Shaking at 65mph+

So, my brakes were.. grinding/rubbing even when I wasn't braking? Making a "sff sff sff sff" noise when I drove slow. when I would brake, it would feel rough as hell. My rotors looked destroyed in the rear, but the fronts looked ok. Along with this, my steering wheel would shimmy hard going 65+. And the braking at that speed was like death.

 

Long story short, I spent the money and changed the pads and rotors out. Brake noise stopped, the old brake pads were actually still in amazing shape and had more than 75% of their life left.

 

The braking is great now. No noise, it's smooth yet responsive.

 

The steering is.. still shaky at 65+ and gets worse the faster I go. I can feel it more on the right front side than anything.

 

You're probably thinking "wheel bearing, for sure," but I'm not. I've tried the conventional DIY test to see if it's that, and it can't be.

 

I'm probably in need of an alignment and maybe rotating my tires? I was told you can't rotate them on AWD vehicles. My front right tire looks like a racing slick on the inner tread, but the rest of the tire looks great. The rear tires are immaculate.

 

Just seeing what I could invest in, or still research. Thanks

Probably will just be in need of an alignment.

 

You can rotate the tyres - just need to make sure that if your tyres are unidirectional that you rotate them in the correct pattern

Here are the instructions from the owners manual.

It could also be a partially frozen front brake caliper piston. Basically one of the two pistons will not fully compress flush. This happened to me twice and will definitely cause the steering wheel shimmy you described. The first time it happened to me it was severe and happened at 40 mph to the point that i could not drive it until it was resolved. The second time it was much more subtle at highway speeds. It's pretty easy to test to see if that is the problem. You can rebuild them or replace with new caliper units. In my case I went with new oem caliper replacements.

 

Also there is no harm in rotating the tires on an AWD Subaru.

Check tie rod ends and ball joints. They can definitely make it shake at speed. Also check to see if a tire has a separated tread. That will make it shake like a monster. If you drive slow, can you feel it kind of wiggling side to side a little bit? If so, that would be a good indicator of a separated tire.

The tires are Falken FK325's 215r45/17's. Definitely no tire separation. I checked the tires thoroughly when I changed out the pads/rotors. No bubbles. Both the front caliper pistons on both the driver and passenger side were good. They receded very nicely when I put the new pads on, and seemed to work well, so I don't imagine the calipers are bad.

 

I don't know. I guess I could try the alignment and rotation. It's just recently this thing has become a money pit. Not that it's a bad thing. I love this car and want to keep it around for as long as possible.

Check to make sure your tires are balanced before you swap them around, if you get the chance. I've had new tires have interior belt separation and slightly used tires go out of balance prematurely and cause what you're describing as well.

Of course. The balance was going to come first anyway. I'm definitely not a rookie at this kind of thing. Rather paranoid, you could say. Winter is coming, and let's face it.. when CT gets those Nor'easters... it snows like no one's business.

Well, I got the rotors and pads replaced. Took me 5 hours and a lot of PB blaster. Everything was fine for a few days, now if I brake "lightly" the brake pedal vibrates, noticably. I'm wondering if I should purge the brake lines..? Getting rather frustrated...

Back to the original post....

 

A few misconceptions:

 

1) on subarus you must rotate tires every 5k miles. So basically every other oil change

2) traditional bearing tests do not show a bad wheel bearing on the Subarus, however you can still have a bad one.

3) the bad tire in the front sounds like the camber or toe is off, have it aligned and most likely will need to replace all 4 tires because of that destroyed one

4) that vibe is most likely a wheel balance issue

 

 

Hope this helps.

 

-Mike Paisan

 

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OP, a bad hub/bearing on the front will feel like a tire is out of balance and some pavement, drive a bit further on the same highway and the shimmy goes away. That's a bad hub/bearing.

 

My left front went first, right was like a year later.

 

Fronts must be OEM or Timken or SKF bearings.

 

Rears can be Moog, Moog will not work in the front. TRUST me in that.

 

Have you had the car aligned by a good shop ?

 

They should be able to check all the front end pieces and make sure all if good.

 

If its a simple tire balance issue the shimmy will always be there at 65mph.

OP, a bad hub/bearing on the front will feel like a tire is out of balance and some pavement, drive a bit further on the same highway and the shimmy goes away. That's a bad hub/bearing.

 

My left front went first, right was like a year later.

 

Fronts must be OEM or Timken or SKF bearings.

 

Rears can be Moog, Moog will not work in the front. TRUST me in that.

 

Have you had the car aligned by a good shop ?

 

They should be able to check all the front end pieces and make sure all if good.

 

If its a simple tire balance issue the shimmy will always be there at 65mph.

 

Quoted! I need my front driver's side wheel bearing soon.

If one of the rotors is not sitting true to the hub, due to corrosion on the hub face or mechanical misalignment, you can get a wheel shake from the rotor tossing the caliper back and forth as it oscillates past. I fixed this over the summer after a year of head scratching.

 

To diagnose, I took the wheel off and dial indicated the rotor.The other indicator of this was the pads on that side wearing faster and that caliper was always hotter than the other side after driving.

 

To fix, I took a die grinder to the corrosion that had built up over a couple years under the rotor hat. Yay, salt!