What is a LSD?

[Drifter-ex]

So in the case of grip driving, theororitically, wouldn't the open diff. be a better choice since it allows the outside wheel to spin at a higher velocity thus allowing you car to initiate a shaper line and be able to exit past the apex at a quicker pace (not always speed...)?If power is equally distributed, during a turn the inside wheel would want to turn slower than the outside wheel since the inside wheel has a less distance to travel in the same time than the outside wheel (like 2 different spots on a record), correct? If this is true would the open diff. be a more suitable choice since it allows the two wheels to travel at different speeds and allowing teh car to turn in a shorter distance?

I think an LSD would still help you there because, its not like the LSD distributes the power to one wheel, all the time it distributes evenly I think. In grip driving you still get some slipage, and a couple times when I went to SCCA events I saw that one wheel would come off the ground in certain types of cars.

[nissanguy_24]

Im sure theres alot of good answer.. im pretty tired so ill post a short explanation ( didnt read all the post)

Power is put from the driveshaft.. the output shaft of the engine and transmission to a differential. the differential sends power to the two wheels. You have two types.

Locked differentials and Open differentials.

A locked differential spins both wheels at the same time period. The problem is when taking a corner the inside wheel travels a shorter distance then the outside wheel, thus it has to spin at a different speed.. slower. If both wheels are trying to turn at the same time then you cant take the corner very well. One wheel wheel keep trying to hop to make up the difference.. Sometimes full drag racers have this setup because its a very good way to put power down.. but a horrible way to turn.

And you have what most passanger cars have an open differential That sends power to one wheel at a time, via gears. This way whatever wheel needs to move faster to corner it recieves the power and can move faster. the other wheel just spins freely like a none drive wheel.. Now this changes depending on corner, its constantly adjusting.. Just the way the gears are setup in the differential. Porblem is if one wheel suddenly has no traction and begins to spin. All the power will go to it.. because its the easiest path. So if you hit ice, or spin your tires, or do a burn out. One wheel will brake traction and will spin, the other will sit there. or be draged in the case of drifting.


Enter the Limited Slip differential. Literally a differential thats allows a limited amount of slip.. By using several different techniques the LSD gives you the best of bothworlds with really no doubt side. You have enough play to corner.. but if one wheel begins to spin then equal mounts of power is sent to both wheels. either causing them to grip, or both to spin.. either way you will come out of the corner faster.. or you will drift smoother..

Open differential makes it hard to hold a drift for very long. It also makes it less predictable as one tire is dragging... and you cant really predict which tire in all cases.

The differential is behind the driveline, which is behind the transmision which is behind the engine its self.. So no worries about RWD motors comming with LSDs or Not.

There are many types of LSDs i sugest you look into them further. They all act alittle different but both try to give you the best of both world. The grip of two tires and the ability to turn of one wheel drive.. Most advanced AWD cars like the evo or STi feature 3 differentials. One between the front and rear wheels, and one in the middle of the drivetrain.

Have fun researching!

Originally posted by Drifter-ex
I think an LSD would still help you there because, its not like the LSD distributes the power to one wheel, all the time it distributes evenly I think. In grip driving you still get some slipage, and a couple times when I went to SCCA events I saw that one wheel would come off the ground in certain types of cars.

Yes.. Ever try to apply power as your comming out of the Apex at high speed? your wheel will spin.. in a LSD powered car you will literally jump out of the corner with twice as much grip.. Guys who install LSDs describe the car as being able to leap into and out of the corners much better limited slip differential.. Basicly Open diff is never better. Ful llocking is only better in striaght out drag racing.

Everyone else from street racers to driftings will want a LSD.. now the question is what type of LSD do you need? thats where it changes depending on what kind of racing you are doing.

Originally posted by 98BlueStang'
Also, wouldn't a cheap way to achieve equal power distribution be to weld the spider gears togather?

THis would give you a full locked differential. Great for drag racing. However you wont be able to turn well. I supose if your going to drift every corner with both wheels spinning its not an issue.. and it was done in the old days in japan i hear.. However its far from ideal.

Originally posted by 98BlueStang'
If this is true would the open diff. be a more suitable choice since it allows the two wheels to travel at different speeds and allowing teh car to turn in a shorter distance?

See thats the beauty of the LSD it allows us to spin one wheel at a different speed so you can corner... to a point.. thats the limited amount of slip.. Too much slip and it will start moving both wheels at the same time. Too alot of gas would start gripping both wheels for example in the corner.. if you had enough power that would cause both wheels to begin to spin. You would find your self in an oversteer posture.

thats why drifters like it..

Likewise if you where going straight and stomped on the gas one wheel would spin, the other would lock in due to whatever mechanism that kind of LSD has, and you would put power to both wheels which literally doubles your grip. Thats why street racers like LSDs

LSD gives us the best of both worlds.

[Drifter-ex]

you mean it transfers power to the one that's slipping .Something I've noticed,clutch LSD's seem to be the choice for drifting,just an observation.

No it transfers all the power to the one that is gripping.

[markeese180sx]

well written explanation, nissanguy.

[MrodDrft]

Originally posted by Drifter-ex
No it transfers all the power to the one that is gripping.

No it transfers it all to the one thats slipping

[CRASHDRIVE]

OMG

Why didn't someone posted the link?

Here's the link:
http://auto.howstuffworks.com/differential.htm

simple as that.

[nissanguy_24]

Originally posted by MrodDrft
No it transfers it all to the one thats slipping

A open differential will transfer all power to the one with the least amount of resistance because it mechanically choses one axel or the other.. a LSD trys to transfer power to both axels evenly after a point. SO that if one is slipping half of its power is sent to the other wheel, because both axels are now locked up (to a degree) the idea is the wheel wont spin very much because now the other wheel is trying to grab too.

Now not all LSD's are that good, but thats what they attempt to do. After a certain mount of play between the two wheels it will try to match there speeds.

think of a VLSD.. it uses a thick liquid in side of it to make it work.. Basicly it acts like an open differential. power is mechanically sent to one or the other wheel.. however if one spins too much and the speed difference is the wheel is too great then the think liquid gets hot and hard and temporarly locks it up.

VLSDs are known for not being that agressive and not locking up all the way.. but thats kindof the idea.. .the link posted above is excellent.


And when i say "sends power here or there" dont think of that as an intelegent thing.. its all mechanical. a open diff doesnt really send power anywhere. it just has a gear set up so that one of the two axels will spin, if you hold down one of them the other will spin and vice versa. very few cars have active differentials..

Anyways just check out the link.

[marshun]

Originally posted by chrisfromda909
acts itchy?

i couldnt think of the term. but its called wheel hop. lets say you had a welded differential and you went around a moderate turn. both of you rear wheels would naturally want to spin at a different speed than the other (www.howstuffworks.com go ahead and look up differentials). then, since you have the welded diff making the the rear wheels spin at the same time all the time, you'd get wheel hop.

i used to wonder how come cars would wiggle funny when they were just turning. old muscle cars.

[new_to_drift]

thanx nissanguy,u really helped me actually understand a lot of stuff about the differential.

[Xantos]

nissanguy, your awesome, seriously! Your my new role model, you have an amazing amount of knowledge of how cars work! I also admire your patience with people new to drifting, and cars in general. I dont think you get thanked enough around here, so i am giving you an "Official Thanking!"

[nissanguy_24]

i really apreciated everything you guys say. But im nothing special, i just read and listen alot, and pass on what i have heard and read plus what i have done, to others. Nothing big. I encourage all you guys to do the same.

[Spy001]

nissan guy, on top of the fact that you just wrote out a perfect explanation, you claimed to be tired first, imagine what you could do fully awake, with caffeine even. Nissanguy for Pres.

[CrazyHawaiian]

I'm gonna experiement with a completely locked rearend soon. Like Nissanguy said, as long as you're drifting all the time ( no re-gripping) then I think it'll work out good. I've seen those types of setups used successfully in the dirt track racing world, although they slide on dirt, not pavement. The thing thats cool about a completely locked rearend is that it locks on de-acceleration. 2 way LSD's can give the same effect, but its not the same because it dosnt happen as fast (and as violently). I will be running a locked rearend on my black car soon. Car is used on the track only (and trailered on the freeway) so its no biggie. Instead of welding the gears, I'm gonna use a spool which costs between $80 and $100 new and will last as long as the axles last. The reason welding the gears has mixed results is because you'll never get the same ammount of strength (as far as the weld) every time. Depending on how you weld it, you could be making the metal weaker, or you could be making it stronger. Any time you weld you are changing how the metal is tempered (because of the heat), so like cutting springs, welding the gears can have mixed results. I'd recommend looking for a spool, but not sure if they make those for the open rearends found on Imports.

[nissanguy_24]

Spools arent common but i think i've seen something like that before on some imports, Tell us how it works man, Im very interested in seeing how a fully locked car differs. Preferable i'd like to drive one my self, but for now ill be happy to hear your report on it..

You know S13 open rear ends arent rare, maybe i should pick one up and weld it, and experiment with it and a LSD down the road. Open differential in a junkyard wouldnt be very expensive. I've not swapped out a differential yet, so switching them for track use for example may be more trouble then its worth, but we will see when the LSD is installed.

[CrazyHawaiian]

Yeah, picking up a cheap open rear to goof with might not be a bad idea. I'm no mechanic either, but happened to come across an open chevy rearend for free, so gonna try the spool and see what happens. If it dosnt work out good, then I'll just swap the Posi (aka LSD) rearend back in. In my case I'm going to be using a mini-spool which is the cheap way to go. Stock Car Racing magazine did a nice article on installing the mini-spool, check it out here. Along with the mini-spool I will also be installing a c-clip eliminator kit so incase the axles break while I'm drifting they dont come out of the housing and fly off the car. Yikes!

Oh yeah, to BlueStang98, the reason open rearends are not preferred for drifting is because they react differently depending on which way you drift. If the drivers side wheel is the power wheel, it will be on the inside when you drift left turns and the outside when you drift right turns. Its possible to get a feel for each direction and make do, but better if the car reacted the same both ways. So thats why people prefer to have both wheels getting the power to the pavement for drifting. But for the record I have seen open dif rearend drifters that kick butt and make a lot of smoke with one power wheel