heinzboehmer's 2002 Topaz 6MT Coupe

[heinzboehmer]

Riveted the flanges in:




Then used plastic epoxy to fill in the gaps:






I then moved on to the rotor backing plate. There's already a hole there, so the only thing I had to do was enlarge it a little. Final product and flange test fit:




Looks fairly simple, but this is the product of about three hours of work, most of which was spent measuring and remeasuring. I wanted to maximize the cross sectional area of the duct that had a clear shot to the rotor, but also wanted to be sure to not have air hit the face of the rotor, so as to avoid a temperature gradient. I managed to get it pretty much spot on, as shown by this next pic:



You can see the edge of the face of the rotor just barely peeking out at the right. Should work well.

Another thing I learned while doing this is that the rotor backing plates are not made of steel, like I always assumed they were. They're not magnetic and I was able to cut through them quite easily, so pretty sure they're aluminum. I was really happy to find this out, as I don't have to worry about them rusting.

Cleaned things up a bit and riveted the flange in. I used four rivets not because I thought I would need that many to keep the flange from falling off, but because I thought it would look better. My thought was that four equally spaced rivets would make it look like I deliberately put them there. Not sure if they look better than two/three (especially with all those marks in the plate from when the dremel slipped a bit), but that's what I ended up going with.



Closeup of the interface with the center of the hub. Pretty happy with how I managed to use the space:



Yeah, those marks left by the dremel are pretty big eye sores. I briefly thought about painting the backing plate, but then decided I didn't care enough. One track day should paint everything in a nice layer of brake dust anyway

And double checking that there's no path for air to hit the rotor face dead on:



Top right corner of the flange looks all mangled because I was bending it bit by bit when test fitting. The other side should look a lot better now that I know how much and where to bend.

Now I just need to copy paste everything onto the passenger's side, cut some holes into the belly pan and I should be done! May not be the nicest looking brake ducts, but I'm pretty confident they'll be very useful on track and they've been fun to make.



Sidenote: The further along I get with this project, the more I realize I'm basically making a copy of the ducts mrgizmo04 made for his car. He texted me some pictures of his progress a while back and they must have gotten stuck in my head. I guess I'm not as original as I thought. Oh well, thanks for the inspiration!

[repoman89]

Do you plan on blocking off the open backs of the cut OE plastic pieces? You might not get much airflow if you don’t but hard to say without testing. Also did you consider removing the backing plates as a first step as suggested in this article? https://www.essexparts.com/news-blog...n-my-track-car

I’ve been trying to decide what direction to go myself re: track brake cooling. Not sure if there’s a big disadvantage to trying the backing plate thing first beyond brake dust getting all over the wheel wells and suspension, which is admittedly pretty annoying

[heinzboehmer]

Do you plan on blocking off the open backs of the cut OE plastic pieces?

Yep, those will get blocked off. I think I still have the stock block off plates somewhere, just need to find them. Might see a WTB post from me though lol
i did a quick test by blowing air at the ducts with a shop vac and the amount of air coming out of the aluminum flanges decreased substantially with the stock hole open (unsurprisingly). If I find that they don't flow enough, I'll design my own ducts from scratch.

I've also bought a nice IR thermometer that can read up to 650C. Plan on doing some testing and gathering brake temps with and without the ducts on track.

Oh and I also plan on blocking off the flanges for the street. An easy option is to get a rubber cap and put it on in place of the hose. However, I'm not too happy about having a protruding area where water/dirt/insects/etc. can collect. Will probably end up 3D printing a cap that sits flush with the inside of the plastic OE duct.

Also did you consider removing the backing plates as a first step as suggested in this article? https://www.essexparts.com/news-blog...n-my-track-car

I’ve been trying to decide what direction to go myself re: track brake cooling. Not sure if there’s a big disadvantage to trying the backing plate thing first beyond brake dust getting all over the wheel wells and suspension, which is admittedly pretty annoying

I briefly considered other options like no backing plate or BBK.

Problem with the backing plate thing is that the hub needs to come out to remove and install it (in one piece). I didn't want to remove it, find out it wasn't enough and then have to go through the whole thing again to reinstall it. And yeah, dust getting everywhere would not be fun, especially since my car is still driven quite a bit on the street.

BBK would be great (and I'm still passively looking for 996 calipers to rebuild, really want those quick pad swaps), but I also wasn't sure if it would solve my issue entirely. Thought it made more sense to spend 10% of the cost of the 996 kit on brake ducts to see how much difference they make and then go from there.

Have a track day scheduled for May 6th, so if everything goes well, I'll have some data after that. I'll probably run a few laps with the air entrance on the ducts taped off and measure the rotor temps. Then remove the tape and measure the temps after one lap to see how much heat the ducts can shed in a shorter period of time. After that, I'll run the rest of the session and measure temps to see what they stabilize at.

Probably a longer answer than what you were expecting, but all of this has been floating around in my head for the last few days, ao I thought I'd use the opportunity to write it all down

[repoman89]

I appreciate the detailed response actually! Good thoughts and info. Yeah the 996 kits seem to be getting harder to find for a good price. I got a black set locally to rebuild last year so already running them. Selling the ZCP stockers almost paid for the kit.

I think that the backing plates can be mangled and hacked off fully if I'm not mistaken without removing the hubs, but not 100% on that. I asked in the dumb question thread and I think someone said they can be.

Looking forward to your heat gun results. I should do that too but am kind of leaning toward just cutting the plates off and sending it. This will be my first year with race pads too (DS1.11) so that might help. The reason it was in my mind at all is that the Textars only lasted ~2 events .. no/minimal fade or anything but not really designed to be a track pad.

[heinzboehmer]

I appreciate the detailed response actually! Good thoughts and info. Yeah the 996 kits seem to be getting harder to find for a good price. I got a black set locally to rebuild last year so already running them. Selling the ZCP stockers almost paid for the kit.

I think that the backing plates can be mangled and hacked off fully if I'm not mistaken without removing the hubs, but not 100% on that. I asked in the dumb question thread and I think someone said they can be.

Looking forward to your heat gun results. I should do that too but am kind of leaning toward just cutting the plates off and sending it. This will be my first year with race pads too (DS1.11) so that might help. The reason it was in my mind at all is that the Textars only lasted ~2 events .. no/minimal fade or anything but not really designed to be a track pad.

Yeah you could cut the shield off, but if you want to reinstall, you'd have to buy a new one and take the hub off still.

Curious to see the temp results as well. Did some napkin math and the max amount of air that can flow through each brake duct opening is ~5000 L/min at 60 mph. That's just considering the opening size, so no consideration for bends in the lines or pressure decreases because of the front bumper or vortices inside the plastic ducts or head/tailwinds. Assuming all that accounts to a 99% reduction in flow, that would still mean 50 L/min at 60 mph. I'm actually slightly concerned that I'll be overcooling the brakes, but maybe I'm overestimating how much air can cool steel rotors. I've seen lighter cars run bigger ducts at the track and be fine, so I think I'll be okay too. I'll be running PFC-11s and they seem to be happiest between 200C and 450C, so as long as I can keep them in that range, I'll be good.

Anyway, will update with results once I have them. Might also do some highway testing since the track day is still far away and the ducts will probably be ready by the weekend. That should at least give me a ballpark figure for temp reductions.

[heinzboehmer]

Making some good progress this week (and being great about updating here too!)

Decided to go with CAD for the passenger's side brake duct:



Bolted the piece of cardboard the the hub I had already done using the two backing plate 10 mm bolts, then traced the everything out. Did some cutting and then bolted it on to the passenger's side. I also made a similar template for the aluminum flange.



Traced, cut, drilled, riveted and cleaned things up a bit:



This side went muuch faster because of the template. Took about an hour from when I started unbolting things to when everything was back together. I also managed to stay within the lines with the dremel this time. Looks much cleaner than the driver's side.

Again, checking clearance and positioning:




As expected, the flange looks much nicer on this side too because I was able to do just one bend. Now I just need to cut some holes in the belly pan and this project will be complete.

Also got my IR thermometer in today. When looking for one, I quickly realized that I wasn't going to be able to get a cheap amazon special tool that would measure temps as high as those seen by brakes on track. So I looked around and settled on the Fluke 62 MAX Plus. Reads up to 650 C, so should be good.

However, I wasn't exactly excited about spending the same amount of money that I spent on all the materials for the ducts on just this one thing. So I went on eBay and found one that wasn't working listed for $40. The description said that the battery leaked and caused it to stop working. Seller also told me that they had opened it up and tried cleaning it, but no luck. I expected the leak to have caused a short and I would need to repair a trace or replace a blown diode or something, but it was much better than that.

Here's the thermometer after I took it apart:






Hmm, I thought it had been cleaned? Negative spring clip also had some oxidation on it.

30 seconds with isopropyl alcohol took care of the brown crud around the positive wire and another 30 seconds with some fine steel wool took care of the oxidation on the negative clip. I also decided to reflow the solder joint that was previously covered in crud because why not.



Tested it and it worked without an issue.

The repair was so quick and easy that I decided to make it look nice too. Scrubbed the case until it looked new and removed all stickers and sharpie marks added by the previous owner. Then I wet sanded and polished the plastic window above the display. Thing looks pretty much brand new now!





$40 and ~1 hour of my time well spent.

I also removed the sticker from that calibration place after taking the pics. Supposedly overdue for calibration, but I'm not sure I trust that. I can't find a calibration interval on Fluke's website and the readings seem fine to me after pointing it at random things around the house. Meh, I'll probably just point it at more things until I convince myself that it's still calibrated lol.

[heinzboehmer]

Finished up the ducts.

Pic of the backing plate flange template, for future reference:



Testing fitment:








The hoses look a bit more stretched in the pics than they really are. There is still a lot of play in them at full lock.

Also, here's some pics of how the inlets look with the plastic ducts on the car. Didn't have the block off plates on yet, but I did manage to find them, so no need to go hunting for a pair that someone no longer wants.




I then cut some holes into the belly pan and routed the hoses through there. I initially wanted to design some sort of quick release mechanism, so that the belly pan was easy to take off with the hoses on. However, I won't be running these unless the car is at the track, so I think I can deal with feeding the hose through the hole. Not really hard to do at all anyway.




I ziptied the hoses to the sway bar to try to keep them in place, but I don't think that's even necessary. Hoses are very rigid and there's a ton more clearance with the car on the ground, as the sway bar moves out of the way. I'll probably still add zip ties just to make sure I don't shred them against the pavement or something.

I did also take the car out over the weekend to see if I could gather any highway data, but unfortunately, I did not see a temp change with the inlets blocked off vs open. I was hoping for at least a few degrees difference, but I guess the brakes are sufficiently cooled on the highway anyway. Guess we'll have to wait and see how they do on the track.

[heinzboehmer]

Did a few other things too.

Friend wanted a pic of the quickfits, so I put them on real quick. Posting the pics here too because why not. Really happy with how simple these are to install.




Then I swapped out the hood latch lever thing. Mine looked a bit old and was sticking, so new one went in. Was expecting this part to be stupid expensive, but the genuine BMW part was only about $35, so not bad.



Here's why it was sticking:



Quite a bit of wear on that plastic cam. Here's the new one with no wear for comparison:



And finally I started getting things ready for the new alternator. Removed the old one and cleaned the areas behind it that are normally inaccessible.

Before:



After:



Yeah, it's not perfect, but it was about as much as I was willing to destroy my fingers for something that is completely invisible most of the time.

[heinzboehmer]

Did a few more things before my next track day.

First, installed the new alternator. Unfortunately, it arrived damaged (probably happened during shipping) and was completely seized.




You can see that the paint mark on the bolt is not aligned. The two halves of the case got moved around and caused the seizing. I managed to get them realigned, but it made a weird noise when spun, so I didn't really trust that the bearings would be okay. FCP was great about it though. They sent out a replacement super fast and fortunately that one arrived with no issues.

Then I flushed brake fluid. I looked for a while but could not find my bleeder bottle (must have lent it to someone), so I had to come up with something.



Ah, perfect.

When I finished the flush, I noticed that there was some weeping around the rear left bleed screw. Fortunately, it seems like the screw itself was the cause, so I just swapped that out.



You can tell that the tapered part on the old one was really worn. There was also some weird white, chalk-like residue on it. I wonder if someone had tried to use valve lapping compound to try to get it to seal. The taper inside the caliper was completely fine though, so a new bleed screw was all it took.

I then installed some bronze caliper bushings to try and fix my pad taper at the track. Went with the ECS bushings (I know, I know) because I thought they were the best designed. I liked that these came with both an o ring and dust cap, so I decided to take the risk and try them.

Fortunately they ended up actually fitting. However, the diameters of all of them were slightly different, but I was able to play around with what bore I put them into to get a snug fit from all of them. Also, the tool for installing them did not fit. I had to cut down the nut so that it wouldn't hit the piston dust boot.

Some install pics:

[heinzboehmer]

Yesterday, I did a track day at Thunderhill 5 mi yesterday and tried out all my new parts/changes.

First, I switched from Hawk DTC-60 pads to PFC-11s and what a difference. They honestly feel pretty similar on track once up to temp, but the PFC pads are so much better everywhere else. They're much more confidence inspiring on the street (not street pad level, but the Hawks feel terrible when cold) and they produce much less dust. I think the Hawks produced as much dust just on the drive up as the PFCs did during the drive up (~150 mi), three 20 min track sessions and the drive back down.

Up next, the caliper bushings. I couldn't tell a difference in pedal feel on the street and I used different pads on track this time, so no clue if there was a feel difference there either, but I don't think so. I've also been lazy and haven't swapped pads yet, so will have to report back about the pad taper.

And finally, the brake ducts. I took some brake temp data to try and quantify how much they actually help. Since it was the 5 mi track, you can really only get 5-6 laps (depending on traffic) per session. I figured I was only going to be able to get 4 laps in since I would be losing time getting off the track and measuring temps, so I decided to do two laps with the ducts taped off, get off the track, measure temps, remove the tape and then go back on and do another two.

Here's the raw data, ambient temp was around 80F:




Because I didn't have enough laps to get everything fully up to temp, the brakes continued to heat up after I opened up the vents, so I also have some data with scaled duct temps.

I was originally planning on using the rear rotors as a control in case the brakes continued to get hotter in the third and fourth laps, but there's something going on with the data. I think I might have written down the temp for the RR rotor incorrectly. If that were 521.8F instead of 621.8F, the temperature trend would have been the same for the two rotors. Oh well, can't use that for a control.

If I instead use the calipers as a control, there was an average of 19% temp increase in the third and fourth laps. I do realize that the increase in caliper temp doesn't exactly represent the increase in rotor temp (because of rotor vents, heat transfer and retention in the fluid, etc.), so I decided to use a scaling factor that was in between the average of the caliper percent increase and the RL rotor percent increase, which is 14.249%.

Here's the scaled data:




Average of the percent change for the front rotors is right around 25%, which is awesome. I realize there's a lot of assumptions and scaling in this, but I tried to do as much as I could with the data that I took.

For completeness, the percent change without any scaling is 12%. Point is, the ducts actually work and I'm pretty happy with the results.

I might repeat the experiment next time I'm on a shorter track (I think Thunderhill 3 mi would be pretty much perfect). However, I'll probably do it over two sessions, so that the brakes have a chance to get fully up to temp. I'll just do it later in the day when the temps are stable.

And last, here's the only pic I took that day. Selfie during a red flag right after I had swapped cars with a friend:

[heinzboehmer]

Realized I never posted this up here. Asked sickfinga on maxbimmer about the production stats for my car and here they are:

215 - 2001-2006 BMW M3 Coupe (BL93) - NA painted in Topaz Blue Metallic (364) with Black Nappa Leather (0522/N5SW) interior were built for the US market. 127 manual, 88 SMG

17 were built for the Canadian market. 12 manual. 5 SMG

The most rare option in this car is the option S490A - Adjuster, backrest width. It was installed on 11,798 out of 26,202 cars.

[heinzboehmer]

Have been trying to lose some weight off of the car recently. I know I haven't done the big things (roof, seats, etc.), but I have way too many projects planned, so those will have to wait.

However, figured I would start to remove things I didn't need/use, as it's cheap and easy. Non-comprehensive list of what I've removed:

• Secondary air pump
• US spec knee protection by steering wheel and under dash
• Rear seat belts and head rests
• Rear floor mats
• Sound deadening below rear seats
• Child seat anchors
• Mobility kit
• Trunk tool holder
• Subwoofers

The last one is the most recent one I've done and probably the one I was most unsure of doing. I do listen to music all the time, but I don't listen to much bass-heavy stuff nor do I really care all that much about how my car's audio system sounds. I care about headphones and home setups, but the M3 is too noisy for me to be worrying about making it sound good. Better speakers are probably as far as I'll ever go, so I decided to remove the subs.

But of course I couldn't just do it without attempting to quantify the change. I improvised a frequency response setup using an app on my phone and playing a frequency sweep through the speakers. I know this is all measured through the shitty mics in my phone, but it's better than nothing (and I wasn't feeling like hauling my actual mics and audio equipment into the garage). The results follow. I did not change the radio's EQ settings between the two tests.

Stock:


No subs:


There is definitely a difference below 40 Hz, but it's nothing crazy. I messed around with the EQ a bit and tested with some of the music I'd usually play and I don't think I'll miss the subs. If I do, they're super easy to reinstall. I'm also pretty certain that upgraded speakers will be able to fill in the gap nicely. Might do bavsound speakers at some point soonish I do still have to get myself some Tesa tape, so that I can wrap the sub connector and tuck it away inside the rear deck. It's currently wedged in there, but I'm not confident that it won't break loose and start rattling.

All in all, I think the sub removal was worth it. Weighed in at 7.1 lbs and it's located decently high up and behind the rear axle (barely).

I also weighed everything I've removed so far and I'm currently right at 35 lbs. Not bad for just unbolting stuff.

[heinzboehmer]

I know I haven't done the big things (roof, seats, etc.), but I have way too many projects planned, so those will have to wait.

Speaking of planned projects.

Got my hands on these recently:


Finish on them is pretty bad, but the area around the pistons and dust boots looks pretty decent:


I'll be testing them later to make sure they hold pressure soon. If they do, I'll just paint them black (yes I know I'm boring when it comes to colors) and put them on the car. I'm pretty sure they'll be totally fine, but a rebuild is pretty simple and I can always do that later if I need to.

I also got an MK60 to swap into the car. No pics unfortunately, but I'll be documenting the swap so lots of pics will come later. I plan on replacing all the brake lines as it's not terribly hard to do and they're pretty cheap. Not particularly excited about the lines going behind the engine, but I'll manage. Currently waiting on parts to arrive to start that project.

[Tbonem3]

They look great! But throw the dampers away.

[heinzboehmer]

Thanks! Yeah dampers are going away. If I'm being honest, most of the reason why I got these calipers is for easier pad swaps, which the dampers kinda ruin.



Also, I've been thinking about when to do what. I still have track pads for my stock calipers and I just recently got those brass bushing things, so it feels like a waste to go straight to the 996 calipers. It does mean I'll have to do two fluid changes in quick succession, but those are pretty quick with the power bleeder.

Current plan is to do the MK60 swap first and leave stock calipers on until I wear down my pads. Then I'll swap in the 996 calipers. This way I also get a bit more time to refinish the calipers (i.e. try it myself, mess it up and then take it to someone who knows what they're doing).