cops and 120MPH - BMW Forum

SpooldUp · 10-12-2005, 10:30 PM

So I've had the 323 for a few months, and I'm returning home to NY from western pennsylvania. Bought new tires/rims about a month ago, so they are broken in. yay, *me thinking* Hmmm, i should drive 120 on this 3 lane uphill stretch. */me thinking* The car actually surprised me achieving 120 in 5th gear quite quickly. Man was my intake screaming as I got a pretty constant 8MPG according to the gauge. Now on the downhill side (of the hill as well as the story) - I spot a cop once halfway down the mountain (not sure of my speed here but it was no less than what I had been traveling at the summit). Now, I DID NOT want to use the brakes above 100 for fear of warping the rotors, but quickly calculated the monetary difference of replacing 4 rotors (with performance ones, mind you) and paying a ticket for 120 in a 55 (big $$ in NY state). OEM brakes work moderatley well at this speed. I almost passed the Sherrif however I was never stopped so I will consider it lucky.

My brakes are good, but I did check the pads and they are nearly to the sensors. Inspection II is 1 green bar away.

superdeadman · 10-12-2005, 11:58 PM

so your lesson is --- don't speed if your breaks are f***ed up!

Torque · 11-01-2005, 11:59 PM

Warping the rotors eh ? I've never heard of one instance where this happened from one quick stop from a high speed.

///M Power · 11-02-2005, 08:36 PM

" Now, I DID NOT want to use the brakes above 100 for fear of warping the rotors, but quickly calculated the monetary difference of replacing 4 rotors (with performance ones, mind you) and paying a ticket for 120 in a 55 (big $$ in NY state)."

Shouldve calculated the antiderivative of the curve and gotten the are under the curve to find the exact point at oh shit nevermind u just got pulled over.

LOL but I love how you "quickly calculated," especially for OEM rotors.

SpooldUp · 11-03-2005, 02:07 AM

Always been good at math.

Actually I just said "Fu<k" and mashed the brake pedal.

I'll be buying the Zimmerman kit off ebay next spring. Folks seem to have good luck with it and it is sub $400.

ldsbeaker · 11-03-2005, 08:45 AM

When I did my 160 run in Germany, I kinda eased off the brakes and then put steady pressure on the brakes to slow down for my exit, as we were approaching it VERY quickly. I told this to my parents (I'm 27, but my parents still think I can't drive), and they said, "oh, that's smart, hit the brakes at 150-160, you're going to flip the car". Well, obviously it didn't flip, because I'm here!! I tried explaining that ///M3's are a practically a streetable race car, and they still wouldn't understand.
Point is, I don't think that warped the rotors. Why do they warp?

used:

I haven't had too much experience, and there are way too many conflicting stories on what will and won't warp your rotors. It's out of our hands.

4evrwyntr · 11-03-2005, 09:45 AM

To warp the rotors, you need to really hit the brakes hard AND be going at higher speed. At high speed if you are nice on the brakes, they may not warp. But even at low speeds, jamming on the brakes can cause warping - it's a combination of both heat stress and pressure (so also how long you've been using your brakes and how fast they cool also change up the variables n stuff). At least, that's how I understand it.

trs998 · 11-16-2005, 09:32 PM

I've never seen brake disks (rotors to you americans) warp from high speed braking. My 318 E30 I did two crash stops from 120-or-so in quick succession. The first was fine, the stock solid disk brakes were fading a little one the second. These were about 3 miles apart (the idiot in a merc e-class pulling out in front of me, and suddenly pulling off without indicating)

The damage from this was all 4 brake pads (cheap-ass Jurid pads) failed - cracked.
One subsequently blew it's surface off, causing total brake failure - that was fun!

Anyway. I know you can warp them through overheating, which isn't mch of an issue with one stop from 120. Racing hard on a track I would expect serious brake fade before the disks warp.
The main cause of warping I find is people coming into the pits after racing on a track day and holding the footbrake or handbrake (emergency brake in america?) on as the car sits for a few minutes. This means the disk cools unevenly.

SpooldUp · 11-17-2005, 10:32 PM

Quote:

Originally Posted by trs998

I've never seen brake disks (rotors to you americans) warp from high speed braking. My 318 E30 I did two crash stops from 120-or-so in quick succession. The first was fine, the stock solid disk brakes were fading a little one the second. These were about 3 miles apart (the idiot in a merc e-class pulling out in front of me, and suddenly pulling off without indicating)

The damage from this was all 4 brake pads (cheap-ass Jurid pads) failed - cracked.
One subsequently blew it's surface off, causing total brake failure - that was fun!

Anyway. I know you can warp them through overheating, which isn't mch of an issue with one stop from 120. Racing hard on a track I would expect serious brake fade before the disks warp.
The main cause of warping I find is people coming into the pits after racing on a track day and holding the footbrake or handbrake (emergency brake in america?) on as the car sits for a few minutes. This means the disk cools unevenly.

Yep, in retrospect I dont think it hurt anything.
lol in my friends mustang, a brake pad fell off once. Made a terrible grinding noise. Turned out the clips were just loose!

nukeduster · 03-10-2006, 07:39 PM

I have new brembos that work for the e36, x-drilled, front and rear. Never used them. bought them for the z3, but realized the 1.9l and the 2.8l both have different rotors and i got the ones for the 2.8(e36 325/328), not the 1.9l.

I'll unload them cheap. They are zinc washed, too.

SpooldUp · 03-11-2006, 09:51 AM

Rear vented discs? I need rear vented discs.

KSE36M3 · 05-15-2006, 12:33 PM

Quote:

Originally Posted by ldsbeaker

When I did my 160 run in Germany, I kinda eased off the brakes and then put steady pressure on the brakes to slow down for my exit, as we were approaching it VERY quickly. I told this to my parents (I'm 27, but my parents still think I can't drive), and they said, "oh, that's smart, hit the brakes at 150-160, you're going to flip the car". Well, obviously it didn't flip, because I'm here!! I tried explaining that ///M3's are a practically a streetable race car, and they still wouldn't understand.
Point is, I don't think that warped the rotors. Why do they warp?

used:

I haven't had too much experience, and there are way too many conflicting stories on what will and won't warp your rotors. It's out of our hands.

haha yea....just find an excuse to get them in the car....take em out and pull 110 (just to be nice) and see how they react. haha

Devinish · 05-22-2006, 10:40 PM

Pumping the brake pedal helps, along with downshifting, at higher speeds. Gives the rotors/pads time to cool off for a few fractions of a second before you use them again.

thejobman · 05-23-2006, 03:42 PM

Hell, I took my '02 Mustang drifting before selling it last year and even after 3 VERY HOT laps, my rotors where still fine. FYI 99-04 Mustang GT's have VERY crappy brakes, and I was literally flooring the pedal every time I hit the hairpin... still the only thing I noticed was that my check engine light went off lol, but it turned off on its own later that night (thank the lord).

BMW brakes are light years ahead and will not warp over one time stints such as the one described in your post. Hot lap or race weekend after weekend and that is a different story!

saltshaker185 · 05-23-2006, 03:51 PM

braking hard in my experience at high speeds isnt what makes the rotors warp... it depends on how hot the brakes get... and they warp when you brake hard (brakes heated up) then you let the car sit like in park... that lets the brakes cool un evenly because the pads and calipers are still hot so they are still heating the rotors and the rest of the rotor is cooling... you shuold roll the car back and forth with in a couple feet so that the rotor never settles in one spot at a time until the brakes cool down... also a cool down lap of barely using the brake at slower speeds is also a great way to let the air blow on the brakes and cool them...

just my 2 cents...