wrs

Picked up a rear end clunk sound when going over speed bumps at low speed. Doesn't always do it and it just started last week. Shop couldn't find anything on first inspection and also was able to hear it. Anyone else experience this? It was an issue on M5s and turned out to be rear springs. It doesn't happen when at speed but will at low speeds and it's not consistent. It also seems to be in the left rear.

redlightrich

Mileage? Did the outside temperature change dramatically where you are?

Your question is a little vague, but I think with a bit more, we can help. My guess is nothing is radically wrong or the tech would have seen it ( I hope). That is why I am considering the mileage and local temp.

wrs

No, we are having milder temperatures, in the 70s instead of 90s now. Some 50s on some mornings but mostly 60-80 during the days now and it's got 10,500 miles. I though it might be related to the new ICs but I reached in there and and they are solid as a rock. It sounds like something bottoming out but there are no scratches underneath. They put it on a lift in the shop to have a look and nothing seemed loose or out of place.

strumbringer

I had this happen. They removed, lubed and reinstalled the stabilizer bar (IIRC), which fixed it.

tlovidiu

Same problem here...the local dealer could not find anything.
The problem isnt always there, just sometimes....I would like to know a fix for this

speed21

Does it sound a bit like a spare wheel laying flat in the boot that isn't properly secured? Like a kerthunk?

wrs

Yes, sometimes and other times it's a little sharper, more like a creaking.

wrs

This sounds promising and also not serious.

speed21

My money is on the sunroof. It may not sound like it's coming from there but in these cars sounds travel. I had the problem in a previous 997 and it took forever to track it down and equally time consuming to properly address. If its what I'm thinking, and it sounds to me like it is, they should look there. I can give more detail if you like.

HassaanAbdeen

Open your sunroof and see if you still hear the sound?

If the sound goes, then it's the sunroof. I reserved an appointment next week for that. They said it takes two days to get it fixed.

wrs

Well I wouldn't have guessed that but I am going to workout in about an hour and the place where I workout has speed bumps that always produce the clunk so I will go through with the sunroof open and see what that does. However, if it's open and still makes the sound does that mean it's not the sunroof?

ETA: That fixed it. Now even closed it doesn't clunk, maybe just opening and closing it readjusted something.

Visceral

Thats pretty cool (sort of). I had a really annoying squeek from the sunroof that went away after I thoroughly washed the car. Didn't help to open/close it several times and it even squeeked while open at the time.

A quick forum search shows that these sunroofs on the 991 are certainly not without their issues.

speed21

I'd be surprised if it cures it permanently....but at least you have some handle on the origin of the noise now. I recall the 997 made more of a kerthunk closed than in open position although how much you open it always varies so that can also have an effect, its a while back now thankfully. I would imagine the same internal deflector arrangement would exist in the 991 even though the roof section pops up and slides over top now. They would still need an internal deflector arrangement in the rear of the roof to stop the wind from blowing the hood-lining out when the roof is open. One reason I was quite happy to have my current car without a roof this time. I can report the 991 is definitely quieter and tighter in the body without it.

wrs

Yeah and I know it's not a sign of anything bad in the suspension. I am definitely going to drag race the car Friday night. I am carrying the proper tools to re-seat the Y-pipe to throttle body hose and tighten the clamp if that comes loose again but I didn't want to be worried about some strut failure or the like.

speed21

Yep I know what you mean there. The suspension is robust though and there really isn't anything that can make that noise if you take a good look at all the parts. Btw are you using the stock rubber connector between the TB and the Y or do you have something AM which goes with the new Y? Once the stock piece has blown off that's generally the end of it.