[///M3NACE]

Im looking to get a quick BJ ( Brake Job) at the right price. I searched but where is the cheapest place to get just brake pads. Im at 50k and anyone know if my rotors need to be changed? I got mixed feelings because some do it just cuz but i want to know if i should.

Vehicle:

BMW E90 N52
330i w/ sportpackage


I want OEM everything.

[JunkStory]

I'm also at 50k miles. I do not drive aggressively and don't slam on the brakes a lot, and my rotors are fine. I just replaced the brake pads recently. If you are like me, and don't notice any rotor noise or vibration, then you can probably don't need to change them until the next brake pad replacement. However, my car is a 335i and the rotors are a little bigger, so that could make a difference. Sorry I do not know where you can get a quick cheap BJ near your location.

[axis]

330i rotors are almost the same size as the 335. And to the OP, there's no real way to know if you need new rotors without measuring the thickness of them and checking them for grooves or other issues.

[///M3NACE]

yeah the 325i/328i are different brakes the 335i and 330i e90 are exactly the same.

[JunkStory]

When I replaced my brake pads, my brother (a mechanic) used this tool to measure evenness of the rotor. Apparently mine were well within spec, no groove and the wear was even and flat, so I did not have to change them. When you go get your brake pads done your shop will probably have the same tool to check for you.

[ENINTY]

It’s not that simple of a question, just to measure the thickness of the rotor and deciding wether to replace them or not. When the first set of pads has been spent and a new set is required, the rotor has been worn down and can be measured to see if it is within spec, but that's not the whole story. First, any proper brake job should include resurfacing the rotors to get the best possible flat and smooth surface for the new pads to bed in into for maximum braking performance.

No rotor that has been through one set of pads will be as smooth and flat as a new rotor, so the rotor should be resurfaced. But that brings in a new problem. The thickness of the rotor after it has been resurfaced is important to consider since the resurfaced rotor needs to be thick enough to last through the life of the second set of pads. Depending on how much material is required to get the old rotor resurfaced properly, it may not have enough material (thickness) to still be within spec at the end of life of the second set of pads. If the rotor were to thin-out to a point where it is below spec with, say, 40% life left on the second set of pads, it could eventually start to warp when there is plenty of life in the second set of pads. In this case you'd end up needing another brake job before the second set of pads has been used to their maximum life. BMWs are known for having "soft" rotors anyway that sometimes do not last the life of the second set of pads (which has been my experience on other BMWs I have owned).

Because of these issues, I always just replace the rotors with new parts, so the brakes start out fresh with all new parts. Since a proper brake job should always include resurfacing the rotors, replacing the rotors should be no additional labor cost since the price should include removing the rotors to resurface them. Also, resurfacing of the rotors has a cost, which is partially offset by the cost of the new rotors.

[yakev724]

Originally Posted by ihsanshaik

the 335i and 330i e90 are exactly the same.

No they're not. Fronts are entirely different. I replaced my front brakes with 335 fronts.

[Saintor]

According to my experience, you need to change the front discs the 1st time, no necessarily so for the rear discs.

Front discs get eaten quicker than in the rear and that's possibly one reason why there is so much dust on front wheels while the rear pads usually need to be changed 1st.

[Saintor]

Originally Posted by yakev724

No they're not. Fronts are entirely different. I replaced my front brakes with 335 fronts.

For the reference, 330i are 330mm and 335i 348mm and M3 360mm (and twice the price of the 335i's)

My 2007 323 front rotors are bigger at 312mm than a 2007 328i at 300mm.
Then I learned that the 2007 328i and 2008 328i front brakes are not the same. They upgraded the 2008 328i at 312mm as well.

... it cost me 100$ to learn this.

[yakev724]

Originally Posted by Saintor

For the reference, 330i are 330mm and 335i 348mm and M3 360mm (and twice the price of the 335i's)

My 2007 323 front rotors are bigger at 312mm than a 2007 328i at 300mm.
Then I learned that the 2007 328i and 2008 328i front brakes are not the same. They upgraded the 2008 328i at 312mm as well.

... it cost me 100$ to learn this.

Yeah, it gets a bit confusing, especially if you're looking to upgrade. The performance brakes (identical to 135 brakes) have a smaller disc and are believed to have less stopping power than stock 335 brakes.

I guess I had it pretty easy...not needing anything besides calipers + rotors which I was fortunate to get a great deal on.

[samchoi604]

Originally Posted by yakev724

No they're not. Fronts are entirely different. I replaced my front brakes with 335 fronts.

Originally Posted by Saintor

For the reference, 330i are 330mm and 335i 348mm and M3 360mm (and twice the price of the 335i's)

My 2007 323 front rotors are bigger at 312mm than a 2007 328i at 300mm.
Then I learned that the 2007 328i and 2008 328i front brakes are not the same. They upgraded the 2008 328i at 312mm as well.

... it cost me 100$ to learn this.

Thanks for the info. I was literally scratching my head when I read the above comments that 330i rotors are same as the 335i rotors.

[///M3NACE]

Im sorry I was mistaken. I'll probably get the front rotors as well