Look, folks.... I'm never gonna be able to do this by myself, if at
all. So, I'm going to go ahead and "unveil" my concept for the ultimate,
and indeed, PERFECT TR6 (TR4A-IRS/TR250/TR5) tube shock conversion. If you
all think it's absurd and ridiculous, you might just be right.
But if there are those who would like to see it become a reality,
and are interested in helping in the development where appropriate, by all
means let me know. I should say right here and now that I don't think
there's any MONEY in it. I've done this mostly just for fun, 'cuz I like
tinkering and designing things.
Is it superfluous? Maybe. Is it costly? Most likely. Is it
practical? Probably not. Does it present some challenging engineering
problems regarding shock valving? Apparently, yes. But, is it brilliant?
Well... I'll leave that up to the listerati...
The design is inspired by so many formula and prototype race cars.
It is also inspired by the complaints about the inadequacy of existing tube
shock kits, and the complaints about lever shocks. Back to the race cars,
any F1 buff knows that every F1 race car since the late 70's has
spring/damper units that are actuated indirectly via either a pushrod or a
pullrod. This does two things: It enables the designers to enclose the
dampers within the nose cones of these cars to reduce aerodynamic drag, (a
benefit we admittedly care NOTHING about) and it reduces unsprung weight.
The latter is of some importance, at least in relation to the aerodynamic
thing.
A brief description of my design: Lever shock bodies would be
replaced with a bolt-on "pivot bracket" of yet unknown construction. built
into the pivot bracket would be a short, large diameter machined shaft.
Also built into the pivot bracket would be an extension that, when
installed, would extend downward and toward the center of the car,
terminating under the rear diff cover. In place of the lever arm of the
lever shocks would be a rather large bellcrank, again of unknown
construction. This bellcrank would pivot around the same axis as the lever
arm from the lever shock, and would have the same acting radius. Also, it
would connect to the semi-trailing arm via the OEM drop-link. On the other
end of the bellcrank would be mounted one end of a telescopic shock. The
other "fixed" end of the shock would mount onto the end of that extension,
near the centerline of the car under the rear diff cover. The entire
assembly would fit within the space between the axle shaft and the rear
crossmember. However, the extensions would drop below the diff... but they
would not drop below the chassis. This system, it should be pointed out,
makes use of the OEM rebound stops in exactly the same way as do the levers.
Now, I've made many drawings and I've even built a model of a pivot
bracket and installed it on the car. It FITS!! I've taken careful
measurements and reproduced the drawings on the computer in an illustration
program, TO SCALE, and I am convinced that, aside from a tweak here and a
tweak there, this thing will fit and WORK.
The important thing to note is that the motion ratio between the
drop-link end of the bellcrank and the damper end of the bellcrank is NOT 1
to 1. It's more like 1 to .49. This creates all kinds of interesting
problems that are beyond my ability to resolve. To sum it up, the shock
would have to be stiffer than otherwise to compensate for the mechanical
advantage of the bellcrank over the shock.
Although the shock would have to be fairly short, (10.75" at full
bump and 13" at full rebound) I think the biggest obstacle will be the
valving.
It's a hair-brained idea, I know, but input is needed from experts
in the following fields:
Physics, shock absorber valving characteristics, welding/fabricating &
machine work.
Anyone who would like to tell me I'm nuts, please be gentle. All
others who either are motivated to help make this thing or who just want
to, well, tell me I'm nuts, throw cold water on me, tell me all the reasons
why this just won't work, please go right ahead. Also, if you'd like me to
e-mail you a .jpg image that shows the arrangement TO SCALE (25%) to
satisfy your curiousity, let me know.
But to those who want to dwell on the "WHY" question, please save
your typing fingers... I am fully aware that properly tweaked lever shocks
are, for all intents and purposes, reasonably adequate for the job. I'm
just trying to have a little fun!
Thank you.
Pete "Am I Crazy Or What?" Chadwell
1973 TR6
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