Light suspension knock - tiny movement in RH front strut….

[ScotFox]

Other than an MOT and a separate service, my 981 hasn’t really been used since last year.

Driving to and from the above, though, a long-standing soft suspension knock over bumpy local town roads is really getting my attention. It’s always been there in the 2 years I’ve had this 2013 40k-miles vehicle but seems worse. It’s generally triggered when the front wheels hit things at different times (e.g. dropping one wheel into a minor pot hole - but not so much when both wheels hit a speed bump at the same time). I think it comes from the FR corner but my partner thinks it’s mostly behind us…

 

Anyway…

Jacked up the front and removed both front wheels - no identifiable ARB/sway-bar issues…

What I did try was heaving up on the hubs by hand. The LH front is fine - smooth compression and release. The RH strut makes a definite ‘hard’ noise when I release the hub and it bottoms out again. 
 

I have two YouTube videos showing my ‘heave’ tests - first one gives an idea of the noise, second one shows that the nut at the top of the RH strut moves a teeny-tiny 0.14mm vertically during my tests - the LH strut does not appear to move at all.

YouTube - strut noise - heave test

YouTube - dial test indicator - 0.14mm

Any thoughts? Strut too-mount/bearing?

 

 

[daz05]

The top mounts have been known to make noise on some cars but a relatively rare issue. Aim to replace but it could be worth checking the torque value of the centre nut.

[andygo]

Try disconnecting one end of one droplink so the arb is not linked side to side. Cable tie it out of the way and go for a drive. If all is quiet, your droplinks need swapping. 
it may not be your droplinks at all, but it costs nothing to rule them out.

if it’s not that, I’d go for tuning forks, another relatively simple thing to change and at 40k miles are likely to be on the ‘to do’ list soon anyway in my experience. 
My 30k mile 2016 car is occasionally letting me know they are getting tired..

[ScotFox]

Thanks - I had planned to do the drop-link test but was distracted when I discovered the strut rebound noise…

Tuning forks???

[andygo]

Tuning forks are the links that go from the front of the car to the coffin arm. Co

Called tuning forks cos that’s what they look like! Also called control arms.

[½cwt]

'Coffin Arms' are the lower control arms at 90° degrees to the chassis (shaped like coffins).  'Tuning Forks' are the control arms that run diagonally forward to the chassis and bolt through the lower control arm.  Porsche owner terminology....  These are 986 ones for illustration, but 981 is similar.

[ScotFox]

Thanks both.

My Indie phoned me today after watching my videos - both he (and a long-standing motorsport friend) both independently suggested that I shouldn’t have been able to get that kind of movement (hub end - ignore the sub-millimetre float) just by heaving up on the hubs…

Suggestion is now knackered damper(s)… I’ll take it in ASAP and get them to have a proper look. 
 

I have no particular desire to upgrade the dampers for the kind of road use I put the car through - (but could be persuaded if there’s a compelling argument) - do is it just Bilstein B4s, realistically?

Edited April 10, 2023 by ScotFox