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2004 Subaru Outback H6 LLBean (Sold); 2012 Honda Civic EX 5MT
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457 Posts
Discussion Starter #1 (Edited)
Hey all, just took a 5 hour trip to Rochester and heard some strange things on my way. I did a search and nobody had the same symptoms but I found some similar cases. Randomly the car would start making a roaring noise, like a bad bearing. This happens twice while I was on a steady cruise control speed. When this noise happened and I pressed the brake, everything shook violently but that stopped when I let off the brake. This noise occurred for about two minutes each time and then went away. Other than this it was smooth sailing.

Some important things:
The car was inspected by the Subaru Dealer for my PA inspection 20 days ago.
I just put on four new tires last Thursday. They're balanced and smooth up to 80 (fastest I tried).
It's. 2004 Outback LLBean with 71,500mi. Recently threw a serpentine belt but that shouldn't be related.
After it shook and I heard the noise, I pulled over and checked the front passenger wheel- all was tight and there wasn't excess heat from what I could tell.

Please help me as I want to fix anything before my drive home on Friday!
 

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03 H6 OBW & 06 WRX Sportwagon
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17,621 Posts
does the car shake under the braking conditions described WITHOUT first hearing the roaring noise? might be unrelated.

when the roaring is occuring, does a turning/sweeping/lane change movement change it?
 

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2005 Legacy 2.5i Wagon 4EAT; 2005 Forester XS 4EAT
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672 Posts
That's a good read, and I'll have to put extra air in my new tires... ugh... wish I would've seen that before I bought those tires...

Back to the OP... he said the violent shaking happens with the brakes applied, which mine does the same thing. I'm thinking warped rotors in both cases.

Mine also has an occasional grinding sound coming from the rear when braking, like a brake pad is shot and grinding the rotor. I had the car full of people the other night, driving through many steep hills. It started grinding louder than ever, but seemed to stop when I applied the brakes.... weird.

I'm going to take a rear wheel off to see if I can find anything unusual. Kinda sucks you can't access the rear of the rotor without ripping it all apart to feel for any deep gouges indicating a problem with a pad.
 

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2004 Subaru Outback H6 LLBean (Sold); 2012 Honda Civic EX 5MT
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457 Posts
Discussion Starter #7
Wow, thanks for the quick replies! The brakes grind a little/shake a little when driving normally but not too badly and only with hard stops. When I changed lanes or went faster the thumping sound didn't go away... I slowed down in case something was about to fail catastrophically and after 2 minutes it went away. When I resumed speed it was as smooth as can be.

I was driving from Pittsburgh so the roads were pretty straight. I hadn't noticed anything like lane changes or bends to make it better.

I can't imagine it being a bearing since that'll howl at any speed and this only does it for a few minutes then goes away. I read somewhere that it could be a moving belt in the tire? How plausible do you guys think this is? A slipping belt that "re-sets" itself would make a thrumming noise and would make braking shake the whole car, right?

My new tires are Hankook H727s, 97T rating- this is the same load rating as the original Potenzas. Before it had some generic crap on it that the dealer gave me when I bought it used a few years ago. The tires were aired to about 37 cold and I heard it happen. At the next gas stop, I checked the tires to find they were at 37, aired them down a bit and it still happened.

The thing that keeps striking me as odd is that it comes and goes and that over 4.5 hours it happened twice, and during that time, the brakes freak out and shake the whole car.
 

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01 Outback LL Bean
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2,427 Posts
Check Trans, front and rear diff fluids and levels. Maybe its something in the drivetrain.

Braking puts load on the drivetrain and if you have a diff or trans issue the braking could make it worse.
 

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03 H6 OBW & 06 WRX Sportwagon
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17,621 Posts
maybe a rotor is not seated well/flat on a hub or there's a cracked lugnut.

possibly uneven pad material deposits ('warped' disk) in addition to some other issue.

do you have pulsation in the brake pedal when braking?

also, though they are new - might be worth moving front tires to back and rears forward.
 

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2004 Subaru Outback H6 LLBean (Sold); 2012 Honda Civic EX 5MT
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457 Posts
Discussion Starter #11
That sucks because I literally am picking up my new car on Saturday... do you guys think I should get it looked at before heading back or it's something that'll hold up?

I assume they would have spotted something serious on the state inspection when it was on the rack.
 
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