Reply to "twitchy, nervous steering on unsmooth roads"

The Pantera as delivered does not have enough caster adjustment in the front suspension to play these games on rough roads. Most Panteras can't quite get 2 degrees per side; Corvettes and other powerful sportscars have 6 degrees. By machining the front upper ball joint housings on one side, then making an extra shim pack, one can gain about one more degree. Offset polyurethane suspension bushings can gain about another degree, making almost enough for hi-speed games. A second Pantera problem is bump-steer. Several correction systems are available but the simplest is a spacer between the rack and body mount to lower the steering arms so they're more level. I assume the stock spring spacers are gone. Yet another problem area is scrub-radius: with stock 7" wheels, the Pantera is very bad with over 3/4" of scrub. Substituting 8" x 15 Campys that have the extra width biased inboard as-stock, fixes most of this problem. Pat Mical in Massachusetts [www.detomasopantera.net] has custom upper front a-arms that allow more than 6 degrees of caster by themselves, and is well versed in making Panteras handle. He;s currently taking care of suspension tuning for a Gp 4 now pro- racing on the East Coast

Wider wheels and big tires make this nervousness worse, as does misaligned or bent rear suspension components. And before you say that your car is not bent, be aware that ALL Panteras including mine have collapsed their rear subframes measurably in the last 30 years. In many caees, so much that one cannot properly align the rear wheels without adjustable upper rear a-arms. Some frame work and a decent adjustable over-the tranny brace will alleviate this; the stock brace is a joke. Vendor-supplied stiffening systems will also help but the real fix is seam-welding the whole car PLUS all the things listed above. Or stay off rough roads at speed.....

As far as running low tire pressures, my experience using radial tires including gumballs in autocross and limited track events, points toward running at least 42 psi in the front tires (size 245-50x 15s), and 46-48 psi in the rear (275-50x 15s), with a 5/8" front and a 7/8" rear anti-swaybar (stock is 3/4" at both ends). Some of my 'Vette competitors ran as much as 52 psi in radials, with bigger tires than mine. More precise steering results from the higher pressures with little if any traction change. IMHO, tire pressure is a 'tweek' after everything else is right, not a primary tuning tool. Worked for me....