(Final update 1/17) 300 miles and something's not right...

[Stewie]

Originally Posted by Lonewolf

As others have said, one or more of the tires may have picked something up. If you are not at the dealer yet, turn the wheels side to side and try to examine the tread of the tires as much as you can.

I had something similar to what you were describing happen once to me and there was a fat screw head protruding almost a quarter of an inch above the tread of the tire, but I had not lost any pressure in that tire.

Hoping for something small...

Thanks for the suggestion. I looked everything over. No screw or debris in the tire or the tire tread.

[Stewie]

Originally Posted by Pkush

Vibration from rear wheels is something I feel on cold starts. I think it's something with the differential. Seems normal operation to me

I was/am thinking it could be the diff. But that's a hard prove

[Stewie]

Update: I took the car to the dealer this morning. The tech and I went for a test drive together... I told him how to replicate the vibration/shudder and he felt it too. We went back to the dealership and he put the car on the lift. We inspected everything and agreed that everything looked tight. I was able to have them throw it on the alignment rack and it was within spec, but not perfect or ideal. I'd have to get the print out to give you guys the figures.

At this point, I plan on finishing out the break in period and treating the vibration as 'whatever' until something develops (read: breaks [wishing nothing does]).

My plan is to have an alignment performed and dial in more negative camber up front for better turn in and to have the tires road force balanced and go from there. The car is a blast and still fun to drive so, no worries...for now.

On a side note, the tech was mad cool. He said they'll switch out the tranny and diff fluid for me with aftermarket fluids if I bring them in, so that's pretty sweet.

[Wilsonk227]

Originally Posted by Stewie

I've noticed that too. Whenever i let off the clutch gently and only apply the minimal amount of power via the gas pedal...there's a strange sound coming from what I imagine to be the tranny/flywheel area that can be heard until about 2200-2300 rpm. Does that match what you've experienced?

hmm shouldn't be that for me. I actually have an Auto. My rear wheels seem to vibrate like it's slipping on the ground. Just a little until it catches itself. Maybe that's when it's cold. Maybe you should take yours in to the dealers and get it checked out D:

[Speed2th]

yes i have a local alignment shop told me that every stock FRS/BRZ right side spec were off from his experience (even after change of suspension would be off more) ! I thought he was BS me

[cwik]

What are you driving on when you notice it? On some grooved highways, I notice a *lot* more tire noise and a slight amount of shuddering. Kind of like driving on a grated bridge, but not nearly as much twitchiness.

[Ganthrithor]

Originally Posted by cwik

What are you driving on when you notice it? On some grooved highways, I notice a *lot* more tire noise and a slight amount of shuddering. Kind of like driving on a grated bridge, but not nearly as much twitchiness.

Hahaha, I hate that texture so much.

[SkAsphalt]

Check that the nuts on the wheels are torqued correctly. All I have to add

[Stewie]

Update: the car has over 800 miles and I can replicate the problem in 4th, 5th, and 6th gear between 2500 - 3100 rpm. It doesn't occur/isn't noticable at lower speeds ie 1st through 3rd. The best way I have been able to describe it is as a light infrequent, non-rhythmic, rotational thump that I feel in my ass and the small of my back that feels like it's coming from the rear pass side tire, wheel, axel, diff area.

I've been talking with CSG mike and we are both hoping that it is something as simple as he wheel and tire being out of balance. I'm taking the car to a tire shop for them to road force balance all 4 tires. I'm hoping that takes care of the problem. I'll keep you guys posted. Thanks for your help thus far...

@cwik - I feel it on any road surface and it doesn't feel like it's road surface related. I drove on a section of brand new/glass smooth asphalt the other night and I could still feel it.

It happens at the rpm range that I find myself in the most. It is beyond annoying and very alarming.

[uRBAN_Metal]

This is why you have a warranty. I would take it to the dealer. Don't just throw money at it.

[Stewie]

Originally Posted by uRBAN_Metal

This is why you have a warranty. I would take it to the dealer. Don't just throw money at it.

So here's a little update. I took it for the balance and everything was perfect. A poor balance wasn't the cause.

I called the service manager at the dealership and he told me that the last time I was there the tech said that the car drove fine and he can't take his tech out of the bay to investigate. He told me to call my salesman and drive another 2015 for an apples to apples comparison.

Now i just don't want to deal with them and I have to find another dealer that's willing to take the time to figure it out.

It's bugging me to the point where it's taking the joy out of driving the car.

[bcj]

Fastest car in the world is a rental.

And that way you don't even have to rent it.

Have at, with all Kundam Soul Force.

[navanodd]

Are you turning even slightly when you get this? In that case I would blame the diff. Mine was really tight when new and would shudder driving around the parking garage whenever I gave any amount of throttle and I wasn't travelling perfectly straight. It has since become a bit more progressive in the past year. The fact that you say it's related to RPM makes me think its related to torque output.


This car does have a very tight torsen diff. I get shudders and tiny chirps from the rear end whenever I need to quickly pull out into traffic. Below 2000 rpm this engine just doesn't have the torque to make the diff lock. Torque is relatively constant in the range you are talking about.


As far as the front vibration, I have no idea. The golden rule for mysterious tire vibrations is to rotate tires and see if the vibration moved.

[Stewie]

Originally Posted by navanodd

Are you turning even slightly when you get this? In that case I would blame the diff. Mine was really tight when new and would shudder driving around the parking garage whenever I gave any amount of throttle and I wasn't travelling perfectly straight. It has since become a bit more progressive in the past year. The fact that you say it's related to RPM makes me think its related to torque output.


This car does have a very tight torsen diff. I get shudders and tiny chirps from the rear end whenever I need to quickly pull out into traffic. Below 2000 rpm this engine just doesn't have the torque to make the diff lock. Torque is relatively constant in the range you are talking about.


As far as the front vibration, I have no idea. The golden rule for mysterious tire vibrations is to rotate tires and see if the vibration moved.

Nope, I feel it when traveling in a straight line. Ive found that the easiest way to duplicate the vibration is to travel in a straight line in 5th gear right around 45-46 mph on a level road. Rpms should be right around 2500 to 2600 rpm. I feel it constantly at that range and then if I accelerate I can drive through it and make it go away, but if i decelerate back down to that speed rpm range you can clearly feel it.

I plan on taking it to a different dealer for them to look at it. I think my "dealer" only has the 1 tech...maybe 2. I also plan on writing to the GM of the dealership, the owner of the dealership, and Subaru of North America.

I'm sure they think that I'm having some sort of buyers remorse. I'm not. I knew what I was getting into with this car long before I purchased it (crickets, tail light condensation, notchy tranny, etc). I was not expecting for there to be a strange feeling in the diff.

I initially thought it was nothing, but after driving my buddies 2014 limited and noting that he didn't have the same vibration is when I started to become concerned. For me, potential problems with the diff are more disconcerting than problems with the engine or transmission. If either of those fail at speed, there's a good chance that you can bring it to a safe stop. If the diff gives out at speed, its going to unsettle the car.

This isnt my first RWD car either. 5spd/6spd RWD cars are all I've driven for the past 19 years.

I'm just going to have to take it to another dealer and hope that they don't blow me off the way that this one did.