Message text written by "Randall Young"
>Anyone have some autocross results handy ? I don't recall a stock IRS
TR4A
ever beating out a comparable live axle car ...
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How often have you seen an autocross set up on a bumpy surface. Typically
they are held on a parking lot which tend to be flat and smooth. Course
designers usually eschew such things as potholes and gravel. Under such
circumstances a fixed beam will outperform an IRS setup. However, the IRS
wasn't meant to address that issue, it's design was to reduce unslung
weight and keep the wheels on the ground over irregular surfaces where the
live axle will loose contact.
Another feature of the IRS is a smoother ride. One problem with the
Triumph IRS setup is they took it too far and fitted springs that are too
soft. This caused excessive pitching, camber changes and bottoming out in
conditions where the live axle would not. I've found that with stock
springs I could steer the back end of my TR6 with the throttle. And it
worked in reverse of what you would expect. Open the throttle and the rear
end squats and the camber goes positive and the front end plows. Lift
throttle and the rear end hops up and the back end comes around. It will
suprise you if you're not expecting it. This is probably why S-T fitted a
front sway bar only. Stiffer springs solves a great many of these issues.
Stiffer springs also restores the "Sports Car Feel" that got lost somewhere
along the way.
Dave Massey
57 TR3 (Live axle)
71 T6 (IRS with Ted's springs and tube shocks. Much nicer, thank you)
80 TR8 (Live axle)
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