THE JBL Roadster
When JBL Motorsports began designing this car, the engineering brief was to build a classic roadster that would provide a competitive edge in various types of racing/road situations while insuring the highest quality construction and the utilization of the finest components available in the racing industry.
As an integral part of the design process, there were some basic goals.
1. Produce a very stiff (minimum 24 HZ frequency) chassis with torsional numbers above 4500 lbs per degree.
2. Optimize the wheelbase to track ratios, the CG height and location, the Roll axis, as well as minimize the polar moment to reduce the yaw characteristics normally found in a front engine/rear drive chassis. (In other words, make the chassis behave as a mid-engine design.)
3. Produce suspension camber curves optimized for current radial tire construction, eliminating the need for excessive static negative camber angles as seen on most roadsters for track use. (This allows optimum slip angle generation, but greatly reduces tire wear and yields very even tire temperatures.)
4. Allow wheel rates in the 175 pound range to insure suspension compliance on rough surfaces (Maintain tire contact patch) and to provide for a pleasant ride for street use.
5. Provide driver aids, such as cockpit adjustable anti-roll bars and brake bias adjustment to allow for changing track and road conditions.
6. The design specifications must insure that all components are the highest quality available and that all critical components of the chassis be built in-house. For example, all chassis tubes and panels are machined on CNC mills and CNC sheet metal cutters. All brackets are Laser CNC produced. All attachment points (Pickup points, cross members, engine mounts, seat belt mounts, etc.) in the chassis are through inserts tig welded into the tubes. All suspension parts, such as A-arms, rockers, front uprights, anti-roll bars, their mounts, and blades are all produced in-house on state of the art CNC machinery.
7. The bodywork must capture the essence of the 60's roadster style, but allow for improved aerodynamics and packaging of the driver and mechanical components. In other words, if you were to build one today, it would look like the JBL.
These design goals have produced a chassis that has shown through its
performance and reliability to be a superior package for track and road usage.
photos © Curt Scott/Cobra Country 2002
A few random comments about the JBL
"A piece of rolling art..."
"I think if I had one of your cars, I'd
need a CLEAR Lexan body! What a piece of
"The chassis setups used today by
the various manufacturers - with the notable exception of the JBL - are
all fairly competitive with each other. The JBL is in a completely different
league...no, a completely different universe than all of the other replicas.
It's an engineering marvel, and I would love to have one. The chassis
is not only functional, but it's also one of the most beautifully finished
ones I've seen."
"I was out there with chuck in the
JBL cobra for a session. He was going thru turn 9 faster than I was, its
still a white knuckle corner for me. That JBL is one of the flatter cars
thru corners I have seen."
"The four fastest Cobras that I have
ever put a stopwatch to out at Willow are: -A Shelby Spec racer, -Scott
"Coyled"'s Hi Tech -Gordon Levy in a small block based FFR.
-Chuck Miller in his 351w crate powered JBL "
"We gave this car the "BEST
ENGINEERING AWARD" at this years Run & Gun as it the most
advanced chassis that we have ever seen. From a design standpoint,
it stands above anything here. And it's track performance proved
that we were correct in giving this award. This car is
"I finally got to see one up close at the
Knott's show this year, and the craftsmanship that goes into that bad boy
"The JBL that Brent saw at the Knott's
show was owned by Chuck Miller in our club here in SD, and he drives the
snot out of the car! It was one of the very first cars, and Chuck drives
it several times a year at Willow, and is also a daily driver. No major
problems to report, and he is consistently one of the fastest cars at
Willow. I understand that they have made several improvements to the car
that Chuck has. Very nice car that always garners attention."
"If it is the ultimate handling kit
car that you want, then the JBL is probably on the top of that list, with
most of the others close behind. If it's authenticity that you want, then
JBL is not the choice. Others are much more authentic but pay the price
in handling compared to the JBL."
"This chassis is without a doubt the
trickest, most advanced piece that we have ever seen in a kit car. It
posted the fastest times ever recorded on the MT slalom course and over
1.2 g's on the skidpad. Unfortunately, a oil line to the cooler broke
before we could get a run in on the drag strip. A very serious kit indeed!
"Even though you asked for 'first
hand' experience, I thought that I would tell you what I found in my research
for the best handling kit cars. My own car, a Superformance, holds the
road pretty well on 17" low profile tires (~1 G), but there is another
manufacturer's car with clearly superior specifications for lateral G's:
JBL. If you look at the JBL suspension, and I have, you will see that
it is unique among kit cars. The published specification is about 1.4
G's for lateral acceleration, about 40 % better than I've found
anywhere else among kit car manufacturers".
"If you are serious about hard core
racing...take a very close look at the JBL, frame and suspension is seriously
"We chose JBL for our car because we felt
this was the highest performance car available."
"From what I could tell, the JBL Roadster
is the result of giving a competent designer his way. The car has a
semi-monocoque chassis that's tubular steel with steel sheets to minimize
twist. For track work, a lower aluminum sheet is bolted up to the bottom of
the frame, enclosing the engine/transmission tunnel area and giving the chassis the
structural rigidity of a NASCAR racer".
For engineering and technical information: