Barney,
A couple of things come to mind, but it depends on the rules for your class.
1) lowering blocks
2) longer droop straps (or remove them altogether)
3) LSD
4) stiffer rear shocks (very stiff bump damping before 'blowoff')
You could also try removing a leaf to drop the ride height a little.
Don't remove any more or you just start lifting inside front.
You could do what I did for my race car and go along to a spring maker
and get him to manufacture a set to your custom requirements. Otherwise
you could get them to re-arch your existing set. For my car, I got the guy
to
make a set from fewer, thicker leaves that had very little arch in the first
place (practically flat). It is a spridget, I used 1 8mm thick main leaf and
a
single 4mm second leaf. That's it. Has the added advantage of less sideways
movement, less twist and no tramping. FYI, it cost me A$250 (or about US$150
or so), probably less than a new set from Moss (or equivilent)
As I said at the beginning, some or all of the above may not be allowable
depending on your class rules. If none of them are, put your old springs
back in
and use different valves in your lever arm shocks to acheive 4).
Mike
----Original Message-----
From: Barney Gaylord <barneymg@ntsource.com>
To: mgs@autox.team.net <mgs@autox.team.net>
Date: Monday, August 10, 1998 12:48 AM
Subject: Why new leaf springs may be a waste
>Lots of us like to special tune our engines for a bit of extra zip. And
>tires and springs and sway bars are frequently kicked around this list in
>the interest of better handling. So let's see if suspension tuning can
>tickle a serious note here.
>
>This recent discussion of lever shocks and suspension travel reminded me of
>a problem I have encountered with my MGA new leaf springs. Bear in mind
>that the front rebound buffers and the rear rebound straps are necessary to
>prevent damage to the shocks from over extension on airborn bounce.
>
>I've been autocrossing my MGA rather seriously for several years now.
>Stock class in SCCA allows only a select few changes to original equipment,
>among these are:
> (1) any DOT approved tires (has a tread patteren - not slicks)
> (2) any front anti-sway bar
>My current setup uses road racing tires with soft rubber compound on the
>track, and a 3/4" front sway bar packed tightly with polyurethane bushings.
>
>A couple years ago I had this package doing marvelous things, was winning
>regularly with SCCA, sometimes taking the event index trophy (ask later).
>The car had neutral handling on the road with standard radial tires (ala VW
>Beetle), and a little oversteer on the track with the race tires, very nice
>for autocrossing.
>
>Early spring last year I was preparing the car for Brit Run to the Sun -
>Alaska '97, and I thought it was a good idea to install new leaf springs to
>regain some ground clearance lost to nearly four decades of gradual sagging
>of the rear springs. So I did. And the trip was fantastic. But when the
>car returned to the track it had a rather dramatic change in personality.
>So here's the problem.
>
>The new springs make the body sit higher at the rear, as was intended. So
>now the rear axel has more upward travel available to the rubber frame
>bumpers, but less downward travel available before it hits the maximum
>length of the rebound straps. Sticky race tires on the car will induce a
>certain amount of body roll in hard cornering, in spite of the heavy front
>sway bar. As the car is approaching the limit of adhesion in hard
>cornering, the body roll gets to the point where the inside rear fender
>lifts until the rebound strap is stretched completely tight. At that point
>the rear roll stifness suddenly transitions to infinity. Then with just a
>little more body roll the inside rear wheel gets lifted right off the
>pavement.
>
>Now the car is running around on three wheels, and no matter what the
>spring rates, stiffness, shocks or sway bars are doing, the one outside
>rear tire is carrying about half the weight of the vehicle. That relative
>extra loading of the tire reduces its grip efficiency a bit, and the rear
>end lets loose and swings wide putting the car into a sever case of
>oversteer. Now I can generally get a handle on it (hang it sideways) and
>keep it from looping, but, it cannot corner any faster because of the loss
>of latteral traction, and it cannot accelerate because one drive wheel is
>in the air (open differential). Grrrrrrrr.
>
>This is precisely why most of our beloved LBCs will benefit substantially
>from a large front sway bar, the rear suspension is WAY too stiff. I was
>thinking that a LARGER front sway bar might help, but some friends tell me
>that the inside rear wheel is sometimes four inches off the pavement!
>Yikes! Stiffer front springs and softer rear springs may be in order, but
>in Stock class one is not allowed to change the springs from the stock
>part. Right about now I am seriously considering reinstalling the old
>sagging rear springs. Maybe nobody will notice and file a protest about
>changing the ride height. If they do, my car could get kicked into Street
>Prepared class, and I'm definitely not "prepared" for that.
>
>So waddaya think folks? Is this stuff worth a few cells af gray matter?
>
>Barney Gaylord
>1958 MGA with an attitude
>
> PS
>If you want to get a good handle on handling, read How To Make Your Car
>Handle, by Fred Puhn.
> BG
>
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