heinzboehmer's 2002 Topaz 6MT Coupe

[heinzboehmer]

Purple!



Surface temps ended up settling at around 60C. 07333 Datasheet.pdf says that you should cure the adhesive for an hour at 60C, so I did that. I'm assuming the adhesive further in will have cured less, but I'm still a couple days away from having the car back on the road, so it should have enough time to fully cure.

I do have to say that 07333 is awesome to work with. Working time is super long and it's fairly viscous, so it doesn't make a mess. Curing can also be accelerated easily, which is always appreciated.

[heinzboehmer]

This should actually work:



Started with the last bit of prep. Masked the bottom of the aluminum piece so I wouldn't get adhesive on the bearing surface. Did the same to the top of the blower motor housing:



No pictures, but I removed the masking tape on the chassis and found no surface rust, nice. Still give it a super quick sand with 220, then the acetone + IPA wipes. Same with the aluminum piece.

Then I wet both surfaces out. Doing that on the chassis was not easy. Had to use a brush and a mirror, but I got it done:



Did the same on the aluminum piece and then did my best to apply an S-ish shaped bead. Again, decently hard to do with the aluminum piece in one hand and the giant applicator in the other:



Grabbed that piece + the greased up bolt beneath it and got it situated in place. Bolt got torqued and any adhesive that squeezed out got cleaned up.

Then blower motor housing and wedges got put in place:



And finally, sketchy space heater was added to help the adhesive cure:



Initial temp readings aren't super high, surfaces were at around 30C with the heater going. 3M says to not exceed 80C for more than half an hour, so should be totally fine. Will see what the temps get to in a couple hours.

[heinzboehmer]

Documented the blower motor stuff in much greater detail here: https://nam3forum.com/forums/forum/m...or-replacement

I feel like I've finally developed a decent approach for that job and I just know that I would have forgotten it within days had I not written it down. Also serves as proof that blower motor replacement is possible with my piece permanently bonded to the chassis!


I did also do a few more things as pre-bonding prep.

Applying the adhesive with the blower motor housing out is gonna be much easier. However, no housing means I have nothing to wedge against and would have to leave the flat section of the piece just kinda floating in midair. Decided to strip down the right side flap assembly so that it's very easy to install (the easier the better cause I'll be rushing when it comes time to apply the adhesive), but still has enough structure to wedge against:



Linkage also came out as it kinda gets in the way of the quick install. Actuator rod needs to be popped out (downwards), back crank tab needs to be released and then the entire linkage falls out:





Plan is to have the plastic flap frame hanging out to the side while I do all the adhesive stuff, like so:



Then hold the aluminum piece in with the front bolt and rotate the flap frame into position. With it in place, I can add the wedges and wait for it to cure:




You might notice there's a bunch of tape over the metal surface I prepped before the adhesive incident. Did this to minimize surface rust that might form while I wait for the replacement adhesive to arrive (thanks again for the tip Bryson!). We'll see how well this worked soon.

Lastly, I swung by tlow98's place and used his big ass vise to press the studs into the E86 brace attachment point:



I printed those press tools so that I wouldn't mar the aluminum and they worked great!





Printed with 100% infill, as I figured this was a good place to go overkill. They honestly still look amazing, I bet I could have made them way less beefy and it would have been fine.

[smee123]

Surface prep is king with 3m structural adhesive just like the importance on the loctite and their activators. Maybe trivial on an oil pan drain time sert l, but on anything that experiences any pulling loads or any inherent vibrations, I cant stress it enough!!

[heinzboehmer]

Maybe I missed it...any reason you chose 07333 vs 08115 (panel bond)?

Based on 3Ms own recommendation

07333 is for structural stuff, 08115 is for non structural body panels:

3M Panel Bonding Adhesive Designed to meet specific strength requirements for outer
sheet metal panel replacement; panel bonding adhesive is
typically used in conjunction with welding, rivets or hem
flange joints. Panel bonding adhesives do not offer the same
level of impact resistance as impact resistant structural
adhesives and should not be used for structural repairs unless
recommended by the specific automotive manufacturer.

3M Impact Resistant Structural Adhesive
Designed to meet specific strength requirements for parts
such as frame rails, strut towers, sills, pillars and other
members where impact resistance is important. This type of
adhesive possesses a much greater ability than traditional
bonding adhesives to absorb and manage energy under a
variety of forces, especially peel and cleavage stresses in
extreme temperature conditions. Typically
impact resistant structural adhesive is used in conjunction
with rivets, spot welds or mechanical fasteners.

Document where that quote came from is attached.

[bigjae46]

Oooohhhh! Now I understand how it fits. I've looked at the part and never understood how it would mount. lol

Maybe I missed it...any reason you chose 07333 vs 08115 (panel bond)?

[heinzboehmer]

Bonding time!

Started by clearing everything I could out of my way. This essentially amounted to airbox, blower motor, blower motor housing, engine beauty cover, wiper linkage (just moved that out of the way) and windshield cowl. I also covered up any openings that metal shavings could fall into:



Removing the blower motor absolutely sucked. It's like there was no effort dedicated to serviceability of that assembly when it was being designed. I did do it all with the windshield mount roughly in place, just to make sure that it was still doable. Fortunately, it didn't get in the way at all.

Gonna do my future self a favor and document the best way I found to remove the blower motor:

1. Remove the front cover. One screw up top and two clips at the bottom. I still don't know how BMW expects you to get that piece past the firewall, but with enough swearing and bending, it'll come out.



2. Remove the passenger side cover. Undo the three screws holding it in (circled) and remove the two linkages attached to it. Take note of how the linkage for the secondary flap is clocked so that it goes back together in the same way.



3. Unhook the blower motor (no need to undo the four screws of the mount) and wiggle it out through the passenger side. Be careful to not catch the vanes on the front cover clips and damage them. Also, the engine harness has to be moved out of the way for it to clear.



Anyway, back to prep.

Started by test fitting the aluminum piece for the final time and then tracing its outline on the chassis:



Then, time to sand. Started manually, but very quickly gave up. Dremel made fairly quick work of it:



I followed that up by sanding with 220 grit, then a bunch of acetone wipes to get rid of all debris and finally an IPA wipe. Adhesive next.

And then this happened:



Bad picture, but one side of the adhesive cartridge blew out the back and leaked everything that was in there.

Admittedly, this was entirely my fault. Turns out the applicator I have does not fit the 07333 cartridge. I didn't realize this until today, so I decided to fix the issue with some zip ties. It worked great until it caused one of the cartridge pistons to spin inside the cylinder and cause the mess above.

Lesson learned. Next time I need to jerry rig an applicator, I'll throw some sockets into the cartridge cylinders to spread the load.

Replacement adhesive (and appropriate applicator) ordered. Will give this another shot in a few days....

[Bry5on]

That’s weird… m3 strut brace fit under my M3 wagon hood without any cutting/trimming 🤔

Mine cleared statically but contacted (just barely) dynamically. Good times!

[heinzboehmer]

Wow there really is a lot more clearance under the M3 hood. I had to cut my non-m hood a little just to clear the factory strut brace.

Mask off the area well before sanding, it’ll be worth it. And don’t skimp on adhesive - wet each surface first then S shaped or fishbone shaped beads to allow air to flow out while you install will give you the best chance of a good bond with fewest air pockets. I always prep with acetone then one directional IPA wipes right before bonding as well.

Good luck!

Thanks! Will do that.

Airbox is just loosely set in place in those pictures. Both that and the blower motor are coming out for the install. Gotta make sure I have the most access possible.

Also got myself a cheapo space heater that I'll throw in there to help with the curing.

[Obioban]

Wow there really is a lot more clearance under the M3 hood. I had to cut my non-m hood a little just to clear the factory strut brace.

Mask off the area well before sanding, it’ll be worth it. And don’t skimp on adhesive - wet each surface first then S shaped or fishbone shaped beads to allow air to flow out while you install will give you the best chance of a good bond with fewest air pockets. I always prep with acetone then one directional IPA wipes right before bonding as well.

Good luck!

That’s weird… m3 strut brace fit under my M3 wagon hood without any cutting/trimming 🤔

[Bry5on]

Wow there really is a lot more clearance under the M3 hood. I had to cut my non-m hood a little just to clear the factory strut brace.

Mask off the area well before sanding, it’ll be worth it. And don’t skimp on adhesive - wet each surface first then S shaped or fishbone shaped beads to allow air to flow out while you install will give you the best chance of a good bond with fewest air pockets. I always prep with acetone then one directional IPA wipes right before bonding as well.

Good luck!

[heinzboehmer]

Timeserts installed and fitment of hardware validated with 3D printed fasteners:




Looking good!

I need to temporarily swap back to the stock airbox this week for, uh, no reason. I'll likely bond this in when everything is out.

Okay, I lied a bit with this post. Timeserts were dry fitted, not actually installed. Couple notes from the real install:

1. By complete coincidence, smee123 made me aware of the fact that Loctite threadlocker is only designed to work on what they call "active" metals. Important thing to know is that if you're using threadlocker on aluminum (or other "inactive" metals), you should also be using their activator, so I did.
2. The clearances on the back hole are tight. I designed it so that a bottoming tap would be needed to cut the thread for the insert. The tap in the timesert kit seems to be a custom diameter, but an M10x1.25 tap is very close and cuts those last few threads just fine.

Piece is actually ready for install now, will be doing the bonding tomorrow. Quick picture of all the hardware needed:



I also modeled some wedges to hold the piece against the chassis while the adhesive cures. Currently being printed:



Moving on to the the strut tower brackets...

One concern I have is that the stock pieces will be spaced up slightly when all is said and done. How much displacement depends on the amount of material I machine off. If I use the 3.75 mm value, that means the brackets and bar will end up 1 mm taller. Additionally, the replacement studs will stick up 2.25 mm more than stock, so max height change will be +3.25 mm.

This is a small amount, but I still wanted to be sure that it wouldn't cause an issue. So I grabbed some modeling clay and squished it in between the hood and potential contact points:

Test setups:




Results:





Honestly, wow. That's way, way more clearance than I was expecting. Not even gonna bother measuring, my stuff will fit just fine

[heinzboehmer]

Wow, just seeing all this wonderfull stuff, great work!

I am very interested in the CSL ducting, what a great idea. Would there be the possibility of having one that let's some air past for brake cooling?
Maybe I could just get this one and cut out a small section in for that purpose.

I would imagine the IAT would see lower temps as a result, very cool. The strut brace project is cool as hell too, I may have to get into this stuff.

You need to talk to Bry5on about the duct! No need to integrate brake cooling in the duct if you also install his Porsche-style brake cooling scoops.

Let me know if you're ever over here! Welcome to drive the car and feel all the bracing for yourself.

[Cubieman]

Wow, just seeing all this wonderfull stuff, great work!

I am very interested in the CSL ducting, what a great idea. Would there be the possibility of having one that let's some air past for brake cooling?
Maybe I could just get this one and cut out a small section in for that purpose.

I would imagine the IAT would see lower temps as a result, very cool. The strut brace project is cool as hell too, I may have to get into this stuff.

[heinzboehmer]

Where do the E86 strut bars boit to? One of the existing press in studs?

I still have to figure out where/how I want those to land, so I haven't modeled the studs in yet. But they'll go somewhere in the protruding yellow surface. I printed up a prototype, so I'll do a test fit and post up some pictures in the coming days.

You can eliminate the S shaped wall because you’ve otherwise boxed the shape in by attaching it to the aluminum strut brace. Pretty sure that little wall will not have much contribution to strength and you can avoid weakening the material by eliminating welds. You might wind up just redesigning strut tower bases entirely when this is said and done though

Oh good call! Completely overlooked the weakening of the material. Will incorporate that suggestion into the design.

And yes, I'm doing my best to keep the stock look, but there is a decent chance that I abandon that entirely and just redesign the entire thing.

If you’re doing new bases, you could also add fastener locations on the fender side for future gusseting to the corners of the windshield too. You know, for a future project..

I do love me some scope creep!