RocketGuy3

iTrader: (1)

I suppose this is a generic enough question to go in the car chat forum, but I remember Lance and Greg (lobux and Gernby) being involved in a discussion about this a while back that was rooted in convincing people not to machine their rotors when they get new pads.

The conclusion, I think, was that it's not a good idea to mix fresh rotors with fresh pads unless it's necessary... I just don't remember why. Are either of those two around? Can anyone else give me an explanation?

lobuxracer

iTrader: (2)

Because the pads are essentially mated to the disc. The material from the pad creates a film of deposits on the disc surface before the brakes start working well. It is also important to heat the pads (by using them) so the lighter elements of the adhesives can burn off and the pad material can be "burnished" in a controlled way.

Race teams will take sets of pads and bed them in with used discs to build up a supply for a race (if pad changes are anticipated, as in long distance endurance racing) so when the car pits, they can pull the old pads out, and stuff new ones in without having to go through the bedding process.

Brake engineers will always tell you it is better to take used pads and break-in a clean disc, then put in a new set of the same pads (once the transfer is completed by the bedding process), bed those pads in and you'll have very fade resistant brakes that will last a long time.

If you don't care about pad or disc life, just slap new stuff on there and go. Racers, and even hard core track junkies have to budget for brakes because they are one of the major consumables when tracking a car.

RocketGuy3

iTrader: (1)

OK, that makes sense for the most part. I can see why you wouldn't want to replace or re-finish the rotors when you get new pads, but I'm still unclear on one thing.

Let's say the rotors had become warped, or worn too thin, but the brake pads still had plenty of usable life left. Are you saying that you should only keep those old pads on for a little while, until the new rotors are broken in? Or would it be a better idea to just keep those old pads on until they need to be replaced?

lobuxracer

iTrader: (2)

Run 'em 'til they're worn out. No need to toss them if they're not near minimums.

RocketGuy3

iTrader: (1)

Cool, thanks Lance.

Fleainat

so I took my IS350 in for a seat sqeak this week and the dealership told me I have less than 10% on my front brakes. He said I could do the front rotors and pads for 790, or just pads for 290.

1. is this the right price?
2. since I have only 14.5k miles, is this normal, and is there a chance warranty could cover this? this seems very unusual because i never really drive hard...

XhyDra

iTrader: (8)

Do you drive aggressively?
I drive pretty aggressive at times,
I have 10k on my car and my stock pads are still at 80%
and to top it off they squeak at times, it's something a lot
of drivers experience with the 2IS so I guess you can say
it's somewhat normal, but if they told you that you only
have 10% get your brake pads somewhere else.

IMHO that's a lot for brake pads.

Fleainat

I only drive aggressively sometimes. Has anyone experienced this at such low mileage?

Should warranty cover this?

darkdream

Do you do a lot of city driving?

Fleainat

yes, almost all city

darkdream

that might be why your pads wear out so fast...because with city driving you are braking countless times more than a driver who does mostly highway driving...

T-Rex06

iTrader: (12)

My pads get worn out around 17k and I do a lot of city driving. If you want to do a DIY on brake pads, it's really easy. The pads will cost you about $50 give and take from our CL vendors. I swapped out both sides in about 45 minutes at most. Check this thread out.

Terrance

Fleainat

Awesome. I've been calling some places and they say I should definitely machine the rotors (if not replace them). What are the risks of not machining them?

T-Rex06

iTrader: (12)

If you are experiencing vibration on your steering wheel when you apply your brakes, then you'll have to resurface the rotor. I have swapped the pads using OEM and it still brakes like the first day I got my car.

Terrance

lobuxracer

iTrader: (2)

Measure them for thickness. If they do not meet minimum thickness then replace them. If they do meet minimum thickness (or more) then stuff new pads in it and call it a day. Machining rotors is only necessary if they are deeply scored or the pads have gone completely and you're on metal to metal contact.

FWIW, the next time they tell you there's only 10% left, ask them to show you the measurements. Minimum pad thickness is 1mm, and you start with 12.5, so if you really only have 10% left, you'd have less than 2mm of pad left.

You can also check this yourself with a digital camera like this:



The pad's thickness can be seen in this pic taken with the camera inside the wheel between the spokes:



See the slot in the pad? If that slot is gone, then you are getting pretty close, but there's still a lot of pad left. FWIW, I've gone 52k in my IS350 and I'm still well over 60% left on my pads.