Cayman S Knocking Steering

[MrDemon]

Ackermann steering geometry is a geometric arrangement of linkages in the steering of a car or other vehicle designed to solve the problem of wheels on the inside and outside of a turn needing to trace out circles of different radii.

there is nothing Porsche Silverstone can do it's simple maths ;/-) all cars do it, tyres can make a massive difference to how bad a car is on full lock.

All my Porkers do it, more so in reverse as I never have a need to do full lock going forward.

I would expect that's what the noise is imo. if Porsche are stuck for a fix and your car did not do it before, get them to fit a set of loan wheels with new tyres on see if that fixes it.

it maybe just worn tyres showing up the Ackermann angle issue.

Ofcourse it might be another issue, but the Ackermann effect on the wheels might be causing a worn bush to knock under this extra load, on a 11 year old 50k mile car it could do with a bush refresh every where anyway imo, also check the top mounts.

Loads to go on , not sure why Silverstone are stuck with a simple problem.

 

[Footdown10]

Hi All

I'm new to the club so firstly hello to everyone!

Since joining in April I have not actually had my car as it it's been at Porsche Centre Silverstone having some work done to try and cure a quite peculiar noise. (Hence no details of the car posted yet)

I have a 2006 Cayman S with 46K on the clock, it has developed a strange knocking noise when the the car is on either left or right full lock, we have ascertained that it is the steering fluid "pulsing" when under load through the cooler pipe that runs from the pump to the rack under the passenger seat, all parts in the system have been changed, expect the pump, this has however been tested and proved to be working with no problems and yet still the noise remains.

The car drives perfectly and you wouldn't know unless you put it on full lock and hold it there.

Has anyone experienced this problem if so can you please let me know what the fix was?

The car is under warranty so no real problems with getting it sorted, except the fact that Porsche Silverstone are unsure what to do next.

I've been without the car for nearly 6 weeks and it's starting to get a little annoying!

Help if there is any would be much appreciated!

Thanks in advance


[/i] post edited by Footdown10 - Saturday, May 20, 2017 8:08 AM

 

[Motorhead]

Hi Matt,

What D is referring to is the the front end skipping around when reversing on full lock, particularly in cold weather, and I don't think that's the problem you're experiencing from your description. Does it happen when the car is stationary and/or when you're driving, presumably at low speed?

As you say, it sounds more like hydraulic knock, and if your PC has changed every component except the pump then I think that you should insist that they change that as well, even though they reckon that it's performing satisfactorily. You have to wonder how the pump was "tested" and at least replacing the pump will answer the question.

Of course, as D has said, it may well be a suspension-related issue but I'm inclined to think that the PC should have had that covered...but you never know!

Jeff

 

[Footdown10]

Thanks Guys,

Yeah this is not the "Ackermann" Effect that D mentions, I've owned the car for 5 years and know exactly what you mean and yes they all do that.

This is defferent and only happens like you say at slow speed or when stationary and when the system is under load.

I'm talking to Silverstone again on Monday and I'm going to insist the pump is changed.

Does anyone know if the pump is a sealed unit? I mean can it be tested?

Thanks

 

[MrDemon]

It's odd it's only on full lock stationary, I am now at a lost as you say it knocks when stationary.

that should be easy to diagnose though if it does it all the time, hardest faults are the ones which go away when you turn up at the OPC

to me that sounds like a bush, if it does not do it on a ramp only under load and stationary on full lock, as again the Ackermann effect gives quite a load on full lock to a point I tend to avoid full lock due to the extra stresses on the whole system.

 

[Motorhead]

Matt,

I would think that to do a proper job the pump would need to be removed from the car and tested comprehensively in a rig, but the PC may have used some other method. Since it only happens on full load maybe the pump is cavitating?

Incidentally, looking at the PET for your car there's no evidence of a cooler in the line; just solid and flexible pipes by the look of it.

http://www.porsche.com/al.../en/E_987C_KATALOG.pdf

You say that everything's been replaced but does that include the steering rack itself? After all, it is part of the system.

Jeff

 

[Footdown10]

Hi Jeff

Yes the rack has been replaced, I'm certain the pump.

Matt

 

[Buddy]

Sounds to me like a cavitating pump or possibly play in a joint or bearing allowing flex and release so pulsing the pressure line but I would expect them to have found any play in a joint or front suspension bearing, if the pump gets changed an it fixes it great you have a full new system on the car, I expect that they have checked pipes for damage or flexing, bulging etc which should have been noted on MOT. Good luck in getting this sorted, I've only delay with that dealership once but found them to be very good.

 

[fsollof]

I have a cayman 2007 been working perfect not driven it for about 3 weeks just went to go for a drive and when I turn the wheel in either direction there is terrible clunking noise , help please if anyone knows

 

[Motorhead]

It’s impossible to say without a detailed examination of the front suspension and steering system: play in the steering/suspension ball joints and bushes, ARB and strut top mount bushes, etc., as well as play in the rack or steering column.

Your best bet is to get someone to activate the steering while you crawl around to see if you can locate the source of the noise. Is there any evidence of PAS leakage?

Jeff