Differential Tech.

[R.W.240]

Im bored so I decided to try and explain some of the Types of Differentials


OPEN (Stock)
- There shouldnt really be any questions about how these work. they divide power with no system to govern which side gets power. From a preformance prespective the biggest problem with an Open diff is power application - that is the wheel with less traction will spin and in most cases lose more traction from spinning. Also Open Differentials will have a problem with stability in high power vehicles.

VLSD (Ritzy stock)
- Viscous Limited Slip Differentials work by having a thick fluid spin in between "paddles" (Imagine a Torque converter with out a Stall). VLSDs work in essentially the same way as a open differentail from a preformance prespective the only difference being that a VLSDs are locked a certain amount . VLSDs are good for low powered vehicles and beginers but cannot handle big power or traction simply due to the way they lock. VLSD's locking are also very dependant on heat, age and fluid. VLSDs are lcked at any speed / torque input however their locking rate is very low since they're OEM and made to control 195 tires comfortably.

--To test for a VLSD, Jack up the rear end of the car with the Transmission in gear (an Open can appear to be a LSD if the transmission is not locked)... the wheels should not spin or be very difficult to spin--

Torsen / Helictical (OEM S15 /Quaife)- I dont rightly know how torsen diffs work... what I do know is they try to send torque to the wheel with more traction with a system of gears and springs and that many people who have used the S15 diff say that they suck for drifting (most likely because of them actively searching for the wheel with the most traction) and it becomes an open when there is zero traction on one wheel.

CLUTCH TYPES (Cusco/Kaaz/OS Giken/ATS and Across)
- Clutch types lock the wheels in exactly the same manner as the clutch pedal locks your Imput /Crankshaft (except with fluid thrown in). Clutch types usually have or can have a high locking rate but when there is no torque input from the driveshaft they are essentially open or have a very low lock (A good way to think of this is that the Torque reaching your Diff Accererative or Decelerative is like a clutch pedal in a transmission)

In relation to driving clutch type diffs can work in varying ways.
INITIAL TORQUE - This is how much Torque input a diff needs to begin to lock (if you have absolutley zero traction on one wheel a worn clutch type will act like an Open due to the lack of torque)
MAX LOCK % - This is how much a wheel spin a diff will allow when locked expressed as a percentage - I belive KAAZ's come set at 60% 100% lock will act the same as a welded diff when torque is applied)
1/1.5/2 WAY - This Tells you when a diff will lock 1-Accel Only 1.5 -Accel / 50% decel and 2 - which is full MAX Lock under both Accel and Decel

1Way - Really only good for FWDs with severe understeering problems. they are very unstable when off throttle due to the wheels being unlocked

1.5Way - Best for any driveline looking for full lock on accel and added stability off throttle but with less of the Turn in understeer of the 2way

2Way. The most stable diff since the wheels will be locked with any torque input. Has a slow turn in due to the wheels being locked off throttle. with good traction 2Ways will also cause understeer on accel. (as will 1 and 1.5Ways)

WELDED (100% Lock)

- Welded diffs work by welding the spider gears so there is NO slip at all at anytime. from a preformance driving prespective weldeds work best for drift or drag (hint: its a cheapass 2-Way). But due to the the fully locked nature your car will not want to turn in (which shouldnt matter when drifting unless you suck)

downside to weldeds - Unlike Clutch types where you can get the diff to unlock by putting in the clutch the welded is 100% all the time so you have no easy escape from a slide when turning (I.e if your not careful in the rain or have bald tires the rear end will come around very quickly.)
-Alot of people will tell you you'll break things which on a sub 400WHP car with less than 265s is not the case. above that you'll be breaking things regaurdless. I have many friends with welded diffs and none have had any problems with their driveline. at low speeds your inside wheel will skip or your car will shudder when making turns (translates to ass turn in at high speeds)

--Make sure you know what your doing when your welding a Diff the last thing you want is for it to frag while driving fast near something hard.--

P.S This got long so I may have missed a few points so I'll prolly be editing and revising this alot for more info / better organization.

also I know alot of my analogies arent how it really works IM JUST TRYING TO GET A POINT ACROSS

[Pavlo]

Welded diffs stretch your axels, you will eventually have to replace diff and axels.
VLSD can be nice with the right fluids.
And my vote for sticky.

[nissanfanatic]

I added this thread to the Tech sticky.

[drftk1d]

what about torsen (although it technically isnt a lsd)

[slideways...]

correct me if im wrong but you said that the only diff that locks under 0 traction is VLSD...
and 1way is best for FWD or high understeer setup, unless you dont do much brake drifting, then you can drift with it
1.5 is best for drift and road racing, as it doesnt cause excess instability when the brake is let off and step on gas mid corner

2way is good for rally, drift, or on cars that oversteer alot but the biggest downfall is the change in cars stability when you brake or accelerate or let off of brake or gas.

i havent heard that helicals are bad for drifting...on the contrary i would think theyd be good because of the more gradual application of torque over clutch type's instant engagement

[R.W.240]

Originally Posted by slideways...

correct me if im wrong but you said that the only diff that locks under 0 traction is VLSD...
and 1way is best for FWD or high understeer setup, unless you dont do much brake drifting, then you can drift with it
1.5 is best for drift and road racing, as it doesnt cause excess instability when the brake is let off and step on gas mid corner

2way is good for rally, drift, or on cars that oversteer alot but the biggest downfall is the change in cars stability when you brake or accelerate or let off of brake or gas.

i havent heard that helicals are bad for drifting...on the contrary i would think theyd be good because of the more gradual application of torque over clutch type's instant engagement

VLSDS and Weldeds

Added more info about differences in handling charactoristics with clutch typd

Added more about VLSDS


What you want from an LSD while drifting is consistancy. the helictical is trying to correct and send traction to the wheel that needs it. clutch types lock quick, hard, and the same every time and it amounts to a more predictable nature.

Thats Why Weldeds are good for drifting... its locked constantly and divides torque the same every time. which is why most Pros set their clutch LSDs with very low intitial torque and very high max lock.

[240SXSlideStar]

If you have a 2way, you really need to know how to heel-and-toe right?

[drftk1d]

you should know anyway

its easy

[R.W.240]

Originally Posted by drftk1d

you should know anyway

Exactly...

But yes... a 2-way should react the worse to a crappy down shift around a corner.

[240SXSlideStar]

I know how, I just can't do it cause my legs are to long. I have no room under there to turn my foot.

[Pavlo]

I do it most of the time before turns, so that I am in gear when entering a turn. I almost always do it in rain, or slippery surface too.

[R.W.240]

Originally Posted by 240SXSlideStar

I know how, I just can't do it cause my legs are to long. I have no room under there to turn my foot.

Heel Toe is really just a concept if your tall. if you have wide feet brake with the left side of your foot and to blip roll your foot over and hit the throttle with the right.

then under hard braking you can do it when your tall its just pretty hard

[240SXSlideStar]

I've tried doing it with the sides of my feet, but if I push the brake pedal enough to slow down, the gas pedal is also pushed down, it's really fucked, I wish I could shrink my legs by 6 inches when I get in my car, lol.

[SHIFT_KA24DE]

nice write up... thnx for all the info.

THis reminded me of a few things i've read/heard in the past. Some say you shouldn't get a diff until you can drift with an open... and some say a diff is the first thing you should get, no matter what.

is this just based off opinions or is there some logic to it? Obviously, an open diff will restrict high speed ass-sliding and having a diff won't necessarily mean you can become some tsuchiya right off the back.

on a side note... heel-toe comes natural if you find the need to get into gear before a corner... i find it annoying to engage after you turn because of the pause or lack of 'smoothness' because of the rev-matching... that's just my opinion. I've heard individuals with big feet actually do a 'toe-heel' (if you wanna play with words) brake with their heels while pivoting around and blipping with their toes... i don't know how this works but i do it the other way so i'm not even going to try it. Your feet doesn't necessarily have to get sideways either... you just need enough to touch the gas... just a slight rotation and gyrating the foot around to hit it momentarily will do it.

haha... anyone notice theres a small pad on the wall next to the gas pedal? Im aware it's for "regular" driving but i'd like to think of it as some protective for the interior from all the "heel-toeing"...

[R.W.240]

Originally Posted by SHIFT_KA24DE

nice write up... thnx for all the info.

THis reminded me of a few things i've read/heard in the past. Some say you shouldn't get a diff until you can drift with an open... and some say a diff is the first thing you should get, no matter what.

is this just based off opinions or is there some logic to it? Obviously, an open diff will restrict high speed ass-sliding and having a diff won't necessarily mean you can become some tsuchiya right off the back.

on a side note... heel-toe comes natural if you find the need to get into gear before a corner... i find it annoying to engage after you turn because of the pause or lack of 'smoothness' because of the rev-matching... that's just my opinion. I've heard individuals with big feet actually do a 'toe-heel' (if you wanna play with words) brake with their heels while pivoting around and blipping with their toes... i don't know how this works but i do it the other way so i'm not even going to try it. Your feet doesn't necessarily have to get sideways either... you just need enough to touch the gas... just a slight rotation and gyrating the foot around to hit it momentarily will do it.

haha... anyone notice theres a small pad on the wall next to the gas pedal? Im aware it's for "regular" driving but i'd like to think of it as some protective for the interior from all the "heel-toeing"...

People are telling you to drift without a Diff so you have to learn weight transfer and speed to drift instead of using clutch kicks.

You can do it either way. you'll learn the same stuff with a Locked but you'll be tempted to use power with the locker.