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Discussion Starter · #1 ·
Hi ya'll. Chuck in Dallas here.

Just got a 2000 Z3 w/ the 2.5L M52TUB25 & 5speed, 94,000 miles. Got it mainly for fun at track days. Fixing stuff that is wrong, or broke, or worn-out. Have done 5 days of HPDE so far and have questions about brakes. And lots of worn-out stuff still to replace...

By way of background, I have 7 years experience on these tracks with the CMRA so am pretty good at seeing what is going on and think I'm pushing the little guy fairly hard. The Z is low on power, so corner speed is real important and at the local track known as Eagle Canyon there are 4 very hard braking areas, all of them left turns.

Last track day I completely wore out, completely!!, the right REAR pads in only 4 sessions of about 25 minutes each. Granted, just over-the-counter regular stuff, but at least from a NAPA (which I consider to generally sell good stuff). The right front lasted 2 more sessions the following day. I do not know why the rights wore out quicker, guess it is just because they were a little more loaded. Any thoughts?

The real thing I need an answer on is - the piston side pad wore dramatically quicker on both the front and rear. Is this normal? The pads were newly installed and I had properly (I think) greased the slide pins. Will not be upgrading calipers, maybe better than OEM rotors soon. Why the uneven wear?

Also, once after they were good and hot I tried to induce the anti-lock system as an experiment and it just didn't kick in. A few days later on a patch of wet street it was easy to do so. Explanation?"

End of brake question. For now.

Would love to get in conversation with anybody nearby that really understands working on this machine.

Chuck
cell at 214-394-5832
is always on to talk about having fun with gasoline
 

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Pads should wear evenly on each side of the caliper no matter how fast the wear.

So first thing you did wrong was grease the slide pins. They should be clean - but put nothing on them at all.

I'd suggest re-manufactured calipers or a caliper rebuild - new seals and guide bushings. There is a option of Brass bushings that do need more maintenance but hold the caliper better.

That should give you even pad wear.

Next you need to step up to a proper track pad. They will last longer and give better performance.
 

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The uneven wear was most likely caused by the pins and guides. Swap them out for the brass guides and new pins (sold as a set). And they DO need lubed, just be sure to use the correct lube. Uneven cooling can also contribute. Stick with the OEM calipers and blanks will be fine. Your pads are not up to the job. There are many kinds available, talk to others that track the Z3 and see what they have luck with. Performance Friction is common. The ABS probably would not kick in when they "good and hot" because you exceeded the operating range, temp wise, that the pad was designed for. ABS works by detecting differences in speed from one wheel to the next and since you where most likely way above the operating range of the pad, on a dry surface, they where not able to generate enough force to lock the wheel. Once cool and on a wet surface it is much easier. Change your brake fluid often.
 

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Discussion Starter · #4 ·
next questions

Guys,

Thanks for the input.

I've put on a set of ?akeobon? ceramic pads. Haven't actually flushed the system, did bleed & refill enough to use 3 pints of AP Racing Super 600 fluid at $20 ea. :-( Never done a flush of a modern system w/ all the valves & pumps. Guess I really should just scrounge-up the vacuum tool & do it properly.

Been thinking the guides & pins would make a difference. Previously at every pad change cleaned the pins and lubed w/ white grease. These new pads came w/ a little packet of grease presumably up to the temps involved.

Seems if taking calipers off and really cleaning (rebuilding?) them, then should go back w/ new hose then seems like SS lines wouldn't be that much more expensive. This is why she watches me like a hawk...my little bike habit made it where she really understands race prep different from "just working on..." :)

Opinions about rotors? Doing this not too different from stock is the plan. EBC has what they call "Ultimax", claim better than OEM, not drilled or slotted. Never replaced rotors before (well, they're just sitting out right there on a bike) - doesn't look like any special tools or techniques required.

The real upgrade I want is 17" wheels and then real track tires. My question is, will refreshed but stock brake system absorb that energy level?

Doing it again at Hallett, Oklahoma in 4 weeks.
 

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TIS specifically states to clean the pins and no to add a lubricant. Now that you have, you really need to replace the rubber insert. Max at http://www.oembimmerparts.com will fix you up with new rotors. no need for anything fancy for the track. they "OEM" rotors he sells work very well hand a a great price.
 

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Discussion Starter · #6 ·
Great looking prices on the oembimmer parts link. Thanks. Looks like replacing the rubber liners and cleaning pins. Much more fun than watching the idiot box til bedtime.
C.
 

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The brass ones need lubed. Just go with the Brembo blanks. While I like the Akebono Ceramic pad, you will probably not find it up to the task of a track day with race tires. Try them and see of course since you have already dropped the $$. Probably something more along the lines of Hawk HT-10 or blue or PFC 97. Best bet is to contact the pad company and tell them what you are doing. DO NOT forget to bed them before you take the track at speed. You can bed them on the track during a practice session if you like or before you go.
 

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Discussion Starter · #8 ·
Thanks for all the info guys. Think I'll have time to get some of these parts changed before Hallett.

Am going to gather some data...what about this as a way to study what's going on and how much improvement changes make:

Using a pair of cheap sensors. Measure rotor temps, both sides of each rotor. Driver do, say, 3 each 50mph to 10mph stops (so to speak) and then a final full stop. Then immediately measure the rotor temps, both sides of each rotor. My guess is, on my car as it is now, the temp will increase more on the piston side of the rotor.

Then after a refresh of seals & fluid, repeat test. I expect the increase in temp will be closer to the same on each side. If not then would that indicate some still existing problem? I think as a control I could do the test on a buddies pampered new 528. If I could get him to actually use the brakes at something near an intense level. If pad wear should be the same then it seems the heat build-up should be the same, eh?
 

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Checking your brake temps is great and is done all the time in racing. There are temp paints and strips that you can use. They indicate max temp and you take the time variable out of the temp equation. All race shops, at least good one, sell them. I will help take the guess work out of your pad selection and help determine what problems you are having.

I have a pretty extensive line of experience supporting, designing and maintaining racing brake systems. If that was my car what I would do is clean everything up, bleed the brakes, bed the bono's (paid for so lets see what happens), install new pins and brass bushings get the temp paint and apply as instructed and go racing. Once I got home I could evaluate the system much better and have some data that indicates what direction needs to be taken next.
 

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Discussion Starter · #10 ·
rdorman,

Again thanks & thanks especially for the paint thingie...never knew that. Just love data! Like the old joke, without it your just another a$$h01e with an opinion. Will check it out, may not do that cause of $s if it's material. Trying to think different lines for car & bike, on a bike Hallett only has 1 really heavy braking area. At least on a 75hp bike...think the same will be true for my car. Point is, no other track in TX or OK has the brake demands of Eagles Canyon, and I wanna spend resources at Hallett, TWS, and Motorsport Ranch before I go back to Eagles. So probably will do just as you suggest, skipping paint for now.

BTW, neither bimmerbum nor Pelican lists the brass sliders.
Have seen them somewhere, perhaps ebay, but didn't see them listed when I looked last night. Vendor suggestion? Interesting factoid - turns out my local PepBoys beats all the on-line prices I've found mfg. by mfg. Especially true for EBC products. Who knew?

Again, thanks rdorman & sunzout. Signing off for a few days to earn an honest living, which takes up a lot of my time. C U
 

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BimmerwWorld actually "invented" teh brass bushings and pins. Very nice guys also.

For track pads, I run Turner Motorsports Cool Willy pads. Great on the track and capable of beign driving to/from the track. With some squealing. But goo dcold bite.
 

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Down on power ??????

Make sure your engine is running as it should be......the o-rings inside the vanos are known to be less than adequate for their job.

http://www.beisansystems.com/index.html

I was simply amazed at how much engine performance (torque especially) and rev -ability improved after rebuilding the vanos.

The procedure is simple on the TU engines (excellant DIY on that website) and its a great time to take a peek at the valve train and replace the 10+ yr old rock hard valve cover gasket and grommets.

Have fun!
 
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