Weird rubbing mark with aftermarket front sway bar endlinks

[BishamontenZC6]

They visually look OK, I cannot see any tear. There's also no play in the ball joint. Still they are the only part of the front suspension that haven't been renewed and are 160'000km.

According to your experience, would it be possible that the subframes got a little bit loose with time even though they have never been touched ?

[Racecomp Engineering]

Originally Posted by BishamontenZC6

They visually look OK, I cannot see any tear. There's also no play in the ball joint. Still they are the only part of the front suspension that haven't been renewed and are 160'000km.

According to your experience, would it be possible that the subframes got a little bit loose with time even though they have never been touched ?

That seems unlikely. Is the noise loud? When does it occur? (potholes, all the time, etc)

- Andrew

[BishamontenZC6]

It's not loud and clear as a loose end link clunk would be, it's more like a muffled thump. You can hear it without music while driving but it's not obnoxious. It sounds a lot like this noise, posted a few years ago on the forum :

It only occurs at low speed (below 40km/h), when small bumps hit one side or general uneven pavement, particularly when those makes the car bounce from left to right quickly. It doesn't occur on speed bumps or at higher speed, when braking nor highway and spirited driving. Only city driving at low speed.

For peace of mind I checked again that the endlinks are tight today, they are ok. Also checked the top mount to struts nuts and they are tight. That's definitely weird.

[bdtbdtbdt]

It looks like maybe the very bottom of your shock is hitting the a-arm

[BishamontenZC6]

5 years with this car and it’s been nothing but pleasure, but that noise problem is really ruining it for me now. I don’t know what to do anymore, and unfortunately have no serious suspension specialist I could give the car to for check up in my surrounding. I’ve had my share of other quirks and problems with the car before but they all had logical and rewarding solutions, this one is just ridiculous and doesn’t make sense. It shouldn’t be anything too complex but the impossibility to solve it makes me want to drive the car straight into a lake and forget about it…

I found another video that shows more how it sounds inside the car when it happens (same road condition as the video, but lower speed in my case) :

[DarkPira7e]

Originally Posted by BishamontenZC6

5 years with this car and it’s been nothing but pleasure, but that noise problem is really ruining it for me now. makes me want to drive the car straight into a lake and forget about it…

I think you need to take a break if you're feeling this way about a noise after modifying your car. If it's a quirk that has no visible impact or detriment to the car, embrace that your car has something unique and continue to love it. It's still a cheap Japanese car, no need to take it to this level

[BishamontenZC6]

You're right that a break is needed, it's what I eventually did .

The thing is that this exact noise is not a quirk. I can live with crickets, DI or vacuum pump thumps as they are known quirks on that platform and I totally embraced them.

That suspension noise is not one of them. I've never had it on my first GT86, neither on my current BRZ that I had been driving for almost 2 years with it's current setup without any suspension noise before last month. If it had been there from the moment I installed the coilovers I would agree with everything you said, but it's not the case.

On top of that, I've been daily driving sports and modified cars for the last 25 years, 86's platforms for 8 years and my current one for 5 years, so it's not exactly that I'm lacking XP in that field.

It's true that so far there is no obvious sign that it might have an effect on the handling nor safety of the car, but as long as it's not proven it's difficult to take it for granted and I'm not great at gambling when it comes to safety. For me, unusual noise means something isn't right, cheap platform or not.

Nevertheless, I had some time during the holidays so I went all over it again and did the following for front and rear :

• Checked the endlinks again and made sure they are tight - OK
• Checked that all the nuts and bolts are tight to spec - OK
• Checked that the top nuts are tight - OK
• Checked that all ball joints are OK with no play - OK
• Checked that every bushings are OK - OK

What's has been replaced :

• Front endlinks (Aftermarket)
• Front sway bar bushings (OEM)
• Rear endlinks (OEM)
• Rear sway bar bushings, mount and bolts (OEM)

I also disconnected the endlinks at the front to figure out if noise was still occuring with the sway bar disconnected : it did. I can therefore definitely state that endlinks are not the culprit and will finally leave them in peace from now on.

Based on that, I really don't know. The only idea I'm having left is that those noises would be caused by the near 0°c we are having where I live since a few weeks. They started to appear mostly after I replaced the front sway bar bushings (OEM), which is also when it started to get colder. So maybe the new sway bar bushings (probably firmer than the 160k old ones), with very cold temperature generate more noise with the coilovers, that could themselves be clunkier in the cold. Problem is there's no way to know for good until temperatures go back up. I don't know what the chassis specialist around here think about this.

[BishamontenZC6]

Ok, here I am with some good news.

I went with the methodical way to finally circle what was the cause of my suspension knocks, which are now ALMOST solved.

I first went back to OEM endlinks up front and removed the Cusco rear side member braces for good (too much NVH for my taste).

Then, it turned out my torque wrench actually was no longer working properly and gave false results in my previous checks. I got a new premium one and went through all the bolts again, front and rear. The front passenger side upper strut to knuckle bolt wasn't actually torqued to 155Nm. It took quite an extra tightening to get it to spec. Looked like I found the culprit for the front knocks.

Also, I checked the trunk for loose equipment and noticed that the jack had been stored with the ring oriented toward the body of the car instead of the interior of the trunk. When shaking the stirofoam part in which it's stored, I could hear it clunking against the body. I put it back to it's intended position (there's even a drawing on it...). Sounded like a good explanation.

After all of that, finally some good relief. No more clunks, pops or anything on bad pavement or bumps. Car drives great and I'm no longer stressing every time there's a little bump on the road. It also seems that the front OEM endlinks no longer rub on the LCA. Feels so great, BUT...

Today I heard a very particular muffled thump in my footwell while taking a quick 90° left turn on flat pavement (the same happened yesterday at the same intersection). It came from the front driver side, but nothing like the horrible creaking of sway to LCA contact. Checked down there and I now have 2 obvious contact marks inside the driver side wheel well...

How come my OEM endlinks all of a sudden start rubbing on my inner wheel well while I'm only running -1.8° camber and 20mm lowering up front ?!?

Everything in there is new and OEM. I really don't understand... I'm really starting to miss my Miata, Corvette and Aston Martin days, where double wishbone suspension were less of a hassle. Those McPherson are really running on my nerves.

[churchx]

Not as if there was any obligation for manufacturer to mandatory design in big extra clearances for possible specific aftermarket customisations with random combination of non OEM components. If one customizes something, imho it's obvious that all possible issues that may arise should be onto self to solve not manufacturer to blame?


As for limitations to clearances, on twins most probably they are caused not by double wishbone vs mcpherson, but rather by wide boxer engine that for weight distribution needed to be in base, that leaves way less for wheel articulation. Reason why twins are not that good as driftcars despite supposed AE86 "legacy", as that means need to space out wheels a LOT & widening body kits to enable higher steering angles

[BishamontenZC6]

It wasn't my argument at any moment. Of course I'm not expecting any manufacturer to take any possible mod in consideration from factory, neither did I use "random" aftermarket parts. I only have ST coilovers, everything else is stock and brand new, so my case is a far cry from the mismatch you suppose. On top of that I do not drift nor track the car, only daily and spirited mountain drive, so nothing uncommon or extreme.

What I said about McPherson vs double wishbone isn't about clearance, it's about the capacity to retain proper geometry in a broader range, thus predictability when modifying. McPherson is a great middle ground when it comes to cost saving and driver involvement, but it's subjet to a lot of variables, which becomes troublesome when even your most basic mod impacts one of them (height, scrub radius, camber, etc). I agree with you on the analysis of the limited front clearance and it's cause, but I never suffered from a lack of steering clearance. I only could not understant why old OEM endlinks wouldn't rub but new OEM would with the exact same setup and alignement. Don't get me wrong, I still adore this car, I just feel like I didn't have such headache on a "simple" problems on some other cars I owned.

Anyway, I talked with chassis engineers and techs about my problem and they suggest that the ~160k old parts (endlinks and bushings) were worn out and thus accumulated a lot of compliance (and slight play) that the brand new parts obviously don't have. With new bushings and endlinks, everything is back to nominal and tighter compliance, which reveals the issues I'm facing.

On their advice I replaced the front OEM endlinks with slightly shorter aftermarket ones (226mm) and after a few hundred km it looks like the problem is solved, no more rubbing on the inner fender and no preload on the sway bar.

They also told me that the muffled thumps I've been experiencing for a few weeks are most probably caused by the near 0°c temperature we're having this winter, made more obvious by tighter new bushings. Apparently bushings aren't great under 10°c and tend to get exponentially hard the closer they get to 0°c. On top of that, oil in the shocks gets less fluid, can make some noise with the valves, etc.

The fact that the whole suspension has been negatively checked for loose components and that those noises tend to disappear after some time driving seem to support that diagnostic. Now the only 100% confirmation will come when temperature will be back above 10°c.