Scraping sound when not scraping
 

So we all know what it sounds like when the little plastic pieces that hang down scrape the road. I'm getting that sound even when I hit little itty-bitty dips in the road that only cause the suspension to rebound less than an inch. It feels like something is hanging down like the cover underneath and it is catching every bump. But when I look under the car... nothing. I checked the sway bar in the front to see if anything was loose. No evidence that was the problem. The rear sway bar appears to be fine. No other suspension mods were done. No exhaust mods. No wheels. No spacers. No springs. Nothing.

So what on earth could cause me to hear and feel the scraping under my feet? It is much more pronounced with a passenger. But I went for a long drive yesterday with a passenger and didn't hear it very much at all. But then today I hit a smooth dip in the road and it sounded like I bottomed out when before this was never a problem.

Is this the sound of a blown shock? Because I've been having a problem with the front left one making a swishing sound over some heavier bumps where the shock unloads too much. But this sounds like it is coming from directly underneath the car or maybe as far over to the right side. Unfortunately my hearing isn't good out of my right ear so its a pain to locate the source.

Any ideas? I'll be taking it to the dealer tomorrow if I can't figure out a way to correct the issue myself. But I'd really like some opinions here first so maybe I'll have some ammo when the dealer comes back and tells me everything checks out.

Thanks in advance for useful responses!

take off the front left wheel and see if the shock is leaking anywhere...

your description sounds like a blown shock

Rog. I'll check it out. Thanks.

Are you lowered? Tire scraping inside of fender or fender-liner?
You can put some painter tape up in there and see if the tire scuffs it.

Could be that annoying little front mud flapper. I took mine off and made a BIG OL DIFFRENCE.

It was the front tires. Who knew?! They apparently don't like the roads here. Can't blame them. Guess it's time for new wheels/tires! :tup:

I'm taking mine in for the sound I'm hearing..

rear differential bushings? Is there a wet mark on your differential?

Endlinks are a clunk. Sway bar bushings is a "creaky door" kind of noise. "Grinding" makes me think metal-on-metal. Have you gotten the car in the air and looked for any shiny spots where something is rubbing when the suspension compresses?

Maybe the backing plate is touching the brake rotor? Get that corner up in the air, take the wheel off and bend the plate back some. See if that works.

Not a problem. I just can't think of too many other places where you can get metal-to-metal contact. If you were complaining about squeaking, clunking or creaking it would be easier to narrow down.

Please post what you come up with mine is starting to make some noises up front. I lowered mine about 2 months on Tien springs, dont drive her much, I havent gotten mine to the lift yet either but I think it has something to do with the fender liners and fro t splash guard.

Haha similar experience today. sounded like exhaust piping touching the ground for a couple seconds. Couldn't find the culprit either.

Tigger, do you get the sound when you hit a bump or dip?

This is why I think it has to be something with the splash guards.

My best guess is the oil pan shroud/cover. There is a big piece of black plastic underneath that covers the oil filter and pan. The screws in it tear out quite easily and there are a ton of them and they are a real PITA. Once one or two of those screws tear loose, that whole thing starts to come loose and sag. If you hit a bump, maybe one side of it is torn out and the bump in the road causes it to scrape. Buy the aluminum one from Z speed? I think sells it.

Thanks for the updates, hopefully its something very simple.

They said it was the front sway bar which was my first guess at the very start of all of this. Thought it was either the bushings or the end links. I'm pretty sure its just the bushings since there has to be quite a bit of suspension travel to make the bar shift. It doesn't quite seem like the end links. So I'm probably going to just get new bushings and swap them out. If it continues I'll get the SPL end links and see where it goes. I'll update again once I have it swapped.

Though I'm not holding my breath because this is the same dealer that attributed that noise to tires. I have little faith in their diagnostic capabilities. I'm wondering if they aren't trying to point fingers because it is an aftermarket part. They seem to not like that stuff so much. Anyhow... updates to follow.

Is the front sway bar hitting the under-shroud? I had the fancy aluminum under-shroud on my 350 and the powdercoat was worn off from the sway bar hitting it. Swaybar was after market, as well as, endlinks.

Not sure how to resolve this.. but helps to know the issue.

Had a discussion with my friend about this. He stated it's the fender liner hitting the tires or bouncing around tye fender. I did check mine and I have one where there is some rubbing going on.

Hmmmm... If it was rubbing I imagine the tech would have figured it out. And it is all the way across the entire front end. Kinda tells me it isn't the fender liner. I mean, I wish it was. Those are easy and cheap to replace.

So I took the shop foreman out for a drive first and then he took a tech out. But this isn't a mod-friendly dealer. I think they just wanted to get rid of me. Every time they see an aftermarket part they freak out. I think that is why they pointed to the sway bar.

A rep from Hotchkis replied to my inquiry this morning and was also questioning their conclusion. It obviously isn't the sway bar itself. That just doesn't make noise. However, I am still leaning towards a bushing issue. I wonder if the grease somehow dried up or leaked out too much over the last 8 months. I've also taken this thing to it's limits and beyond many times. I drive her pretty hard.

I think I'm going to get some new grease, the upgraded billet bushing brackets and replacement bushings from Hotchkis and the SPL endlinks and go from there. I wanted to do the upgrade anyway so it wouldn't be a loss if it isn't the issue. It'll only prove it isn't the problem and I can further isolate it. We'll see. I'll keep y'all posted. Thanks for the responses and ideas. Much appreciated.

I got the Hotchkis billet sway bar brackets. When you get yours. Make sure you get a tube of their silicon grease for them. ;) And make sure you got your sway bar mounted right side up.

The title reminded me of this. Lol

Any update on this ? Mine clunks and squeeks now. Had hotchkis bar with OEM endlink for 20k miles, maybe its time to change them out.

Did u ever figure out the problem?

It looks like his Hotchkis bushings were the culprit. Here is his response when I asked him if they fixed his problem.

You can see the grooves in the middle photo in Rusty's post. Here is a another pic:

http://www.carid.com/images/hotchkis...s/23190625.jpg

Sorry guys for leaving you hanging as I rarely check into these threads anymore. If ever. JAR was kinda enough to uodate this for me.

And to re-assure everyone, if you have those older style bushings you may want to contact Hotchkis for the updated parts so when you wind up needing to tear them off again for greasing you can just swap in the new, smooth sided bushings. Should work a little better. Jwick also recommends wrapping Teflon tape around the bar first and then greasing. If using teflon, you may not need grease. I can't say for certain either way. Certain greases/oils may contain polyalfaolefin which will cause Teflon to disintegrate. Just use your best judgement and common sense. Just try not to shred your bushings. Mine are showing signs of needing replacement but they'lol been on there nearly 37,000 miles.

Hope this helps out!

I wanted to share my experience with the same noise scraping noise albeit mine was more pronounced as the temps would drops and what I found this weekend will make some sense.

I've had this on and off annoying scraping noise for a couple of years :| I could never figure it out blaming tire scrape on the fender liners or the plastic rivets that hold the wheel liner were not holding it in place thinking they moved to cause the scrape sound.

I lifted the front end up and decided to take a close look at the swaybar bushings to see that maybe just maybe it would be from there

I took them out and found them dry to the bone and thought hum thats what more than likely causing the scraping sound since the plastic bushing was making direct contact or metal in my case to swaybar.

I removed and cleaned the bushing and braket and apllied plenty of grease to the inside of the bushings and reinstalled.

It was 55º this morning coming to work and where I would normally hear the scraping sound along the drive there was NO MORE scraping sounds coming from the front end.

I highly recommend everyone who has encountered this particular sound to just make sure that the front swaybar is greased even after a year of use.

Thats all for now carry on :)

Thanks Tigger for the thread. :tup:

This is what made me finally look at the bushings since Im the Hotchkis also :)

Check the the brakes -- I seem to recall that there is a thin metal dust/heat shield (?) that can scrape the caliper as the wheel rotates and needs to be adjusted like a mm or so to avoid light contact.

Another possibility is the sliding pins for the calipers

I think there were TSB's for the G37 on these issue, and I had the first one on my Z.

Finally, there could be a small pebble trapped in the caliper that is scraping.

I've gotten that several times with a damn pebble. A short, quick acceleration usually takes care of that.

Oh. And if you hit a deep puddle of water at speed, there is a chance you could bend the shield underr the driveshaft causing it to make contact and it is more pronounced when engine braking. You'll have to bend the shield back. Happened to me last spring. But, that's actually scraping I suppose. Not sure how many people have ever dealt with that. I might be the only one. But it sounds a lot like a rotor/wheel issue. Kinda scary.

I have the squishy sound coming from the front drivers side strut in the mornings going over the last speed bump leaving my place. The approach is with the wheel going straight perfectly, and only the front drivers side tire goes over it (the right side has enough room to avoid the speed bump).

Now strangely: If both tires go over the speed bump at the same time, no noise.

It doesn't really bother me, but I'm thinking it's going to get worse/sign of things to come.

Is there a stupid donut thing above spring/perch that needs replacing? I'd like to avoid going to the aftermarket nightmare of trying to find new springs or blowing thousands on KW's...

Other than that, this car has been a HUGE step up from the POS tin can on wheels chassis 07 wrx I once had. Maybe it lacks a bit in the all out excitement factor and low end tq, but it's been a stress free/fun car to own for the daily commute...and, there are not ten million Z's in the Portland area...I use my "sick days" now when it snows... so no AWD needed.

I take it the issue was fixed and the noise completely went away?

Yes,

It does seems that the Hotchkis bushing need to be greased periodically

So they don't go dry, and develop the plastic scraping sounds from the front end.

Thanks for this post Tigger and everyone's response. This pretty much confirmed my suspicion about the need to grease up the bushings. I have a similar issue and is more pronounced when cold as Trips mentioned. Strange how I hear it in the morning and never on my way home.