup on the track and the LSD made a world of a difference on cornering and overall track time. TIA

hokey45 said:
Mike.Com said:



"No the unit just has to be replaced when it goes bad."

I know these are sealed units but has anyone actually tried opening one to replace the fluid? I have heard that what goes bad is the silicone fluid inside breaks down from shearing action.

CraigM3 said:
)

"The other one would be GMs Locking Differential.... still the only company to have a true Locking differential..... Where both wheels will turn the same rate."

The infamous "Detroit Locker". I have heard that these make a lot of tire squal in a turn.
not sure but i think mitsubishi has a full locking differential on thier suv. it i activated with a switch in the drivers compartment.
 

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hmmmm this is a good topic....I have been wanting to test my LSD out but I dont want to hurt my baby...lol
 

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Re: Re: Viscous LSD...Does it really work on our cars? if so, then for what situations?

P10 WRC said:





not sure but i think mitsubishi has a full locking differential on thier suv. it i activated with a switch in the drivers compartment.

Oh you're talking about O.E. locking diffs. Don't those work kinda like the ARB Air Locker, it's a regular open diff but when you engage it the axles are locked together?

My dad has a '61 Vette that had a locked differential with 4.56 gears when we bought it. Tires squealed everytime you turned and powerslides were too easy, esp. in the rain. Prolly a good drift setup though. :cheeky:
 

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I don't think this is exactly an "instance" you are wondering about but, here in Denver we get cold obviously... we get ice obviously n' snow too... My driveway is MAD steep, and while my girls Saturn can not make it up the driveway while there is snow/ice on it, my car makes it up like a champ... not that I usually do such things, as I don't really want to burn out the LSD over garageing the car... I'd rather just sweep or shovel the shit so I don't have to worry bout it, but I have been in the situation and it's worked like a dream... =)
 

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just to stir things up a little...

remember that while there are different types of lsds (viscous, helical, clutch) there are also different diffs depending on when they work... 1-way works with acceleration, 1.5-way works with acceleration and some deceleration, and a 2-way diff works with both acceleration and deceleration...
 

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Yeah, and each type of differential has it's own inherent advantages and disadvantages. Some will provide better turn in response, others may start to work more quickly than others, etc...


And FWIW, it's actually the outside wheel that spins around a turn in our cars. My guess is that it's due to the tire's inability to hold the increased cornering forces from the weight transfer, etc.. and then the acceleration just overwhelms the tire causing it to lose traction. And I have verfied this with wheel speed sensors and data logging equipment, so I'm not just pulling this out of my ass :p
 

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JustinP10 said:
And FWIW, it's actually the outside wheel that spins around a turn in our cars. My guess is that it's due to the tire's inability to hold the increased cornering forces from the weight transfer, etc.. and then the acceleration just overwhelms the tire causing it to lose traction. And I have verfied this with wheel speed sensors and data logging equipment, so I'm not just pulling this out of my ass :p
The outside wheel turns faster because it follows a longer arc than the inside wheel therefore it takes less force to turn it. Think of the outside wheel as being "geared down" compared to the inside.

Seems like a few years ago Honda came up with some kinda diff that puts the power to the inside wheel.
 
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