Review – Nismo GT LSD Pro For Nissan 240SX/Silvia
By Staff, Photography by Joey Leh
When it comes to 240SXs, a limited-slip differential is a must. Look at it this way – when a S13 or S14 (or any rear-drive car, really – Ed.) goes around a corner, its rear wheels travel in two different arcs and thus the two wheels are moving at different speeds.
With an open differential, the same amount of torque is distributed to both wheels at all times and as you corner harder and one tire begins to lose traction, that tire will go up in smoke and continue to do so unless you ease off the gas.
As the tire spins into dust, that wheel is exhibiting a much higher wheel speed than the wheel opposite of it. The problem with this is that the non-spinning wheel, the one with grip, will ultimately be fed the same low amount of torque that the spinning wheel is capable of holding.
A limited-slip differential limits the difference in wheel speed between the drive wheels by diverting torque from the spinning wheel over to the non-spinning wheel. This allows you to take advantage of a greater overall level of grip and to play more with the slip angle of the rear tires, allowing a driver to easily play with the balance of the car using the throttle.
For the best balance and power application, you’ll want a LSD that is responsive and provides a smooth, easy breakaway at the limit. For 240SXs, some of the best parts are made by Nissan’s own racing division – Nismo.
Enter the adjustable, clutch-type Nismo GT L.S.D Pro, distributed in the US by engine parts manufacturer Tomei. Clutch-type LSDs work by using springs that apply an “initial torque” to the clutch plates found within the LSD itself.
As one wheel begins to spin more than the other, it locks the clutches together, transferring power to the opposite wheel. A higher initial torque value or tighter clutch pack will allow less speed differential between the wheels, locking the wheels together sooner. Drifters will often use a higher initial torque value than road racers as they actually want their cars to kick out soon after applying the gas during cornering.
Unique on the market, the GT L.S.D. Pro features an externally adjustable initial torque setting. The standard Nismo GT L.S.D. makes use of 20 clutch plates to help smooth over the locking transition. The GT L.S.D. Pro then adds three grooves of different depth to its pinion mate shaft, which is connected externally to a 19mm head.
By unbolting the right side axle and popping off the stub axle, a ratchet and socket can be inserted to turn the pinion mate shaft left (47.0 lb-ft initial torque), center (61.5 lb-ft), and right (101 lb-ft). With this capability, the LSD can be set trackside to compensate for power, tires or even the difference between a drift day and a track day. This level of fine-tuning, for changes in parts and conditions, is not normally found in a LSD.
SR Motorcars in Gardena, CA handled the Nismo LSD install and it dropped right in without any trouble, although it was all too easy to be found playing with the external adjustment of the LSD. Impressively, the Nismo kit is all-inclusive. In the box was the LSD, fluid, pumpkin cover gasket, side bearings, new ring gear bolts, and axle stubs.
The LSD uses pure synthetic 80W-90 gear oil, which isn’t too common at the local Pep Boys. Be sure to have another jug on hand for a change following initial break-in. Nismo suggests a break-in of 186-miles at no more than 37mph.
The only downside, of course, to a kit of this caliber is the price. There are much cheaper LSDs on the market for the 240SX but these other kits don’t include everything you’ll need and often come with compromises such as noise or poor grabbing characteristics across the clutch faces. Chatter, clanking and noise-free, the GT L.S.D. Pro has proven to be quite the usable street LSD.
We set our GT L.S.D. Pro to the low setting, in order to soften the rear breakaway characteristics for track use, and hit Buttonwillow Raceway in our tester S13 240SX fastback. Our test car was equipped with a 200whp SR20DET, TEIN coilovers, Carbotech XP8 brake pads, and Michelin Pilot Sport Cup tires.
Compared to the test car’s original clutch-type LSD, the Nismo GT L.S.D. Pro was by far smoother on acceleration and provided great feedback to the rear end’s behavior leaving corners. Compared to the OEM viscous LSD, the Nismo GT L.S.D. Pro goes lap after lap, instead of overheating and failing to finish an entire run session. If our car made more power, the difference in endurance and torque handling would be even more immediate.
After trying out the LSD, we have to say that the low setting is highly recommended for all you non-drifters out there, on account of the S13 chassis’ notorious abundance of rear anti-squat geometry. At the higher settings, the LSD will break away sooner on corner exit, making the driver wait longer before being able to hit the gas. Of course, the higher lock also makes it easier to break the rear loose and keep it that way during drifts.
After another 550-miles on the car, we’ve only experienced the slightest of clunking when the car is cold and warming up. But once up to temperature, there is nothing from the LSD but glorious throttle steering. Faster and more fun? Works for us – just be sure to save up those pennies.
Contact
Tomei USA
www.tomeiusa.com
How much is this lsd? The adjustability looks like just what i need for my ITE racecar. My kaaz isn’t wearing so great.
I have the non Pro Nismo GT LSD in my S14. Works great. Adjustability would be cool though.