[Tanqueray]

Many of you know that I have KW coilovers.

There's been a strange noise from the passenger side (front) that sounds very much like rubber bushing noise every time I go over a large bump or a dip.

It doesn't sound like a mental "clank" but a hard rubber sound. (I had an old dried out bushing in my Passat and it sounds very similar to that)

But I'm wondering how a 2015 car can have a dried out bushing...

I'm taking it to the dealership tomorrow, I know this won't be covered by warranty since I have coilovers.

If the bill is really high, I will take it to the shop that installed the coilovers (I can't go there right now cause they are not open on weekends)

 

[rnlabas]

You may have a bump stop (a big rubber piece) that has moved - I am curious what the visual says -

 

[Tanqueray]

You may have a bump stop (a big rubber piece) that has moved - I am curious what the visual says -

Is this bump stop part of stock suspension system? or would it be a new one from the KW? Also do you think the dealership service would be able to do anything about it? (not under warranty, of course)

I will be taking it to the dealership this afternoon.

 

[rnlabas]

Prolly the stock ones - BUT, there could be new ones for the coil-overs too - usually of a different compound to match the shocks.

 

[Tanqueray]

Thanks Roger!

I took it to the dealership this afternoon. I described the noise to the service manager and also explained the fact that I have aftermarket suspension.

So what's the first thing he tells me? "It could be due to your aftermarket coilover"

So I told him what I was going to tell him anyway, "I understand it's not going to be covered under warranty, just find the noise source and fix it"

Hopefully the fix is simple and I have the car back by tomorrow with not-so-high bill

 

[Tanqueray]

So the audi service just called me.

They said the noise is coming from the rear and it's because KW variant 1 doesn't have a bump stop on the rear and that the perch is directly on the spring.

I don't know exactly what this means....

 

[Tanqueray]

Here's what the Report from Audi Services states

"Found aftermarket coilover spring perch for rear has no rubber bushing from body to perch and is at lowest point at spring perch"

What does THAT mean? haha

 

[Tanqueray]

Also found this on a BMW forum, it sounds very similar to my issue. (i.e. noise when suspension "drops" or "unloaded" and 'gronk' noise rather than 'clunk' noise)

I'm passing along this advice/experience in the hopes that someone else may benefit from our discovery via long period of trial and error.

I had a recurring thunk/clunk coming from the left rear corner. It made a 'gronk' noise that was rather loud and very annoying. Easily replicated in a quiet parking lot at 10-15mph by first loading and then unloading the left rear corner. Even a small bump would do it.

I suspected worn bushings in the Rogue RSMs; bought a new set and replaced them. Noise abated for around 50 miles then returned. Both Rogue and KW were helpful and responsive on support questions but we could not find the cause.

I Went through much trial and error with my smart and very patient mechanic (Plug for Bruce Barthel, bmwmd.com). We inspected and verified torques on all the bolts of the rear end (frame, suspension, differential, exhaust, etc) but noise persisted. We eventually tracked the problem to the uppermost two coils of the KW spring rubbing together when loading/unloading that corner. The friction had worn through plastic outer coating of the KW spring, allowing the plastic/metal of the coils to bind/rub against one another, especially when that corner got unloaded.

Wrapping the individual coils of that spring with two layers of 3M electrical tape has so far totally eliminated the noise. Not sure yet about the long term reliability on the tape. It will probably last a while here in SoCal. I plan to replace the tape with a synthetic rubber coating product like Plasti-Dip, or some other permanent rubber tubing that I can slip over the coils.

Also, we noticed also that the KW threaded collar was loose enough to wobble slightly on the threaded perch post. This seems odd and not very "German" if you get my drift. We used two passes of plumber’s teflon tape to snug up the fit between the collar and the threaded post.

 

[rnlabas]

I guess that your bump stops either moved right off/out or never existed - strange to me. Perhaps the original ones can be found and fitted to work - they're basically a rubber gasket between the spring and the perch (or tower cap that the spring fits into) - I'm surprised that KW kits would leave these out or the installer did ... maybe a brain fart -

 

[Tanqueray]

I've emailed KW and this is the response I received from them:

John,

Thank you for contacting KW.

The rear does not need a bushing for the rear perch and this has been our design for ALL divorce rear end suspension with no issue.

I would make sure the mounts are TQed properly.

Usually if the mount is not tqed to spec you will hear this noise.

I'm going to the garage that installed the coilover this Saturday and have them diagnose and suggest they check the torques.

 

[Tanqueray]

They inspected the front suspension and said everything is tight. So they suspected the noise to be from back only.

So the shop cut up a pair of rubber bushing that was at the shop and placed it between the spring and perch in the rear and seemed to have eliminated the "part" of the noise. Now the clanking metal noise is gone. However, the front passenger side still has what seems more of rubber or spring bind noise than metal. (It's more prominently rubber or spring sound now that the metal noise from rear passenger side is eliminated)

I guess I had two noise to begin with.

I really wonder if it's the rubber bushing in suspension parts other than the coilover. I doubt it's the original rubber bushing because the car is new with less than 200 miles. I'm taking the car back to the shop next Saturday to get the front suspension looked at. (Shop didn't have time to take care of the front coils) They will install nylon rings between the springs and perch to see if what I'm hearing is spring bind noise.

 

[Tanqueray]

UPDATE

Because I've been terribly busy and the shop that installed the coilovers, originally does not open on Saturdays, I've been just putting it off until today; I got the afternoon off from the laboratory.

The shop owner test-drove it and immediately noticed that the bushing noise is from the sway bar bushing and he suggested ordering a pair of new bushings. He will trim 1-2 mm off it to support the lowered ride height (lowered ride increased the travel range). He had seen this happen to many VWs with coilovers.

About the metallic rattle noise over potholes, he re-torqued and guess what; it is dead silent!

I'm amazed that it's as simple as re-torquing to the correct limit. The shop owner (who specialized on Audi/VW for 14 years) said, the fact that coilover started to make noise 2-3 weeks after the installation tells him that I probably hit big potholes to loosened up the parts to initiate the noise. In fact, I did hit handful of potholes on the right side that were big enough that I remember specifically, between the installation and start of the noise. Darn road in front of Target near my house! And darn D.C. roads especially 50 West bound coming out the D.C.

Audi service (although, I don't blame them since this is an aftermarket part) and the other shop simply checked the components by shaking/pulling/pushing to tell me everything is installed properly and I have to live with the noise, if I don't want to part with coilovers. I bet they didn't even bother re-torquing the components after their visual checks.

I will update again when sway bar bushing is replaced next Wednesday.

 

[AudiFox]

That shop owner and his garage is a keeper! No more odd noises now?
At least the sway bar bushing is cheap to replace.

 

[Tanqueray]

That shop owner and his garage is a keeper! No more odd noises now?
At least the sway bar bushing is cheap to replace.

Nope, no noise now! He also lubricated the sway bar bushing and the noise is gone. He still suggests replacing to the trimmed bushing since the lubrication is not a permanent fix.
Plus, he didn't charge me anything for the work, he said since his shop installed the coilovers, he feels that he needs to work on it until the noise is gone, free of charge. What a great shop.

The shop is called S2Dynamics in Rockville MD, I will my car serviced here from now on, for sure.

 

[AudiFox]

May as well ask them to order a new bushing to replace the trimmed one and have them install it too. One good visit deserves another and that's why I'm still going to the same garage for the past few years.