Driving fast on crappy roads, my CS is nervous

I live in Houston, home of the F150, and what might the crappiest roads in america. Im a new owner to porsche, the last time I drove was in 03 in a 330i. Thing is, my 07 caymans gets really jittery at 75. Could be that Im really used to having that damped numb steering, but in fast traffic, Im nervous to get it going any faster. I just had the wheels re-rebalanced, so the steering wheel isn't vibrating (as much). I leave the PASM in normal pretty much always. as for houston, i have all of 2 miles of smooth road, where the car seems in its element (we have concrete, not pavement here...). otherwise, its a constant battle of bumpy pavement, nose scrapes, and constant rowing the shifter in 1st and 2nd. I'll deal with the low speed stuff, but I don't like that nervous twitching at the higher speeds. Is it me? do you guys get that rock solid steering feel at 75+? Thanks for looking!

Welcome to the site - might help if we know a little more about your car: Did you buy it used, and any suspension mods? Do you know your wheel alignment settings? What tires and tire pressures are you running? The Cayman normally should feel well-planted and secure at 75, and actually at speeds well in excess of that - this is a car that is designed to cruise the autobahn at 120 mph+. The steering does feel light at speed, but I don't think the car should feel "nervous". As a rule, I think that Porsches also handle fairly rough roads quite well. My first guess is that it may be an alignment problem.

Ya, I agree. I live in L.A. and the roads are the worst but as far as jittery I don't get that unless I'm hitting the bumps at a high rpm and then you'll feel a little bronko'ing. And ya, the suspension feels like it getting the snott kicked out of it. Take the advice from kscs. There are a lot of reasons you could be experiencing that, A lot of them are probably a little of this, a little of that. Congrades on a great car.

Congrats on the new car. As a NY City area driver, I can relate. My car has PASM also. Not trying to be smart, but if certain road are broken up and rough, don't go that fast on them or find alternate roads to your destination. The PASM will help to soften some of the blows, but it won't work miracles, especially at speed. Second, check your tire pressure. I've found that the car feels different and more "jumpy" if my 18" rear tires go above 42 PSI (warm) as indicated my TPMS. As the weather warms up, I adjust my cold pressure accordingly not to exceed this when driving.

It sounds like a balance and or alignment problem to me. Your Cayman should solid above 75 and nimble enough to dodge the pot holes.

Welcome and congrats. Have the wheels checked and balanced, also check the tire preassure as suggested. An alignment might be necessary, i get one almost every year, as the streets here in the DC area are terrible. How many miles did the car have when you bought it? Also don't forget the car is light, especially in the front, it has fairly wide tires and will more likely follow grooves etc in the road surface. This combined with more steering feedback is certainly something you need to get used to.

I don't think a normal Cayman or S version should act jittery....even at speeds much higher than 75mph....seems to me that a Porsche knowledgable person that works on suspension...should check it out....and the other point might be what if any mods were don't to it that might be he culprit. My experience with AMG/MB and Porsche is that alignments can best be done by a dealer....or possibly some with the latest gear and deep experience....but even then I usually had to have it redone by a dealer to get it dead on....

My cayman feels better at 75+ then the bmw I got rid of 6 months ago, I live in area full of farm roads any many aren't that smooth. The BMW didn't handle them well at all, I'm just getting out of my break-in period and have been up to 100 just fine on my roads and felt completely in control. Sounds like you make have some suspension issues. I broke a strut on my BMW and it felt nervous at higher speeds on bumpy roads.

i did buy it used, it had 35k miles on it when I bought it. Incidentally, it was the only PASM equipped cayman in the entirety of Texas (new or used) that was listed to buy... I haven't modified it in any way, it was a CPO vehicle from Momentum Porsche (who leave much to be desired..). I did get my wheels rebalanced, in fact, I just got it back from the dealer yesterday. the steering had bad vibration in it before, that seems to be mostly eliminated. As for tire pressures, the fronts read 31, and the backs are at 34, I assume that when it gets hotter, these will expand (and it does get HOT here). Anyone live in Houston that wants to drive my car to corroborate? This is the first time I've driven a mid engined car...

oh, and I have the 19 inch wheels and the sport chrono pkg, if that makes any difference..

my impression is that 19" wheels makes ride much worse...

I was in Houston this week - I cannot believe the condition of the arterial streets - narrow lanes which don't let you avoid cracks or potholes! Westheimer Road is a disaster, some of the cracks on that and other routes are frightening. The freeways seem to be like LA's - concrete freeway hopfests in many places.

now you see what I have to deal with? it gets worse... at least 50% of the entry ramps are too steep. at good 10% have an initial entry >45 degrees. I live on Post Oak, I see lamborghinis all the time, but I have yet to figure out where they are going in them. you cant get into parking garages without nailing the front bumper on something.. Damned trucks, I think they should mount the bumpers at honda civic levels just to give the rest of us a chance.

Drove back from Reno on 395 to 38 to 44 to I-5 Northern California into Oregon. 2006 Cayman S with Sport Chrono, 19" Carrera Classics, no PASM, and rear tires near end of use. Solid all the way up 125mph but I did not try going faster. Back road highways were in decent condition. Nothing like driving on the autobahn though. There are certain sections of I-5 / 405 in the Seattle area that are just horrible in a regular car and much more accentuated with my 19" wheels and no PASM. I drive slower due to bumpiness. Have not had a chance to try 75mph + on those sections. Maybe I will try it out late this weekend when no traffic is around.

I live in Pearland (south of Houston) and work Southwest Fwy near Bellaire, so I drive Beltway 8 (poured concrete) and Hwy 59 every day. My 09 CS w/ stock 18" & PASM does not jump around, even when hitting speeds higher than 75 going up ramp from BW8 to 59 heading into town. But then again, I have PDK so the shifting is a non-issue for me. Yes, side streets are the pits, and not the Formula-1/NASCAR type! So at or below speed limit on those is the norm. From what others have posted in other threads, your 19" will definitely make a difference in ride quality. My tire pressure is 30/31 cold (factory spec); highest TPMS has registered is 34/37 after running I-45 up near Madisonville @ 105 mph for 10 miles on new asphalt - smoothest surface I've driven, very comfortable.

Welcome to what I feel is a truly fantastic enthusiast community. I would agree that 19's are partly to blame. My street wheels are 19's and my track wheels are 18's and I can definitely feel the difference in ride quality. If after exhausting the other options, you're still unhappy, a set of take-off or aftermarket 18" wheels could be a solution. I will suspect though that the culprit is a bad alignment with possibly the front toe being out of whack. The difference a good/bad alignment makes on a sports car is largely underestimated. So my suggestions in order would be: 1. get a quality tire gauge and after driving and getting the car up to temp, take your hot pressures. My TPS system is off by about 3-4psi most of the time so you might be in the 40's hot. Try to keep them in the mid/upper 30's to soften the ride. 2. take the car to a reputable enthusiast shop for an alignment / suspension checkup. Most shops just open the spec book and align your car to that. A decent performance shop will inquire about your driving habits, experience and align accordingly. This adjustment can make a HUGE difference. 3. source a set of 18" wheels/tires Best of luck.

I have an '03 Boxster S that seemed to behave the same way when first purchased second have in '08. It was in great shape with an impeccable service record and less that 10,000 miles. I had to replace the tires due to dry rotting from sitting around the majority of it's life. My garage, a Porsche specialist in our area, recommended an alignment with the tire change (18" rims). I begrudgingly agreed although I could not beleive why it would need it. All I can same is I got back an entirely different car. They said it was out and out by quite a lot. Turned out to be the best $350 I've spent on the car so far. Rock solid with no more twitchiness. Have it checked.

All I can add to the good advice already given is make sure all the suspension mounting points, bushings, rod ends, ball joints etc aren't loose, broken, torn, bent or otherwise damaged. Same for the steering rack and column. This all should have been checked in the CPO process but if the dealer leaves much to be desired could have been overlooked. I can echo what the others have said. If it's working as designed a Porsche doesn't dart off in all directions when hitting a bump but goes where pointed. They've always done a fine job of eliminating bump steer.

anyone know a good performance/porsche shop in the houston area to check out my car? I just had the alignment done (100+ dollars, great..). that shored it up quite a bit. Still a touch of steering wheel vibration, especially after passing 75 mph. I might have to let some air out of the tires. they get up to 33/37 via TPMS, and its not even hot out yet (by houston standards). still, would like the suspension checked by someone other than momentum porsche. suggestions?

For Porsche on the south side of town, eurocar-werk, S. Rice @ Fournace. See my earlier post in this thread.

Michigan Roads are terrible and always broken up. Despite that my car is fine at 75+ but you have to remember everything is relative....our cars give a lot of feedback so when you travel over rough roads the steering wheel will be twitchy....

I'm tending to believe that if you do put a bigger diameter wheel on in place of oem that it defiantly does make the front end more susceptible to vibration. I didn't want to admit it but when I upgraded 16" to 18" on my 93 E500 the shimmy or vibration increased 3 fold. Since I've purchased my 08'cs that came with 19' turbo rims (no pcm/sprt-crono,and tip) I find the ride really ruff, with a slight vibration under 65mph. But over 75 it feels fine. Over 120 I feel nothing,kinda like floating on air........aahh.:kiss:

On broken sections of hwy pressures become important. I found that when I put my fronts too high, there was 'nervousness' up front. They have to be 30-31 cold, 32 and above they don't grip as well on bad roads. 36-37r back (again for street driving). Also let the tires warm up. I have 18's so that might helping, but then 33/37 warm is not that high, I'm sure that's where my tires warm up to. Also the car is very communicative, it is perhaps telling you to 'back off' before a more numb car would.