heinzboehmer's 2002 Topaz 6MT Coupe

[Obioban]

Nice.

[Bry5on]

the rectangular bracket seems to be missing the bend line-- got a location/bend angle for that?

Since the SS tolerances aren’t very good, and it’s usable on all exhaust pipe diameters/dimensions, it’s bend-to-fit. Super easy to bend.

Oh about the hardware. I found that you can install the brace without dropping any section of the exhaust if you use hex head screws and an open ended wrench for the transmission attachment. Not sure how you'd get the bit for the cap head screws in with section 1 in place.

I have some short allen tools that did the job for me, but yeah I think you’re right that hex head might be easier.

[heinzboehmer]

Not off hand but I believe I used M6 x 16 or 20mm cap head screws, washer and nuts. You’ll need 4 fasteners, 2 nuts, 2 or 4 washers to suit. For the bigger SSv1 pipes, this is the clamp we’ve been using: EVIL ENERGY 2.5 Inch Exhaust... https://www.amazon.com/dp/B08HW8ZF4Z...p_mob_ap_share

Oh about the hardware. I found that you can install the brace without dropping any section of the exhaust if you use hex head screws and an open ended wrench for the transmission attachment. Not sure how you'd get the bit for the cap head screws in with section 1 in place.

[heinzboehmer]

Exciting about the ducts! Especially because, if these work well... maybe a CSL bumper can finally be in my future :P

I mean, I haven't done any actual science on them. Mostly just "brakes feel good" and "nice, these pads aren't wearing as fast as I expected", but real science coming soon!

I installed the current set of girodisc dust boots before a long 3 mi Thunderhill day and cooked them without any sort of cooling. Have ordered a brand new set of girodisc dust boots and will be installing them before doing the same track day (as in, same layout, same duration and similar temps) in September. Pads will have less heat capacity because more wear, but the rest of the setup will be exactly the same. If the dust boots survive, then that'll be a pretty good indication that the scoops are doing their job.

Here ya go! Attached. You’ll just need a relevant exhaust clamp for your pipes and some fasteners.

edit: the brace parts on my car and Heinz’s car are made from 304 SS - spacer is .125” and the two brace parts are .074” thick.

The very scientific leaf blower test showed that the ducts may even work better without open bumper brake ducts. We’d need someone to A/B test that though .. maybe Heinz can break out the tape on his next track/test day.

Oh right, forgot to mention that my stock brake ducts are blocked with two of the solid wheel well liner covers. If I have some sessions left over after getting the data I need, I'll do some A/B testing with the covers on/off.

Also, uh, spacer? I think I forgot to install that...

It should be somewhere on my workbench, I'll go looking for it. I'm guessing it goes between the bracket attached to the exhaust and the bracket attached to the transmission?

[Obioban]

Here ya go! Attached. You’ll just need a relevant exhaust clamp for your pipes and some fasteners.

edit: the brace parts on my car and Heinz’s car are made from 304 SS - spacer is .125” and the two brace parts are .074” thick.

The very scientific leaf blower test showed that the ducts may even work better without open bumper brake ducts. We’d need someone to A/B test that though .. maybe Heinz can break out the tape on his next track/test day.

the rectangular bracket seems to be missing the bend line-- got a location/bend angle for that?

[Bry5on]

Got a McMaster link for the hardware/clamp? We could make this an easy to order kit, between sendcutsend and McMaster.

Not off hand but I believe I used M8 x 16 or 20mm cap head screws, washer and nuts. You’ll need 4 fasteners, 2 nuts, 2 or 4 washers to suit. For the bigger SSv1 pipes, this is the clamp we’ve been using: EVIL ENERGY 2.5 Inch Exhaust... https://www.amazon.com/dp/B08HW8ZF4Z...p_mob_ap_share

[Obioban]

Here ya go! Attached. You’ll just need a relevant exhaust clamp for your pipes and some fasteners.

edit: the brace parts on my car and Heinz’s car are made from 304 SS - spacer is .125” and the two brace parts are .074” thick.

The very scientific leaf blower test showed that the ducts may even work better without open bumper brake ducts. We’d need someone to A/B test that though .. maybe Heinz can break out the tape on his next track/test day.

Got a McMaster link for the hardware/clamp? We could make this an easy to order kit, between sendcutsend and McMaster.

[Bry5on]

Sooooo where can we get the CAD files for that exhaust brace?

Exciting about the ducts! Especially because, if these work well... maybe a CSL bumper can finally be in my future :P

Here ya go! Attached. You’ll just need a relevant exhaust clamp for your pipes and some fasteners.

edit: the brace parts on my car and Heinz’s car are made from 304 SS - spacer is .125” and the two brace parts are .074” thick.

The very scientific leaf blower test showed that the ducts may even work better without open bumper brake ducts. We’d need someone to A/B test that though .. maybe Heinz can break out the tape on his next track/test day.

[Obioban]

Sooooo where can we get the CAD files for that exhaust brace?

Exciting about the ducts! Especially because, if these work well... maybe a CSL bumper can finally be in my future :P

[Ubaderb]

Holy crap, I've got this same noise and couldn't figure out where it was coming from, lol. This has to be it.

I really thought it was the nature of the M3. I need to try this now for sure.

[oceansize]

I forget, are you on stock headers/section 1? It's nowhere nearly as pronounced with those as it is with the supersprint stuff, but the transmission brace should still make a difference. Wonder why BMW included it on the non-Ms but not on the M3...

Stock headers and RE Rasp and the noise is most pronounced in the RPM range you quoted, plus its a hard noise to describe but high frequency vibrations pretty much sums it up.

[heinzboehmer]

Holy crap, I've got this same noise and couldn't figure out where it was coming from, lol. This has to be it.

I forget, are you on stock headers/section 1? It's nowhere nearly as pronounced with those as it is with the supersprint stuff, but the transmission brace should still make a difference. Wonder why BMW included it on the non-Ms but not on the M3...

Hell yeah on the scoop test! If you’re going to modify, you should tweak the brake shield side as that little corner at the top of the main duct really is there to straighten the flow out as much as possible. If you do decide to bring it inward, you might consider adding some vanes to help the flow follow the curve and arrive basically straight into the brake shield duct. The main duct is there to direct the flow and the little duct is there to contain/compress/guide it into the rotor center.

That makes sense. Was trying to avoid reprinting those so I didn't have to dip into my stash of PET CF, but seems worth it. Will probably start by trimming the existing ones and then decide if I want to tweak and reprint.

[Bry5on]

Hell yeah on the scoop test! If you’re going to modify, you should tweak the brake shield side as that little corner at the top of the main duct really is there to straighten the flow out as much as possible. If you do decide to bring it inward, you might consider adding some vanes to help the flow follow the curve and arrive basically straight into the brake shield duct. The main duct is there to direct the flow and the little duct is there to contain/compress/guide it into the rotor center.

[oceansize]

Couple of updates.

First up, the transmission exhaust brace is great. Greatly dampens the tinny, high frequency vibrations at about 2.5-2.7k rpm. They're not eliminated, but rather the brace seems to shift their frequency down quite a bit. It's no longer a rattly metallic noise and is now more reminiscent of the typical low frequency engine NVH present in most ICE cars.

Holy crap, I've got this same noise and couldn't figure out where it was coming from, lol. This has to be it.

[heinzboehmer]

Couple of updates.

First up, the transmission exhaust brace is great. Greatly dampens the tinny, high frequency vibrations at about 2.5-2.7k rpm. They're not eliminated, but rather the brace seems to shift their frequency down quite a bit. It's no longer a rattly metallic noise and is now more reminiscent of the typical low frequency engine NVH present in most ICE cars.

And now onto track stuff. Shockingly, PET CF did not survive being in direct contact with the caliper at a brake heavy track. I didn't even bother mounting the duct after seeing how distorted the small mounting tab was getting. Unfortunately, I stepped on the piece and broke it when installing all the street stuff back on the car, but you can kinda still see the distortion:



Tried to make it more obvious with some highlighting. Most obvious issues are how much the "legs" started to pull up away from the rotor face (red) and how much the mounting tab that the caliper pin goes through bent back (green):



Also, early in the day, I took a line through the corkscrew that was way too far left and ended up basically jumping the car off the top. Full droop + slight right turn of the front wheels resulted in the mounting features (and some others) getting crunched off the control arm part of the left brake scoop:



Picture from Bryson's car to show how it's supposed to look:



Tightened up the zip ties and got through the day without much issue. Gonna need to print a new scoop though:



I'll likely try to fix this slight contact between the two scoop parts before reprinting. Seems like bringing the outer edge in a bit will do it.

Good news is that the dust shield part of the scoop held up perfectly. I printed that one out of PET CF for the thermal properties and it still looks just like it did when it came out of the printer.

But all in all, the scoops worked great! Had zero fade issues, did not find any newly failed dust boots and the pads look almost exactly the same as they did before the track day. I completely forgot to take measurements before, but they're currently at 13 mm thickness (including backing plate which is about 5 mm). Product name (0776.08.17.44) says they're 17 mm thick with backing pad, so there's still about 2/3 left after 3 days (~8 hours) of track time. Not bad.

Also, I did say I would be taking brake temp measurements to have some data, but for some reason the turn 10 paddock entry was closed. This meant that the brakes had cooled significantly by the time I was back in the paddock and any data would have been meaningless. I think I'll try to make the next track day a real science day. Will swap in new dust boots, install the tweaked scoops and take temp measurements throughout the day.