The rear driver's side brakes are sticking to the rotor, I have no clue how long this has been an issue. As the problem was only intermediate, it'd just come and go. It only recently became apparent 2 days ago when I was 60 miles away from home. I didn't have the key for my rims and I had no clue what was causing the issue in the first place. I initially thought it was the front wheel because I could feel vibration in the steering wheel. It just felt like there was a flat or a knot in the front tire. My girl said it sounded like it was coming from the rear driver's side and she was correct. I noticed there was an excessive amount of brake dust on that wheel. I jacked up the car on all 4 corners and spun each wheel. The rear driver's side was the only one that wouldn't spin freely. I'm not sure if the piston has seized or if it's the guide pins causing the issue? I figured I should just rebuild the whole caliper since it's only $20 for a piston, seals, and new guide pins. I should just go ahead and replace the boots as well so it'll be $26 total to replace the worn parts. A new caliper is around $150 or I could get a rebuilt one for $50 after I return the core. Or I can just rebuild the damn thing for half the price. I'll need new pads as well, the rotor surprisingly looks to still be in decent shape. I'm planning on getting another set of vented cross drilled rotors for the rear to match the set Ive already installed for the front. I have ceramic pads up front, and will go for a set of semi metallic for the rear. I'm also going to replace the e brake shoes since it's only $25 for the set. They are completely worn anyways, 2 wks ago I was driving for 20 miles before I even realized I was driving with the e brake engaged. Needless to say they are shot.

Ive searched everywhere and can't seem to find what the exact size of the piston. Went through the FSM, and have searched through every forum and Google as well to no avail. Not sure why I'm having difficulty finding the correct size piston that I'll need. I could just clean it up really well and reinstall,but it's only $5.99 for a new one. Problem is that Autozone doesn't carry them, so Orielys it is. But they have 5 different sizes listed online that claim to fit my vehicle. 57mm, 44mm, 38mm, 36mm, and 33mm. I've rules out 3 of them so it's either going to be 36mm or 33mm. I'm leaning towards it being the 33mm one. I'd like to receive some input in regards of the correct size that I'll need in order to rebuild the caliper. I suppose I could always return it if it doesn't fit. I'd just rather have the correct one at my first try. Hopefully this will resolve my issue, it appears to be a fairly common issue. Which is why Im finding it unusual that I'm having such a difficult time trying to find the correct size that I'm will to need. I'm needing the correct piston for single piston brakes for rear RH side non Brembo's on a 2004.5 G35X sedan.

I've also read that some ppl had continuously kept having this particular issue over and over again to no avail. When I installed the vented cross drilled rotors and ceramic pads I also drained all of the old brake fluid out while I bled the system. The old fluid was dark brown and murky, had some residue that I noticed come out while I bled the line. Brake fluid is clear, so yeah no telling how long that fluid has been in it, wouldn't surprise me if the fluid has never been drained and refilled before. It's something that is often left neglected. Meaning that the brake fluid in there was 10-16yrs old! Either way it needed out, I actually noticed a huge leap in brake performance after I did this. I didn't think that the new vented cross drilled rotors would make that much of a difference. Hell just flushing the system and filling it with new brake fluid probably made the most difference? I should of ordered all 4 sets, but was pretty broke around the time. I had just purchased this car and it was the first thing he told me. The front rotors were warped, so this was the first thing that I did to the car. I just dropped over $600 on new NGK plugs, coil packs, new valve covers w/gaskets, a 5/16th Blox plenum spacer, throttle body spacer, installed a CAI so my K&N filter is relocated to the driver's side bumper and fever well. Which has helped tremendously with heat soak, the plenum never gets hot to the touch. Before I did this, I couldn't touch it at all without nearly getting burnt. Put it this way the car responded very well to having more air displacement as well as the air being much cooler than ever before.

So now I have to catch myself from speeding 20mph over the speed limit on the constant. Speed limit is only 75mph and I'm steadily going 100 plus now. It doesn't even feel like I'm going that fast, the increase hp in the high rpm range is very noticable. Its a night or day difference between how it was before I installed everything. I also made sure to drain and fill the atf, transfer case, as well as the front and rear diffs. It even does great milage wise, even with my lead foot. This is also how I noticed that something was wrong. My gas mileage Started getting worse than it was before I did anything to my car. I can't exactly quite pin point when this initially started. I never smelt any brake material burning, had no clue besides this loud knocking noise. Just from driving it a ¼ mile down the street, the rotor becomes really hot to the touch. Scorching hot that I can barely touch it, the other side however isn't hot at all. Can't believe I was able to drive 60 miles back home without any issue arising.

Anyways so hopefully I can resolve this issue and it doesn't become a reoccurring problem. I know it can't be good for the rear diff, transfer case and transmission if there is constant resistance on this one wheel. I'll get the matching set of rotors in a few wks when I have the funds. Until then I hope that rebuilding the caliper itself will be the wisest choice. I hate having to second guess things, but if I can't find the correct size piston that I'm going to need. Than I will be stuck at the house, which I'm trying to avoid altogether. Screw it I'm just going to order the 33mm & 36mm piston and call it a day. Will just return the one that won't fit and have the money refunded to my CC. I've managed to ramble off subject quite a bit in that case. Oh well, but for anyone that finds themselves with this same issue. I highly recommend rebuilding the caliper yourself than our purchasing a rebuilt one. Atleast you can be reassured that it'll work and be if good quality because it'll be your work. Your brakes should never be overlooked, it's shocking actually how often they are indeed overlooked. It really isn't much effort at all to rebuild the caliper. Just pop the piston out, replace the seals, reinstall new piston, guide pins and boots. Then you'll be all done with a rebuilt caliper. I'll make sure to update this whenever I find out the correct size piston I'll need. Again this is for a sedan with the non brembo option. I'll be satisfied with this brake set up, there's really no need for a big brake set up. Ceramic pads with vented cross drilled rotors have enough bite for a minimal performance brake set up. Anything bigger would only be necessary if you're intending to have a track or drift car.

 

Personally I'd just pull the slide pins and see what condition they are inside the holes. If it's all dried up and rusty that's probably the issue, with the slide pins removed if you can suddenly spin the rotor (with the caliper just sort of floating in place, hold it with one hand) then you know the issue isn't a sticking caliper, just sticking slide pins.

Apply the correct amount of lube (I prefer Permatex 24110) and reinstall. DON'T use too much lube, just apply a fairly generous coat to the slide pin (basically dip the whole thing in the bottle then pull it out a wipe it off a little on the edge of the bottle) then reinstall the slide pin.

 

Check RockAuto for the part number for a caliper rebuilt kit. Sometimes they put the size in the description.
You can always avoid the guesswork and just buy the OEM caliper rebuild kits. I bought one from CZP to rebuild junkyard front calipers for my future 05/06 brake swap. It comes with everything you need, even the dust boots and assembly grease.
For caliper slide pins, I use ONLY silicone paste. Regular caliper grease is fine for the edge of the pads, but it can make the rubber swell, which isn't a good thing.