PatrickBateman

Vitals
Model: 991.1 C2 (BASE) Non-PASM, Non-PDCC
Mileage: 44,xxx
Modifications: TechArt lowering springs on factory shocks and wheels
Car condition: Zero accidents, sway bar end link boot cracked. No leakage yet.

Issue: experiencing a very, very floaty ride in my 991.1 C2 . The car does not feel planted at all. The lowering springs were installed about 10K miles ago, with the shop electing to perform an alignment immediately after spring install rather than waiting for them to settle. I didn't drive the car in a spirited manner since, and just recently went out and stretched its legs.
If there's the slightest wind outside, the car will be pushed and feel very floaty... the best way to describe it is as if I'm experiencing some lift, rather than feeling stuck to the ground. It's not very stable through corners and when driving in a straight line on the highway, the steering wheel has some play side to side without the car responding.

When I lived in LA (a few months ago) I hit a massive pothole or bump in the road and heard the LOUDEST metallic clank. I felt the impact in the steering wheel, it almost felt like the wheels hit the fenders, or something. I took it to a race shop who didn't remove any underbody cladding but noted they couldn't find any damage to any visible components. Shocks were not leaking, but they mentioned they felt 'a bit soft' in the front. Sway bar end link boot is cracked, though it is not yet leaking.

Here is the alignment I had performed today. Haven't got a chance to really test it out but there is still play in the steering wheel at highway speeds (2-3"?), seems to drift to the right, and still doesn't really feel like a 911 should, in my opinion. Take that with a grain of salt, however, as I'm not incredibly knowledgable in the suspension realm.

Any thoughts as to what's going on? I'm assuming I need to go to a better alignment shop who can try to adjust the camber a bit, but would that really account for the almost Toyota Camry handling I'm getting? Keep in mind it feels this way without me driving super fast. I'm not pushing it super hard and it's very unsettled.

The race shop owner drove it and was blown away at how poorly it handled, and he's a pretty accomplished driver.

Wujohn

Likely the tech art springs. I have seen several folks comment about how these lowering springs will cause the car to porpoise. Not sure why this happens but they are progressive springs vs the linear springs that come with the car.

ICNU

Lowering springs on their own can sometimes make it really hard to get the toe correct without additional 3rd party hardware links to get things back where they need to be. They may simply run out of adjustment range after lowering, although yours is showing as in range after the new alignment, but based on what? Porsche has different value recommendations for different setups. For example my 981 has been lowered so it was redone using the Porsche sport suspension values which is 20mm lower and uses different alignment values than the standard suspension my car came with. Wrong toe will make the car wander all over and be very sensitive to any crowning on the pavement. Many use more negative camber than you are showing as well.

BlueShell

I would also try to lower the tire pressure as well. The factory specs make the tires a bit too bloated in my opinion. I run 29/33 for autocross which is really aggressive. But 34/36 feels good for street driving.

dannyss

Check your tire pressure.
And the Toe was way off!
Go drive the car, should be different.

PatrickBateman

tire pressure is as indicated in the door jambs, but with continental extreme contact DSW 06+. “Performance all season” category. Any tips on where I should be pressure wise?

GSIRM3

The tire pressure listed on the door jambs is for full load conditions.

BlueShell

Check my previous post for a suggestion.

PatrickBateman

Thanks, I’m now assuming that should work for the Conti’s? I’ll give it a try. Do you air down when aggressively driving or simply always run less pressure?

PatrickBateman

Meaning a passenger? Luggage? As a rule of thumb, how much does one deduct if not at full load?

koala

I run my Bridgestone all seasons at 31/34 and it helps a little bit. They're going to feel floaty compared to summer rubber.

I won't do all seasons on this car again. I'm not sure why so many people thought it was a worthwhile compromise as it absolutely ruins the steering feel.

dannyss

Tire pressure on the door jam is too high for everyday. I run those when I’m fully loaded with luggage going on vacation with my wife.
I had Contis on my 750i and was running about 34-36 all 4 corners. Always had PS4S on the 911. Running about 33F and 35R hot in the twisties

Laszlo_Laz

Do you still have your factory set up? I’d personally go that route.

stout

991.1 Carrera w/o PASM was arguably already under-damped on the stock springs, but it sounds like something is definitely wrong.

Whatever the case, I suspect you need new dampers anyway. A 991.1 Carrera 7MT on 19s was the only modern 911 that bottomed out (one rear damper, iirc) on a test route I regularly ran for 20~ years. Really surprised me, given the longer damper piston stroke, as I'd been over that mid-corner bump in so many 911s. It was the only notable flaw with the setup other than the "flaws" of the car being too high and too soft, overall, for some…though it was probably right for most of the intended customers, especially when you could still order sport suspension on a base Carrera.

Adding stiffer/shorter lowering springs to those dampers was probably a bad idea even when they were new. Doing so when they were used and then adding another 10,000 miles…well, it would be interesting to run your dampers on a shock dyno. Or just see if you can collapse them by hand. Were I in your shoes, I'd be looking at a decent set of analog coil-overs (Bilstein PSS, etc). Bonus: You gain the ability to adjust the right height exactly to your liking and corner-balance the car if you wish to go that far. Not a cheap solution, but the right springs and dampers will greatly improve your enjoyment…and there's no way a 911 should feel floaty.

PatrickBateman

How do you feel about BC coil overs?

Thanks for the help guys. Lowered pressures to 31/34 on my Contis. Will buy summer tires soon too.