Hi all - quick question. I'm no brake guy, but I'm pretty sure the "pulsing groan" at low speed is due to a warped passenger rear rotor (low speed, very low pitch vibration, goes away when parking brake or brakes are lightly applied). Is it safe to replace just the two rear rotors? I'm hoping to not have to replace the pads since they only have about 500 miles on them, but if you talk me into it I will.

P.S.
I assume the rotor is warped because the passenger rear was stuck on the guide pin (right name?) and had forced the pad onto the outside. The wheel was too hot to touch! The shop cleaned the pads up for me, but the groan has not gone away.

 

i just replaced my rear rotors and left the original pads.

it really depends what kind of rotor you end up getting as to what kind of pads you should have.

like i replaced all rotors with drilled/slotted rotors..
originals had alot of pad left but are metallic. cased horrible noises when stopping so i replaced the front pads with ceramics and the noise went away in the front, now i just need to replace the rear pads with ceramics.

if you do replace the pads i have heard good things about ebc red stuff.
i just got the duralast cermaic c-max pads from autozone. 72$ for the front, now im trying to find the rears in the same brand. i have no complaints with them.

what kind of rotors did you buy? if you didn't buy any yet i would check ebay for a company called brake motive. i bought all four rotors from them for 138$. auto stores in my area wanted 184$ just for the fronts, and jaguarparts.com wants 112$ per rotor (crazy).

i have had no issues with them

 

Check the rotor with a straightedge for runout, it may be warped or your guide pin sticking is really your problem. Did the shop fix that?

Eh, 500 miles you could probably get away with just doing rotors and not pads, but I would highly suggest you take a straightedge to those pads and check for any uneveness caused by the warped rotor. If they are slightly uneven you could possibly get away with slightly sanding them straight (wear dust mask). If they are noticeably uneven get some new pads.

You may wish to get some new pins from the dealer and replace them while you are at it. Sometimes you can clean/wire brush them adequately, lube, and replace, but if they have severe pitting then just get new ones.

 

Yeah - the shop noticed that the guide pin must have been forced into place and ended up having to use a grinder to get a burr down. That's what it turned out actually caused the caliper to stick in place. I asked them at the time and looked at the pin itself if it needed to be replaced, but we all agreed the fix was pretty obvious.