Speed Stability

From what I've heard . . .

the front end gets light at around 130, the rear @ 180.

this, of course, is without aerodynamic aids.

As-stock, they're pretty stable, but a better 'feel' comes from more caster than the factory used. The std front end is limited in its caster relative to most other similar cars. Offset a-arm bushings, all the caster-shims on one side of the upright and even machining one side of the upright still only gives marginal caster for really high-speed work. And of course, a front spoiler of your choice or at least a 3 degree nose-down 'rake' will increase stability. Note than at 100 mph, none of this is really needed; at 140 & above, all of it is. Most well-tuned Panteras with a stock engine will run 150 at least for a while, so this is not a theoretical requirement unless you only drive within city limits.

I know these speedometers read a little Higher than what the actual speed is. The other day I had the needle just going past the 140 Mark, and the nose never felt light (not yet), I still had total steering control, NO vibrations, NO wander. There is NO front spoiler of any kind. There IS a rear delta wing. I was a little nervous as I know that the suspension bushings are 30 years old. Sure to be my next "fix-it" project. I have since gone from the P215/60-15's in the front to P205/50-15's.(they are 1" wider tread with almost a 3" smaller diameter. This dropped the nose edge height(NO "L" bumper)1-1/8", (from 19.0" down to 17-7/8" from the ground surface). Regards, Marlin.

[This message has been edited by MARLIN JACK (edited 02-08-2003).]

[This message has been edited by MARLIN JACK (edited 02-08-2003).]

When my car was set up as a GTS with a revson front spoiler and no rear spoiler,koni coil overs set as low as they could go with Gt4 springs with a slight nose down rake it was perfectly stable at about 165mph?Speedo read 180 i think(didnt look at it too long)stuff goes by with a quickness!When i reset the car up as a GT5 with a modified gt5 front spoiler(no fog light holes)Rear delta wing(wing definitly has drag but it works!)Shorter sidewall tires it feels better but ive only done about 145mph with this set up so far.I once drove the car with only the rear delta wing on and no front spoiler there was definitly a lighter front end feel at about 130?It scared me so i backed off.Ive heard stories of stock unspoilered cars getting spuirly around 150mph but i dont know how much true vs rumor.hope this helps.

If you wanna go fast...and I mean really fast..you need a nice big spoiler in the front to redirect all that air around the car.

A rear wing works if it sits high enough to catch clean air. The stock position is a bit too low.

Soon after I bought my car, I ran it up about to max speed. No spoilers, air dams, or rear wings, stock bodied '72L (with L bumper). It felt great at 90 MPH, and then about 130 the steering was noticeably lighter, above 140-145 was another feeling change and at 155 steering was beginning to feel nervously light, but then it was 155.
Tires & wheels were 7" front 8" rear campys, with Euro T/As (195 and 305).
Someday I'll get the front spoiler. I'm looking for a ABS plastic GTS-style with ducts. Have one for sale ?

Chuck

There was a nice article run in the POCA news last Fall concerning a '71 Pantera street car running at Bonneville. Short version: the car was so unstable at 130 mph, that two drivers could barely hold the car in a straight line for 4 miles, and one eventually spun the car. This Pantera had no rake, no spoiler and no rear wing. It may not apply equally to all cars, but I'd say that for any speeds over 100 mph, some changes from stock will be needed, and if you wish to disprove this, find a BIG WIDE area to try out your theories responsibly. Muroc dry lake near Edwards AFB is one such area that fits the bill. SCTA (Southern CA Timing Ass'n) sponsors top-end runs for any cars 3 or 4 times a year.

another feeling change and at 155 steering was beginning to feel nervously light, but then it was 155.
Tires & wheels were 7" front 8" rear campys, with Euro T/As (195 and 305).


Uh, those tires are only supposed to be good up to 130 in bursts. Just don't kill yerself before I can give you the 125 I owe you...

I vill bring this issue up in the PI magazine. As part of "wheels and tires" story. Wheels and tires are closley related to the Pantera stability as most front tires nowdays has a to large a diameter. We can not get the car as low as needed. As already mentioned by Marlin. A low nose is vital for Pantera stability. Bjorn Carapi has gone 211 mph with a stock body, low nose, without problem. There was no wings, in order to get a good CW. This rake with more aerodynamic devices, like spoiler, will make it even better. But as soon as the car get to much ride height, the wrong rake, i will be unstable.
Goran M.