Warped Rotor Question

[elerner61]

On my non-BMW I've got a brake vibration most notable at highway speeds. It was initially diagnosed by the (Acura dealer) as a warped rear rotor. Car is under warranty and only 11K miles on it but they wanted $$ to fix it so I told them to forget it.

The vibration has gotten noticably worse and is going back to dealer on Tuesday. The vibration at highway speeds is now at the disturbing level, I am not feeling it through the steering wheel however. It really shakes the car though and "feels" like it's coming from the front end. My question is this: will a warped front rotor(s) ALWAYS be felt at the steering wheel? The car's parking brake actuates the rear calipers on the rotors and I've applied the parking brake on the highway but this test hasn't resulted in the vibration. I'm a little stumped on this one.

[Jstic]

Depends on how bad the warp is. Rear rotors will shake the car, not the steering in my experience. Front rotors will do both. If the warp is bad, even when you are not braking it can shake the car and steering. This should be a warranty repair IMHO.

[gas-can]

I've seen a lot of shops call any issue with a shaking car as being a "Warped rotor". Did they tell you how they diagnosed it? Can you perhaps get the run out numbers from them? (An instrument called a dial gauge is used to measure this value- it's the proper way to figure out if the rotor really is warped.)

It's actually kind of difficult to warp a rotor- did you perhaps run into a giant puddle after some heavy braking?

The fact that it does it all the time makes me wonder if it's not actually the wheels... If the rotor is warped so much that it is off spec enough to contact the pads even when the brakes are not applied, you'll have one hell of a shaking when you do brake...Perhaps you lost a wheel weight?


gas-can

[Ovaltine]

I've never seen a rear rotor warp - always fronts. And regardless you'd typically only notice while braking. I'm with gas-can in that I'd be looking at something else. Loose suspension bolt(s), bad tire, bent rim, missing wheel weight, etc.

[The HACK]

Wheel bearing.

[EenyBear]

Ditto Gas Can's observation.

A warped rotor will cause that familiar shudder when the brakes are applied. Not cruising at highway speed. Something is loose or a bearing is damaged.

I would be uncomfortable driving the thing (at speed) until it checks out.

Acura should be a little more willing to help with a warranty issue than you have reported. What a pain.

[elerner61]

Sorry if I was unclear, the vibration is ONLY under braking, does not occur at any other time. The mechanic said they did check the runout and determined it was a rear rotor (or both rears, can't remember). Another indicator that it is a rotor situation is that the vibration get's worse after the rotors are heated up (as in playing cat and mouse on the highway for a couple of minutes).

This is also a common thread on the Acura forums. I really hope they'll warranty the problem now. It's beyond annoying and affecting my enjoyment of the vehicle. For a tin-can (god, can the Japanese use any thinner sheet metal on their cars?) the car is a nice compromise for a daily driver for the price. I leased it year end and got a very nice deal.

Just gas, oil and wiper blades (oh, and rotors too now).

[thekurgan]

If just one rotor, maybe a caliper is seizing? There may be a rebuild DIY here somewhere.

[gas-can]

Ah that makes sense... Still say it's hard to warp those though....

As for the repair under warranty, most dealerships will probably consider rotors a wear item.. Now since your car is still so new, they might do it for you as a courtesy if you ask nicely, but then again it's up to them...

If you don't mind getting a bit dirty, the job is actually quite easy. Only real tool you might need may be a impact screwdriver (~15 bucks at harbor freight) for the only real difficulty you may face- removing those bloody phillips screws that honda uses to hold those rotors in. They have a nasty habit of rusting in there, and the only way to remove them without stripping the screws is with the impact screwdriver.

If you object to being a grease monkey for an hour, you may be able to just take it to an indy- it should be a pretty cheap swap... or depending on the warp amount, you may also be able to have them turned, but replacement might be better in the long term.

good luck!

[elerner61]

Originally Posted by gas-can

Ah that makes sense... Still say it's hard to warp those though....

As for the repair under warranty, most dealerships will probably consider rotors a wear item.. Now since your car is still so new, they might do it for you as a courtesy if you ask nicely, but then again it's up to them...

If you don't mind getting a bit dirty, the job is actually quite easy. Only real tool you might need may be a impact screwdriver (~15 bucks at harbor freight) for the only real difficulty you may face- removing those bloody phillips screws that honda uses to hold those rotors in. They have a nasty habit of rusting in there, and the only way to remove them without stripping the screws is with the impact screwdriver.

If you object to being a grease monkey for an hour, you may be able to just take it to an indy- it should be a pretty cheap swap... or depending on the warp amount, you may also be able to have them turned, but replacement might be better in the long term.

good luck!

I love wrenching on my cars...just not my daily driver. I get two weekend days to relax, spending that time not doing something I really want to pisses me off. I always have a japanese car in the garage because of one reason; they're not supposed to break.