heinzboehmer's 2002 Topaz 6MT Coupe

[Obioban]

Awesome! Chassis stiffness is the second best mod after lightness

... I am surprised you're thinking stiffer springs as a result. IIRC conventional wisdom is that a stiff chassis lets you get away with softer springs, all else equal (and soft springs = more grip).

[discoelk]

Strut bar is really cool. Are you planning on using the OEM cabin filter?

[Bry5on]

Awesome! Chassis stiffness is the second best mod after lightness

... I am surprised you're thinking stiffer springs as a result. IIRC conventional wisdom is that a stiff chassis lets you get away with softer springs, all else equal (and soft springs = more grip).

I had a similar conclusion to Heinz. It feels like the car ‘wants’ more spring now. It’s definitely working the springs harder and you can feel it. It’s also better damped. In mine, I’m able to push it to its g-limit much more consistently now and since I’m on stock springs (and he’s a little lowered/stiffer) we’re probably both using the bump stops too regularly in hard corners.

The carbon roof is worth a 4% body roll reduction on a 3400lb e46, which is roughly an equivalent change to an 8% stiffer spring. In conclusion, I think carbon roofs are the correct next steps.

[Obioban]

I had a similar conclusion to Heinz. It feels like the car ‘wants’ more spring now. It’s definitely working the springs harder and you can feel it. It’s also better damped. In mine, I’m able to push it to its g-limit much more consistently now and since I’m on stock springs (and he’s a little lowered/stiffer) we’re probably both using the bump stops too regularly in hard corners.

The carbon roof is worth a 4% body roll reduction on a 3400lb e46, which is roughly an equivalent change to an 8% stiffer spring. In conclusion, I think carbon roofs are the correct next steps.

Didn't realize your (plural) suspensions were so stock. Since I'm 19 years into various aftermarket suspensions, I sort of consider them... stock? standard? not sure what the word is, but stock didn't occur to me as a possibility 🤣

... Carbon roof was my least favorite DIY project I've ever done.

[Bry5on]

Didn't realize your (plural) suspensions were so stock. Since I'm 19 years into various aftermarket suspensions, I sort of consider them... stock? standard? not sure what the word is, but stock didn't occur to me as a possibility 🤣

... Carbon roof was my least favorite DIY project I've ever done.

Honestly, the stock suspension feels pretty firm after all the chassis stiffening. Pretty wild. But the car can finally accept more spring rate and still control the body, which I didn’t think it did a great job at before with aftermarket/stiffer springs personally. I actually went from aftermarket -> stock!

[Obioban]

Honestly, the stock suspension feels pretty firm after all the chassis stiffening. Pretty wild. But the car can finally accept more spring rate and still control the body, which I didn’t think it did a great job at before with aftermarket/stiffer springs personally. I actually went from aftermarket -> stock!

My aftermarket setups have gotten softer and higher every time I've changed setups!

[heinzboehmer]

Strut bar is really cool. Are you planning on using the OEM cabin filter?

Posted quick mockups of where the plastic pieces interfere with the braces some posts back. In short, I'm likely going to need to remake both the cabin air filter housing and the firewall plug. I thought I might be able to cut some holes in them and bond in covers, but they need more modifications than what I originally thought.

I would like to keep the stock filter. Looks like I can get away with tilting it up a bit, but I have yet to get to that part of the design. Currently bogged down recreating the firewall plug, whose geometry is much more complicated than I expected.

Didn't realize your (plural) suspensions were so stock. Since I'm 19 years into various aftermarket suspensions, I sort of consider them... stock? standard? not sure what the word is, but stock didn't occur to me as a possibility 🤣

... Carbon roof was my least favorite DIY project I've ever done.

Yeah I'm on the Eibach spring kit. If I didn't need the slight drop to get my rear camber + toe in the range I want, then I'd still be at stock ride height and stiffness

One day I'll tackle that project (with custom RTAB brackets or similar) and go back to stock ride height.

Not at all looking forward to the carbon roof install. I should have asked 3M if the 07333 was okay to use with CF when I called a couple days ago. Would at least make that part of the project much nicer.

[Obioban]

Even scarier now the the stock windshield is NLA. Don't screw up removing that!

[heinzboehmer]

Tool arrived for the last little detail on the mechanical side of the braces:



BMW spec for the nuts is 41 Nm, so a regular box wrench is more than adequate for doing them up, but using a torque wrench makes my brain happy.

Adapter measures 51 mm from center of box end to center of drive end and torque wrench measures 330 mm from center of drive end to middle of handle. Quick bit of math tells me torque wrench needs to be set to 35.5 Nm (26 lb ft) to achieve 41 Nm at the fastener with the adapter completely parallel to the torque wrench.

Looks like I got my tool clearance measurements right cause I can torque both nuts no problem



Side note: this is probably the first time I've ever found a use for the center position on the torque wrench ratchet mechanism. This position doesn't let the wrench ratchet, so it ensures the adapter stays parallel. Pretty nice.

Also, it's been getting warmer and audio system is back to overheating and shutting off when parked in the sun

There's a heatsink inside the head unit with thermal paste that looked just as bad as the stuff in the HK amp, so I serviced it:





(yeah I suck at applying thermal paste, leave me alone)

The issue seems to only happen when the car is parked in direct sun, so it sounds to me like the HK amp is a more likely culprit. I honestly doubt this is going to fix it, but it was super quick, so worth a shot. I might be looking into replacing that HK amp soon though.

Also, disassembling the head unit reminded me of this awesome gift that the previous owner forgot in there when he sold the car to me:



It's mostly 70s and 80s stuff, it's great. This is full track list, just for fun:

1. You Should Be Dancing - Bee Gees
2. Overkill - Men At Work
3. Refugee - Tom Petty & The Heartbreakers
4. I Don't Want To Live Without You - Foreigner
5. No. 1 - Chaz Jankel
6. Everything She Wants - Wham
7. Promises, Promises - Naked Eyes
8. Cold As Ice - Foreigner
9. This Must Be the Place (Naive Melody) - Talking Heads
10. Gypsy - Fleetwood Mac
11. Tiny Dancer - Elton John
12. Careless Whisper - George Michael
13. I Guess That's Why They Call It the Blues - Elton John
14. Sister Christian - Night Ranger
15. Ai No Corrida - Chas Jankel

CD is back in the head unit, waiting to be rediscovered sometime in the future

[Bry5on]

Hell yeah. I’d also add 5Nm or something to account for that cut thread running torque issue above if those are the same fasteners, you know, just to be pedantic. You’ll be fine either way really.

[heinzboehmer]

Re(re)wired the MAP and IAT sensor connectors:



To get the boots on, I lubricated a deep 10 mm socket with some krytox and slipped the boots over that first. Worked like a charm:




Some crimping later and done:




Very happy with the quality of this new MAP connector. Definitely nicer than what was on there before.

Unfortunately, not at all happy with the quality of the ECS kit I ordered for the IAT connector. I thought it was composed of genuine parts, but that is most definitely not the case. Should have looked more closely.

Had BMW parts on there before and quality was way better. To boot, the ECS crimp terminals are bigger than the BMW ones, so I wasn't able to reuse the old stuff.

I know this is insane, but I'm gonna order some genuine crimp terminals (12521427612) with my next FCP order and swap back to the old connector. Will do that off camera cause this work is getting repetitive and boring.

[Ramage]

I know this is insane, but I'm gonna order some genuine crimp terminals (12521427612) with my next FCP order and swap back to the old connector. Will do that off camera cause this work is getting repetitive and boring.

This is not insane at all, it is these little details that my ADHD fixates on and must be fixed so I can find something else to fixate on.

The 10mm deep socket over the boots is a great idea, I ended up using solid core wire on my IAT because for the life of me I could not get 2 stupid wires inside of (12517508831) to make the 90° turn in (12521732635). I am going to give this a shot as solid core wire is not a great idea.

Cheers!

[Ramage]

Heard my airbox start rattling again so went and checked on it. Turns out the bushings I printed rode up on the posts so much that they were no longer doing their job:



This is what they looked like (well, two of them, the third is lost forever in the engine bay abyss):




They've certainly taken some damage! This might be one of those "replace at every oil change" things. Oh well, they require 0.5 g of material to print and can be installed in 5 min, so not super worried about the short replacement interval.

To combat the riding up issue I created a V2. Part is the same as before, but with a base, which should keep them in place:



I made the base the same thickness as the grey "weatherstripping" on the unfiltered section and notched that out for clearance:



Everything installed:




Let's see how long these last!

This looks like a solid fix.

I’ve added more foam to the non-filter section, which has stopped the rattle. However, I’m concerned it will return since the engine’s heat tends to degrade the foam pretty quickly. I think the rattling has also somewhat damaged the clear gel on the tabs the screws for the unfiltered section pass through as I can clearly see the gel is fogging around the screws.

I need to reach out to Karbonius as my airbox was new in May of this year and I am kind of bummed that it is not holding up.

[heinzboehmer]

This is not insane at all, it is these little details that my ADHD fixates on and must be fixed so I can find something else to fixate on.

The 10mm deep socket over the boots is a great idea, I ended up using solid core wire on my IAT because for the life of me I could not get 2 stupid wires inside of (12517508831) to make the 90° turn in (12521732635). I am going to give this a shot as solid core wire is not a great idea.

Cheers!

Oh I forgot to mention, I ended up cutting the last little bit of the boot off as it was too small to stretch over the socket. You might be able to get away with leaving it if you use the BMW conduit and a much smaller socket. The OD of the conduit I had laying around is larger than the BMW stuff, so had to resort to chopping.

This looks like a solid fix.

I’ve added more foam to the non-filter section, which has stopped the rattle. However, I’m concerned it will return since the engine’s heat tends to degrade the foam pretty quickly. I think the rattling has also somewhat damaged the clear gel on the tabs the screws for the unfiltered section pass through as I can clearly see the gel is fogging around the screws.

I need to reach out to Karbonius as my airbox was new in May of this year and I am kind of bummed that it is not holding up.

I tried doubling up on the foam before these bushings and it didn't last long. So far the bushings have been great.

Are you using the hardware Karbonius sends out with the airbox? The epoxy around the screw holes on mine was also starting to get damaged with the original hardware, but I switched over to bolts with a washer underneath (like on a real CSL) and the issue has gone away.

[Ramage]

Are you using the hardware Karbonius sends out with the airbox? The epoxy around the screw holes on mine was also starting to get damaged with the original hardware, but I switched over to bolts with a washer underneath (like on a real CSL) and the issue has gone away.

I'm still using the Karbonius hardware and noticed the screws and washers you're using. I'm wondering if Karbonius updated their design over time, as the pegs holding the non-filtered side of my airbox seem different. I'll snap some photos to confirm and share them to tie up loose ends.

I'm considering switching to countersunk washers and screws for a sleeker look and better load distribution on the tabs. Do you happen to remember the outer diameter of the washers you're using?

Yep, I can confirm I see how ridiculous my last question is after reading it out loud

You can only pick one thing to remember:

A: OD of 4 washers used on my car a few years ago.
B: Cherished childhood memory.

Mad respect for all the stuff you have done, these journals are both awesome and fear inducing (mostly for my wallet).