# Rear wheel noise only when applying brakes coming to a stop ? "SHSHSH SH SH SH sh sh sh s h s h s h "



## itsinthgam7 (Jul 29, 2009)

Hello VWers, I wish i won the lottery so i can just sit in my own fancy garage and tinker around my VW all day. =) 

Anyway, I found a youtube video of the exact sound issue i'm having. It ONLY happens when slowing down while applying the brakes. The obvious "SH SH SH SH SH SH sh sh sh sh s h s h " sound it makes slows down until stopped. speed up and don't hear anything until i'm slowing down while applying brakes. This started happening after working on my car for rear squeaking issues due to the rear sway bar. I was taking the wheel off and BAM ! it fell on the dust cover/rotor/caliper. didn't look to bad with minor wipe way mark on dust cover and thin side of rotor. I cleaned up the area even the calipers and put wheel back on and since then the noise has surfaced. I looked again last night to see if it was something sticking and rubbing against the rotor but my thought is it only makes noise when brakes applied and slowing down. 

So please listen to this great youtube video of noise. https://www.youtube.com/watch?v=MzH7Wl6_hOU

the few things that make sense is rotor warped, anti rattle spring on caliper damaged? a bent dust cover would make that noise all the time the wheel is rolling wouldn't it?


anybody know exactly what this is? APPRECIATE the expertise.

oh its my mk4 337. 

update: driving home at lunch sounded closer to a "CHUH CHUH " sound lol i'm going to just take everything off and inspect.


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## a_riot (Jun 14, 2005)

You've likely got brake pad material stuck to a section of the rotor. This can happen if you heat up the brakes, then stop and apply the brakes and just sit there, or put on the ebrake while the pads are still very hot. It will leave a thin layer of pad material that will make that noise when applying the brakes at certain speeds. It will eventually go away as the pads/rotors wear down but if its the rear it can take a long time.


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## Thy_Harrowing (Dec 7, 2014)

> the few things that make sense is rotor warped


Contrary to popular belief modern rotors don't warp, not in street applications anyway. They did back in the day but it doesn't happen outside of race/track conditions anymore. Instead, what a lot of people and even misinformed mechanics call rotor warp, is usually cementite deposit on rotor can begin when rotor metallurgy changes rapidly. This happens most often in the situation that a_riot referenced above, such as heating up the brakes a lot and then coming to a stop right after and sitting on the brakes or applying the parking brake while super hot. It is literally a change in the metallurgy and once it begins it really won't go away. When that small portion of the rotor is swept it leads to the symptoms that are commonly associated with warped rotors.

All this to say, it's possible this has occurred rotor or it's possible that you just have some brake pad deposit on there like a_riot said and need to burn it off. But the conditions that lend themselves to brake pad deposit stay on rotor surface are the same as those that lead to cementite occurring so... 

It's not the anti-rattle clip or dust shield or any of that. Most likely if you replace the rotor it will be dealt with. May as well replace both and make sure you mate the pads and new rotors properly.


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## a_riot (Jun 14, 2005)

Thy_Harrowing said:


> Contrary to popular belief modern rotors don't warp, not in street applications anyway.


I guess it depends on your definition of "warp". Cast iron rotors aren't likely to actually "warp" like a vinyl record left in the sun except in extreme circumstances, but you can certainly get runout from improper torqueing of wheel bolts, or issues related to a poor hub/rotor interface that have similar symptoms. I'd be curious to know if actual warpage is possible under circumstances like a red hot rotor getting soaked by ice cold water repeatedly. I would think it would given a large enough temperature differential. You can warp a cast iron frying pan using temperature differentials, but obviously its much thinner than a rotor, at least a new rotor. This fellow made his rotor explode, so if they'll explode they'll warp under the right circ


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## Thy_Harrowing (Dec 7, 2014)

a_riot said:


> I guess it depends on your definition of "warp". Cast iron rotors aren't likely to actually "warp" like a vinyl record left in the sun except in extreme circumstances, but you can certainly get runout from improper torqueing of wheel bolts, or issues related to a poor hub/rotor interface that have similar symptoms. I'd be curious to know if actual warpage is possible under circumstances like a red hot rotor getting soaked by ice cold water repeatedly. I would think it would given a large enough temperature differential. You can warp a cast iron frying pan using temperature differentials, but obviously its much thinner than a rotor, at least a new rotor. This fellow made his rotor explode, so if they'll explode they'll warp under the right circ



I should have been more specific, I was only referring to warping from even the heaviest of braking in street applications. Improper torquing of wheel bolts or intentionally subjecting rotors to unnatural temperature differentials, or the kind of abuse a rotor gets at the track (which will never be seen on the street) can cause some degree of warpage.


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## itsinthgam7 (Jul 29, 2009)

*shiz i guess i don't have that big of a problem compared to that video*

Hey guys, thanks for the feedback and visuals lol So just wanted to update and close out this thread. I got my hands dirty and took the caliper off (such a newb so this was a big deal) and cleaned up everthing and regreased and put back in place and put back on and noise is gone. I think i was doing some caliper cleaning in the grooves and such and probably moved, tweaked, or left something behind in the cracks that may have caused the noise. amazing how something small could create a loud annoying noise.

I appreciate you taking time to read and give feedback. Off to keep tinkering and working on things. eventually i'll get or upgrade Rotors and Brake pads. OH and i did notice a little slight wobble which sounds like wearing out ball bearing..............google diy here i come ! VW 4 LIFE !


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## petethepug (May 25, 2001)

That sounds like a wheel bearing in a the video of the other car. Reading back, hearing that the full weight of the vehicle fell on the dust shield/disc, I’d say replace the bearing on the next maintenance.




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## itsinthgam7 (Jul 29, 2009)

*actually*

it was the wheel/tire that clipped the dust cover. nothing major but did happen and i cursed myself. i believe the loose wheel bearing was there prior too.


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