Guys,
I tried to post this a few days back, but was not quite up to speed with
Microsoft Outlook versus Outlook Express and other arcane aspects of the
Win95, etc. protocols. Anyway, here's a few of my comments regarding the
subject of Tiger Suspension:
Pardon me if I re-name this thread as I don't think we're talking about the
Tiger ID manual any more ( at least for the time being). Anyway, having
tried a lot of different setups over the years I have a few comments to add
to the already extensive comments on this topic.
First of all, I've come to the opinion that the place to start with
controlling suspension is with SPRINGS. Dick Guldstrand and others with a
lot more experience than any of us have the philosophy that springs are the
primary way to control suspension travel and roll stiffness, NOT sway bars.
The purpose of a sway bar within this philosophy is to fine tune roll
stiffness. Accordingly, use BIG springs and a small sway bar up front. By
BIG springs I mean at least 400 #/in. Depending on a variety of factors,
including your relationship with your chiropractor, you may want to go to
450 or even 500 #/in. The 400-450 range is still reasonable for the
street, again depending on your personal tastes. I am using 425 #/in and
use a 7/8" sway bar (3/4" is stock and went with very weak stock springs).
Recently, I have found a cheap and easy way to adjust front stiffness.
Buy a set of the rubber coil spring helpers from Pep Boys, etc., for about
$5 and add them to the front springs to increase stiffness. Changes ride
height scarcely at all and allows easy installation and removal to adjust
for street versus autocross (in for street, out for autocross). The
problem with using a big stiff sway bar (front or back) is that it takes
the "independent" out of you independent suspension. Granted, with a big
stiff sway bar you won't lean in the turns (good), but now both wheels are
essentially tied together and go up and down as a unit instead of
independently following the contour of the road/track. If you have soft
springs and the car wallows like a Buick, then after adding a big sway bar,
it will still wallow; just straight up and down. Now 400-500 #/in springs
might seem kind of stiff, but if you are running a track at high speed
(>100 mph) and hit even a fairly small bump the compression of your
suspension will be considerable if not controlled by rather stiff springs.
I think the principle here is to try and keep as many wheels on the ground
for as much of the time as possible, which independent suspension does
best. I advise not to use 330#/in (CAT) springs because they are too weak
for autocross etc., they sag, and other reasons I could mention. Go to
Coil Spring Specialties, Dale's Restorations, or other good source and get
a set of top quality springs. I think the cost is still not much over $100
bucks for a pair.
Now on to the rear suspension: The key here is to match it to the front
suspension. It's harder to adjust the rear roll stiffness directly if you
don't have an adjustable sway bar. This would be the only valid reason, in
my opinion, to install one. Most people like to set up their suspension
with a lot more roll stiffness up front because it gives them a more
predictable feel. Basically, with soft rear springs, the rear end just
follows the car around. However, if you want more cornering capability out
of your car, increase the rear springs and/or sway bar stiffness relative
to the front. Guys who race Porches complain bitterly about the car's
tendency to oversteer, but they do win!! A really neutral handling car is
a bit scary. Where to set the balance is a matter of what your are willing
to cope with and how good your reflexes are. I think about two more leaves
added to the stock rear springs is more-or-less about right, but you will
have to play around and, again, the rear setup depends on how stiff you are
up front (sounds like the basis for a bumper sticker). I could get into
the issue of roll steer in the back, but will defer this topic to a later
date.
Regarding the torque arm: A lot of folks out there like this approach.
Bolt-on traction bars have been a very good option and have the advantage
of being "stock" on a Tiger. My problem with the torque arm is that,
contrary to what you suggest, it adds to the tendency of the front end to
dive during braking. If you read Dan's tech notes he alludes to this fact
and the related tendency for the rear end to lose traction in reverse gear.
Also, I don't see any relationship between the torque arm and the Panhard
rod or Watts link. The torque arm does nothing I can see to limit
side-to-side motion of the axle. I've tried mine with and without the
Panhard rod and prefer it without. Can't really explain why, but it just
feels better without it. I know Dale tried a really nifty Watts link on
his vintage racer and took it off immediately after he tried it. He can't
explain it either, but then hardly any of us take the time to research
these issues. With the torque arm, or any other nifty new gadget, there's
a tendency to view it as a "magic bullet" that's going to solve all our
problems. Truth is, success is more a matter of getting all the parts to
work together which involves a fair amount of good engineering,
trial-and-error, and just plain hard work.
Now, I have a question for you. Can you please tell me a little more about
the "over-riders running on top of the springs"? I've been thinking about
something along these lines and would like to know how it is implemented in
some other vehicles. Thanks.
Bob Palmer
B9472134, SHO, etc.
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