Suspension ride height

[Shoppinit]

66.5 cm on mine.
On really poor roads I can hear the juddering and feel it at the steering wheel.
Almost like a machine gun going off
Pisses me off but not much else to renew.

Maybe you are mistaking this for the peddle box rattle ?

Could be this.

[Shoppinit]

On really poor roads I can hear the juddering and feel it at the steering wheel.
Almost like a machine gun going off
Pisses me off but not much else to renew.

Actually, that description reminded me of what broken DRC feels like. Your suspension is set at 9, right? IMO that's waaay too soft and your ride will be underdamped. You could be experiencing the wheel bouncing off the imperfections like with a failed shock. If you've got a Go Pro stick it to the side of the car and film your wheel going over poor surfaces. See what it's doing.

[steve2003rs6]

Mark. Not the pedal box. Definitely feel it through the steering column.
As I say only on crap roads.

Shop set on 8 at the moment. I had the same symptoms when set on 4
Hence why I went to 8

[steve2003rs6]

Mark. Not the pedal box. Definitely feel it through the steering column.
As I say only on crap roads.

Shop. I had the same symptoms when I had the settings at 4. Hence why I went to 8.

[Classik]

Shopp: strangely enough your car's height seems quite similar to mine, but the springs seem less compressed.

[Shoppinit]

Shopp: strangely enough your car's height seems quite similar to mine, but the springs seem less compressed.

That photos shows the springs installed at factory height. i.e. way too low. And the car is in the air there.

[steve2003rs6]

IIIC I have had this problem since purchasing the car in 2012.
Despite all my efforts I have still not resolved it to my satisfaction.
Back over in Neston shortly so will see if grizz has any recommendations.
It’s a niggle that spoils a great drive out.

[Shoppinit]

It’s an odd one. Mine feels planted even on poor surfaces. Maybe you've got a worn bush or steering rack is loose. Happens.

[steve2003rs6]

That would be my best guess Ben.
Will see what transpires. When I think about it. The steering rack is about the only thing that hasn’t been looked at or replaced.
Many thanks for all the feedback.

[chunky79]

Mark. Not the pedal box. Definitely feel it through the steering column.
As I say only on crap roads.

Shop set on 8 at the moment. I had the same symptoms when set on 4
Hence why I went to 8

Have you had your pedal box bushes replaced or the MRC mod done to it? If no to both, it sounds like it's your pedal box Steve.

Also, if the car is stationary and you turn the steering wheel left to right quickly, do you get a knocking? If not, doubt it's your steering rack.

[IchBautAuto]

The PSS10 mounting instruction are quite explicit in that the PSS10 coilovers only have a very narrow adjustment range for both the front (10mm) and the rear (5mm)!! Once you set the ride height outside of this narrow range as defined by Bilstein, you are essentially outside of the optimum operating envelope as designed by Bilstein.

This information is contained in the PSS10 TUV certificate:

The adjustment range of the spring plates is only approved within the range of the values given in the table below. Adjustments must be set so that the body is level when the vehicle is empty apart from the driver. The lowest approved adjustment and the permissible adjustment range are to be entered, stating the fixed axle reference points. (this example is Porsche).

Manufacturer PORSCHE
ABE-/ EG- BE- No. e13*98/14*0059*..
type designation 996 Turbo (4WD)
model 996 Turbo

FRONT according to permissible axle load and adjusting dimensions
spring part number
main spring E4-FD1-Y623A00
helper spring E4-FD1-Z349A00
shock absorber part number with damping force adjustment VM3-E716

permissible adjustment range
maximum permissible axle load 825 kg (1815 lb)
80 – 90 mm* = 10 mm range
* measurement: top edge of spring seat down to the center of mounting screw

REAR according to permissible axle load and adjusting dimensions
spring part number main spring E4-FD1-Y518A00
helper spring E4-FD1-Y504A01
shock absorber part number with damping force adjustment BM5-D541

permissible adjustment range
maximum permissible axle load 1250 kg (2750 lb)
205 - 210 mm* = 5 mm range
* measurement: top edge of spring seat down to the center of mounting screw

Maybe this is why some people encounter problems if they have the suspension height set other that what is spelled out by Bilstein.

[IchBautAuto]

To raise the suspension, you compress the springs more which pushes the car up. This means that there is less available travel before the spring coils touch, effectively making them solid blocks and acting like a bump stop. I'd be surprised if you were hitting the bump stops unless you have an extreme height setting. Are you having any issues? If not, and you are happy with the height, leave it alone.

Can I question that statement. It would seem from a mechanical perspective that when the car is sitting on it's wheels with the suspension loaded, the damper rod is not fully extended. That would be borne out by the difference in hub to mudguard clearance between fully extended and when siting on the ground with the suspension settled. I think we all agree that the damper is only fully extended on the bench or when the cars wheel is fully unloaded. The loaded spring rate can't increase until the downward force exceeds the corner weight of the car by the damper rod being fully extended. At that point it will become stiffer but will still only compress to equal the corner force. Equal and opposite reactions?

I submit that the springs should not compress one iota more until the damper rod is fully extended with all the cars weight on the suspension. I'm not even sure that you could sensibly do that although it might be possible.

I posted up some info on the damper adjustment as well and I don't pretend to have analalysed that but it is what it says.

I'll take up the position and add blindfold. Ready....Fire

[Shoppinit]

Sorry, I didn't understand. No doubt my fault. Can you explain again what you don't agree with in a way that a thicko like me can understand?

Don't think there are any PSS10 for the RS6 are there?

[steve2003rs6]

Dunc. No mate. No knocking when I turn the steering.
Will look into the pedal box mod.
Whatever that is ?
Mark also advised on this.
Thank you all for your advice.

[steve2003rs6]

The best way I can explain this.
Doing 70 mph on the A180 when you are nearing the end the speed reduces to 30 mph
300 yards before you hit the 30 mph. There are lots of raised humps in the road (speed restrictors).
Hitting these at 40 or 50 mph sounds like a machine gun going off and you feel all of it through the steering wheel.

I was convinced it was the suspension set up.
So gradually replaced the whole set up. Including new alloys and tyres.
It has improved but still not sorted.
Now I have plenty of free time it would be great to sort this out. On good tarmac the car is absolutely amazing.