The Rearward Rattle From Hell

[Strokerswild]

My '15 has developed a maddening clunk/rattle coming from the rear of the car. Most of the time I drive it with the windows down, but recent tropical conditions have had me running the AC and with the windows up it's impossible to miss. It's less common at highway speed although expansion joints will trigger it at 60, but anywhere from 0-30 is the worst. My garage floor is about an inch above the approach, and even just slowly backing out will net a clunk.

What it sounds sort of like is an improperly adjusted trunk latch or bad seals, where the decklid can clunk with every little bump on the latch. However, I've adjusted the trunk bumpers in increments from one end of their travel to the other with no change. Removed the gas struts, no change. Stuffed a towel in the trunk opening so the latch won't even latch, no change. All decklid hardware is tight, no difference whether my spare and jack are in the car or not. I'm not sure it's decklid related at this point, but can't be entirely sure.

I'm stumped. I'm about to start pulling wheels off and poking around underneath the back third of the car. I have lifted both sides of the car slightly to see if I have a compromised shock mount, but both look OK.

It is MADDENING driving this thing around. If anyone has had something similar, post up.

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[StangTime]

Inspect your rubber differential mounts for cracks. This can be a source of clunking when everything else on the car checks out. On a 2015 you've probably got enough miles that they have failed or are beginning to.

 

[Strokerswild]

If it were a normally driven car, it just sits in the garage most of the time - it just cracked 9,000 miles over the weekend.

I'll check those though, you never know.

 

[Lime1GT]

Do you have a sub woofer? If I remember correctly, I read somewhere there's a unit?? behind it that can come loose. Maybe an amp? Try thumping the box to see if any rattles are heard.

 

[Strokerswild]

No sub, mine has the standard Premium system.

 

[Strokerswild]

OK, so another month down the road, and I'm about to burn this car on the side of the road.....

I've had the rear of the car up in the air looking for anything suspect or loose, and everything checks out. Besides, it seems totally isolated to the trunk. However, just last night, I noticed that there was sort of a witness mark on the hinge stop on the driver side (see pic). Aha. The paint on the corresponding spot to it on the hinge bar is also showing wear. I backed it out two full turns and took it for a drive, and it seemed to help at first but now it's as bad as it ever was.

I assume I need to keep backing it out so it continues to put pressure on the hinge when the decklid is closed. Correct? Anybody got a PDF of the Ford repair manual?

The only positive in this ordeal is that I have the trunk latch adjusted to perfection, I can close it with barely any effort now.

 

[Cobra Jet]

Here ya go, you might find the detailed adjusting info:

https://www.mustang6g.com/forums/threads/free-s550-repair-manuals.134712/

 

[Strokerswild]

Very cool. Bookmarked.

Unfortunately, it doesn't provide much information as to what I'm looking for in this instance, however. I guess I'll have to keep adjusting at random.

 

[Cobra Jet]

Very cool. Bookmarked.

Unfortunately, it doesn't provide much information as to what I'm looking for in this instance, however. I guess I'll have to keep adjusting at random.

Go to this thread (stickied in this forum above), Post # 44, open pdf and start at Page 11:
https://www.mustang6g.com/forums/th...out-for-tips-with-a-happy-ending.19261/page-3

Hopefully that helps.

 

[Strokerswild]

Right. Again, the PDF doesn't give enough info. I'll just have to keep adjusting the hinge stop at random as stated above throughout its range of travel and see if I can get the rattle to stop.

The real question is what changed - I didn't have the rattle until this spring. The car used to be dead quiet. Apparently weatherstripping has settled or something.

 

[Elp_jc]

The only positive in this ordeal is that I have the trunk latch adjusted to perfection, I can close it with barely any effort now.

Mine too, but wish I could say the same about the freaking hood; nothing helps. I loosened the rubber bumpers on both sides, and raised the hood latch a little Iittle (it was too low), and now it's aligned perfectly. But it still requires massive force to close properly. And more worrisome, the effort to open it with the interior lever is massive, and I'm sure it'll crap out sooner rather than later, especially since I open the hood every time I use the car. The spring that pushes the latch is crazy strong; why? Seems stupid. Hopefully somebody has an easy fix. Thx.

 

[Arknsawchuck]

We have a 17 and one of the rear shocks which are coil overs had some how backed off and loosened ever so slightly making a bumping sound when going over anything rough on the road. Looked good, even felt tight when just grabbing it by hand, but when we put the wrench to...loose. If you are certain it's the trunk, how about putting some temporary padding around hinge or where it might touch on one side, take for drive, then the other if that side doesn't work. I hate those darn mystery noises.

 

[Strokerswild]

We have a 17 and one of the rear shocks which are coil overs had some how backed off and loosened ever so slightly making a bumping sound when going over anything rough on the road. Looked good, even felt tight when just grabbing it by hand, but when we put the wrench to...loose. If you are certain it's the trunk, how about putting some temporary padding around hinge or where it might touch on one side, take for drive, then the other if that side doesn't work. I hate those darn mystery noises.

Tried packing the hinges with shop rags to no avail....

But see that part in the bold? That was essentially it. I had checked shocks once before as mounted in the car, but didn't think that was it until I ran across a thread last week that mentioned that some guys with the older design of the Steeda shock mounts (which I have) ended up with a noise. I pulled the driver side shock out, and there was just a hair (probably .010") of slack between the nut and spherical bearing. Not sure how it loosened up with my liberal use of threadlocker, but I tightened it back up and reinstalled it, and the noise is gone.

Steeda has stepped up and is going to send me the updated hardware. Good stuff. I don't want to trade the car off anymore.....

 

[Arknsawchuck]

Tried packing the hinges with shop rags to no avail....

But see that part in the bold? That was essentially it. I had checked shocks once before as mounted in the car, but didn't think that was it until I ran across a thread last week that mentioned that some guys with the older design of the Steeda shock mounts (which I have) ended up with a noise. I pulled the driver side shock out, and there was just a hair (probably .010") of slack between the nut and spherical bearing. Not sure how it loosened up with my liberal use of threadlocker, but I tightened it back up and reinstalled it, and the noise is gone.

Steeda has stepped up and is going to send me the updated hardware. Good stuff. I don't want to trade the car off anymore.....

Cool, always feels good when the gremlin has been silenced. Good of Steeda to step up and send updated hardware too.

 

[Strokerswild]

Yep.

Bonus is that my decklid now fits and closes the best it possibly could....

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