Machining rotors

[Day-mow]

Can you machine rotors and leave old pads in if they have enough life in them?

[KR1STO]

You can, but it's not a good idea...
Because the pads have formed to the shape of the discs before machining, they wont sit flush against the disc..
That will cause them to squeak...

Also depending on how bad the discs were, it could also cause issues with braking and pedal feel..

If I were you I'd just change the pads..
If $$$ is tight, just wait a few more weeks..!

Cheers
Kris

[Sox]

Yes, no problem.

[JC]

I'm gonna say combo of the previous 2 responses. If the brakes are shuddering, and you get rotors machined, and use the old pads, you may still feel some shudder, in which case buy new pads. If no shudder with old pads, continue........

[Day-mow]

thanks guys!

[Sox]

Originally Posted by JC

I'm gonna say combo of the previous 2 responses. If the brakes are shuddering, and you get rotors machined, and use the old pads, you may still feel some shudder, in which case buy new pads. If no shudder with old pads, continue........

If the rotors are machined true, there won't be any shudder, no matter what pads are used.
The only thing which happens with old pads on new or machined rotors is the mating surface isn't perfect for a little while, perhaps a 100k's or so.

Once the high spots have worn off the pads, all will be back to normal.

If you were really pedantic, you could always scuff the face of the pads with some 80 grit sand paper to flatten them. It's not really necessary though.

[GK]

I'd go new pads with machining.

I simply figure, if I change the pads as well, I'll not have to be concerned about it again for ages.

GK

[mik]

i`d put the old pads back in and save new ones for the next new set of disc`s, once you`ve had your discs machined they will probably have a shorter life span anyway, they heat up faster and warp again in a shorter time, and they will be closer to minimum thickness next time(probably throw aways) .

[Day-mow]

these have been machined once alredy so its possible im dreaming to get them done again. but hoping i can.
if i have to replace them DBA 4000 and probably epic QFM pads

[Sox]

I guess the big question is, why are you machining them?

[Day-mow]

Warping. I drive hard at times and they tend to warp a bit. Altho qfm pads are a lot nicer then my experience with bendix.

Regular bendix had them warping in bout 10,000 km.

[4ford]

Guys...
The very first thing you do following the replacement of disc pads, whether they are new pads/new rotors, or new pads/machined rotors, or old pads/ new rotors, or old pads/machined rotors, it doesn't matter which, the first thing you should do is "bed them in", that is, go for a short drive,(after pumping the brakes up), and do a couple, maybe three, very hard stops, but don't actually stop, just down to a very low speed (walking speed).
This technique will ensure the pad surface has re-aligned to the new rotor surface, thereby giving best braking performance right away!
The reason I say 'don't stop' is that I don't want the now very hot pads remaining in one spot on the rotor, which may cause the initial stages of rotor warping.

Just like, whenever you are subsequently driving and have to brake hard for some reason, like a red light etc., you get off the brakes as soon as you can after you've stopped, or if it's an auto, just allow the car to creep very small amounts forward after stopping, to spread the resultant heat build-up all around the rotor, instead of just in one place!

Concentration of heat in one spot will cause the eventual warping of the rotors.

Cheers...

[Day-mow]

I always bed pads in. Even when it says they don't need it.