In fact, the opposite is true. As with any small organization, it's not possible to "make" time to report on progress... we can only "take" time away from making progress. We'd much rather spend our time finalizing the design and fabricating the tooling required to build your dream car than sitting in front of the computer writing about it.

But enough of the excuses…. here's a look at some of the things that have been happening since the last update:

Over the past few months, a large number of jigs and fixtures have been fabricated. Many of these have required only a couple of hours or so while others have taken several weeks of machining, welding, testing and modifying to allow high quality parts to be produced efficiently. Items discussed in the balance of this update provide a sample of some of the requirements for this special tooling.

During the past few months, the development of the L6B has progressed slowly but steadily as we address the literally thousands of small but significant details that make the difference between a collection of parts and a truly builder-friendly kit. While some time has been devoted to cosmetic improvements, most of the effort has gone into finalizing the design of mechanical systems and fabricating tooling for the myriad of components required to facilitate their installation.

For many months after a break-in that virtually emptied the shop of engines, wheels, tires, tools and equipment, the prototype remained on axle stands. We are now happy to report that it is once again fitted with wheels and tires. The new three-piece racing wheels, fabricated by Kodiak Motorsports in Abbotsford BC, are magnificent and amazingly light considering their rather large size (the rear wheels are 18 by 12 inches to accommodate a pair of 335/30 by 18 tires). Please note that this information is not intended as an invitation for the midnight bandits to return for a second helping. If our new state-of-the-art security system does not sufficiently discourage them, Maxx the resident shop Rottweiler will be more than happy to demonstrate his prowess.

After months of searching, we finally found a source for modern headlights that not only provide an excellent combination of light intensity and distribution pattern, they are very easy to install and adjust. Incorporating these lights, however, has forced yet another change to the front end bodywork to reshape the headlight pockets and move the headlight bulkhead forward. The end result is a more attractive body design that has met with universal approval from everyone who has seen it.

One of the methods used to make the building of an L6B a fun experience (rather than a lesson in frustration) is the design of subassemblies that can be pre-assembled on the workbench before being installed in the chassis. An example of this, where a recent redesign has greatly simplified assembly, is the hydraulic system. In the new design, the entire pedal plate assembly (including the brake and clutch pedals, the remote adjustable brake balance bar, all three master cylinders, residual pressure valves, and many of the hydraulic hoses and their supports) is assembled as a module that is then secured in the chassis by the installation of only two bolts. This design improvement not only reduces the time spent curled uncomfortably under the dashboard, it provides an easy method for positioning the pedals to suit driver preference.

Another area that has required extensive development is the gear shift linkage. As most readers know, the L6B is a mid-engine car using a transaxle adapted from a rear-engine Porsche. This means that the shifter rod which protrudes from the forward end of the Porsche transaxle now faces rearward. To accommodate this, the interconnecting mechanical linkage must be routed from the rear of the transaxle, around the engine and back to the centerline of the car, then forward to the driver operated shift lever (all of this while maintaining the correct relationship between the shift lever position and the selected gear). This is not a new problem and it has been solved many times by many different design concepts on many different cars, including every one of those ubiquitous Formula 1200s.

While most of these shifter designs have been made to work, few of the drivers forced to use them are truly satisfied with their operating characteristics. The two most common complaints are stiffness or binding and imprecise shifting. The recently completed L6B shift linkage design has successfully eliminated both of these deficiencies.

To select a particular gear, the shifter rod that exits the rear of the transaxle must be subjected to a combination of rotational and translational (in/out) motions. Most previous designs have attempted to address both of these motions simultaneously with a single mechanical linkage. Typically, these systems have relied on either (a) a combination of torque tubes, push/pull rods, pivots, and universal joints (which tends to be awkward, stiff and imprecise due to the high forces imposed by operation the joints at strange angles) or (b) a push-pull “flexible” cable that, due to the requirement to “push-on-a-rope”, tends to be large, inflexible, stiff and sluggish while completely obliterating any tactile feedback from the transaxle.

The L6B approach is to completely separate the rotational and translational motions so that each can be independently optimized without being compromised by the other. This we do by using four lightweight Bowden cables…two for rotational motion and two for translational. By using two cables for each operating mode, each cable is active only in tension. This allows the cables to be very small and, by the use of multi-stranded stainless steel wire, extremely flexible. This high flexibility, coupled with a very slippery high density polyethylene conduit lining, reduces the cable drag to a very low level.

The result of all of this is a shifter system with an operating friction so low that the only noticeable resistance to the movement of the shift lever is that produced by the transaxle. What this means to the driver is that each detent in the transaxle can be very easily felt from the shift lever. This allows each gear to be precisely selected based on guidance from the transaxle, not from a Ferrari style shifter gate or the need to remember just how hard to push or pull for each gear.

A racing team owner who visited the shop a few months ago mentioned that he has seen several instances where one of his Porsche drivers has missed a shift (and subsequently blown an engine) due to a tendency for the shift lever to move when the engine and transaxle rotate in their rubber mounts under high engine torque. An advantage of the L6_B shifter concept is that the use of low friction cables mechanically references the shift lever to the transaxle, not to the chassis. The significance of this is that, when the engine and transaxle move in their rubber mounts, the shift lever remains stationary. While, to be honest, this was not a consideration during the development of the L6B shifter concept, it’s always a good feeling when you discover that you solved a problem before you even knew it existed.

Although the shift linkage concept was designed and prototyped some time ago, only recently have the detail designs, drawings and production tooling for all the components been completed. The prototype chassis has now been completely retrofitted with production shift linkage components and the shifter operation is outstanding.

From September, 2005

If you have visited the Lawrence Technologies site before you have already discovered that we have a new URL on the web with a shorter address. We have done this in preparation for a stronger web presence and to establish key e-mail addresses to a simpler domain.

Work has progressed nicely. The appearance of the front body clamshell has been altered for a sleeker and more aerodynamic look and to make room for the larger width tires necessary in racing applications. Stay tuned for updated information from the chief designer, Peter Lawrence, and for new photographs.