Help needed, interior vibration/noise/rattle after decat
Discussion
On Friday I secondary decatted my N420 with the quality bits provided by Lord Bret Sinclair.
On my way home, after enjoying the glorious sound, I also started to hear a weird interior noise, coming from up & behind me (LHD), similar to metal on metal, also a little squeaky.
I thought it must have been the old secondary cats in the boot, moving around in the bubble paper.
Sadly, Saturday the noise came back when the boot was empty. I run some “tests”: it does not seems dependant on RPM, gear, steering, road conditions or speed. It can go away then come back. Tend to show up when car has been running for some time.
I took a look at under the battery shelf, moved around all the tools. Checked the puncture kit in the boot, rear parcel shelf, rear lights nuts, warning triangle, boot rubber stopper.
Honestly, the only event that could have caused was being lifted and decat fitting. But the noise does not really seem to be coming from under/outside the car but from the cabin/boot area, so my brain does not really believe it might have been this.
Useless to say, I am anal about interior noises, this is driving me bonkers.
On my way home, after enjoying the glorious sound, I also started to hear a weird interior noise, coming from up & behind me (LHD), similar to metal on metal, also a little squeaky.
I thought it must have been the old secondary cats in the boot, moving around in the bubble paper.
Sadly, Saturday the noise came back when the boot was empty. I run some “tests”: it does not seems dependant on RPM, gear, steering, road conditions or speed. It can go away then come back. Tend to show up when car has been running for some time.
I took a look at under the battery shelf, moved around all the tools. Checked the puncture kit in the boot, rear parcel shelf, rear lights nuts, warning triangle, boot rubber stopper.
Honestly, the only event that could have caused was being lifted and decat fitting. But the noise does not really seem to be coming from under/outside the car but from the cabin/boot area, so my brain does not really believe it might have been this.
Useless to say, I am anal about interior noises, this is driving me bonkers.
Herbs said:
Had similar on a Lotus Elise and it turned out to be the exhaust/bracket making contact with the floor . That sounded like it was coming from a different location as it transmitted the vibration/noise.
Yes, it does make sense, since it was the only thing that happened to the car and I never heard this noise prior. Will check with the shop that installed the decats, sadly they will be back from holidays on September. 
Meanwhile, I will check what has been suggested by Pete and Goat, thanks guys, really appreciate.
goatherder2001 said:
Bizarrely I had something similar happen to me although unrelated to the secondary decat. I identified mine as coming from the rear passenger side speaker rubbing with the seatbelt holder. Thermal expansion caused it to start happening. Felt tape stopped it
Played with both, I never removed them before so I learned something new, but sadly it wasn't neither of them. But thank you!V8V Pete said:
Whilst it is more likely to be something transmitted from the exhaust also try adjusting the hatch hinge stops (half a turn either way) and if you're completely obsessive put a little bit of bike handlebar tape on them every couple of months to completely eliminate it.
Tried this too and while none of them were the culprit, I am curious about what those do. I turn them as tight as I could (they were halfway), is this the right/default position or should they be more loose? I notice no changes in how the boot is closing by doing so.On the actual problem: I am slowly accepting it must be the exhaust, it's the only thing that has been touched. I am wondering if I should try to find an exhaust shop that is still open in this season and have them check it by paying or wait until the guy that installed the decats is back from holiday.
EVR said:
Tried this too and while none of them were the culprit, I am curious about what those do. I turn them as tight as I could (they were halfway), is this the right/default position or should they be more loose? I notice no changes in how the boot is closing by doing so.
Mine are about half way down I think. They affect the fit of the leading (top) edge of the hatch.Finally fixed (knock on wood) this today, it was indeed a heat shield touching the subframe. Specifically, the left the one on top the exhaust section around the gearbox, they get very close to the rear subframe in this region. Thanks to DAE who chipped in via mail spotting the problem, real pros.
The exhaust guy moved them around while fitting the decats. He is an honest guy, didn't ask for being paid this time but a bit intimidated by the Aston and forgetful.
The exhaust guy moved them around while fitting the decats. He is an honest guy, didn't ask for being paid this time but a bit intimidated by the Aston and forgetful.
Edited by EVR on Monday 16th September 09:52
Bringing this thread of mine back because I wanted some clarification on those:
- what spanner should I use? (I have to buy it, I don't have any)
- in which way should I turn them to achieve what exactly?
Thanks for the help, I recently had a new cabin noise showing up (nothing to do with the original one) and I suspect those are the culprit, since I messed with them when trying to resolve said original noise.
Basically, what those bolts do exactly and how I know they are perfectly adjusted?
- what spanner should I use? (I have to buy it, I don't have any)
- in which way should I turn them to achieve what exactly?
Thanks for the help, I recently had a new cabin noise showing up (nothing to do with the original one) and I suspect those are the culprit, since I messed with them when trying to resolve said original noise.
Basically, what those bolts do exactly and how I know they are perfectly adjusted?
I played around with these a few weeks ago. I wanted to adjust the way the leading edge of the tailgate sat in relation to the roof line. I'm by no means an expert, so please take my comments as such, but it seems these adjust the height of the tailgate leading edge (slightly) when closed. The trailing edge is adjusted using the two rubber screws at the other end, and I guess to some degree the catch.
Anyway, mine are an 11 mm hex head, but not very difficult to turn. An open ended spanner might be difficult to get in, but a socket or ring spanner should work. I think they only start to have an influence once they are sufficiently wound out to touch the other bit of the hinge that rests on them. Obviously, you can't see this as the boot is closed, so I screwed them in, then out incremently until an imprint was left on a bit of plastigauge I had placed on the screw head. Sufficiently thin plasticine or bluetack would achieve similar results. The pitch of the thread looks around 0.75 mm (but i haven't measured it), so every turn anticlockwise will close the gap by 0.75 mm. Once I could see there was little gap I slowly screwed them out to achive the better roof line. It sounds like a bit of a faff but it did want to adjust them blindly and put undue tension and stress on the tailgate; I'm conscious of the big lump of glass in it!
Anyway, mine are an 11 mm hex head, but not very difficult to turn. An open ended spanner might be difficult to get in, but a socket or ring spanner should work. I think they only start to have an influence once they are sufficiently wound out to touch the other bit of the hinge that rests on them. Obviously, you can't see this as the boot is closed, so I screwed them in, then out incremently until an imprint was left on a bit of plastigauge I had placed on the screw head. Sufficiently thin plasticine or bluetack would achieve similar results. The pitch of the thread looks around 0.75 mm (but i haven't measured it), so every turn anticlockwise will close the gap by 0.75 mm. Once I could see there was little gap I slowly screwed them out to achive the better roof line. It sounds like a bit of a faff but it did want to adjust them blindly and put undue tension and stress on the tailgate; I'm conscious of the big lump of glass in it!
Yesterday, with the impromptu help of MisterBlu whom I had met for a coffee, we tried to adjust those bolts, but the rattle is still there.
I then bought an 11 spanner and when home, I tighten them as much as I could, since this was what I did back in 2019. I'll test this adjustment; if not resolved, next step is some felt tape on them, as suggested by Pete.
I then bought an 11 spanner and when home, I tighten them as much as I could, since this was what I did back in 2019. I'll test this adjustment; if not resolved, next step is some felt tape on them, as suggested by Pete.
Meh, the rattle is still there.
Tried to unscrew said bolts, no improvements and for the life of me, I can't see what they do, to me the roof line is always the same.
Now I don't know if I should keep them tight, loose, semi-tight... Could they come off? I wasn't brave enough to unscrew them completely to the max.
Tried some felt too, does not seem to do anything. But I am pretty sure the rattle is caused by messing around with them.
Tried to unscrew said bolts, no improvements and for the life of me, I can't see what they do, to me the roof line is always the same.
Now I don't know if I should keep them tight, loose, semi-tight... Could they come off? I wasn't brave enough to unscrew them completely to the max.
Tried some felt too, does not seem to do anything. But I am pretty sure the rattle is caused by messing around with them.
EVR said:
Meh, the rattle is still there.
Tried to unscrew said bolts, no improvements and for the life of me, I can't see what they do, to me the roof line is always the same.
Now I don't know if I should keep them tight, loose, semi-tight... Could they come off? I wasn't brave enough to unscrew them completely to the max.
Tried some felt too, does not seem to do anything. But I am pretty sure the rattle is caused by messing around with them.
The tailgate hinges are four-bar linkages and need a positive stop, which is what I believe the bolts provide. As far as I know the adjusting the bolts will alter the stop position of the hinges, which will alter the position of the top of the tailgate relative to the roof; screw them out and I think the top edge of the tailgate should rise - not that I've tried adjusting mine. To prevent wind noise the top edge of the tailgate should be slightly sub-flush with the roof.Tried to unscrew said bolts, no improvements and for the life of me, I can't see what they do, to me the roof line is always the same.
Now I don't know if I should keep them tight, loose, semi-tight... Could they come off? I wasn't brave enough to unscrew them completely to the max.
Tried some felt too, does not seem to do anything. But I am pretty sure the rattle is caused by messing around with them.
LTP said:
The tailgate hinges are four-bar linkages and need a positive stop, which is what I believe the bolts provide. As far as I know the adjusting the bolts will alter the stop position of the hinges, which will alter the position of the top of the tailgate relative to the roof; screw them out and I think the top edge of the tailgate should rise - not that I've tried adjusting mine. To prevent wind noise the top edge of the tailgate should be slightly sub-flush with the roof.
Cheers.This morning I put some better felt pad, the one I used yesterday was a quite thin. Also, instead of on the top pf the screw, I placed it on the piece that will rest on it, on the tailgate itself. I believe contact will be better. If it works, I will post some pics. I have to wait though since the car is at a detailer, can't wait to see the result!
Gassing Station | Aston Martin | Top of Page | What's New | My Stuff