Hello antidentit
Well I took the car apart exactly as you described and just as you suggested very easy, in fact if I am being honest unbelievably easy. Obviously, once apart, I focused on the horizontal brace and tried to estimate just how tight or loose the brace bolts were. In the event I would suggest tight but not incredibly so. Some rule of thumb I learnt many years ago was to tighten a bolt/nut according to the size of spanner/wrench that fitted and not beyond what it might require. Obviously not very scientific, so my son and I looked at the bolt head(s) and there were two parallel "11" or perhaps "II" markings. This would suggest the bolts were graded in some way, but we couldn't find what the markings meant, every other marking on this planet but not these!. So we set about trying to assess whether they were high tensile or not and came to the conclusion they were "normal" steel bolts, and this was based on how they looked. That being the case, we figured a 10 mm bolt should be torqued to circa 50/55 NM. Having tightened them to that value I suggested to my son that my rule of thumb was probably being compromised and in the end I took an executive decision to tighten them as if they were high tensile and to 75 NM. I'm sure this will prove to be controversial, but hey ho it's done now. Frankly I don't think I overcooked it and prior to tightening I wiped off all remnants of grease that had been applied to the bolts heads and the meeting brace areas. I figured more friction here would be a good thing, but we left grease on the inner brace/car body.surfaces. I'd also add at this point that the official fix indicates these bolts should be tightened to 20 NM and to be honest I could have achieved that with my teeth! Quite where and why this figure came from is a bit beyond me. BTW, in the end I did not use any Loctite and whilst I was going to use a locking washer I didn't because I hadn't realised the bolt heads were hex and washer shaped but if the noise reappears then I will fit shake proof washers which I unfortunately didn't have to hand this weekend.

Right enough waffling, did it work, yes it did! I've just taken the car out on a short drive and not a peep from it. Even before I got off the drive I knew it was problem solved for now. I'd also add I tightened just about every other bolt I could find, but like you found, it is clearly the brace that is the problem. With no back seats in the car, it was quite a revelation hearing the fuel slopping in the tank and makes me wonder whether I might put some specialised sound deadening in the back seat area's. It's been sat in my garage for some 4 or 5 years, so I may finally have found a use for it!

I'll be putting the trim back in later this morning and I was pleased to notice only one plastic clip had been damaged following previous attempts to fix the noise and I liked the touch where very thin felt washers had been placed over the clip heads to reduce/eliminate clip to trim noise.

So one happy bunny this side of the pond and many thanks for your very informative descriptions. I'd also add for anyone researching this brace problem and also looking for a fix then bite the bullet and give this a go, it really is an hour (maybe 1.5 hours) job and nothing to be fearful about.

 

If I ever need to confront this issue this writing has given me the confidence to deal with it. Thanks for sharing your resolution to a problem which many are experiencing. My 2018 with 19k miles has yet to make a peep or squeak in the rear brace area but if it does, I'm ready to shut it up!

 

I'm happy to hear that your results were as positive as mine in fixing the annoying squeak. I agree that 20NM is not very tight, so am very curious to see how long it takes for the noise to come back, although hopefully it doesn't come back at all!

Driving the car without the rear seats is a bit weird since you're right about being able to hear the gas sloshing around so clearly. It really shows how well the back seats do in filtering out most of the noise - except for the b-pillar noise!

 

Gents, any updates on this fix? how has it been so far ?

Would the same steps work for the convertible? I figure the trim would be a similar procedure to remove.

 

Yes it did work, but I had to dive back in last week given the noise was slowly re-appearing, but nowhere near as bad as before. This time around I replaced the 7 bolts that secure the brace each side of the car and used high tensile units along with shakeproof countersunk external washers and I hope that combo will prove to be effective for longer. As for whether this is the solution for a convertible then just possibly so but I would suggest dependent on the noise. If it knocks/clunks on very modest acceleration or slow speed braking, then maybe you have the same problem albeit it does seem as if it is older coupe's that are affected. As for taking the trim apart, I would suspect just as easy as it is for the coupe and if so it really is so simple and takes no time at all.

I'd also add I have been in contact with another owner who has this problem, and he has used blue Loctite to (hopefully) further improve his chances of a permanent fix. That was around a month ago so early days and we've agreed to share any updates as they become available to one another.BTW, his is a 2019 coupe.

 

Has anyone removed the braces, and kept them off, and tested over a period of time?

If the sound disappears, you've found the smoking gun!

If the sound persists, one now knows the root of the problem is NOT the brace, and can focus one's attention elsewhere.

No matter which way it goes, it is a win-win situation.

 

I hear what you are saying, but for me at least removing the brace in its entirety proved impossible, albeit I saw that the body shop had done just that. However, it seems every time the brace bolts are tightened, the noise goes away. Whilst that may seem cut and dried you could also wonder whether it is something to do with the actual B pillar which is effectively being drawn into the cabin but at that point it is double skinned and all but impossible to access in a meaningful way. Having said that, I now have a new toy and namely a borescope. If the car needs to come apart again, I'll use that to look around to see if it can provide any clues/solutions.
From anecdotal evidence, I suspect this is an age related matter, and more recently I was surprised to see a 2019 car now joining the afflicted. Whether this will become more prevalent as time goes on I'm not too sure but we'll know soon enough.

 

Sounds like the brace bolts might be the key tightening them stops the noise, so it’s likely a fitment or stress issue in that area. The B-pillar theory makes sense, but without better access, it’s tough to confirm. The borescope could help next time you dig into it. Age and wear seem to play a role, especially if even newer models are starting to show the same problem. Time will tell if it gets worse.

 

i still dont think my convertible noise is the same kind of "crack" that you guys are hearing. i was really hoping you guys could record the noise so we can compare.

 

If it starts up again, I'll try and record the sound. However, if you could imagine say a roll bar or a worn suspension bushing, then you'd be getting close to the sound. Essentially, it's more akin to a dull knock or a dull clonk and typically only happens at pull off or slow down. By way of an example, at its worst mine would make the noise when I engaged reverse to come off my drive, once off and then wishing to go forward it may or may not do it again. It's also very distinctly behind me (remember I drive on the right side) and this seems common to those cars that have this problem. Don't get me wrong, it's not loud, but it is annoying when you just know it's coming but shouldn't be. My dealer who has been quite dogged in his attempts to cure this willingly concedes there is a problem, as does the master tech, but no amount of investigation has categorically identified what the cause is.

 

Has anyone tried jacking at each corner of the car to try to get a pop?

Jacking a corner will cause the chassis to twist and might cause 'the part' to shift and make its noise.

Let's say that worked and is reproducible, then one could hopefully follow and zero-in on the origin of the sound.

 

Good point and worth a try albeit it will be a very fleeting experience which could easily be missed when mixed in with the lifting noises a jack creates. I have heard the noise one or twice simply as I get in/out of the car but it's not something I can generate at will. Following my latest "intervention" all is quiet, but I am so tuned into this I am expecting it to happen and I will not be convinced it is game over for at least 3 months of silence.

 

Any update on the final solution is it welding or just tightening?

 

So far it seems as if tightening seems to be the answer. I say "so far" because some of us have tightened according to the TSB i.e. 20 Nm only to find the noise returned some weeks later. I went whole hog and tightened to 70 Nm and again the noise returned! However, my latest attempt to resolve this very annoying problem was to replace the 7 bolts (on your nearside) with high tensile versions along with these shake proof washers:
It's been something like 4 weeks now with no noise, and I would also add an owner in Australia arranged for the existing bolts on his car to be tightened and blue Loctited. That was some 4 or 5 weeks ago and so far problem solved.

 

I'm really hoping the new bolts and washers prevent the squeak from returning for more than six months, as that would be a win!