heinzboehmer's 2002 Topaz 6MT Coupe

[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]

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....

[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]

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.

[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]

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.

[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]

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.

[karter16]

Purple!



Surface temps ended up settling at around 60C. 07333 datasheet (attached) 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.

Great work!! must be so satisfying seeing the pieces, literally, all coming together!

Yeah I felt exactly the same about the 07333 when I used it for my RACP mounts - it's lovely stuff to work with, is fairly self explanatory in terms of how much to use and the way that it's embedded with the tiny balls to get the right thickness of application is really cool. (that purple is a very satisfying visual cue!)

[Obioban]

Your level of prep really makes me hope I don't regret my... lesser level of prep for that part.

Well done!

[Bry5on]

Very nice! That’s a really really quick cure too at a pretty low temp.

[heinzboehmer]

Great work!! must be so satisfying seeing the pieces, literally, all coming together!

Yeah I felt exactly the same about the 07333 when I used it for my RACP mounts - it's lovely stuff to work with, is fairly self explanatory in terms of how much to use and the way that it's embedded with the tiny balls to get the right thickness of application is really cool. (that purple is a very satisfying visual cue!)

Right? It's by far the best structural adhesive I've worked with. My only complaint is that it goes on silver, which makes it a little hard to see what bare metal surfaces are covered, but it's a minor issue.

Your level of prep really makes me hope I don't regret my... lesser level of prep for that part.

Well done!

Ha, I think I went a bit overboard with the prep, you should be fine.

Very nice! That’s a really really quick cure too at a pretty low temp.

Yeah this thing is the best. If you can get everything up to 80C, it cures in 30 min!

For reference:



My favorite part is that it seems to never fully cure if the parts are under 23C

[heinzboehmer]

Adhesive is cured, so time to put everything back together.

First up, the last details of the brace mounting point.

Replaced the grommet in the chassis with a new one because I lost the original somewhere along the way. I wasn't sure exactly which part number it was (cause I lost it and couldn't measure it ), so I ordered a few different ones. Turns out it's 51718110199:



I then reassembled the blower motor housing (not gonna cover that again and yes it still sucked) and bolted in the E86 brace attachment point. Torqued the bolts to 26 lb-ft, since that's the number I used when I was running all the simulations:



The front bolts are easy to get to with normal tools, but space is a bit tight with the rear one. I bought these super low profile hex socket bit things, which allowed me to get back there with a torque wrench:



I couldn't help myself and threw the E86 braces on:




Three of the four ends of the braces still need to be shortened, which is why they don't really fit. The intersecting lines on the driver's side brace are a rough guesstimate of where the stud on the strut tower bracket will live. My plan is to put everything back together, reinstall the E86 braces, swap out the stock strut tower brackets for my 3D printed prototypes and scan everything. This will give me an excellent reference for where they need to land. With that, I can go finish the design for my brackets and then get them manufactured.

Anyway, I need to get the engine bay back together first, so let's start there.

I noticed the idle air rail o rings weren't in the best shape, so I swapped those out and cleaned up the tubes:



<insert picture of the cleaned up tubes with new o rings that I forgot to take>

I then installed the airbox and anything else I had removed.

Last thing I needed to do was to clean up the area under the cowl and install the new one I've had sitting in the stash for years. Old one was not looking good at all:





Feels good to have that brand new piece installed.

Also, I think this is the coolest part of this entire project. Without the braces installed, my design does not get in the way of absolutely any stock part:



It's essentially invisible unless you're looking for it .

This does mean that I'll have a bit of a harder time designing the replacement firewall plug, but I think it's worth it. More on that once I have the strut tower brackets finished, manufactured and installed.

[heinzboehmer]

Installed this piece after being inspired/reminded by Obioban's recent post in his journal:



Curiously, the cutouts for the isofix brackets did not line up and I had to extend them a bit. This part seems to fit well on Obioban and karter16's cars. Maybe it's an early production thing?

The other thing I had to trim was the flange the extends into the trunk, but only because I have the Slon wall in the way. Looks like it would have fit just fine without that.

Also, pleasantly surprised that the extra cutouts on the side line up perfectly with the anchor points for my harnesses. Very nice.

[YoitsTmac]

Do you have a link to the soundproofing you put back there? I was going to pull off my rear seat, but perhaps I hold off so I can put some insulation in there