Rear brake rotor install problem

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BajaTim
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Rear brake rotor install problem

Post by BajaTim » Sun Nov 04, 2018 5:27 pm

So my searches have revealed there are a FREQUENT install problems when replacing or upgrading rear rotors on 2000-2004 Outbacks and up to 2006 Bajas and maybe other earlier models of Subaru as well - all
the mechs say “oh yeah” but I STILL have a scraping sound after 3 tries - 2 with my Suby (non-dealer) mech and 1 with local Monro (who installed new parkng brake pads BEFORE new rotors went in).

Seems my OLD Powerstops had “ground” away any fitting issues and NEW rotors are too “tight” to clear minimal tolerances (design flaw)...

My mech did the “6 pm” cutout of dust cover, which fixed “scraping” but then a “moaning” from rears became audible which he said was “parking brake pads”.

Took it to Monro (as they had installed new parking brakes) who said solution was to “grind rotor” but now the “scraping” is back.

Anybody found a PERFECT solution to this rear rotor issue?

Anybody remove dust covers completrly without ill effect?

Thanks in advance,

Tim

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Guacamole
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Re: Rear brake rotor install problem

Post by Guacamole » Sun Nov 04, 2018 8:04 pm

BajaTim wrote:
Sun Nov 04, 2018 5:27 pm
Anybody found a PERFECT solution to this rear rotor issue?
Get the dealership to do it. :lol:
No joke, had my rotors and pads done a few years back at a local shop to save some money, but the brand new Moog rotors ground against the shields. So I bit the bullet and had the Subie dealership replace them with OEM and they're working fine as of today. No idea if removing it will affect anything though but I would caution against it- it's there for a reason (supposedly).
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BajaTim
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Re: Rear brake rotor install problem

Post by BajaTim » Sun Nov 04, 2018 9:07 pm

I can’t bring myself to go to Dealer and get *****:)

There’s a mech in Pittsfield who did a nice job installing aftermarket stuff (swaybars, lowering springs) on my WRX wagon in 2004 - I’ll
see if he is willing to “make things perfect”:)


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walfredo
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Re: Rear brake rotor install problem

Post by walfredo » Tue Nov 06, 2018 9:38 am

I had a scraping so I took the wheel off and used a flathead screwdriver to bend the dust shield away from the rotor (you can do this even without taking off the wheel). Do this at 45 degree intervals all the way around the rotor.

In terms of the parking brake pads, there is an adjustment screw for those, recommend dialing it back a bit. You will need to remove the brake caliper, lower carrier and rotor to access it. Mechanic probably over adjusted it so it was too close.

I just did my rotors about 6 months ago, all four corners, not having issues besides the dust shield scraping, which just needed to be bent back (I had inadvertently bent it while doing the brake job).

The actual brake pads should not be "too tight" to go over the rotor, the piston in the brake caliper should be fully depressed when installing the new pads (a c-clamp works). The new pads and caliper should slide over the rotor without any issues, unless someone bought the wrong part (too thick).

All of this is pretty doable for any diy mechanic assuming you have a jack, jackstands and tools. You can save a good bunch of money and learn about how automotive systems work in the process. In the age of youtube, there are many resources online to help.
Last edited by walfredo on Thu Nov 08, 2018 2:23 pm, edited 1 time in total.

BajaTim
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Re: Rear brake rotor install problem

Post by BajaTim » Tue Nov 06, 2018 11:37 am

Thank you so much - these are the same points I gleaned from my searches - but the two mechs (and my DIY buddy who tried first) can’t seem to pull it together.

But I realize now from your comment that Monro - in attempting to adjust the parking brake “moan” must have pushed the dust shields back out because the “scraping” is back (there was no scraping after my Suby mech installed rear rotors - just the parking brake “moan” which he said was from the pads (maybe trim the pads he said?) but he did not want to do that job (no charge to check it out).

Geez...I’m busy assembling a new couch for my Airbnb... I’m hopeless at handyman stuff (3x as long and always eff up and have to redo).

Will re-explain to Monro and see if they can do it - thanks again!




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walfredo
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Re: Rear brake rotor install problem

Post by walfredo » Thu Nov 08, 2018 2:23 pm

One thing to keep in mind as well if the parking brake pads are over adjusted, they will wear out eventually. So long as its not super tight and causing excess heat (warpage to the rotor), the problem may fix itself over time. If you smell burning brakes, thats an indicator its too tight. Again, if you take off the rotor there is a little adjustment "star" gear like what you commonly see on drum brakes. Using a screw driver you can turn the star gear to tighten or loosen the pad clearance to the rotor hub. Any mechanic should be able to easily understand and accomplish this.

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Re: Rear brake rotor install problem

Post by BajaTim » Thu Nov 08, 2018 11:51 pm

Sounds good. Now just a clarification: if adjusted “perfectly” the parking brake pads should not be rubbing at all when parking brake not applied - correct?

The “moaning” I heard was parking brake pad rubbing against the inside of rear rotor - correct?


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walfredo
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Re: Rear brake rotor install problem

Post by walfredo » Fri Nov 09, 2018 1:51 pm

Yes that is correct. The moaning could also be a wheel bearing but I will assume you have it correctly diagnosed as pads rubbing.

You want the pads adjusted so they are not touching the rotor "drum" when the parking brake is disengaged.

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Re: Rear brake rotor install problem

Post by BajaTim » Fri Nov 09, 2018 9:49 pm

Thanks!

I think bearing would be noisier (but I’ll go listen on YouTube just in case).


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kamesama980
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Re: Rear brake rotor install problem

Post by kamesama980 » Tue Nov 13, 2018 1:41 pm

BajaTim wrote:
Fri Nov 09, 2018 9:49 pm
Thanks!

I think bearing would be noisier (but I’ll go listen on YouTube just in case).


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Assume nothing. I've changed hundreds of bearings for my own and customer cars with symptoms all over the place:
-humming and/or vibration at all speeds
-humming and/or vibration at certain speeds (15-100+ mph)
-humming and/or vibration at all but certain speeds
-pulsing, harmonic hum and/or vibration at specific speeds
-symptoms only when turning
-symptoms only when not turning
-play
-no play
-play at certain angles
-tiny barely noticeable hum and/or vibration with horrible bearings
-OMG I'm gonna die noise from bearings with no other symptoms
-some that last a week and the wheel's almost off
-some that last 100k miles with no change

BajaTim
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Re: Rear brake rotor install problem

Post by BajaTim » Sun Nov 18, 2018 4:37 pm

I’ll ask my guy to doublecheck...agree - no assuming.


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