Bedding in new pads = warped rotors!?!

**nickk** · 07-09-2010 11:35 AM

Hey guys, need a bit of advice here.

Changed my pads, went for a drive.
Pads felt like they were grabbing slightly when brake was released, now they aren't.
I took the car for a drive, did some slight braking about 3 or 4 times, no complete stops.
Then did some harder braking, again no complete stops, pulled into my driveway and i thought my car was on fire, i couldn't even touch the rim it was that hot.
(I really didn't think I was braking that massively)

Anyway, now I have brake shudder under hard braking. Did i heat the rotors up that much that they warped?

**aaronng** · 07-09-2010 12:40 PM

Sounds like the caliper pistons were still pushing the pad onto the rotor when you released the brake pedal. Was it the front or rear rims that were hot? Did you push the rear piston back in sufficiently when installing the pads? Could the caliper piston be sticking?

**DLO01** · 07-09-2010 12:48 PM

^^^ as above. Front, rear? Front right, front left. Was it pulling to one side when OFF the brakes?

**na-118** · 07-09-2010 12:50 PM

pump the brake pedal a few times, might be stuck
did you check the disc if it had a lip,
did you get the verniers out and check the thickness of the rotars ( measurements on back of disc )?
what pads you buy?
as like AARONNG stated "Did you push the rear piston back in sufficiently when installing the pads?"

**nickk** · 08-09-2010 03:48 PM

I'm so dumb! I'm referring to the front pads.
It did not pull to any side when off brakes.
I think the fairly severe camber wear on the front tyres are exacerbating the issue (the shuddering that is.)
The shims didn't fit so I just installed the pads on their own.... maybe that?
I dunno! I'm a noob when it comes to brakes.
Reservoir hasn't dropped and is filled with correct spec brake fluid.
Pushed the pistons back enough with a pry bar (3-5mm clearance?)... through that (inspection slot??) on the front end of the caliper.

**vinnY** · 09-09-2010 03:30 PM

I say get them machined anyway, usually a good idea to machine the rotor(if it's still within thickness spec) if you're whacking on new pads
machining is cheap anyway so it won't hurt either way

**grifty** · 09-09-2010 04:40 PM

Originally Posted by vinnY

I say get them machined anyway, usually a good idea to machine the rotor(if it's still within thickness spec) if you're whacking on new pads
machining is cheap anyway so it won't hurt either way

do you happen to know anyone that machines them off car not on the car?

**vinnY** · 09-09-2010 04:44 PM

last time I took my rotors down to turbo auto spares in cabramatta
ended up being something like 25 bucks for two slotted fronts

**HKS200** · 09-09-2010 04:45 PM

brake shudder can be either warped rotors or stuffed tread. Was it new pads with old rotors or both new? Rims getting hot is normal as both are metal and the wheels are bolted onto the rotors. Machining rotors aren't always a good idea, check them before you machine. Some rotors are designed to be fine for machining some aren't, depends on the materiel or design. Machining can be done at any brake repairer or midas

**Riviera** · 09-09-2010 07:04 PM

bro people go on about pushing the piston back there is no set position to put it to before installing pads if the caliper slides over with the new pads in thats fine...

back to the issue:

what you might be experiencing is the slide bolts top and bottom, the boots may be damaged and grit and grime has got into it and mixed with the grease stopping the caliper from sliding
with the pads removed you should bolt the caliper back on and see whether you can slide the caliper freely in and out

Also cleaning the sections top and bottom where the pad fits into and apply a anti seize paste to the top and bottom.
By not applying the shims that would not be causing the trouble the shims are designed to stop the steel piston from rubbing and potentially rusting with the steel plate on the back of the pad.

If the caliper slide bolts are fine you might wana check out the piston, check the rubber seal around the piston for damage... i recently rebuilt my rear caliper because i had water inside the caliper
and it was beginning to seize, also the seal was damaged rebuilt the caliper and shes all good

rebuild kits are very cheap...

few traders hav OEM parts sections and sell them

cheers