Greetings,
FWIW, and hoping this may be helpful to other suspension/chassis tuners, here's what I've done to the car:
Frame/body:
1.) 1" x 3" x 0.120"- wall rectangular steel tubing attached to
bottom of side frame rails, extending from front wheel wells
to just in front of rear tires.
2.) Front frame triangular brace.
3.) Front fenders with original inner well removed from inside
fender and reconstructed with 16-ga sheet metal, to provide
absolute maximum inner clearance for wide tires, and to
improve fender rigidity.
4.) Trunk area reinforced with 1"-dia, 0.060"-wall steel tubing,
running from base of C-pillar, down to trunk floor next to
#7 bushing mounts.
5.) Rear seat area completely skinned with 16-ga sheetmetal.
6.) Diagonal braces at top of radiator support to inner fender
wells added. (Mysteriously, the car didn't have them
originally.)
7.) Solid Delrin bushings at #1 body location.
8.) Stock body bushings for a 1978 Malibu, for locations #2 - #6,
top/bottom all, plus #5.
9.) PU bushings left over from an Energy Suspension bushing kit,
at #7.
10.) Car weight with 1/2-tank gas and no occupants - 3,250 lb.
Weight distribution: 52% front, 48% rear. Lots and lots
of work, and more than a little money, to achieve this weight
distribution.
Suspension:
1.) Polygraphite PU bushings at all points, save for upper front
control arms, and upper differential case. There - original
factory rubber. Even though complex movement of rear
control arms could theoretically cause binding, I've never had
the slightest indication of such, even when introducing severe
roll to the rear by traveling over 6"- tall curbs and the like.
The PU suspension bushings are now on their fifth year of
use on the car.
I've heard countless warnings of PU bushing binding on the
G-bodies, even from some very well respected names, without
hearing a shred of evidence to support the claim. I think the
presumption is that a bushing which is stiff compared to
rubber, and which rotates instead of torsionally deforming as
does a rubber bushing under normal deflection, creates the
impression that it must bind once twisted in a side-loaded
condition. Again, on several G-bodies that I've tried, I've
never had this problem happen.
Does anyone out there have any proof that they do bind?
While I can't offer definitive proof that they would never
bind on our cars under * every * conceivable circumstance,
I don't buy the claim for one second that the bindings must
bind "from the physics of the situation." And, by the way,
I'm a physicist.
2.) Lower front control arms lengthened 0.56"
3.) Upper front control arm cross-shafts lowered approx. 0.70".
Alignment settings: +1/16" toe-in, +4 deg caster, -1.2 deg
camber.
4.) Approx. 420 lb/in front springs, cut down from originals.
Front ride height approx. 1" lower than stock.
5.) Bilstein shocks at all corners.
6.) 1-5/16" Hellwig solid front sway bar, with PU bushings
at all attachment points.
7.) Firestone SZ-50 255 - 45 ZR 17" at all corners, no contact
except imperceptible rub on sway bar at full steering lock.
8.) Guldstrandt 35PSI Saginaw 800 steering box.
9.) Rear control arms fully boxed.
10.) Lower rear attachment points for rear lower control arms
dropped by 2" by welding extensions to axle brackets.
(eliminates roll-understeer designed into rear by GM, and
creates 125% anti-squat at stock ride height, vs. 50% anti-
squat designed by GM.)
11.) 138lb/in linear springs for rear.
12.) Custom 1-1/8" Hellwig sway bar for rear.
13.) Baer racing "touring" disc brakes at front; stock light-alloy
drums at rear; adjustable rear proportioning valve.
The results of all of these modifications: two racers have driven this car. One is a cricle-track guy; the other a drag-strip/road race guy. Both independently told me, that the car feels very, very much like a C5 Corvette. Since they've both driven C5's and I haven't, I can't make the direct comparison, but from all that I've read and heard, it sounds like getting a G-body to behave anything like a C5 in the ride/handling department is a major accomplishment. The only quantitative data I have is 0.97g steady-state cornering acceleration (although this is with the tires worn with not much tread depth left.)
"Ordinary" hot-rodders that have driven the car, who are used mostly to '60's through '80's performance cars, just shake their heads in disbelief at the way the car handles and rides.
My point of writing all of this is not to blow my own horn - apologies in advance if it comes across this way - but my intention *is* to share a formula that works exceptionally well with the readers here, so that may benefit from, and hopefully improve on, the combination which I've found works best for street handling/ride/performance on the G-bodies, after some 19 years of experience. And even what I've described is by no means the limit - but further modifications will tend to involve much more work, cost more money, and will tend to intrude in the cabin space.
Best regards!
MAP
