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Brake service - parts suggestions

Discussion in 'E30 (1984-1993)' started by az3579, Nov 20, 2008.

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    az3579

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    I'm planning on changing all four rotors and pads in the near future. I don't want to start another argument such as the strut brace thread in the Z4-M section, but would I really gain by getting at least slotted rotors?

    What I want to get are slotted rotors, not cross-drilled. I've been told that cross-drilled rotors tend to crack, and that is not appealing to me at all. Slotted rotors do the same job, don't they? Would I actually benefit from getting these rotors over the stock plain vented rotors? What about frozen/cyrogenically treated rotors? Keep in mind I am looking for an overall increase in braking performance if possible, but wouldn't mind if the braking performance stayed the same as now. I am a bit concerned that my plain vented rotors overheat at times, almost always on the track and rarely during spirited driving. I do not want overheating brakes!

    I do want it to look cool too, kind of like sleeper status. You can't see much of it under the basketweaves, but I like the "wow" factor every time the wheel is taken off, though this isn't as important as braking performance and cooling. :)



    As for brake pads, I'm thinking of migrating away from the Hawk HPS' I'm running right now. My brakes squeal like pigs at this times and also make some other strange noise under hard braking, but I don't know if that's because my rotors are completely worn out or if it's the pads. The braking performance is great and all, but I just don't know if I could bring myself to buy another set after this squealing started. It started right after I replaced my brake pads to Hawk HPS'. Does anyone else have this issue and would anyone buy this set again? What other pad options do I have if I want 0 noise and good braking performance? It doesn't have to be track-grippy, but I want it to be pretty darned good for a street car.


    And, the all-important question: Will I track the car?

    I do plan on attending multiple HPDE's throughout the year, depending on how much I want to afford. I do want to do at least 2 a year and am not keen on swapping out rotors and pads just to go to a track event, so it's important for the rotors and pads to last a while even after attending a track day. If they don't last all that long after the day, fine, but they should at least be cheap. I'm willing to spend up to about $60/rotor, so for that price, I hope it would last quite a bit after an HPDE. Keep in mind, my regular plain rotors haven't been changed on my car since I bought it over 2 years ago and the rotors have survived two track days, both of which I experienced the pleasant smell of burning brakes. The pads lasted me a track day and were fine up until I swapped out my pads to Hawk HPS' with no noise at all. I don't know what pads they were; they were on the car when I bought it.

    If anyone can provide some insight, it would be greatly appreciated.

    When this is done, I'll be posting about shocks/struts and springs. :D
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    MGarrison

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    I tried some slotted rotors, I didn't like them.

    So, I'd recommend stock rotors. I haven't tried cryo'd rotors yet, but in theory, that should extend their life a bit.

    I don't think it's all that ez to find a brake pad that's going to offer good on-track and street performance; you go for one at the expense of the other. On track, brakes are going to get hot (obviously) - on the street, most of the time, the pads are going to be mostly cold unless you get into an emergency level stop, or are flogging the car around. You also have to take into consideration your driving style.

    I swap out street pads for track pads before schools, and drive them to/from the track.

    If you want a rotor friendly street pad with some cold stopping power (at the expense of their hot performance) - Axxis Deluxe. These are good for normal braking, and fine for a hard stop or two, but will fade fairly readily if pushed.

    I used Axxis metal masters for years on both the street and track, until I got to the point where I was burning through a set of front pads in 3-4 track sessions. I still use metal masters for rear pads. However, their winter performance is a little less than optimal - when backing out of my driveway on a cold winter morning, they sure didn't want to grip the rotors much and stop the car. I didn't have problems w/ them otherwise in winter usage, but always felt they might increase my emergency stopping distance in the winter months. Flipside, if I pushed them on the street, they would hang in there well.

    I've been using the Axxis Ultimate ceramics on my 535i all year around - I have to say they've worked just fine cold, and when pushed, but I don't have a comment for their on-track performance.

    The tips to getting your non-M3 E30 to having some on-track braking performance -

    Stainless steel brake lines
    Hi-performance brake fluid - Many go for ATE Super-Blue, or ATE Gold; I use Motul.
    Getting the rotors some cooling air flow - this takes some hoses & ducting, either getting some air over the rotor surface, or, more ideally, into the middle and out through the rotor vanes.

    Without the air, it's quite likely you'll suffer brake fade, and/or warped rotors, eventually. I've seen multiple non-M3 E30's on track that just had to tolerate having rotors warp quickly as a matter of course.

    If the brake lines are original, keep in mind the age of those rubber lines at each corner and the stress they're under; plus, as I've mentioned elsewhere, at this point it's advisable to closely check the steel brake line sections for rust.

    I can't remember where I got them now, (Pegasus maybe), but they had these stick-on temperature indicators that would show what temperature range they reached. Those can be helpful for showing how hot your brakes got, and whether the temps you see are within your brake fluid's dry boiling point.
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    az3579

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    I'm not all too concerned with the track characteristics of my upcoming brake upgrade. Whatever I get, I'm sure will be better than what I had before, and I only experience brake fade towards the end of my track days. I must not be pushing the car hard enough, though I think I'm pretty darned aggressive on the brakes and suspension. :)

    Some garden variety pads lasted you 3-4 sessions? That's it??? That's not even an entire day's worth...

    I know I can't have great on-track and off-track performance, but I want a pretty darned good combination. This is a daily driver, so the brakes need to be better on the street if possible, but I am worried about brake fade on and off the track. Need that down to an absolute minimum. I love my twisty roads...


    Why don't you like slotted rotors?
    • Member

    MGarrison

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    If you're worried about brake fade at your schools, it sounds like you _are_ concerned w/ how your brakes may perform at the track. I don't think I've heard anyone make the claim that slotted rotors make for a really major improvement in braking performance, either track or street. They might help a bit, but I doubt you'd find a dramatic difference between stock & slotted, performance-wise. If you want 'em, there's no harm in giving them a try. I tried the ATE powerslot rotors - they were noisier than stock rotors, and transmitted sort of a grinding sound (noticeably audible) and that grinding was felt through the steering wheel while braking as a vibration.

    The other couple of types of slotted rotors I recall seeing have straight slots cut in them, or a sort-of spiraled cut, as opposed to the eliptical cut of the ATE powerslots. I would think those might be quieter and induce less vibration than the powerslots, maybe someone else will post a response and comment whether they are felt through the steering wheel when braking, or if they didn't notice a difference from stock.

    I consider a garden-variety pad to be something completely generic, the cheapest or most basic from some auto-parts house - I've found Axxis metalmasters to be a good performance/value option over the years and certainly better than anything I'd consider garden-variety. They're not terribly expensive, and they work well. My point about how long they lasted was to suggest that they should work well for you as you progress through your learning curve at driver's schools for a long time, up to the point where you start driving the car hard enough and braking hard enough that you find yourself burning them up in a day. Unless you like changing brake pads at the track a couple of times each weekend, at that point, it's worthwhile to consider switching to a racing brake pad compound (if you ask me).

    The tips suggested all address parts of things that can cause brake fade -

    Stock lines are rubber - when they get hot, as they do under hard braking on-track, they get flexible, and swell - that makes for a spongy brake pedal. Stainless lines are far less temperature-sensitive, and reinforced, to minimize any heat-related swelling. Plus, there's age related wear/tear on the original stock lines at this point, with the youngest E30 being 16 yrs old, and the oldest 24. You wouldn't want one of those rubber lines bursting at the worst possible time (actually, any time you brake and can't stop is going to be the worst possible time). I can't comment on how likely it is for an original, old rubber brake line to fail under duress, but you certainly don't want to find out, particularly on track.

    Fresh, hi-temp brake fluid. Brake fluid absorbs moisture from the atmosphere over time, which lowers its boiling point (and may rust brake component internals over time, if changed infrequently). If your brake fluid's boiling point is below the temperatures it will experience, you'll have the brakes fade, perhaps substantially, when the fluid boils.

    Additional air-flow facilitates the heat exchange - that simple. If you get some air flowing directly through the centers of the rotors, they'll stay cooler, be a more effective heat sink, and help to keep the brake fluid from boiling.

    There are lots and lots of pad options of course - the axxis pads are what I have experience with that I can share -

    hope that helps a bit! :)
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    TeamStowell We love driving!

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    Turner Motorsport has just announced 10% off all brake parts. I have been using their cross drilled rotors and Axxis Pads for the M3 and 540 without any issue, but I don't put them on a track.
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    az3579

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    Well, what I meant was that I'm not too concerned as to how well they stop. I am worried about the fade, but don't care as much about how well they stop because I'm confident that whatever I will get it will be better than what I've got now.


    I haven't even thought about the brake lines. Prices on eBay seem to be pretty low, so I can probably expect to pay up to $80 for a decent set? Is this a good time to do an ABS delete? I have ABS in the car but it doesn't work.


    I already have ATE SuperBlue fluid as my brake fluid, which was put in not long before my first track event in April. That should last a good while, but before I do another track event, I will do a full flush/refill of the brake fluid.


    I didn't want to get the ATE PowerSlot rotors as you mentioned because I found the design to be really... wonky. Since all of the other slotted rotors I saw had the straight lines, I did start to wonder why those had the really strange pattern to the slot. I have to admit though, when it comes to slotted rotors, it seems to be the cheapest one on Tire Rack. Since it's where I plan on getting my suspension parts, I want to get brakes there as well.

    Or, is there another place I could get brake parts? BavAuto has a very limited selection (or almost no selection) of rotors for my car. The main site I've been browsing was Tire Rack as they seem to have a pretty good pick of what goes on my car.

    The cyro rotors look appealing; I like the "extended life" aspect of it, but would it really be all that extended? With no track days, would it be possible to live through maybe two sets of pads to a rotor? It's my understanding that BMWs require new rotors whenever the pads are changed. Is this true? Currently, I'm on my second set of pads on the same rotors and I think I may be feeling the effects of it now with this terrible noise.



    I'm willing to give Hawk HPS pads another try with fresh rotors. I honestly have no clue what pads I had in my car previous to these, but they were fantastic, with much lower dusting than the Hawks. I'm not so worried about dusting, but if I can have lower dust with the same stopping power and less noise, then I'm all for it.


    I would like to get a cheaper (in price) set of pads though, because the Hawk HPS pads are bloody expensive for a street pad. Or is someone going to talk me out of it and just get HPS's again?



    I'm getting close to pulling the trigger on this one. Brakes are critical and mine are starting to make more noise every day. I think I might be eating through the rotors...

    [A friend of mine, who knows nothing about maintenance, ate completely through the brake pads in her Chevy van [[tank, mind you]] and it ate through the rotors. She almost crashed because she had no brakes!]
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    • Technical Service Advisor

    mooseheadm5

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    ABS good, just find the bad sensor and fix it. I have powerslot rotors on the 327i, and they are good, and have lasted for years even though I tow with it. Slotted rotors are also referred to as gas slotted rotors because they are designed to prevent gas planing. The heat in the pads causes them to off-gas and that can build a gas wedge between the pads and rotors that prevents them making good contact. The slots give the gas a place to go like the sipes on tires do with water. This is just one of the factors that reduces braking performance. I never had a problem with odd noise or vibration with the powerslots, and neithr did any of the customers that we sold them to.
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    MGarrison

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    I would think you could google up a lot of places offering stuff - since I've stuck to stock rotors, I either get them from the dealer or my mechanic, and haven't shopped around otherwise for brake rotors. I did find a few sites selling stock rotors for E30's, but the confidence factor came into play - stock rotors are proven, someone else's cheaper-but-unheard-of, weren't. I'd rather stick w/ what I know works than risk a failure or problem w/ a critical component, for something that isn't so terribly expensive but oh-so crucial, at least in this case. For some slotted rotors, might be worthwhile to stick w/ a known vendor.

    I don't think I've ever heard that you have to replace rotors everytime you get pads. The Bentley manual provides the min-thickness specs for the rotors, but you'll need a micrometer to get an accurate reading. New pads do need to 'bed-in' to the groove variations of old rotors, and depending on the pads and pad material, may need a specific 'bedding-in' procedure, to not only make them conform, but to get a 'transfer layer' of the new pad material across the face of the older rotors.

    I haven't used the Hawk HPS's, but I was wondering if they had any specific bedding in procedure that you followed - hopefully someone else with HPS experience will comment.

    If your ABS isn't working, I'd just leave it as it is and not worry about it. Either you, or somebody else down the line, might eventually decide to make it functional again. I'd say there's certainly nothing wrong w/ learning & practicing threshold braking without ABS, but, it's also all to easy to flat spot a tire. Sometime down the road you might find yourself having flat-spotted an expensive new piece of race-rubber, the steering wheel shaking itself out of your hands because of that, and mulling over the possibility of making the ABS work to avoid such travails in the future.

    I don't know what ss brake lines are going for these days, haven't had to shop for them in a long time - fwiw, mine are Precise Lines or Precision Lines - I think Turner Motorsport may offer that brand.

    Use an inspection mirror & flashlight to get a good look at your pad thickness (or, pull off each wheel - with those basketweaves, you perhaps can't fit anything through the spokes, ya?). As evidenced by your friend's unfortunate experience, getting down to the backing plates and not realizing it can have potentially disastrous consequences.

    Axxis deluxe pads were the lowest dusting pads I've had, but as mentioned - can fade when pushed.

    Pad & rotor life is going to depend on your driving. I wouldn't be surprised if you got 2 sets of pads per set of rotors, but you can monitor it by measuring thickness, and visually making sure they aren't stress cracking on you (which would primarily happen from driver's schools).

    Rotor-friendly (I think) is reasonably important for street/occasional track pads - but I wouldn't expect your HPS's or any pad shy of full-blown race pads to be eating up your rotors. By the same token, if you don't think your brakes are doing what they should - don't wait to check it out!

    BIMMIR guest

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    Bavarian Autosports in New Hampshire is a great resource to buy parts and answer questions.

    www.bavauto.com
    • Member

    az3579

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    These?
    http://www.tirerack.com/brakes/brak...el=325e&autoYear=1987&autoModClar=&perfCode=S


    I've heard it from two separate sources, one being a mechanic and the other being a trusted BMW source (I don't remember where though).

    The procedure is to make 6-10 moderate-pressure stops from about 30-35mph (I did 8 stops at 35mph). Then make 2-3 additional hard stops from 40-45mph (I did 3 stops @ 45mph). Then allow the brakes to cool off, and since it was well past midnight when I finished doing my pads (took me 5 or so hours, it was my first time) I just let the car sit overnight.

    Well if I'm not going to be fixing it, then nobody else will. This car will go to the grave after I'm done with it!

    I'm on top of my threshold braking. I do it quite frequently because the idiots 'round here aren't what I would call attentive drivers. If I could do it on the track without locking up, then I think I'm all set in that department.

    My braking performance isn't the issue - it's performing fine. I'm just doing some major preventative maintenance to ease my OCD mind. Besides, it's been a while since my car actually got new rotors, so I figure it can't hurt to get new ones. The OCD side of me wants to swap pads too, but that's my problem so don't worry about it. :)

    They pretty much have no selection of rotors or pads for my car. Maybe 1 or 2, but that's it.

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