But a bad behaviour at speed might conceal other issues. I would be checking the car properly. These things were built to be run flat out on the autobahn.... 130 should be a piece of cake...

If it gets squirrley at 120 - then in the rain or other slick surface it will also exhibit bad behavior.

JBO, I am aware of new car performance vs old and I do not expect my SC to be rocket ship by any means, I guess I was just a little shocked by the hairy high speed performance of my "dream car". Like many of the 35-40 yr old 911 owners, I dreamed of owning one of these cars since I was in grade school. I just felt a bit let down this morning. Sorry if it sounds like whining.

I can count on one hand how many times I have been over 110 mph (on the ground at least) in the last five yrs. I do not engage in "street racing". This morning I just had a hankering to check out the high speed traits of my car and a high speed crotch rocket passing me on a straight clear section of back road was just enough to coax me into a short WFO speed run.

Maybe I missed it, but I didn't see you ever mention the shocks. That could be the problem. There's definitely something wrong. My '88 felt stable up until about 140 and then felt a little light, but not scary, and that was with really bad shocks (found that out after).

Good point Steve -

Tie rods and tire pressure. Pressure needs to go up to run at speed.

If the car is lowered already, as speed increases as does downforce thus making the front end even lower? So if Tim doesn't have the bump-steer kit, I am picturing his tierods at a pretty severe angle instead of parallel as they should be. So theoretically, as Tim's speed increases his toe is increasing as well? Just a guess.

Tim, for years I've set my own alignments using the string / tape measure method on my H2O cooled VW's. I brought my '74 to a prof. to have the alignment done. Money well spent. -John

p.s. Check your tire pressures too.

My shocks are probably shot, I am in the process of obtaining new front cartridges. The section of road I was on was flat and smooth, so I assumed that the shocks were not playing a role. My ball joints have no discernable play. I repacked my front wheel bearings when I rebuilt my calipers, my rear wheel bearings are tight and I recently freshened up my steering rack with new bearings when I installed the turbo tie rods.
I am fairly confident that my suspension is solid (except the shocks).

I wonder if my front end is too high compared to the rear, allowing the front to get light? When I checked my ride hieght, it seemed after searching the archives, that I was pretty good compared to what others were running (24.75 frt, 24.25 rear).

Another thing to consider is tires. I have never heard anything good about Avons on 911s. On heavier 928s yes, but not on 911s. I had the same problem with a set of Dunop 9000 that nearly threw me off the road at 100+ speeds, that disappeared with other tires.

I think your F/R ride heights are fine. Were these done properly? I still don't think I have read if you have the bump steer kit or not.

Shocks and alignment sound like good areas to check. Maybe you can try another brand of tire by swapping w/ another Pelicanite.

My car has no rear spoiler and 15" ballons for tires. Yet the car hunkers down and actually feels better as speeds rise to 130.

Keep the faith. You are a pilot. Lose the deathgrip, you know it is not necessary.

If you know the shocks need replacing, then that would be next. More Negative on the front too.

Don't worry, you will have this behind you soon enough and your smile will return. Either in your car or just go up in the plane to get your mind back into its happy place :) .

Are there any Porsche shops (i.e race shops)near you who can align it for you after you replace the shocks. Find one and together you will have her sorted out. That's what I did on my SC and Carerra, now I do most of my own work, and corroborate with them (live and on-line) prior and after. An good Tuner will help you accomplish your golas. Good luck.

Regards,

If each wheel is set at 1/16, then that's 1/8 total toe, which should be enough. If its 1/16th total toe, maybe not.

If you don't know about the shocks, try that first. All 4.

What about the road surface? At 130, surfaces on which the car might tend to tramline can really make things interesting.

No bump steer kit, but I could easily install one if you think my lowered suspension at speed is compressing enough to change my slight toe-in at rest to toe out at high speed.

Tim... bump steer kit is not a big deal... Trust me... I redesigned my whole front suspension and had a long conversation with the "experts" (Steve Weiner for one) about it...

Unless you have raised spindles and your car is sitting very low not having it should not be the cause of the behaviour you are experiencing.

Shocks
Sways

Quite a bit of air heads under the front of an SC - mine was properly setup, yet still felt odd after about 120 mph - same as yours.

Bernard, the death grip came on probably at about 110 due to the perceived impending doom!:D

I am a fingertip flier under most circumstances.

My lowered and self aligned (strings, electronic level, anti-friction stands) 325i and my old trusty 951 (self aligned also) both feel much more stable at speeds over 100 FWIW.

Unfortunately there a no good shops that have experience doing alignments on older euro cars in my area. (In fact just having them change and balance tires is a major sore spot) I have gotten to the point where I basically will not let any of these places touch my older euro cars anymore. I bought a lift and other than head re-working, line boring and tire mounting/balancing (someday I WILL buy a used electrinic balancer), I am a hardcore DIY guy. If I had a TRE or John Walker nearby, I might consider taking the car in. The Porsche stealership in town is a joke when it comes to older cars.
Man I need to stop, my blood pressure is rising!:D

I think Flying Toaster may be on to it. You car has been lowered below the euro-spec height, but no bump steer reducing kit or parts have been installed. That's a recipe for dartiness that increases with speed for the reason FT mentioned. Couple that with lack of dampening from bad shocks, you should expect handling to be just what you experienced.

Re: 1st high speed SC run = disgust
 

951s are damn good high speed cars.

I will check out my steering geometry to see if the tie rod angles appear to be such that any appreciable toe out will result from a slight amount of suspension compression to to aero loading. I just assumed that it was not low enough to worry about and I admit I did not think of the toe changing issue when talking about bump steer.

These cars don't make downforce at speed with the standard aero aids. Only the lift is reduced, so they sit at normal height instead of raising up.

at 130 a road that normally seems smooth and flat is bound to have more imperfections than you ever realized.

24.75 is pretty low in the front. I thought anything lower than 25.5 needed bump steer.