Anyone know what happened to the Herder Truggy in the Baja 500?
Team Kwik Racing
Team Kwik Racing
Some high dollar cars have already stopped using by-pass shocks and coil springs. They are using
single, very large gas pressure shocks (these can be identified by a “shaft” size of around 3
inches. (hollow of course) These provide damping and springing. The huge shaft-piston provides a
lot of fluid flow to work with both internally and externally out the top. This does not mean that
by-pass shocks and coil springs are obsolete. They are still winning races and will be around for a
while. And history has not been kind to gas-pressure-only springs in racing applications. So far, in dezert applications at least, internal by-pass shocks just can’t flow enough fluid at the right time and are not easy to tune like their tube covered counterparts.
One drawback to by-pass shocks are that they cause mechanical pressure spikes on the chassis
and control arms. These components then have to be made stronger. This raises sprung and
unsprung weight. A lot of control arm cracking is from this and often NOT from bushes, rocks or
“unexplainable” racing stresses. They also cannot hold the coil spring, so you have to mount
another shock just for that. This also adds weight and interferes with proper design of the upper
control arm on front suspensions. The by-pass tubes give the shock the critically needed position
sensitivity. This position sensitivity is just as critically needed by the spring. This is why coil-over
shocks are laid down, springs are stacked on top of each other or both. This is not done just to
give the overall “right spring rate.” It is done to create a custom spring rate at different positions
or "position sensitivity." Unfortunately, laying the shock down does not provide nearly enough
rising rate or more specifically the needed rates. Stacking springs does not provide it either
because there just is not enough room on any shock for enough of them the right size. You end up
with a compromise of mismatched spring and damping rates. If you watch closely at some of the
most successful cars like the Herbst’s Truggy for example, you can see the wheels actually stay up
and hang in place for nearly a full half second after hitting a big bump, before beginning to
descend during rebound. It’s quite amazing to watch. This is because of the very high damping
rate at the top of the piston travel but lack of matching high spring rate at that spot only. Right
now this all still works because of the brute strength and weight of the cars. As they become more
sophisticated and efficiently designed these drawbacks will become more pronounced. Herder’s
Truggy may well be another dilemma unfolding. Some of these vehicles are becoming too light to
work well with a 500 to 600 pound solid rear axle (with wheels, etc.). When unsprung weight
exceeds around 7% per corner (12 to 14% per axle) you will start have problems controlling axle-
chassis movement. Actually, 600 pounds unsprung in the rear of the heavy TT’s at over 6000
pounds (10%) is not far from Formula 1 ratios! (70 plus 70 or 140 in a 1400 lb car = 10%)
I apologize for not directly answering your question. But unless by-pass shocks get a little more
sophisticated, this is why they are slowly on their way out. I can tell you that front suspensions
will probably be using a simple single coil over unit with a flat rate spring and smooth, spike free
pressure application before long. How, is the real trick...
Was reading the oldest threads on this site and have come across some interesting and funny threads for sure.
Remember this post Fabricator? Haha, I think by pass shocks are still leading the game.
Bypass technology is a good example that if something works even just marginally, not only can there not be a problem with it but not one of the many millions of dollars spent on it can be called wasted. They say they like to keep things simple, but have no clue of what simple is. FWIW, there is a shock absorber available that is superior in every important way to the best state-of-the-art by-pass shock of today. Not that anyone would care, but it beats it on price too.Ahhh its easy...Use a link that increases the shocks leverage on the lower control arm throughout its travel.....Smooth rising spring and damping rate..