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E46 M3 (2001-2006) Engine: S54 - Max Hp: 333 hp at 7,900 rpm / 262 lb/ft at 4,900 rpm
Total Produced: 45,000+ - Years Produced: 2001 to 2006.


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Old Sun, Sep-23-2012, 09:10:09 PM   #1
SYT_Shadow
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Cool DIY: Subframe Foam reinforcement

Ok, I finally did this!

Disclaimer: I'm not responsible for you following these instructions and waking up dead, maimed or otherwise impaired. This is what I did, there is no guarantee of you getting similar results.

I wanted to do a little writeup of this process as it wasn't clear to me before starting. There are a couple good DIYs already but I hope to bring some additional clarity.
Other DIY: http://www.m3forum.net/m3forum/showthread.php?t=287849

I know there's an endless discussion about welding plates vs using structural foam. I have an IE/ME undergrad with a minor in Materials Science and have it very clear that Foam is the preferable method.
There is no way that welding a plate on will yield the same effect as filling these cavities. Besides, welding anything will make that area prone to rusting, the very last thing I want in my subframe.

I reinforced both sides, so I used 4 cartridges in total.

Materials needed:
-Pot large enough to fit all 4 cartridges
-Heat gun
-2 BMW Foam kits. They're available at thebmwpartstore.com PN 83 42 0 307 530
Update: P/N 83190445721, link http://www.thebmwpartstore.com/oempa...190445721.html

-1 can of 'big gap sealer'. This is the insulating foam you can find at any Ace Hardware
-Two makeshift body plugs. I used the ones that go in the doors, PN 51418224768
-Applicator gun from Grainger. http://www.grainger.com/Grainger/COX...temDescription
It isn't cheap, but it's a high quality item that works perfectly for this application. I have mine available so PM if needed.


PLUGGING HOLES IN THE BOTTOM

We use two clips to plug up the two holes (one per side) in the bottom of the subframe. Push them in with pliers or something. They fit perfectly!




Here you can see the left hole we want to plug:




After plugging it up:




Now the other side:




Closeup of where it is:




All nice and plugged as well:



Now we can lower the car. Remember it can't be moved for 24h once the foam is in there, so be sure you can leave it wherever it is.



DRILL MIDDLE HOLE

At first, when we lift the cover of the trunk we see this. You can see two big black body plugs (around the center of the pic).




Roll the trunk liner out of the way to expose the sound deadening material. This is what we'll be cutting out of the way to expose the two existing holes:



Measure the distance between them. You'll want to drill a hole right between both exterior ones. There are two layers of sheet metal and the second, inner layer already has a hole in the center, so you're trying to create the first hole which will let you see the second one.

Here you see the center hole already drilled. Ignore the seam sealer, it was black silicone and not at all what we need for this.




This is the right stuff:





UNCOVER ADDITIONAL HOLES

You'll want a knife of screwdriver to remove some of the sound deadening black gunk and get to the existing holes. If you look carefully you can see where they are because the insulation will be slightly recessed there.

Here is one:




All uncovered:




The other one seems to be hiding, but we can also find it looking for a recessed spot in the insulation:




Both uncovered!





CREATE COMPARTMENTS

The reason we need seam sealer is that we have to block off areas of the subframe where we don't want the foam to go into. We're interested in the Foam being in the areas where the subframe leans on.

Here's a pic after using the gap filler:




After it dries (25 min and it's dry to the touch) I remove the excess foam:





UNCOVER BIG PLUGS

Here (and in the previous two pics) you can see the plug has been removed:




Here are some pics that show the double layer sheet metal, looking straight down:







You want to put the entire contents of the first cartridge into the BOTTOM area (so under the second layer of sheet metal). The process is to put one cartridge into the bottom area, then another in the top area and then move on to the other side, and also start with putting a whole cartridge into the bottom area and then another into the top.



HEAT UP STRUCTURAL FOAM

Some people say this should be heated to 140F. I recommend 160-180F for 30 min so it's nice and hot, ready to be used!
You'll also want to heat up the mixing nozzles that are included in the BMW kit. I used a heat gun to not get them wet, as drying the inside mixing area of the tubes must be quite a challenge... If they're cold the Foam will cool off while it passes through the nozzle, and the last thing we want is to have a clogged tube halfway through the procedure! As long as you keep everything nice and hot, you should be fine.
Once everything is hot enough, remove the plug that's on the head of each cartridge, insert the plastic mixing tube and them screw the cap back on to hold the tube in place.



APPLY FOAM

Like I said before, empty a whole cartridge into the bottom section. Never mind the masking tape you see, it's because I didn't screw the cap back on after inserting the tube (thankfully, I learned how to do it right after the first cartridge). Follow instructions and you won't have this problem

Mind you, these two pictures show a pretty steep elbow in the tube, you want to try to avoid it getting pinched like that so the foam flows freely!






Once the bottom cavity is full you'll have to switch to the next cartridge and start filling the top cavity. When you're done with the second one, empty out the clear flexible tube to get the maximum foam inside the subframe. It'll look like this:




Now, do the same to the other side, add on the body plugs and let the car sit for 24h!


I feel a lot better now that this is reinforced. The sandwich structure it now has is almost impossible to break with the kind of force the subframe exerts on this.

I hope this was useful!

SYT_Shadow
__________________
Rod bearing replacement DIY
Vanos hub / bolts DIY
30k on TT V3 Vanos hub
Oil Pan Removal DIY
Foam subframe reinforcement DIY
ESS NA Tune Review

Tools:
-Shim kit -Timing tool -Engine support -Grainger foam applicator gun
DIY stuff
-Available in the NY/Westchester area

Last edited by SYT_Shadow; Tue, Oct-29-2013 at 05:14:30 PM. Reason: Minor tweaks
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Old Sun, Sep-23-2012, 09:10:32 PM   #2
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Default Re: DIY: Subframe Foam reinforcement

A forum member, maruscumn, has done a great job at modeling the inside of the cavities we're trying to fill with foam.

Here's a link:
http://www.m3forum.net/m3forum/showt...post1066085604




NOTE: the TIS apparently says to inject all the foam into the bottom cavity, not half in the bottom and half in the top.
If I were to do this again I would buy more foam so I can also fill the top cavity.
__________________
Rod bearing replacement DIY
Vanos hub / bolts DIY
30k on TT V3 Vanos hub
Oil Pan Removal DIY
Foam subframe reinforcement DIY
ESS NA Tune Review

Tools:
-Shim kit -Timing tool -Engine support -Grainger foam applicator gun
DIY stuff
-Available in the NY/Westchester area

Last edited by SYT_Shadow; Sat, Nov-01-2014 at 08:21:02 PM.
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Old Sun, Sep-23-2012, 09:29:20 PM   #3
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Default Re: DIY: Subframe Foam reinforcement

GREAT DIY!!

I and another local forum member plan to do this in the upcoming weeks/month. I'll PM you to rent that applicator.
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Old Sun, Sep-23-2012, 09:30:53 PM   #4
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Default Re: DIY: Subframe Foam reinforcement

Quote:
Originally Posted by p0lar View Post
GREAT DIY!!

I and another local forum member plan to do this in the upcoming weeks/month. I'll PM you to rent that applicator.
Thanks man. It's much shorter than the other DIY's I've done, but I just wanted people to avoid the same issues I had.

This is SUCH cheap insurance! For $300 or less you have your full subframe reinforced!

PM away!
__________________
Rod bearing replacement DIY
Vanos hub / bolts DIY
30k on TT V3 Vanos hub
Oil Pan Removal DIY
Foam subframe reinforcement DIY
ESS NA Tune Review

Tools:
-Shim kit -Timing tool -Engine support -Grainger foam applicator gun
DIY stuff
-Available in the NY/Westchester area
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Old Sun, Sep-23-2012, 09:43:48 PM   #5
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Default Re: DIY: Subframe Foam reinforcement

So, did you decide not to do the epoxy + structural plate reinforcement as well? We were considering going both routes, but welding was categorically out of the question.

Edit: How much was just the foam? (the BMW-specific foam)
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Old Sun, Sep-23-2012, 09:51:10 PM   #6
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Default Re: DIY: Subframe Foam reinforcement

Quote:
Originally Posted by p0lar View Post
So, did you decide not to do the epoxy + structural plate reinforcement as well? We were considering going both routes, but welding was categorically out of the question.

Edit: How much was just the foam? (the BMW-specific foam)
I think it was around 130 per kit, so 260 for what I did.

I bought the TMS plates and specific epoxy for that but don't think I'll use it. The way the subframe breaks is that the subframe leans on a hollow piece of sheet metal. When we do the foam reinforcement we're filling it up, so I just don't see how it's possible for anything to tear.
The plates require a lot of work... Dropping the whole subframe must be a complete PITA.
__________________
Rod bearing replacement DIY
Vanos hub / bolts DIY
30k on TT V3 Vanos hub
Oil Pan Removal DIY
Foam subframe reinforcement DIY
ESS NA Tune Review

Tools:
-Shim kit -Timing tool -Engine support -Grainger foam applicator gun
DIY stuff
-Available in the NY/Westchester area
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Old Sun, Sep-23-2012, 09:57:19 PM   #7
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Default Re: DIY: Subframe Foam reinforcement

Another great DIY, Thank you. PM has been sent for rental info.
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Old Sun, Sep-23-2012, 10:35:20 PM   #8
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Default Re: DIY: Subframe Foam reinforcement

Quote:
Originally Posted by SYT_Shadow View Post

I bought the TMS plates and specific epoxy for that but don't think I'll use it. The way the subframe breaks is that the subframe leans on a hollow piece of sheet metal. When we do the foam reinforcement we're filling it up, so I just don't see how it's possible for anything to tear.
Well if you have a bunch of miles on the car and want to replace the subframe bushings you might as well epoxy the plates...
Quote:
Originally Posted by SYT_Shadow View Post
The plates require a lot of work... Dropping the whole subframe must be a complete PITA.
It is.

Mike
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Old Sun, Sep-23-2012, 11:02:21 PM   #9
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Default Re: DIY: Subframe Foam reinforcement

Thanks for clearly depicting how this is done! I planned on doing this over the winter. This certainly clears up some of the past confusion in other threads.

Your contribution to this forum is priceless.
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Old Sun, Sep-23-2012, 11:47:43 PM   #10
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Default Re: DIY: Subframe Foam reinforcement

sub'd
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Discussing DIY: Subframe Foam reinforcement in the E46 M3 (2001-2006) Forum - Engine: S54 - Max Hp: 333 hp at 7,900 rpm / 262 lb/ft at 4,900 rpm
Total Produced: 45,000+ - Years Produced: 2001 to 2006. at BMW M3 Forum.com (E30 M3 | E36 M3 | E46 M3 | E92 M3 | F80/X)