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

[RCA]

The August 2007 issue of Modified Magazine has an AWESOME article on differentials. It explains open, viscus, helical & torsen, Quaife and clutch types. Also it explains the diffrence between 1.5way and 2way diffs.

They basicly say that:OPEN diffs are the cheapest and most common

TORQUE SENSITIVE LSDsare mechanical in nature, using either gears or clutches. Gear-type LSD's include Helical or Torsen designs. Quaife's ATB diff is perhaps the best-known aftermarket gear-type LSD. These diffs use a series of "worm" gears to "sense" torque on each driveshaft, biasing power to the outside wheel to reduce inside wheel spin and therefore allowing the driver to begin accelerating earlier and exiting the corner at a higher speed. This rugged design is low maintenance and very street friendly making it popular for dual purpose cars

Clutch Type DiffsTransfer torque more aggresively which makes 1.5 way and 2way clutch type LSDs very useful in motorsports enviroments like drifting and time attack. 2way is the prefured drift setup, since the diff behaves predictably despite constant and rapid changes in throttle and brake application. This predicabillity while sliding a car also makes it the most common for rally racing. 1.5way clutch type diffs tend to be better suited to road racing and time attack use, since throttle and brake applications are generally of a more gradual and predictable nature, plus too much lockup under overrun (ie. While braking and downshifting) can cause a drive wheel to lockup if the driver doesn't rev-match correctly and as a result destabilized the car.The down side of most clutch type diffs is that they require a very careful and specific break in procedure, tend to clunk and clatter durring slow speed turns (ie. Pulling into a parking space), the metallic clutch material wears out overtime, and require more frequesnt fluid changes. This makes clutch type diffs more expensive and less street friendly option, though a recent innovation in clutch type LSD's in the use of carbon friction material instead of metallic clutch disc material. Carbon has many advantages when put to use in a clutch type diff including twice the locking strenth as a result of a higher coefficent of friction, greatly increased service life, and virtually noiseless operation. In other words, many of the negative aspects assosiated with clutch type LSDs are eliminated via the use of carbon friction material, with the only downside being higher purchase price.(Carbonetic makes these)

VISCOUS-TYPE LSDsAre the most prevalent of the speed sensitive LSDs on the market. Two of the most popular platforms on the spo-com scene today, the S13 & S14 Nissan 240SXs, came with viscus LSDs as a factory option. These LSDs use fairly simple design that includes a cylindrical chamber of fluid filled with a stack of perforated discs that rotate with the drive axles. These discs do not come in contact with each other, but instead move throught a silicons-based fluid. The faster these discs spin, the more the fluid thickens and resists this motion. So if one wheel loses traction and begins to spin, the viscous fluid on that side of the diff will try to catch up with the faster moving discs, dragging the slower moving discs on the other side along for the ride. This transfers more torque to the slower moving wheel, which also happens to be the wheel that is not slipping and therefore better able to put power to the ground. This simple design has pros and cons.

The PROs:1) Being that it engauges torque transfer in a gradual and "soft" manner that does not disrupt the driving experience.

The CONs 1) There is more power lose with a viscous type LSD than a gear type.

2) Viscus diffs do not stand up well to repeated abuse since the fluid heats up and can permentantly lose its torque-transferring abillity if severly over cooked. 3) Generally speaking, after about 60K miles a viscus type diff loses its limited slip characteristics and behaves like a standard open differental.

4) Because the viscus fluid is sealed in a separate compartment from the rest of the diff cannot be replaced or otherwise serviced

As a result of the relatively short lifespan and fairly mild torque-transferring capabilities of a viscus limited slip differentials, most owners tend to upgrade to a gear type LSD once there viscous units are worn.

NOW U KNOW THE DIFFRENCE BETWEEN DIFFERENTIALS! I hope this helps people and answers people questions

(Most of my imformation I wrote was quoted from the August 07 issue of Modified Mag. I take no credit for any iinformation that is correct or incorrect. But to my knowlege of diffs this article is very credible.)

* For the record I would like to appologize for basicly writing the same thing ISUJinX wrote. Only after writing my post I read the whole thread and saw his. Sry*
Modified by rcabrita at 8:28 PM 8/14/2007