Hi fellas,

I hope everybody is having an excellent holiday season!

I recently curbed my '02 WRX sedan's rear passenger-side wheel. Since then, I've got a rotational vibration that appears at around 70 km/h (~42 MPH) and peaks out around 110 - 120 km/h (~70 - 75 MPH). It's there regardless of engine RPM (i.e. clutch in or out). Apparently, the rear differential is still aligned to the frame mounting points so the drive shaft and rear diff might still be OK.

*** Where should I look so I waste as little money and time as possible at the dealer? ***

Here are some more details below. I would greatly appreciate any help. And yes, it was a stupid thing, and no I wasn't drinking and I've been driving for 15 years. I'll never do it again . . . blah blah blah. I'm really sorry about my pre-emptive rant but I've seen so many pointless and unproductive on-line crucifixions. Please fellas, I don't want sympathy or more parents . . . just your informed technical advice. I'm already mad enough at myself for this terrible waste of time and money.



The front passenger wheel also hit the curb after the car pivoted. My linear speed was fairly low (guess 20 - 25 km/h [12 - 15 MPH]), but I had a lot of (i.e. major oversteer). The car probably rotated 120 deg. in around 3 - 4 seconds starting from a dead stop. A section of the rear wheel bead (stock 16" alloy rims) was completely sheared off over an arc length of approximately 8". The front wheel suffered much less damage, but a few inches of its lip were also sheared off to a depth of around 1/4". My suspension mods so far have been limited to the rear. Cusco aluminum OS rear strutbar, Cusco adjustable rear swaybar (bolted through holes closest to the end of the bar), and Kartboy solid aluminum endlinks.

Since then, I've replaced both damaged wheels and re-balanced all four wheels. The directionality of all four snow tires is correct. I also had a 4-wheel alignment done by a good tech with a laser set-up. The vibration is still there so the wheels are not the problem.

There's something tweaked in my front suspension or the suspension mount points because I am limited to -0.8 deg. camber. I'm running 0 deg. toe-in up front. That's seems alright for now to me. The rear suspension is bad. Rear left wheel is set to -.5 deg camber, 0.10 deg. toe. Rear left (damaged side) is +1.1 deg. camber, 0.15 deg. toe.

I bought a new rear strut and will replace it to try and correct the rear camber problem. There isn't any obvious frame buckling or bent suspension components, but I just noticed the rear trunk is sitting a couple of millimeters closer to the passenger side. I didn't want to get into frame checking with lasers because that's big money.

So what should I check out first to eliminate the vibration? That's my biggest concern for now.

Seasons greetings and thanks again for your help.

Dave.

 

Check to see if you have bent any suspension components. Another thing to check would be the bushings also. Check the hub and make sure that is not bent along with the bearings also.

Basically take apart the areas where it was hit and see if there is anything that does not look normal.

 

Okay, I'm gonna post this but I cannot be sure that it is correct. I recently bent both my rear wheels landing from a jump. I was told by a person who owns a shop that even though the wheels are balanced, the bend in the wheels will still cause them to vibrate.

The bends are very slight but are definitely there. I saw them with my own eyes. I have not felt any vibration since the wheels were balanced.

Now I'm trying to think how to explain how the above statement could be explained using the laws of physics. The answer eludes me. Perhaps that's why I only have 3 semesters as an engineering major instead of 8. Economics is better anyways.

 

Haha, don't feel bad... I am already working as an engineer but I'm still like 7 semesters from getting my degree. Yeah for joining the military out of high school instead of heading straight to JC. Although I'm not complaining when the GI Bill checks come rolling in... they are bigger than my paychecks.

 

Hey, there is nothing wrong with engineering. I only have 5 quarters left and then I will be graduating with an EE degree.

Anyhow, It is possible that slight bends in the wheel could cause unwanted vibrations.

 

Hi fellas,

thanks for the replies. I've already replaced both damaged wheels. I also re-balanced them but the vibration still remains. I suspect there's something bad about the wheel bearings also. Will I also have to replace the spindle if the bearing is shot?

I feel small vibrations through the steering wheel and seat when I turn the steering wheel at low parking lot speeds. How can I tell if these vibrations are from the front or the rear?

But I also feel and hear vibrations at higher speeds while driving in a straight line! The disturbing thing is that I don't feel vibrations below 40 km/h. Then I feel and hear small vibrations between 50 - 60 km/h that fade in and out with speed until 70 km/h. It gets worse until beyond 120 - 130 km/h. I've been told wheel bearings are supposed to make noise at all speeds if they're damaged. Is this true? The other funny thing is that I don't feel vibrations when the car is cold, but they kick in after a minute of driving. Does that definitely mean wheel bearing damage?

Is this vibration a wheel bearing problem, CV joint, both . . . or worse, something else? Are there any other shaft components that fit between the CV joint and the wheel bearing?

Thanks for your advice, fellas!

Dave.

p.s. yeah I'm also an engineer . . . supposedly a mechanical . . . formerly a mining-mechanical . . . though I work in microwave engineering now. Funny how life turns out nothing like planned.

 

All I know is that Subarus have been known for their humming as cruising speeds. That is pretty normal. It is possible that your wheels might still not be balanced correctly. I had one shop rebalance my wheels 3 times and it still had a horrible vibration. Then I had my friend rebalance them for me and now the vibrations are gone. It really depends on how bad the bearings for you to replace the spindles. It is possible that you could have a bent CV Joint. At this point it could be a number of things.

 

Hmmm. I never had this problem before the curbing. I'm pretty certain the new wheels are alright now. There was absolutely no change in vibration after I had them balanced. And I've balanced two of them twice already at different places.

Any thoughts about a slightly bent half-shaft? Or is that very unlikely with the sliding CV joints?

Dave.

 

Thanks X1_SRT,

that was helpful. I noticed the steering wheel vibrates at 80 km/h (50 MPH) when turning to the left (driver side). It doesn't seem as bad turning to the right (the damaged side). The other speed-sensitive vibration / noise seems to be more prominent through the floor, pedals, and a bit through the seat. That vibration never goes away regardless of steering wheel angle. I can't tell if it's coming from the left or right side. I agree this speed-sensitive vibration sounds suspiciously like a wheel / tire problem. I wonder if it's from uneven tire wear?

More about the possibility of a bent frame :
-trunk offset from centre by approx. 1 mm --> biased towards passenger side
-gap between top of passenger rear wheel and wheel well is ~1 cm taller than driver side

I'm going to replace rear strut now, but I'm not holding my breath. I'm also going to buy some crash bolts because this does not bode well. I'll also try substituting out my Cusco rear swaybar and re-installing my stock swaybar, just in case the Cusco adjustable bar is bent and forcing a misalignment. I'm doubtful because the weight of the car should force a bent swaybar (spring) back into shape, but I've gotta try everything at this point.

Dave.

 

hey guys I been in my family tire business for about 25 years & can say one thing for sure about viberation complaints is that no two are alike !! right off from my experience if your viberation only existis above 80 km's and then disapates above 130 ish look to wheel balance first ( try to a shop with a "road force balancer" ) if the wheel is bent you may not "see" it but still feel it ... if a wheel was bent or a tire was damaged in the impact the viberation will exist at all speeds ,getting worse the faster you travel... generally ( I stress generally) if the viberation is in the steering wheel the problem will be in the front & if you can feel shaking in the seats & floor look to the rear... irregular wear patterns will cause a sound and a viberation if severe enough ( to the point of sounding like a wheel bearing) but an easy way to check is to simply rotate the tires front to rear and see if the sound/viberation changes ...if the problem is deeper like a cv joint or bent shaft it will most likely "not come & go" but again be there all the time getting worse with speed ... alignment will not cause the car to shake( unless the tires are pointed at each other which is not the case here) ... ok so what have I told you ?? my suggestion first is to find a good tire shop with a road force wheel balancer ( this balance can detect out of spec conditions by putting the tire/wheel package on a drum and simulate driving on the road ) by doing this you will eliminate tires and wheels but I'm still guesssing this will fix the shake too !! I hope this helps a little
steve

 

Hi Quig,

I'll look for one of those "road force wheel balancer". I'll also visit a friend with 16" wheels and try swapping his wheels. If that eliminates the vibration, then I'll go out and buy some new tires. I have a sneaking suspicion that I broke some belts inside the sidewalls during that impact. The tire tech warned me he couldn't achieve perfect balance with those damaged tires, but it said it was very minor. If there's a broken belt, maybe the imbalance worsens as the tire RPMs increase. Something to do perhaps with the damaged belts deforming more frequently?

I'll inspect my sidewalls closely for damage. Can you recommend any tell-tale signs of a broken belt (other than frayed steel belts protruding from the sidewalls )?

Thanks very much!

Dave.

 

two things visually #1 if you see any kind extruding lump on the side wall as if you were to lay your finger on the side of the tire (approximate visual) running from the bead to the shoulder of the tread... but a note of caution for all who read this there are radial "depressions" on the sidewall of "ALL" radial tires these depressions usually occur in a triangular pattern around the tire and are completly safe as they are suppose to be there... if you inspect your tires at home and find something that you are uncomfortable with then a trip to you favorite tire store is in order (sorry for the plug ) #2 when a belt seperates or breaks it will (again a general statement here) make the tread lump up( i know thats technical but...) or twist like a snake and at slow speed 5-10 kph you will feel the car "moving around" on the lump usually accompanied with u hearing a corresponding "thump" if your shop has not taken the tires apart & inspected the inner carcass for damage have that done ASAP!!! for what can look fine on the outside might not be on the inside apart from these things visually, bearings ,hubs rotors sticky calipers cv-joints axles etc,etc... have to happen all of the time I mean a bearing will not be bad once in a while if its bad its bad it will just get worse... does that make any sense ??? the only thing I can add here is that if a wheel bearing is failing an easy test to try is simply drive on a flat straight paved road and turn the steering wheel slowly from right to left if the bearing is failing you will here a " growl or wine from the failing side and once you begin to turn the wheel in the opposite direction a prevelant sound change will be heard ( and possibly felt) although not fool proof this works very well(note here that irregular wear patterns on a tire not rotated often enough will produce a "like"sound ) please ask any questions I will try to answer I have had a ton of training and have lots of unique experience that will probable be of some use to peeps here on the forum
steve

 

Well I replaced my rear strut. It was apparently bent. I also replaced the wheel bearing which was apparently loose. My rear wheel camber is still way off. It is currently +0.6 deg (spec = -1.3 deg.) The master tech thinks the rear suspension cross-member may be bent, though I couldn't see any obvious deformation when I slid around under my car for 30 minutes. Replacing the rear cross-member is a big job . . . which means big dollars. Off goes the rear diff., axle assemblies, driveshaft, tie arms, and perhaps even the gas tank (according to the tech). I don't want to open that can of worms.

The wheel spindle looks like a a pretty massive piece to deflect, but I can't find any evidence of bending in the rear cross-member (thank God) or lateral links. Has anybody else ever bent a spindle before? Can I check for perpendicularity or parallelism between any surfaces? It's pretty rusty (I park in a heated underground garage in a heavily salted city).

I still have this persistent rotational vibration from the rear. It's definitely not the wheels or tires. I swapped another set of wheels and tires on my car but the vibration remained. Then I rode in another car with those wheels. There was no vibration.

My first guess is the axle assembly. But it's a guess. Are there any tell-tale signs that would indicate the vibration is from the half-shaft? Anywhere else? What about the short axle after the outer C/V joint attached to the wheel? Anything I can do to check if the vibration is from the driveshaft or within the rear differential (*gulp*)?

Dave.

 

Dave, I am beginning to suspect that you may take a smaller loss by trading in on a new one. Or, better yet, what an excuse to upgrade to STi! Hahaha. Seriously, you are starting to get into the land of 4-digit repair bills, so getting something new is a serious option at this point I'd say.