just today my rear right brakes starting making noise, after I had to stop in a hurry because someone cut me off. it's a grinding noise, and I'm pretty sure it's caused by the fact that the pad has worn right through to the rivets. I took a look through the spokes of the wheel, and there's 2 obvious grooves in the rotor. sh*t! so I'm fairly certain that rotor is shot, and I'll have to replace it. my question is, if I'm replacing the right one, do I have to replace the left as well? it looks fine, and I'll obviously change both left and right pads so would it hurt anything to only replace one rotor? I have no idea what they cost for an A4, but I'll assume they're not cheap until I find out so I'd rather only have to buy one.

help me out here?

 

You can buy just one rotor, but your gonna have to replace the other side at un-even intervals which makes it a pain in the ***.
Its not gonna pull if thats what your wondering.

 

ok cool, thanks auditech. what I think I'll do is just find a cheapo rotor and replace the one side for now, and then down the line when the other sideneeds replacementI'll replace them both again with slotted rotors.

 

IMHO, you don't mess with brakes!

If one side is that bad, my bet is the other also needs to be replaced! If one side is stronger then the other, it can cause you to spin, under braking.

Just get 2 rotors, & 4 pads, we are not talking about a ton of money here, especially compared to crashing into another car not taking care of it.

 

the driver's side rotor looks great though... I'll definitely replace the pads on both sides, so both sides should wear roughly the same if my logic is correct. I don't know what caused the passenger side outboard pad to wear faster and hit the rivets sooner, but it evidently hasn't happened (yet) on the driver's side.

I'll see what kind of prices I can find. if it's not too bad, I'll do both rotors but I'm tight on cash right now because of some other unexpected expenses.

 

Unless you're talking about some sort of super-duper, high performance, space age brake rotor and pad (ie. carbon fiber) - replacing one side of the brakes won't pull the vehicle into an out of control spin. The line pressure to the caliper is the same to both sides, and the performance gain of new brakes (of similar initial quality) over old ones is minimal (meaning unnoticeable). Prefacing the statement with "if" enables you to make sweeping generalizations, so I guess I can't tell you you're flat out wrong - but... it sure would scare me into buying a whole new rear set

 

Your thinking about it the wrong way. Yes, the brakes are balanced, & have the same pressure. That is the problem. If you have a higher friction coefficient on one side what is going to happen? The tires will stop at different speeds, & cause the car to pull to the higher side. Granted on the street it's not much a problem. But if are braking in a corner, it can cause a spin, if you have to jam on the brakes, it can also cause a spin.

I'm not saying it will happen, but can happen, the time it does will be in a panic situation, that this will only make worse. I have seen to many cars wreak due to poor brake maintaince.

This video just happened a couple of weeks ago. He thought his rear brakes were fine....
http://www.youtube.com/watch?v=sx-zmGm3Kj4