2 Brake Questions (rotor surfaces, brake booster)

Okay, gang - Two brake questions for you all, one of which is 987 specific. Figured I'd run my reasoning by you all before proceeding. Issue #1 : The first question involves one of my rotors, which of which is currently on my BMW E30 (which applies to all of our P-cars anyhow). The short version is I’m trying to double check if I must/should change out my front brake rotors, one of which I suspect is uneven due to high/low points with unseen “cementite” deposits —where the rotor itself is likely not physically warped and there are severe crevices that I can tell (at least on the outward facing rotor surface -- nothing as deep as a pen scribble). As the calipers don’t really back off the rotors when one lets off the brake, there’s a slight dragging sound for about 1/3 of each rotation on the front right wheel that’s audible when coasting . This happened years ago on my BMW motorcycle as well. As the brake pads aren't moving, the uneven surface must be coming from the rotor -- which is changing during rotation. The backstory is that my E30 had sat a lot these past few years due to space constraints, and saw some outdoor time. I suspect that one of the brake pads fused with rust to the front rotor after a rainstorm and sitting, and left some deposits on it that can’t be scrubbed away. As there’s plenty of meat left on the rotors and brake pads, it would be a shame to have to redo both. I think both have seen 20K miles since the last change. It’s not difficult to do to be sure, but it’s additional rotor cost and more time. I suspect that I could do some driving with hard braking, but I doubt it’ll make the rotor even again as the deposits would be eaten away at the same rate as the rest of the rotor. Cost-wise, apparently resurfacing rotors went by the wayside long ago, so that’s out. When I went in there, the first thing I did was to clean and re-lube the points that move (using Permatex brake-safe lube), but that didn’t change anything. I also don’t think it’s a wheel bearing issue and I made sure it wasn't a back-plate rubbing issue either. What I could do, which is a $30 gamble, is to check for rotor runout as measured by a dial gauge. That was my original plan as I bought a kit from Amazon — but if I’m better off applying that $30 to new rotors and calling it a day (I already have a fresh pair of Brembo brake pads from years back), then I'll just order two new rotors and that'll be that. Issue #2 - I’ve got the loud “whoosh” sound coming from my 987.2’s brake booster area when braking. There's apparently no major loss of stopping power, but I’ll freely admit that I figured seemed like was “a feature and not a bug” after likely misreading older posts. I’ll have to go in and do some testing when I have a chance — especially checking for vacuum leaks and the like. What’s normal for you all? Plus, anyone encounter this and do a fix? If it does need a repair, I suspect it’s a joint leak that’s easily repaired (once accessed) and hopefully not the actual brake booster. Thanks, everyone.

My two cents? You’re in there once the wheel is off, doing it at the dealer would be a very large cost. Replace ALL of it, apply the cost for the rotors and skip the dial gauge just like you typed. I even went for the stretch bolts too although as an old guy I’m not sure I’m buying “the OMG reuse will cause death” warnings. But for the same reason, they’re cheap, do it all right, it’s your baby, over correction isn’t just for race cars and brakes may one day save your life. PS exceptional cleaning, using the textar paste and taking my time yielded results you won’t get at the dealer. My brakes came out stellar. And I got an improved anti sail device for my patio umbrella.

I'm with Boris - replace the pieces and be done with it. Do it right, once. I did mine with FCP Sebro slotted... well worth it, plus you won't have to spend on them again I'd recommend "better" pads to eliminate future deposition. I love my Akebonos, as I've mentioned before... the Textars make for a TON of dust, especially on the fronts. Not sure why you'd get deposits so fast... do you have something weird? Also, another habit I make is after a hard braking event, I will purposely NOT stay pressed on the brake pedal... or if I have to roll a little bit instead of staying on one spot. I feel this helps eliminate the deposit issue further as well... just in case. I do this on all my cars. I'll admit, I didn't do the bolts... I kept the old ones, as I recall. Mostly because I didn't realize they were stretch-bolts when I did mine. They've been fine to-date. Dial gauge is a nice idea, but with all the effort and such, it's not worth it. Swap is faster and easier. I can't speak to the brake booster noise. Doesn't seem right to make noise, but maybe I'm not hearing it so I don't know it's happening? Have you ever flushed them? Maybe it's old fluid making noises?

Add me to that list of those recommending total replacement of pads and rotors. There is no better feel than a new set of pads and rotors, everything mating together for superior stopping power. I remember many years ago it was common to resurface rotors, but they were meant to be ground for re-use, not so for modern rotors. For those instances where the rotors look near perfect, but there are blemishes, deposits and an overall glaze, too bad they don’t make a pad that has a gritted finish that one could install temporarily, drive in a parking lot a low speeds with a steady, measured force on the pedal to remove some minimal surface area, restoring them to a near new condition, avoiding a full replacement. The remove the temporary resurfacing pads and install the news ones with the newly minted surface of the rotors. Almost every time I go to do a brake job and examine the need to replace pads only or pads and rotors, I can’t seem to want to place fresh pads on an already worn rotor , and opt to go all in.

Thanks, gents. That's what I suspected. Given that I already have the set of Brembo brake pads in hand, I'm just going to order new rotors today and call it a day. @Boristhespyder - I LOVE the idea about the umbrella stand. Going to try that on our apartment deck! LOL. Come to think of it, if it was either the 987.2 or the 981 Outlaw, I would just swap the rotors and be done with it. But as I'm selling the '92 E30 Convertible I've had for nearly 30 years, it's more of simply ensuring that everything is all set pre-sale. The noise personally didn't bother me and the braking power is just fine. TBH, I wasn't even sure if it would go away if I started driving the car regularly. However, it sounds like it's best that I just prophylactically order rotors and be done with it. Let me know if you gents hear any whooshing sounds from the front when you hit the brakes. Again, it's a funny thing where my brakes work just fine, but I "don't know what I'm missing" given a potential vacuum leak. Not sure if I'll be able to hear it at standstill while the car is operating, but we'll see.

Rotor cuts are akin to “ I’m selling it the tires don’t need to match” IMO, they are temporary fixes. The real problem is back in the day when 90 mph was pushing it, brakes were under less stress, also many were single plate. We cut many, and we spun drums too. Our customers weren’t rich so we offered a spectrum of work offerings. However when my dad, brother or I did ours? All new, some customer enthusiasts as well. Lastly, these vented rotors do not dissipate heat well after a machining again my opinion. So sooner than later you’re back on them, many times because they warp and pulse in your brake foot when brakes the are applied.

I figured you'd really know the answer to this, @Boristhespyder - knowing your history. If this was a pulsing situation, I'd be replacing the rotors in a heartbeat. It was more of "it's making a brake pad scraping sound that's periodic (as opposed to all on/ all off) and does that mean replace" situation. I think it's the right move.

I wasn’t saying you were pulsing yet, I was trying to make the point that cutting rotors usually leads to pulsing, the rotors don’t dissipate heat as well with less material. Then you toss out pads that aren’t fully worn when you decide it’s time for the new rotors. Like I said if you want to feel really good about the investment, slide by a dealer for a quote chat. I’m more than satisfied with Brembo and Texstar and my cost when I did them was a great deal.

Many of the vaunted "German" rotors are now made from blanks made in China, and some come directly from China. Cast iron brake rotors is technology that hasn't changed a lot in 50 years. When you get into the ceramic and surface-coated rotors is when you'll find them made in Europe (but again - possibly using Chinese blanks to start with..)

Personally, I don't like to turn the rotors, when they are done I replace them.. Now regarding the 'dragging calipers', you could replace the seals and clean the pistons, you will have to remove the calipers and remove the pistons (with compressed air) and clean them with a 3M green pad (as long as they are not pitted/too rusted), replace the rubber seals inside the calipers, the rubber rebuilding kits are not expensive and you will have a nice brakes again, it is not really difficult just takes a bit of time.

OP, rotors and street pads are pretty inexpensive these days and as others have mentioned just replace them. Turning rotors is rarely done as they are so inexpensive to get new plus labor rates are high, you'll end up with a rotor with very little life left once the defects are machined out. The only time I might even consider turning a rotor is in the scenario of having a very rare car where new or even good used rotors are simply not easily available. Here's a link for a 2009 987.2 rotor , don't know what kind of budget you have but in my book this is pretty inexpensive. No affiliation but I have bought parts from several cars from them over the years and have been satisfied. More Information for BENDIX PRT6308

Rotors are inexpensive so don't resurface just buy a good quality rotors like Zimmermann, brembo etc and ceramic formula pads for less wear and dust.

Meh. Good rotors aren't inexpensive at all.

Well, some of them are.. I am saving for a set if Girodisc two piece floating rotors 😍