Creaking from rear going over speed bumps

[joeluth]

I'm getting a creaking sound from the back of the car when I go over speed bumps. 

Could the creaking be the rear top mounts? 

I've replaced all the obviously worn out and noisy stuff as in the coffin arms, the  tracking arms, the tuning forks and drop links with new ones a few months back and it's been silent up until now.   

But the shocks and springs are still original and I didn't change the rear top mounts  yet, just the front ones.

I tried pushing down on the rear end whist parked up but i couldn't get any noise out if it,  just noticing it sometimes when I go slowly over speedbumps. 

I thought worn top mounts would knock rather that creak... 🤔    cheers, Joel  

 

[bally4563]

Have you done the Anti roll bar bushes?

[paul111s]

Had creaking on my 986 on rough roads, had top mounts replaced and creaking has gone 👍🏻

[joeluth]

11 hours ago, paul111s said:

Had creaking on my 986 on rough roads, had top mounts replaced and creaking has gone 👍🏻

Hi Paul, was it the rear top mounts you had replaced? 

 

[joeluth]

11 hours ago, bally4563 said:

Have you done the Anti roll bar bushes?

Ah, I haven't done the rear anti roll bar bushes, and the reason for that is some of the bolts have seized!

I did buy new bushes and tried to change them a while back, but felt like I was going to snap the bolts off so I left it.

It's pretty tight back there, the backs of the roll bar bolts are almost flush with the wheel alignment bolts so there's not much room to work if they snap 
 

Good shout though, I'll try to spray some grease in and around the bushes and see if quietens down a bit. 

 

 

[bally4563]

32 minutes ago, joeluth said:

Ah, I haven't done the rear anti roll bar bushes, and the reason for that is some of the bolts have seized!

I did buy new bushes and tried to change them a while back, but felt like I was going to snap the bolts off so I left it.

It's pretty tight back there, the backs of the roll bar bolts are almost flush with the wheel alignment bolts so there's not much room to work if they snap 
 

Good shout though, I'll try to spray some grease in and around the bushes and see if quietens down a bit. 

 

 

Try that , if it works points to the problem, and if so rather than going at those bolts like a bull at a gate ! Try tightening first just a tad and then work back… old school engineering but often works , and spend a week spraying plus gas around them before you attempt ( my credentials are x Millwright)

[joeluth]

16 hours ago, bally4563 said:

Try that , if it works points to the problem, and if so rather than going at those bolts like a bull at a gate ! Try tightening first just a tad and then work back… old school engineering but often works , and spend a week spraying plus gas around them before you attempt ( my credentials are x Millwright)

Thanks mate, drove to the station this morning after spraying those arb bushes with some grease and it didn't make any difference, so I don't think it's the arb, though I must admit it doesn't look great!  I'll have another go at removing the bolts.     meanwhile I've ordered a new pair of rear top mounts, hopefully that will cure it, I expect they have had it, the front ones were a right state when I replaced them.

[bally4563]

32 minutes ago, joeluth said:

Thanks mate, drove to the station this morning after spraying those arb bushes with some grease and it didn't make any difference, so I don't think it's the arb, though I must admit it doesn't look great!  I'll have another go at removing the bolts.     meanwhile I've ordered a new pair of rear top mounts, hopefully that will cure it, I expect they have had it, the front ones were a right state when I replaced them.

Could be, rare for rear top mounts to go through and to be fair if they were squeaking only, yes grease would identify that, but if they are worn out , grease won’t remove clonking!

[Ninesomething]

Haven't done it but I'm told that creaking esp from the rear can be coffins. Is it both sides?

[½cwt]

A thought just struck me, are the coffin arm inboard bolts correctly torqued up after being tracked.  It is mighty difficult to get the 100Nm torque onto them when the car is up on a ramp.  Mine needed at least 2 more flats of turn to click off when I checked them with the wheel off and the hub supported on a jack so the suspension was in the normal rest position.  I was getting an creak or knock before correcting the torque and frustratingly after doing the top mounts...

[joeluth]

1 hour ago, JonSta said:

Haven't done it but I'm told that creaking esp from the rear can be coffins. Is it both sides?

Hope it's not! They are pretty much new. Decent ones from Spyder Performance. 

I think the noise is occasionally both sides, but much more obvious from passenger side.

it really sounds like it coming from high up the suspension, where the top mounts are. 

I had experienced the usual knocking on rough roads from my old coffin arms,  it's not that.

And it's not the worn out suspension bush window cleaner type squeek either. 

This is a totally different sound, high up at the back of the car,  like old wooden pirate ship style creaking! 

I blame the roads around me, 20 zones with speed bumps as far as the eye can see. They even speedbump the 30 zones. 

  

 

[joeluth]

26 minutes ago, ½cwt said:

A thought just struck me, are the coffin arm inboard bolts correctly torqued up after being tracked.  It is mighty difficult to get the 100Nm torque onto them when the car is up on a ramp.  Mine needed at least 2 more flats of turn to click off when I checked them with the wheel off and the hub supported on a jack so the suspension was in the normal rest position.  I was getting an creak or knock before correcting the torque and frustratingly after doing the top mounts...

Wow really,  Hmm... that is interesting.  The last person to tighten them was at the alignment shop.   I went back there a few times because it was dragging to the left.   They started to get a bit fed up with me, but it was an expensive alignment so I kept going back until it behaved. 

  Worth checking for sure, I've got some ramps at home, maybe I can reverse up them and tighten the bolts.

 

 

[½cwt]

4 minutes ago, joeluth said:

Wow really,  Hmm... that is interesting.  The last person to tighten them was at the alignment shop.   I went back there a few times because it was dragging to the left.   They started to get a bit fed up with me, but it was an expensive alignment so I kept going back until it behaved. 

  Worth checking for sure, I've got some ramps at home, maybe I can reverse up them and tighten the bolts.

 

 

Axle stands would be better.  You really need the wheel off to get proper access with a torque wrench.

[joeluth]

4 hours ago, ½cwt said:

Axle stands would be better.  You really need the wheel off to get proper access with a torque wrench.

Ah yes, I see what you mean. I remember reading you're supposed to tighten them with the wheels on and thinking "how!?" So I left it to the alignment tech. I'll try your way with the jack and see if I can cure it. Thanks! 🤞 

[paul111s]

On 3/27/2022 at 9:20 PM, joeluth said:

Hi Paul, was it the rear top mounts you had replaced? 

 

Yep sure was

[joeluth]

On 3/29/2022 at 2:12 PM, ½cwt said:

Axle stands would be better.  You really need the wheel off to get proper access with a torque wrench.

Drove to the station this morning , rear suspension still creaking away at every bump and turn.

Taking your advice, this afternoon I re-torqued all of the rear suspension arms, most were completely tight, but a few moved a bit before the wrench clicked, trailing arm to body bolts moved the most, I really didn't expect it to make any difference but went for a test drive this evening.

Like a new car, suspension was silent.   
 

 

 

 

[½cwt]

2 hours ago, joeluth said:

Drove to the station this morning , rear suspension still creaking away at every bump and turn.

Taking your advice, this afternoon I re-torqued all of the rear suspension arms, most were completely tight, but a few moved a bit before the wrench clicked, trailing arm to body bolts moved the most, I really didn't expect it to make any difference but went for a test drive this evening.

Like a new car, suspension was silent.   
 

You might ahve guessed, been there, done that, got the tee-shirt.!  These cars will have silent suspension if it is all new and correctly fitted.  Glad it is sorted and it a strange way it will feel a little faster too!

[joeluth]

16 hours ago, ½cwt said:

You might ahve guessed, been there, done that, got the tee-shirt.!  These cars will have silent suspension if it is all new and correctly fitted.  Glad it is sorted and it a strange way it will feel a little faster too!

Yeah! it feels great now!   I took it out again this morning, there's a Cars & Coffee morning every Sunday at The Motorist near me. 

I didn't know but there were a few Porsche clubs meeting there today,  the place was rammed!  all types of Porsches, was a nice surprise!