NP993

I suspect there's nothing wrong with your suspension and you simply drove over some rough or wavy pavement, based on the contradictory statements above.

Martin S.

These address bump steer. Your car is pretty low it seems to me. You can get a pair that includes all new wheel bearings from Gert at Carnewal in Belgium, about $1,300 and includes new wheel bearings in the wheel carriers. You can also get them from Sunset Imports in Beaverton, OR

911PERVY

That is quite low, I think you need to really consider the upright change, it will make alot of difference, Gerts price is actually over $1500

Martin S.

Gert's price is 1,375 Euro, but it includes the correct tie rods, and you get new wheel bearings with the wheel carriers. I bought mine from Sunset in Beaverton, OR a long time ago.The package was $1,300 then, but now, who knows?

911PERVY

After Friday its cheaper to buy from the UK!

911F1

What does bump steer feel like exactly? Thanks

NYC993

When you go over a bump, your steering wheel will turn and then retun back. The bigger the compressions more the steering wheel wants to move.

jscott82

Actually its the opposite...

The wheel does not move, but the car "steers" on its own in response to changes in ride height (bumps). Its really just changes in toe, but since each side is independent, the result is steering/turning.

NYC993

Ok so I must be describing something else or something related. What you are saying does make sense, although I've never really noticed that. Jumping steering wheel in my hands is another story - I thought that was the infamous bump steer

Drisump

Richard I know you must often drive in killer heat but I have always gravitated toward the idea that higher PSI values would result in sharper steering response, less sidewall flex and as a result more capable handling characteristics....to a point. During that day, when road temperatures were off the charts, the tires set to factory recommended cold pressures, let me assure you that at lower pressures the tires were less greasy.
To the OP, with my PSS9s I tried to set ride height to significantly below ROW...it ended up being a less than happy experience. To get to very low heights in these cars you need RS hub carriers that change the angle of how the tie rod attachs to the hub. My cars handling at that height could only be descibed as "squirrelly. Even minor bumps while hiway driving required significant driver inputs. At euro height she drives perfectly. I know people who have gone lower with no issues, but there appears to be a fine line. Cheers

911F1

Drisump,
Thanks for your input. I'm going to raise the car up this weekend. The rear is a pain, but its what I need to do to diagnose my issue. RS hub carriers are out of my budget so the car is going to be raised up a bit. I'll report back after.

Another quick question. At what point height wise are the RS hub carriers recommended? I'm at 129mm F and 114mm R. Should I go all the way back up to ROW M030?

phoneyman

if you go lower than RS + 10mm (aka RoW height), RS carriers have been recommended on this forum. I am at RS height and plan to raise the car to get rid of my bump steer.

Also, if you raise the suspension, you'll want a new alignment to keep your tires from wearing improperly.

Ed Hughes

Unless you have a failing shock, it isn't your shock/spring combo.

Drisump

I can't give you an exact number, no doubt there are a few threads to read about this topic. I do hear you about the price of the RS hub carriers. Since I live on an island, any time I take my car out, I have to deal with ferry ramps....and I'm not even mentioning my 800 ft long "rustic" dirt driveway. So, as you can see, for me lowering to (+or-)RS spec is not really practical....even if it would be kind of cool!I reasoned a good compromise was euro height. She does very well set to that height and offers a very confidence inspiring drive. It is quite difficult to offer opinion based on your description, but I simply offered my experience with respect to my overly lowered 993. I think Ed is right in that what you describe (or seem to) is not likely an incompatibility between your coil and shock rates. Cheers

JDB1

I recommend before you do anything, research some of the many technical and non-technical articles regarding suspension spring and damper tuning. I found both technical and not-so-technical postings by respected authors that will help dispel myths and perhaps save you some money. I suggest that the physics and engineering of these matters is not Porsche exclusive, so do not limit your inquiries.