History of the INTENSE Limited Slip Differential

INTENSE First Gen LSD, introduced December 2001

The INTENSE First Gen LSD, designed by Jeff McClurg and introduced in December 2001, replaced the OEM thrust washers with four spring-loaded clutches. These clutches were thicker than the thrust washers, so we had to machine the side gears down for proper clearance. This design significantly outperformed stock differentials, but over time we found that there wasn't enough preload to produce good, consistent burnouts, and the spider gears could still score the pinion shaft (just like the stock differential) in a one-wheeled burnout situation.

The INTENSE Second Gen LSD, also designed by Jeff McClurg, was introduced in February 2004. It added significant preload via the center preloader with two heavy springs. By this time, we had paid the big bucks for a custom die to build very nicely knurled clutches, and we were able to get better results with two of the new clutches than we were with four of the old. We also switched to a custom made, oversized pinion shaft with pressed in bronze bushings, in an attempt to eliminate the pinion shaft scoring issue when a one-wheeled burnout would occur.

INTENSE Second Gen LSD, introduced February 2004

INTENSE Second Gen LSD (updated), released March 2005

In February 2005, the inventor of the previous LSD designs had left the company, and the following month he announced there was an issue with premature wear of the bronze bushings. We were able to verify this to be true by disassembling several vehicles, so an immediate short-term solution was put into place. We replaced all the Second Gen LSD’s in the field at no charge – even installing them for free for customers who brought their cars to our shop. The tranny filter was able to stop the bronze particles from contaminating any other components in the transaxle, so we recommended changing the LSD, then the filter and fluid. We also included a new filter (no charge) with all the updated LSD's that we shipped out and/or installed. Our Second Gen LSD updates incorporated the best features of the First Gen design (stock pinion shaft and spider gears) along with the best features of the Second Gen (better clutches and much more preload). Due to the nature of the bronze wear issue, a fix had to quickly be brought to market. While the fix addressed that single problem no time was available to address other areas in which we believed advances could be made.

Our goal with the new Third Gen LSD was to address as many shortcomings in previous designs as we could and ultimately provide the best clutch-based LSD possible. The INTENSE Third Gen LSD was designed by Nick Robinson of British Engineering, in conjunction with Tim King , Todd Allen and Scott Cook of INTENSE-Racing, and Rob Archer of Hoosier Performance. It is the culmination of nearly a year of testing that included a dozen cars (ranging from 225 to almost 900 horsepower), hundreds of burnouts and ~ 50,000 street miles.

INTENSE Third Gen LSD, introduced February 2006

We disassembled the first Third Gen prototype LSD after 1,000 400 horsepower street miles and two track days including burnouts with slicks. Total pinion shaft wear was not measurable by our machinist's gauge which is able to measure as little as .0001” (one ten-thousandth of an inch). Even today after several thousand miles and countless burnouts, the pieces still look the same, and no discernable wear is present.
Our original intention with the Third Gen design was to retain a preloader design similar to the one in our Second Gen LSD. But in analyzing the failures over the last year, we were able to engineer a completely different approach that has proven superior to the current design. It is now physically impossible for the preloader to shift or ‘walk’ out of place, which has led to cases of differential destruction in the past.

So at this point our Third Gen LSD effectively addresses all five of the previously known weaknesses of previous and competitive clutch-based designs:

• The new custom built pinion shaft is made from a material with much higher sheer strength and better finish than ever before. We're using hardened steel, such as C1541 steel and 4037 and 4140 alloy steels. Rockwell hardness measures C47 to C58 and single shear strength is 130,000 psi. This completely eliminates the possibility of the shaft bending, as we’ve seen previously on some of our highest horsepower cars.
• The preloader pins that were too short early on have been eliminated completely as part of an innovative new preloader design. The preloaders will no longer be able to disassemble themselves over time as the clutches wear.
• The bronze bushings that were wearing excessively have been replaced with full roller bearings. There will be no more bronze particles in the tranny pan, and the spider gears can no longer seize to the pinion shaft if you get into a one-wheeled burnout situation.
• The preloader has been completely reengineered to eliminate the possibility of it shifting or ‘walking’ out of place. This will keep the preloaders from getting digested by the spider gears, and regurgitated via the extension housing.
• Thrust washers have been added where the preloaders previously contacted the side gears, completely eliminating all wear in this area.
  

What about an upgrade?
The Third Gen LSD retails for $499.99 plus $100.00 core charge and shipping. The core charge is 100% refundable with the return of your original differential in "good" condition. Anyone returning a stock -HD differential core will receive a $100.00 core refund. Anyone returning a C-Ya LSD, Engineered Performance LSD, or other non-INTENSE LSD will receive a double core refund totaling $200.00. If you return any previous INTENSE LSD (Gen 1, Gen 2, Gen 2U) you will get a $350.00 refund making your final upgrade cost only $250.00.

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