Ken7258

I just replaced my rear rotors with new factory rotors. I didn't replace my pads. It's easy to see where the pads are hitting. On one rotor only the inside and outside .5 inch is making contact with the pads. On the other side the pads are hitting about 60% and as I drive it's making more and more contact.



Is this because the pads wore differently on the other rotors and it will take time for the pads to "wear into" this rotor? Tomorrow I'm driving about 200 highway miles. I plan on breaking the rotors in and hopefully the pads will "wear into" the rotors and make 100% even contact.



Does this make sense what I said or should I be worrying about any other problems. Thanks a lot.

Edgy01

It's never recommended to replace rotors and NOT to replace pads at the same time.

I highly recommend that you put brand new pads in. Once these are worn down then you can readdress putting those old pads back in.

Doug Donsbach

They'll wear in. Don't sweat it.

jyoteen

what?? You should never replace new rotors and new pads at the same time.

Macster

other way many times, that is renewing pads and not rotors.

What's going on is as you suspect. The friction surfaces of the old pads are not flat and thus do not conform to the flat surfaces of the rotors.

Even with new pads/rotors a "break in' process is recommended to ensure as soon as possible and under controlled conditions pads and rotors make full contact under braking.

Take car out and up to speed and where safe apply brakes hard, not hard enough to trigger ABS. Do not bring car to a stop. After speed drops to say under 30 miles an hour then take car up to speed again and repeat the braking action.

Do this several times. I do it until I feel the braking "bite" improve. Do not over do it can you don't want to over heat the pads/rotors.

The 1st couple of these you might want to raise the speed at which you release the brakes. This is because given the pads/rotors are not making full contact where they do make contact will generate that much more heat and in a very local area too.

The first couple of these braking exercises wil/should see the pads and rotors wear and make more complete contact.

A downside is that once you have done this you have caused the rotors to assume the shape of the old pads. Chances are high new pads will be needed before new rotors and the new pads will of course have nice flat friction surfaces that require considerable bedding in to the old rotors. This bedding in process then constitutes considerable wear and results in a shorter service life of both pads and rotors.

If not too late I'd advise you to simply replace the old pads with new ones and start out brakes with the new rotors and replace the old pads with new pads.

Sincerely,

Macster.

Edgy01

I don't know what planet you're from but what about a brand new car? It has new rotors and new pads on it. Oh,--yea, I forgot, Porsche goes out and finds old pads and puts them on the new cars.

jyoteen

I'm located on Earth Rotor life and pad life are very different, and suffice to say, if you change out the pad material, it could be even more different. So to say that you should throw out a perfectly good pad OR rotor in lieu of the other is laughable. Secondly, if done right, your pad is the thing that is wearing quicker than the rotor. So do you throw out a perfectly good rotor when you get new pads?

[It is better to bed new pads on older rotors. Older rotors are seasoned and more dimensionally stable making them less likely to warp or crack while bedding. Older rotors for some reason are less likely to glaze new pads.]

-Carrol Smith

springgeyser

If my old rotor and pads are grooved...I install ALL new pads and rotors at the same time.

Braking kinda suck initially until the pad/rotor gets bedded in.

dresler

Like Doug said, don't sweat it. They will wear in on their own.

TrackDays247.com

New pads/old rotor or old pads/new rotor is the ideal recipe -

Sounds like your old pads might have a bit of pad taper and/or the pads were more than likely *reinserted into different postions* upon reinstallation.