Mike,
I will try to hit the high spots as it would be tough to try to describe in
detail something that your not seeing in pictures or better yet having the car
on a rack. Tom has a digital camera and we may just do that...i.e. put
together a picture presentation that can be sent right to your desk top.
A little background..The current crop of Tiger Road race cars is best
exemplified by Dale Akuszewski's, Al Denson's, Dan Walters, Doug Yip, Stark
Shelby ect..I won't go into all the modifications, which are considerable, but
they all share the same basic design or concepts..
Namely, none of them have race car solutions but rather what Griggs and others
term street solutions to such problems as fixing the ackermen angle problem
ect.
The reason is they can't. They are all constrained by the racing organization
rules.
What they left with is to work around the edges and mitigate as much as
possible the impact of the design flaws without really fixing them. They have
done a good job of unbinding the suspension and actually getting it to work as
good as it can given the design. This may not sound like much, but 90% of the
traditional mods we have all made to the car over the years basically just
eliminated what little suspension travel and action the car had to begin with.
Anyway, Griggs measured all the suspension pickup points, angles, ect, and put
the numbers through his proprietary computer model, looked at the spaces
available to work in and came up with a broad plan to totally fix the design
limitations of the car and turn it into a perfectly tunable race car. In the
meantime I formulated my own rules i.e. The car had to retain all of what
makes it a Tiger such as leaf springs, the front cross member ect.. Further,
no sheet metal mods such as fender flares or cutting out inner panels ect. The
best way to put it is that the solution had to be packaged inside the current
structure like the quick ratio steering for example..The outside is just
normal stock Tiger, with a solution living inside. The stated purpose or goal
was an all around performance/sports touring car perfectly capable of safe
open track wanna-be road racing. I don't care about auto-crossing.
So, naturally his fix and my rules were contradictory. One wouln't work with
the other. Griggs wanted to fix the car since the fundamental weight balance
was so good and the basic platform was pretty stiff except for the front of
the car. He sent me away to think about it.
I decided to keep my rules and go as far as possible with the street solution
with a big big emphasis on safety...He's a long time racer so the idea of
doing 3/4's of job wasn't his favorite choice but he agreed to do it since we
were fixing all the potential safety problems.
Enough already!!! Here is what we did to the rear end
Adjustable torque arm running from the X to the Differential. Slides forward
and back adjusting the amount of bite. Also has an adjustable link running to
the top of the differential used to set the pinion angle. A watts link has
been installed which pivots off a large urethane bushing located in a box
built around the pumpkin assembly...fully adjustable heim jointed. The shocks
were slightly relocated to vertical. There are two control arms running
forward which look like heim jointed traction masters. They are part of a
"slider assembly marrying the rear axle the leaf springs. (Sprint car
technology from the 70"s) The rear axle actually slides back and forth as it
moves up through the arc so the control arms are not fixed length like
traction masters. Marks in the grease indicate that it moves about 3/8". The
suspension has 3" of travel both directions. Springs are custom solid bushed
units very light compared to most Tigers. Shocks are custom built 12 position
double adjustable Bump & Rebound Koni's also set towards the lighter side.
Rear end is a Detroit Tru-Trak in the stock Dana 44 housing with Dales disc
brakes. Griggs has built two more of this setup, only they scrapped the leaf
springs in favor of coil overs... a better setup but outside my rules.
The Front:
w/ Dale's race car crossmember... steering sunk back into the cross member as
far as the damper on the engine would allow. Quich ratio rack w/ track rod
adjusters and heim jointed bump steer kit replacing tie rod ends. Bigger
stronger spindle building in the "dropped" aspect of the Super Minx spindle.
Dales Aluminum hub and bearing assembly. Stainless racing duty fulcrum pins
and alum/nylon greaseable bushings at all pickup points. Custom steering arm
disguised as the MGB unit w/o the spacer bushing and even a little farther
reach forward. Upper and lower ball joints replaced w/ modern for racing screw
in style. Dale's adjustable 5 position front sway bar. Buildsport 4-Piston
disc brakes w/ ventilated Rotor..This is a Lockheed unit two sizes up from the
standard Tiger. Found on the Austin Princess and all London Taxi Cabs. Custom
aluminum double adjustable Koni's.
The stock front suspension is so bound up its not funny..When you change the
way the sway bar mounts and allow the suspension to move, suddenly you need
much stiffer front coils. Bound up, 300-400# springs seem stiff...Unbound
500-600# springs seem silky smooth.
All these changes produce a really nice touring car suspension. Doesn't have
that go-kart feel of most modified Tigers, doesn't clang and bang over tar
strips.. It really moves and works on the race track. Dale says its faster
than his race car on the track from a suspension point of view. The car is
very predictable and controllable..gone is the white knuckle Tiger norm..
Sorry to be so long but you asked for this kind of punishment. This probably
doesn't help much w/o seeing it and of course, I wasn't able to explain it
from an engineering perspective....
Best Regards,
Ken Mattice
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