AlanW

Generally speaking, what causes rotors to wear kind of like record grooves? Just regular wear? pads harder than rotors? grit?, not bedded right?, etc??

I rarely have trouble with "warped" rotors that others complain of, on any of my vehicles. However, I'm not much on having rotors resurfaced between pad changes either. The ones currently on my TLS are in pretty good shape, but have this on many past vehicles & my truck I tow my 3,200 lb boat with.

jdjohn84

The pads are not harder than the rotors, or else we would always be replacing rotors instead of pads. The pads are made of particles pressed together, and some of the particles are pretty hard. When the rotors get hot during braking, it softens the metal enough to allow the 'grooving' you mentioned from the pads. The pads are more heat resistant because of what they are made of (asbestos, ceramic, etc.), so they withstand the heat better than the rotors, and produce the grooving in the super-heated rotors.

Unless the pads get down to the rivets and cause deep grooves, I don't worry about 'turning', or shaving the rotors during every pad change. If the rotors feel smooth, I leave them alone. Let the flaming begin now on this forum.

Incidentally, slotted and/or drilled rotors help to dissipate heat in the rotors, allowing them to cool more quickly. One tip my dad gave me was to let your call inch forward after coming to a hard stop in traffic or at traffic light - like after exiting the interstate. When the rotors are still hot, by inching forward while waiting for traffic to move or the light to change when the rotors and pads are still hot, you keep the pads from staying on one spot on the rotors and possibly causing a soft spot that could warp. By rolling just a smidge, you keep the pads moving around the rotors instead of staying on one spot.

MIKE8898

Also uneven pad wear can cause these grooves or hotspots.

01tl4tl

for your truck: the boat is wearing out those brakes--added load under forward motion increase its appearent weight to the front brakes
weight x arm = moment (aviation balance/loading referance)

some rotor grooving is just hard metal of bits in pads in contact with rotor
extreme grooving or warping can be so many things- may as well take the brakes apart- clean and lube all the sliders.,caliper piston... see what the problem is.
rust on edge of center hub throws alignment of system off

(often overlooked fact is the caliper pulls itself together on the sliders and pins)

change/flush your brake fluid --should be done every year for max braking
On the tow vehicle twice a year-- fresh fluid works better

01tl4tl

rotors worn to, or past their min thickness can cause problems too

fsttyms1

Also to add to what tom posted, IF the previous pad has slightly cut into the rotor the new pad will wear into that shape and continue the groved wearing. That is why you SHOULD have rotors turned when installing new pads. It creates a fresh new surface for the new pad to bed into.

richardparker

iTrader: (7)

I alway thought the groves would come from not keeping up with the maintaince.
Like riding worn pads till there is nothing or broken piece's left and still keep driving till the rotors are shot too.

mvpel

I've found that at least around here in New England, it's cheaper to buy brand new rotors from AutoPartsWarehouse.com rather than trying to find someone willing and able to turn your rotors for you. You can get a nice Centric or Bendix front disc for a TL for around $40, and you don't have to leave your car up on jackstands in the garage while you take the rotors to the shop. Yank the old ones off, and slap the new ones on, and you're done.

JterrorC

iTrader: (1)

a bit off topic ohwell:

whats going on when the pads tackle the rotors instead of hugging them.. sometimes ive been in cars where u tap on the brake n u feel like the brakes hit something....like its wasnt a smooth transition from a cm away to being on the rotors...

TLer trash

I see more grooving on cars and trucks that get a lot of dirt road use as well.

jdjohn84

I think that means your brake 'hardware' (clips and slides) are not lubed properly. The pads aren't moving freely enough in the slides, getting stuck, then moving abruptly when the pistons apply pressure. Most instructions call for replacing this 'hardware' during every pad replacement, but I think a good cleaning with a metal brush and brake cleaner is good enough, then follow-up with the proper brake lube or grease. The grease should also be applied to the back of the pads where they contact the pad backing plate, and also the tabs on the pads where they fit into the guides.

Also, or alternatively, the spring that holds the pads in place could be mounted improperly. If so, it can keep the pads at some weird angle until the pistons press them, and then cause that noise.

01tl4tl

on that prob I would flush the brake fluid and lube everything

I use a rag and brake cleaner, not a wire brush- to remove crud from the sliders and piston caliper edges

Want smooth surfaces to lube with caliper grease when done

JterrorC

iTrader: (1)

thanks good to know....