Bad rotor(s) giving symptoms of an out of balance wheel(s)?

[SilvererSHO]

Is it possible to have a warped front rotor(s) give symptoms of a wheel(s) out of balance or a bent wheel(s)?  I never had any symptoms until I put different wheels and tires on for the winter 3-4 weeks back and my rotors have been getting worse ever since I've had the vehicle.  After a couple of weeks I took the vehicle to a different shop and they re-balanced the wheels and checked for out of round tires and bent wheels.  Everything checked out fine.  One wheel was perfectly balanced, one was 1/2 oz. off and the other 2 were 1/4 oz. off.  The car feels like a wheel is bent at about 30 MPH and vibrates at higher speeds on the freeway.  And it all comes and goes in the intensity of it all and doesn't necessarily coincide with brake usage.  Another thing that crossed my mind.  Is it typical for most vehicles to just have a single bolt that holds the rotor on to the hub while the wheels are off?  Seems like a half-assed way to do it.  2 or 3 would be better in my eyes to prevent any crap from getting between the hub and rotor when you loosen the lug nuts.  With just one I would think the rotor would tend to lift off the hub on the side without the bolt.  It's just a matter of how much.

[5ohSHO]

It doesn't sound like a warped front rotor to me since you said the issue doesn't coincide with brake usage. If your front rotors were warped bad enough to feel it just driving around then the brake pedal would pulsate when pressed and the steering wheel would probably oscillate at the same time. That's just my experience driving vehicles with warped rotors. I would check and make sure all the wheels are completely seated up against the rotor/hub. I'm not sure if you're using aftermarket wheels for your winter set, but maybe the center bore could be really tight and a little rust build up could make it hard to get on all the way? As far as the single bolt holding the rotor to the hub, this is the first car I've had with this set up. All my other cars used the retainer rings that went around a lug stud. They also went in the trash after the first brake change. The caliper will hold the rotor in place when the wheel is off and the wheel with lugs tightened will hold it tight so there isn't really a reason to worry about stuff getting behind the rotor. I would also check to see if the bolts are tightened down all the way that hold the rotor on to the hub. 

[Dxlnt1]

Warped or "untrue" rotors/brakes do indeed give the feel vibrating at speeds. No matter if brake is pressed or not. But when brakes are applied the sensation can get better or worse.

Another consideration in addition to brakes is wheel/tire combo. If using a non oem size/setup there "could" be the same symptoms. Or if you changed pads without turning rotors. Or rotors out of spec. (thickness)

And lastly, not sure of the exact setup for AWD cars but, a drive axle or boot balance can cause same issue or feeling.

I have the issue myself. But I am running 275/40-20 tires. And by your signature, I am running the firehawk tires as well. So I get a very little when car is on a slight pull above 70 mph for a few seconds. My thought is tire tread and how it contacts road may be a contributor as well.

[SilvererSHO]

I was running factory 20" wheels with the Firehawks.  I switched to 18" PI steelies with all seasons.  The brakes have always been marginal and getting worse but these symptoms didn't happen 'till I swapped out the wheels.  I just don't understand how a warped rotor would cause this going down the freeway at 75 MPH 20 minutes after you last used the brakes.

[SHOdded]

Used wheels or new?  Might be cracked or torqued too tight?

[SilvererSHO]

It doesn't sound like a warped front rotor to me since you said the issue doesn't coincide with brake usage. If your front rotors were warped bad enough to feel it just driving around then the brake pedal would pulsate when pressed and the steering wheel would probably oscillate at the same time. That's just my experience driving vehicles with warped rotors. I would check and make sure all the wheels are completely seated up against the rotor/hub. I'm not sure if you're using aftermarket wheels for your winter set, but maybe the center bore could be really tight and a little rust build up could make it hard to get on all the way? As far as the single bolt holding the rotor to the hub, this is the first car I've had with this set up. All my other cars used the retainer rings that went around a lug stud. They also went in the trash after the first brake change. The caliper will hold the rotor in place when the wheel is off and the wheel with lugs tightened will hold it tight so there isn't really a reason to worry about stuff getting behind the rotor. I would also check to see if the bolts are tightened down all the way that hold the rotor on to the hub.

It doesn't sound like a warped front rotor to me since you said the issue doesn't coincide with brake usage.

No, what I mean is that the symptoms I'm talking about don't really get better or worse if the brakes have been recently used or not.  I do have a bad rotor or two.  Just don't understand how it would effect the vehicle when they haven't been used for 20 minutes like when you're going down the freeway.

[SilvererSHO]

Used wheels or new?  Might be cracked or torqued too tight?

Used.  Tire shop said they're true on the balancing machine.  I put the wheels on the vehicle myself the first time around and they were pulled off, rebalanced and put back on the vehicle last Friday at the tire shop and I have the same symptoms going on.

[SHOdded]

Are the firehawks asymmetric /directional  by any chance

[SilvererSHO]

Are the firehawks asymmetric /directional  by any chance

They are asymmetrical but not directional.

[pmezo33]

Doesn't sound like rotors to me.  Rotors you'll only notice when braking especially at higher speeds.  That rotor screw you mentioned earlier is pointless.  I don't even have them in my car.  I just throw them in the garbage when i replace rotors. 

Since these are your winter wheels and tires, can you throw the summer wheels and tires back on and check to see if that changes anything?

Since the balance is fine, it sounds like you have a bent wheel or your lug nuts aren't properly torqued down.  That would cause a wobble or shake.  Make sure everything is torqued down to 100 ft/lb.

[SilvererSHO]

Doesn't sound like rotors to me.  Rotors you'll only notice when braking especially at higher speeds.  That rotor screw you mentioned earlier is pointless.  I don't even have them in my car.  I just throw them in the garbage when i replace rotors. 

Since these are your winter wheels and tires, can you throw the summer wheels and tires back on and check to see if that changes anything?

Since the balance is fine, it sounds like you have a bent wheel or your lug nuts aren't properly torqued down.  That would cause a wobble or shake.  Make sure everything is torqued down to 100 ft/lb.

Doesn't sound like rotors to me.  Rotors you'll only notice when braking especially at higher speeds.

Dxlnt1 above begs to differ.  I wouldn't think so either, but that's why I'm asking the question.  When I initially installed the wheels myself I torqued them all to 100 ft. lbs. sneaking up to that with a criss cross pattern in 3-4 increments.

It's getting too cold out to put the Firehawks back on.

[SHOdded]

ok wait.  what tires are you using with the PI wheels?

[pmezo33]

Dxlnt1 above begs to differ.  I wouldn't think so either, but that's why I'm asking the question.  When I initially installed the wheels myself I torqued them all to 100 ft. lbs. sneaking up to that with a criss cross pattern in 3-4 increments.

It's getting too cold out to put the Firehawks back on.

My front rotors are extremely warped and they drive as smooth as can be when i'm not braking.  I'm changing them out as soon as the ups man delivers them.  Never heard of a rotor causing issues while not braking, but i guess anything's possible.

Just swap the firehawks back on and go for a test drive.  They're on their own separate wheels, right?  Shouldn't take longer than 20 minutes to do.  Just go for a ride to see if the symptoms go away and you'll have your answer.

[sholxgt]

An out of balance rotor can cause these effects BUT...rotors don't generally get out of balance.  They are usually either right from the beginning or wrong from the beginning.  Warped rotors generally only have an affect when braking.

I know it's cold, but on a dry day, I'd swap wheels/tires and see if the problem goes away.  If too cold, have a tire shop to it.  I think that's your fastest way to rule out one large possibility.

Anything is possible, but I'm doubting this is a rotor issue.

[sholxgt]

ok wait.  what tires are you using with the PI wheels?

New or used?  If these are used, you may have a belt separation issue.