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New Brakes

So I got new brakes and rotors, which I've needed for months, so I can loan my truck to Noah without worrying about him dying. And now it's harder to stop my truck than it was before I got said new front brakes and rotors. WTF?? Is this normal? My brakes seem all spongy now, and I have to push down really hard to get the truck to come to a complete halt, where before my breaks were really twitchy/sensitive, and there was a very small displacement between no-braking and abruptly coming to a halt. Which I liked. Kinda like I like a fast mouse. It seems so hard to stop all the way now that I'm worried about it. I'll do the obvious thing and call the mechanic, but does anyone I know understand brakes and why this is happening??

Comments

( 6 comments — Leave a comment )
bk2w
Sep. 16th, 2004 04:41 pm (UTC)
I can only think of two reasons for brakes failing like that: grease on the rotors/pads, and air in the fluid. Does the pedal go down much farther than before the swap? Did you wash the new rotors and pad faces down with brake cleaner before assembling?

I'm happy to take a look at the brakes if you're up to driving it to Fremont as it is now.
katharos
Sep. 16th, 2004 04:48 pm (UTC)
:D I haven't done anything with my brakes. Yet...

It almost feels like there isn't enough throw in the pedal anymore to fully engage the breaks. I *assume* my mechanic did the right thing assembling them, but I just called them and I'm going to take the truck in again tomorrow morning. If they tell me I'm a hysterical female, I'll have you look at them. It would be nice if I could get the truck up this weekend, we'll see what happens tomorrow morning.

I'd say the pedal goes down about the same distance as it used to, but the braking starts happening at a much lighter depression than it used to, and never wants to finish braking... Wouldn't want to see how it handled like this with a load in the back. :(
bk2w
Sep. 16th, 2004 05:05 pm (UTC)
Ah, silly me forgetting that most people actually pay mechanics to do car work rather than leave the car up on blocks for three days while parts are shipped. Ahem.

It's my uncomfirmed belief that new pads and rotors don't mate as well as mid-life pads. The apparently smooth surfaces don't mate quite as well as surfaces that have worn against each other for a while. The added surface area increases friction and decreases required pedal force. This kind of condition should remedy itself quickly, though. But I always thought the difference was close to unnoticable.

Another issue is that newly manufactured pads could still have a lot of comparatively volatile chems embedded in them that 'cook' out as the pads are used, and can create an unusually thick layer of gas between the pads and rotors. I've heard that some pads should be 'bedded in' right after installation, which basically heat-cycles the pads to bake the volatiles out.

I'm definately interested in hearing what the mechanics have to say.
bn29
Sep. 16th, 2004 11:02 pm (UTC)
FWIW, I just got new brakes a few months ago and had exactly the same problem Katherine is having, and believe it is simply related to having new brakes which don't yet mate perfectly. The problem self corrected in a week or two, so I don't think it's anything to worry about beyond allowing extra stopping distance until the pads wear in.
katharos
Sep. 17th, 2004 09:25 am (UTC)
Woo! Two Bri/yans in one thread! Heh. Ehem.

I don't think you're going to get to hear what the mechanic says Brian, cause I think Bryan and you are right. I took my truck up to the empty top of the Caltrain parking structure and accel/braked really hard a couple of times and it started to feel normal. I'm not sure if this is me getting used to new brakes, or them burning off chemicals/grease or what, but the end result is they're starting to feel pretty normal. I'll try them again this morning, and if they feel really weird then maybe I'll start feeling paranoid again.

-k
jd5p
Sep. 16th, 2004 04:47 pm (UTC)
Brakes
Yeah . . . what BK said. Spongy brakes sounds like either air in the lines or possibly a leaky line.
( 6 comments — Leave a comment )