Is S15 Helical Lsd Actually Good For Our Cars???

[spider_slayer]

where did you get a vlsd for 250? sounds like you gotsa hook up....

these are what i've been looking at. so 600 wouldn't sound to bad compared to paying an extra $300 for one cause is says nismo

[2_Liter_Turbo]

I actually got mine from a member here at NICO. $600 Isn't bad at all if you're getting the S15 (with output shafts of course). The Nismo LSD is a clutch type, and a mild one at that. It's decent for the street don't get me wrong, but not as good as a KAAZ or Tomei unit; or so I've heard. I have not tested them myself. I am getting this info from others here and at the shop I used to hang out at, in the Bay Area.

[vvaffle]

howstuffworks.com doesn't explain how a helical LSD works. Anyone wish to explain or has a link that does?

[Chingon]

search torsen

[vvaffle]

Thanks, I get it now. Is there anyone who has used both a helical and a clutch LSD in a race application to tell what they think is better?

[dfw240_EE]

If I am not mistaken, they used the lower final drive ratio in the S15 because of the incresed power? (~250hp in the S15, I believe)

[Chingon]

3.69 vs 4.1 if I recall. As for the race applications, i think clutch is preferred. Once a rear wheel is in the air, the torsen starts showing it's ugly face.

[dfw240_EE]

I would think it depends on the racing. Like road racing on a well-paved and well-maintained racetrack your wheels shouldn't leave the ground. Key word "Shouldn't"

[s13sr20chris]

If I am not mistaken, they used the lower final drive ratio in the S15 because of the incresed power? (~250hp in the S15, I believe)

six speed

[importer]

Well, if you consider every IRL, every CART, every Trans-AM, and just about every other real road race type car uses a helical, I would want you to use a clutch type if I knew I was going to race you down some twisty canyon road.The cam-lock clutch types (Cusco, ATS, KAZZ) will lock harder with more power applied, even if it isn't the best thing for what the car is doing (or what you are trying to do with the car). OK for drag racing, but not so good for going fast thru corners. A helical applies upwards of 3 times the torque to the wheel with the most bite, and works by sensing one wheel trying to overspeed the other. Thus it is less likely to cause both wheels to break traction. The S15 helical is one of my best sellers, and the same unit (with even larger output shafts) is what comes in the R34 Skyline.

[importer]

"Once a rear wheel is in the air, the torsen starts showing it's ugly face."

If you are lifting one rear wheel, you really have the suspension screwed up !

[dfw240_EE]

Or are doing Rally in a 240SX.

So the Quaiffe is indeed a helical type?

[fatboy]

if you do change gearing however, pinion depth changes and you will have to compensate by use of shims. what iu do i buy 2 new pinion bearings and get one machined out. if you've done this before, you'd know what i was talking about

[OMG im sideways]

Hi, i saw that you are a SUPERMODERATOR!!!! so i decided to ask you a question. i have found a 1990 240 for $1k. it is in really good condition and has a clean record. i was considering buying it and then doing the sr20det swap. red or black top im not sure. but i was wondering if you know anyone who has done it, and some of the problems and tips for doing it. or if you at least have help in getting the front clip of a silvia. anything would be extrememly helpful.

[s13sr20chris]

bro i think you were asking me.first you just jacked the thread (or attempted to). i reccomend you search like crazy and dont listen to just any one person on this subject(including me). it is all about the luck of the draw. 1)how good of a car you find2)how good of a motor you find3)how lucky you are at installation timeetc.before you do the swap you have to come to grips with the fact that it may NEVER work out.

[GripR]

hey guys i'm really trying to understand the HLSD. now you say that it is helical type. helical as in gears that are cut in an angle? now are your talking about the pinion and ring gear being helical or the gears in the differential case? to my knowledge there are Clutch, Cone, Ratchet and Torsen differentials.

[GripR]

Or are doing Rally in a 240SX.

So the Quaiffe is indeed a helical type?

quaiffe is torsen type of lsd (worm gears)

[GripR]

so does anyone know? or doesn't want to tell me? anybody got pictures of this s15 diff? i've dealt with clutch types, vlsd and torsen. never encountered a helical lsd.

[GripR]

nevermind fig'd it out, i rather stick to clutch type lsd's hahha

[importer]

Well, I guess you know your application, but.........

All IRL cars, All CART cars, Most cars that run the 24 Hrs of LeMans, and Daytona, Most European Touring cars, Most Trans-Am cars all use a Torsen.All Skylines, JDM RX-7 twin turbo, and the JDM WRX come equipped with Torsens.All Atlantic light cars, and all SAE chalange cars run a Torsen.All JDM Integra-Rs, and Civic-Rs come with a Torsen.All JDM JZA70 & JZA80 Supras come with a Torsen.

They Never wear out, unless they have been run without oil.The S15 Torsen uses larger diameter output shafts, so they will take more abuse that any S13/S14 LSD.

But you know your application (I have no idea what it may be except for an all-out drag car. And if it is, you should be running a spool, not a diff.).

[ADiamond75]

Sorry for this repeat question ... but here goes..

If one wheel looses all traction the other will not have any force applied to it?

The reason I ask is because I was debating getting one but drive my car on the street. I have pretty stiff coilovers and every once in a while when I pull in a funky drivewayI will lift one wheel off the ground slightly (yeah, I know, helper srpings would fix this, thats latter on) so in these cases I would basically be screwed cause the car would just sit there?

[DuckyD]

I would assume yes. You'd be screwed.

[ISUJinX]

Sorry for this repeat question ... but here goes..

If one wheel looses all traction the other will not have any force applied to it?

The reason I ask is because I was debating getting one but drive my car on the street. I have pretty stiff coilovers and every once in a while when I pull in a funky drivewayI will lift one wheel off the ground slightly (yeah, I know, helper srpings would fix this, thats latter on) so in these cases I would basically be screwed cause the car would just sit there?

Lifting a rear wheel going into a driveway? Eeeps. With a Torsen, worm gear/helical whatever you want to call it... yes, you would be stuck if you have one wheel in the air. Howstuffworks suggests applying the brakes to create some resistance for the one wheel that is up in the air. There was a Torsen Type IIR (race) that had a preloaded clutch pack to take care of this problem... but I've never seen one.

Somebody asked... not sure if they got an answer or not:

VLSDs use a set of plates with gear oil containing Silicone between them. As one wheel spins, it spins faster than the other one, creating heat and expanding the Silicone to lock the plates together, keeping power to both wheels. The dis advantage is that one wheel has to spin first.

Clutch types use springs to lock clutch plates together when one side is trying to spin faster than the other. So, the clutches just sit there doing nothing until then, at which point you need to have more power to overcome the clutch disc friction (Hence why they loosened them up on the aforementioned cars). They wear down and have to be replaces/fixed. They are also fairly noisy and have trouble dealing with situations at full steering lock.

Torsen (worm gear/helical) uses the binding gears (as stated above from Howstuffworks) to limit wheel spin by locking the axle that is spinning too fast to the diff., which in turn will spin the opposite wheel. It works on the principle that worm gears can drive normal cut gears, but not vice versa.

The diff drives a worm gear on each side, which drives a straight cut gear attached to the axle. When one side trys to spin too fast, the normal cut gear on the axle binds up to the worm gear and locks that side to the center part, locking it, and driving the worm gear on the opposite side, which drives the straight cut gear etc... Thus, with no traction at all going to a wheel in the air, the gears wont bind, and it will think the wheel in the air has more traction, and thus will give it more power.

Advantages: very durable and reliable, no clutches to wear out, quiet. Disadvantages: Completely non adjustable, the wheel in the air thing, and due to how the sensing works, hard to get used to driving (going from overpowered outer wheel to underpowered, coming from the traction shift due to the weight relocation during cornering)

More than you ever wanted to know about Diffs! :-p

So to answer the original poster... it all depends on your style of driving. The bogging you mentioned is probably more of a final drive ratio (which can be changed easily like people said)

[AZhitman]

ISUjinx - You need to make this a seperate thread: All You Ever Wanted To Know About Nissan Differentials.

It'll be a great article!!!

[ISUJinX]

Enh. Its a general diff type explanation. Feel free to copy and post it in the FAQ about LSD swaps if you see fit

I'll revise it sometime when I'm not dead tired and repost or something.

[ADiamond75]

ISUJinX -

Thank you for the informative write up. I like the idea of a torsen, I just need to find a way to fix my wheel lift on inclines. I wish megan made helper springs for their coilovers.

[shrapnail]

So, i've been reading my articles all wrong apparently.. wiki seems to lean towards clutch type; and all i ever seem to read on here is 2-way this and VLSD that... And I have no itention of going the VLSD route

You say the worm type are not adjustable, what kind of adjustments would one make on a LSD ??

[Bronze MFP]

with clutch type LSD's you can adjust the lockup torque on them by adding or removing plates from the diff itself. i believe one of the nismo units can be adjusted by pulling an axel out (drivers or passengers, i forgot) and sticking a deep socket in it and adjusting it that way. Either way, its a PITA. I've been running around on a tomei clutch lsd for about a year and have no problems with it on the stock torque setting. Even autocrossing it does fine. would I like to try a HLSD? heck yeah, but i love the tomei (kaaz or cusco are great too, so is ATS, but they are $$$ )

[DuckyD]

Exactly. A clutch-type can be adjusted by changing the direction of the plates (not removing or adding, eek!) to determine % lock. A helical does all the thinking for you, nothing to adjust.

[shrapnail]

awesome, thanks guys; i'd read about moving plates but had thought that was just for (pardon the use of the term) alignment (of the unit itself).