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Clank sound from rear O/S


Obela

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Hello chaps,

Been a passive member of this forum for 2-3 years now. This is my first post so please be kind :) 

I've had a clank sound from rear O/S on my 05 3.2 Boxster S for a while now and would really like to get to the bottom of it. The car had several inspections in the last 2 years, including a service at Porsche recently, and no issues had been reported. No leaking from shocks, no badly warn bushings or play in any suspension components. I’ve replaced the tuning forks at a local indi which didn’t help at all with the noise. 
I’ve decided to investigate myself today. Now I’m no mechanic and do not proclaim to have any particular mechanical knowledge, but I also could not find any play in the suspension when the car was on a jack and the wheel off, nor could I replicate the knock sound from the suspension. 
What I did find, however, was a play in the drive shaft when I pulled and pushed on it in the direction towards and away from the gearbox, and the end of the play on both sides made a metal on metal sound, which I thought was quite similar to what I am hearing while driving. 
question is - is such play is normal? I’m assuming the drive shaft must be able to have a bit of a play in that direction, but is the metal knock normal or should it be dampen by grease normally? I could not see any breaks in the CV boots or any signs of leaking grease. 

would really appreciate some advice in the matter as I gather it’s quite a big job to rebuild the inner CV joint and very expensive if drive shaft needs replacing, and would like to avoid it if it’s not the source of my problem… 

Any help would be much appreciated!

Omri

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The drive shaft movement you describe sounds normal as the shaft has to be able to slide in and out a little with the up/down suspension movement.  My only other immediate thought is whether the spring is correctly seated in the platform on the shock.  I'm sure others will be along with thoughts soon.

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Thank you for the answer, yeah I figured the drive shaft must be able to travel in that direction but wasn’t sure if the metal sounds in the end of travel are normal. 

I have checked the spring and it is correctly seated in the shock absorber platform. The car has a greatly detailed history so I can fairly confidently say that apart from the tuning forks, no other suspension components have been replaced, so I’m assuming all are still in their original position from factory. 

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I have exactly the same problem. Been inspected several times and have replaced tuning fork, top mount, arb bush, droplink and heatshield fixings. It's better than it was but I can still hear it. It's worse when it's cold. Almost disappears after a few miles. Also no-one can hear it but me. Clank is the correct term though. Not a clonk or a clunk.

I'm thinking now it's the ball joint on the end of the track control arm. Mainly because that's the only thing left apart from the coffin arm and everyone tells me they don't clank they creak. Either that or it's the shock but I had them tested at centre gravity and they were all fine. I've poked and I've prodded and I've pulled but can't find anything loose.

If you do figure it out I'd love to know.....

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The noise is so bad in my car that even my wife commented on it! 
have you tried inspecting the suspension while the load is taken off (i.e. by resting the wheel carrier on something like planks of wood and lowering the jack)? I’ve read that it’s often impossible to identify loose ball joints when they are under load.
I’m hoping to get to the bottom of the problem because it is really annoying, but your experience doesn’t inspire much confidence in me… 

 

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I would definitely put the car up and prod all around the heatshields. They make a terrible noise if the clips are missing - I needed three and one part was so bad I took snips and cut it off - and of course it's worse cold because when the exhaust heats it up it expands into place. 

Other than that it's a case of throwing parts at it. Cheapest is ARB bushes followed by droplinks followed by tuning forks followed by coffin arms. Could also be exhaust mounts although I've had a new exhaust and that didn't cure it. I also fitted new trans mounts and have a new engine mount to do. All of them seemed to help at the time but the core noise is still there. 

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Thanks! This is for the ball joint I assume. What about the asymmetrical bolt to the chassis? I found 120 Nm but that was for a 997.1, I’m assuming it’s the same?

 

Edited by Obela
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7 hours ago, Obela said:

Thanks! This is for the ball joint I assume. What about the asymmetrical bolt to the chassis? I found 120 Nm but that was for a 997.1, I’m assuming it’s the same?

 

The eccentric bolts are only 100Nm.  All the other bolts that size are 120Nm, but because of the slot for the eccentric washer they are weaker for their diameter so have a lower torque.  A tip here - after the tracking has been done, recheck the torque on these bolts as it is virtually impossible to apply the correct torque when the car is on a ramp unless you have a 90° crank fitting with the correct offset and reach for a torque wrench.  Mine needed about 2½ flats more turning to get to the correct torque last time.

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