E46 BMW Social Directory E46 FAQ 3-Series Discussion Forums BMW Photo Gallery BMW 3-Series Technical Information E46 Fanatics - The Ultimate BMW Resource BMW Vendors General E46 Forum The Tire Rack's Tire Wheel Forum Forced Induction Forum The Off-Topic The E46 BMW Showroom For Sale, For Trade or Wanting to Buy

Welcome to the E46Fanatics forums. E46Fanatics is the premiere website for BMW 3 series owners around the world with interactive forums, a geographical enthusiast directory, photo galleries, and technical information for BMW enthusiasts.

You are currently viewing our boards as a guest which gives you limited access to view most discussions and access our other features. By joining our free community you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is fast, simple and absolutely free so please, join our community today!

If you have any problems with the registration process or your account login, please contact contact us.

Go Back   E46Fanatics > E46 BMW > General E46 Forum

General E46 Forum
This is the place to get answers, opinions and everything you need related to your E46 (sedan, coupe, convertible and wagon) BMW!

Reply
 
Thread Tools Search this Thread Rating: Thread Rating: 14 votes, 4.93 average. Display Modes
Old 08-16-2012, 07:59 PM   #1
Megalocnus
Registered User
 
Join Date: Oct 2008
Location: Los Angeles, CA
Posts: 2,749
My Ride: 05 330i ZHP/MT
BMW structural foam DIY update

Those driving an early E46 model, and especially those of us owners of a pre-Feb 2000 E46 know the rear mounting points of the differential carrier are weak. Some were lucky to have this fixed and covered by BMW, others not so much.
My car had checked OK when inspected under the class action lawsuit settlement, by as soon as the settlement program expired, I knew that if the trunk floor cracks and tears, I'll be on my own.

Basically there are a few methods to reinforce the trunk floor or the mounting points before they fail:
- on the outside, by welding or epoxying metal plates
- on the inside, by filling the mounting point cavities with structural foam
- some are using a custom made brace that mounts inside the trunk to the shock and the mounting points, but this is less common.

Out of these options the only one I could do on my own is the structural foam. This method was originally used by BMW to fix the issue if discovered in its early stage, when the cracks are still small. The original service bulletin from Oct 2003 (see JeppeJ's thread linked below) was replaced by SI B41 04 08 in 2009, reflecting a change of foam and sealant products used in the process. In principle the method hasn't changed though - it relies on filling the cavity above the mounting element, which is welded on the metal floor, with special epoxy foam. This foam becomes very hard upon polymerization, thus supporting the floor to reduce the stress under load.

All this and more is very nicely covered by JeppeJ, so I'll only add a few new things since dmax requested it.

The structural foams offered by BMW- P/N 83420307530 (2003-2009) and P/N 83190445721 (since 2009) came in two cartridges of 420 ml each. In addition to these products, there was another one with very similar specs - Lord FUSOR 1908 (see below). It came in 225 ml cartridges, so four of these could substitute for the two BMW cartridges required per mounting point.
I filled the most vulnerable rear left cavity with FUS-1908 about a year ago. Unfortunately, this product was discontinued shortly after that and I don't know of any other with similar specs available in the US market.
Meanwhile the BMW foam is also becoming unavailable or so was told by a dealer I buy parts from. Luckily, Tischer had it on stock and I quickly ordered a set for the rear right mounting point.

Some pics. Most of these were taken after injecting the structural foam. I didn't want to waste time during the process.

There was a hole on the floor sheet next to each rear mounting point. I cleaned the area and put a piece of paper tape over these. This was enough to prevent the structural foam from flowing outside.


When all is done, you can see the structural foam through this hole (red arrow).


This shows the working area in the trunk. Holes 1 (left and right) already exist and are covered by plastic plugs. Under these holes lies a second metal sheet, which also has holes at these positions. The foam should be injected in the cavities under the second metal sheet, not above it.
Hole 3 is also there already, but is covered with a sound deadening material. Hole 2 has to be drilled. The metal sheet underneath already has a hole there.


I began this project about a year ago. First I injected a seam sealer (see the service bulletin above for details) under the second metal sheet at hole 2 and as deep as I could reach inside hole 3. Then I covered both these holes with body plugs. At this point I injected four cartridges of Lord FUSOR 1908 into the rear left mounting point cavity.
A week ago I continued by reinforcing the rear right mounting point with structural foam from BMW.

These are the cartridges and the mechanical applicator. The Lord FUSOR gun I had didn't fit the BMW foam dual cartridge, unfortunately. Many thanks to the guy who posted on the M3 forums that the COX 31400X MR dispensing gun works for these. I was able to obtain this gun at a reasonable price from Zoro tools.


This is a quality product and worked great. The injecting process is not as easy as it may seem because the components of the structural foam are very viscous. I had the cartridges submerged in water at 65 C / 150 F for 15-20 minutes to soften the contents. Once I started injecting, I wanted to finish quickly since I was afraid the foam may cool down during the process.


This pic shows hole 1 on the right a day after the injection.


Compare with hole 1 on the left.


This is a structural foam leftover that polymerized in the guide tube. Nice dark glossy finish. It will snap if bent, but it takes a considerable effort to do this. The material is hard - I squeezed by large pliers with full strength and there were only tiny scratch marks left.


It is also elastic. This piece works as a spring when pressed down hard.


What is this structural foam? It is not very likely that BMW has custom formulated and manufactured this product on their own. Turns out the BMW 83190445721 foam really is a Henkel Terocore 1401.

420ml or 400ml? Who cares?


The mechanical properties of Terocore 1401 CA 25 and Lord FUSOR 1908 look pretty similar. Let's hope they are not going to discontinue this product too.

Last edited by Megalocnus; 08-17-2012 at 04:14 AM.
Megalocnus is offline   Reply With Quote
Ads by Google

Guests, get your FREE E46Fanatics.com membership to remove this ad.
Old 08-16-2012, 08:05 PM   #2
BMWBMX'er
Registered User
 
Join Date: Nov 2011
Location: Richmond, Virginia
Posts: 117
My Ride: '00 323i
Would this be a good preventative measure to take against failure? And if so, is it possible to weld in the reinforcement kit after filling the cavity with the foam?
BMWBMX'er is offline   Reply With Quote
Old 08-16-2012, 08:07 PM   #3
dmax
Registered User
 
dmax's Avatar
 
Join Date: Aug 2006
Location: NJ
Posts: 23,564
My Ride: '99 328i 300K miles
I've been waiting for this just out of curiosity to know what my car has. Great work and thank you!
__________________
I don't want to beg, but please, please come to a show sometime!
In NYC Fri, Sept. 30, 8 p.m. at Broadway Comedy Club! Sat, Oct. 8, 6 p.m. at Greenwich Village Comedy Club.
Facebook.com/DMAXstandup
Mangofy your E46!
dmax is offline   Reply With Quote
Old 08-16-2012, 09:09 PM   #4
Megalocnus
Registered User
 
Join Date: Oct 2008
Location: Los Angeles, CA
Posts: 2,749
My Ride: 05 330i ZHP/MT
Quote:
Originally Posted by BMWBMX'er View Post
Would this be a good preventative measure to take against failure? And if so, is it possible to weld in the reinforcement kit after filling the cavity with the foam?
Would be preferable to do it the other way around. These epoxy foams may release toxic chlorine oxides when burnt. Can't remember the details now, but there definitely was a warning about this somewhere.
For preventive reinforcement, I think what JeppeJ did is the way to go. I wish I knew back in 2007 or 2008 it is possible to epoxy the reinforcement plates instead of welding them. Around that time my car's differential and carrier were taken down to replace the bushings, so it would have been easy to add the plates.

-
Dmax, you're welcome.
Megalocnus is offline   Reply With Quote
Old 08-16-2012, 10:59 PM   #5
TrippinBimmer
Registered User
 
Join Date: Jan 2008
Location: Ridgeland, MS
Posts: 5,403
My Ride: ZHP Custom Stage 3.5
Send a message via AIM to TrippinBimmer Send a message via Yahoo to TrippinBimmer
I need to get some asap!
TrippinBimmer is offline   Reply With Quote
Old 08-17-2012, 02:07 PM   #6
Marek555
Registered User
 
Join Date: Aug 2010
Location: Estonia
Posts: 115
My Ride: E46 328i 173kW
Great info
When I looked my car maintenance history, I noticed this:

Foam reinforcement was done by german BMW dealer, so I think I am one of the lucky one
You did not mention, that car should be still until 24 h after applying foam

Last edited by Marek555; 08-17-2012 at 02:18 PM.
Marek555 is offline   Reply With Quote
Old 08-19-2012, 07:38 PM   #7
dmax
Registered User
 
dmax's Avatar
 
Join Date: Aug 2006
Location: NJ
Posts: 23,564
My Ride: '99 328i 300K miles
Marek...interesting. You have a date or know what mileage that was done at?
__________________
I don't want to beg, but please, please come to a show sometime!
In NYC Fri, Sept. 30, 8 p.m. at Broadway Comedy Club! Sat, Oct. 8, 6 p.m. at Greenwich Village Comedy Club.
Facebook.com/DMAXstandup
Mangofy your E46!
dmax is offline   Reply With Quote
Old 08-19-2012, 08:52 PM   #8
Megalocnus
Registered User
 
Join Date: Oct 2008
Location: Los Angeles, CA
Posts: 2,749
My Ride: 05 330i ZHP/MT
Quote:
Originally Posted by Marek555 View Post
Foam reinforcement was done by german BMW dealer, so I think I am one of the lucky one
You did not mention, that car should be still until 24 h after applying foam
Yes, looks like sometimes before 2009 they have filled one of the mounting point cavities with foam. Can you check which one?
Chances are they haven't done this as a preventive measure - perhaps they've found crack(s) less than 20 mm long?
It may be a good idea to check this out thouroughly and make sure if crack(s) are present, they haven't grown longer.
Find out just how lucky you are.

Yes, I did not mention the car should not be driven for 24 hours after injecting the foam, but it wasn't my intention to cover every detail in JeppeJ thread and the service bulletin.
This reminds me that threre are a few more things I forgot to add:

1. The structural foam has a shelf life of one year. It should come with labels (Use by...date) both on the box and on the cartridges. Make sure the foam has not expired. If an expired foam is injected, who knows if it will acquire the intended physical strength? If it doesn't, then it may not be doing much reinforcement. But once it's in the cavity, it's there for good - you can't get it out without removing the whole trunk floor section.
I think this is important since I have seen structural foam offered on eBay more than two years after its expiration date.

2. This job is messy. Make sure to get a box of gloves (you may need more than just a pair of gloves). Have some nylon bags, rags, paper towels etc. at the ready.
The epoxy foam contains toxic components you don't want on your skin. And eslewhere.

Last edited by Megalocnus; 08-20-2012 at 01:05 AM.
Megalocnus is offline   Reply With Quote
Old 08-21-2012, 02:16 PM   #9
Marek555
Registered User
 
Join Date: Aug 2010
Location: Estonia
Posts: 115
My Ride: E46 328i 173kW
Quote:
Originally Posted by dmax View Post
Marek...interesting. You have a date or know what mileage that was done at?
Looks like it was done 22.07.2005 at 75419 kms (car build date is 19.03.1999 and currently is car at 210000 kms)

Quote:
Originally Posted by Megalocnus View Post
Yes, looks like sometimes before 2009 they have filled one of the mounting point cavities with foam. Can you check which one?
Chances are they haven't done this as a preventive measure - perhaps they've found crack(s) less than 20 mm long?
It may be a good idea to check this out thouroughly and make sure if crack(s) are present, they haven't grown longer.
Find out just how lucky you are.
I looked at old pictures, that I took after car purchase.

From here I dont see any crack at left mounting point

And after couple months, I bought all new bushings for rear axle. My local mechanic removed rear axle and replaced all those bushings. He didnt saw any cracks
(he has reinforced at least 5-6 E46 rear axels, so he knows what to look for). Or should I double check rear axle for cracks?
Marek555 is offline   Reply With Quote
Old 08-21-2012, 02:31 PM   #10
Mango
e46mango.com
 
Mango's Avatar
 
Join Date: Mar 2006
Location: Southern California
Posts: 25,405
My Ride: 2016 Lexus
Any photos/more info on epoxying of exterior plates on the outside? i'd be interested in this when i drop my rear subframe to address all the bushings back there. but hell at that point.. might as well weld. anyone made their own custom plates? (vs. buying turner's)
Mango is offline   Reply With Quote
Old 08-21-2012, 05:11 PM   #11
BMWBMX'er
Registered User
 
Join Date: Nov 2011
Location: Richmond, Virginia
Posts: 117
My Ride: '00 323i
^^^ +1 for epoxy info. I've always thought about the epoxy that you see (albeit painted over) in contact points in truck beds. Especially since I don't own a welder and I worry about metal fatigue and just the general "weakness" of the subfloor to begin with.
BMWBMX'er is offline   Reply With Quote
Old 08-21-2012, 05:16 PM   #12
Grande D
Registered User
 
Join Date: Dec 2006
Location: Mountain View
Posts: 3,434
My Ride: E36 M3
Quote:
Originally Posted by E46Mango View Post
Any photos/more info on epoxying of exterior plates on the outside? i'd be interested in this when i drop my rear subframe to address all the bushings back there. but hell at that point.. might as well weld. anyone made their own custom plates? (vs. buying turner's)
Some have. The F/I guys are all over it. I know some prefer epoxy as it is self sealing, and any imperfection with the welding can and has caused some massive rust problems on some m3f member's cars. The epoxy can be stronger than a weld if done correctly as well.

http://m3forum.net/m3forum/showthread.php?t=287849

BTW I thought the structural foam was NLA?
__________________

Quote:
Originally Posted by yousharenow View Post
Get out and walk. Meet people.
It will change your life!
------------------------------------
Quote:
Originally Posted by cowmoo32 View Post
It's ok, the world needs boring people
Grande D is offline   Reply With Quote
Old 08-21-2012, 05:22 PM   #13
Mango
e46mango.com
 
Mango's Avatar
 
Join Date: Mar 2006
Location: Southern California
Posts: 25,405
My Ride: 2016 Lexus
Thanks. Saved to favorites. Definitely doing this. Whats the total cost of everything? foam.. guns.. plates. then i'd need to rent the rear subframe bushing service kit (from where I don't even know)
Mango is offline   Reply With Quote
Old 08-21-2012, 05:37 PM   #14
flashmeow
Banned User
 
Join Date: Apr 2008
Location: Dallas, TX
Posts: 2,217
My Ride: E30-E46-E90-E90M-F30
great post. thanks for the contribution
flashmeow is offline   Reply With Quote
Old 08-21-2012, 06:00 PM   #15
aziz
Registered User
 
Join Date: Aug 2004
Location: ottawa
Posts: 175
My Ride: 01xi
do I need to do this on my 01 xi sedan?
__________________
aziz is offline   Reply With Quote
Old 08-21-2012, 06:05 PM   #16
Mango
e46mango.com
 
Mango's Avatar
 
Join Date: Mar 2006
Location: Southern California
Posts: 25,405
My Ride: 2016 Lexus
Quote:
Originally Posted by aziz View Post
do I need to do this on my 01 xi sedan?
Every E46.
Mango is offline   Reply With Quote
Old 08-21-2012, 07:16 PM   #17
Grande D
Registered User
 
Join Date: Dec 2006
Location: Mountain View
Posts: 3,434
My Ride: E36 M3
Structural foam availability? Bump! I do have reading issues so I might have missed it.

Edit: Looks like it still works at Tischer. Though I won't be doing it this year I'm gunna order some just in case it becomes NLA. I thought in another thread I read it was NLA.
__________________

Quote:
Originally Posted by yousharenow View Post
Get out and walk. Meet people.
It will change your life!
------------------------------------
Quote:
Originally Posted by cowmoo32 View Post
It's ok, the world needs boring people

Last edited by Grande D; 08-21-2012 at 07:18 PM.
Grande D is offline   Reply With Quote
Old 08-21-2012, 08:22 PM   #18
Megalocnus
Registered User
 
Join Date: Oct 2008
Location: Los Angeles, CA
Posts: 2,749
My Ride: 05 330i ZHP/MT
Quote:
Originally Posted by Marek555 View Post
Looks like it was done 22.07.2005 at 75419 kms (car build date is 19.03.1999 and currently is car at 210000 kms)
I looked at old pictures, that I took after car purchase.
From here I dont see any crack at left mounting point
And after couple months, I bought all new bushings for rear axle. My local mechanic removed rear axle and replaced all those bushings. He didnt saw any cracks
(he has reinforced at least 5-6 E46 rear axels, so he knows what to look for). Or should I double check rear axle for cracks?
Hm, no cracks, but BMW did reinforce one of the two rear mounting points of the differential carrier. The trunk photo clearly shows they have worked there. It's not that obvious which one did they worked on though. Can you remove the plugs and take a look at the holes on both sides?

Quote:
Originally Posted by E46Mango View Post
Any photos/more info on epoxying of exterior plates on the outside? i'd be interested in this when i drop my rear subframe to address all the bushings back there. but hell at that point.. might as well weld. anyone made their own custom plates? (vs. buying turner's)
From the discussion on the m3forum it looks to me the 3M ScotchWeld DP-420 epoxy is a good product to use, better than the 3M Epoxy 08115.

Quote:
Originally Posted by E46Mango View Post
Thanks. Saved to favorites. Definitely doing this. Whats the total cost of everything? foam.. guns.. plates. then i'd need to rent the rear subframe bushing service kit (from where I don't even know)
The foam was about $140 per set of two cartridges from Tischer. You'll need two if you want to fill both cavities. The Wurth seam sealer was between $20-$30. The 400 ml applicator gun was $88, but you can borrow mine. The TSM plates are about $130. Not sure about the cost of the ScotchWeld and the rust proof.

Quote:
Originally Posted by zhp43867 View Post
Structural foam availability? Bump! I do have reading issues so I might have missed it.

Edit: Looks like it still works at Tischer. Though I won't be doing it this year I'm gunna order some just in case it becomes NLA. I thought in another thread I read it was NLA.
If you order the foam, you better be ready to inject. The one I got from Tischer had about a month until the expiration date.

Last edited by Megalocnus; 01-24-2013 at 11:35 AM.
Megalocnus is offline   Reply With Quote
Old 08-21-2012, 08:49 PM   #19
auto180sx
Registered User
 
Join Date: Nov 2010
Location: Lexvagas, KY
Posts: 548
My Ride: '02 Steel Blue 330Ci
Jeez, I NEED to jump on this!

Sub'd!
__________________
Steel Blue FTMFW!!


OKI BMW
BMW CCA Member #444186
auto180sx is offline   Reply With Quote
Old 08-21-2012, 09:02 PM   #20
TrippinBimmer
Registered User
 
Join Date: Jan 2008
Location: Ridgeland, MS
Posts: 5,403
My Ride: ZHP Custom Stage 3.5
Send a message via AIM to TrippinBimmer Send a message via Yahoo to TrippinBimmer
Quote:
Originally Posted by Megalocnus View Post
From the discussion on the m3forum it looks to me the 3M ScotchWeld DP-420 epoxy is a good product to use, better than the 3M Epoxy 08115.
Could you link me this thread?
TrippinBimmer is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Censor is ON





All times are GMT -5. The time now is 05:58 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2016, vBulletin Solutions, Inc.
(c) 1999 - 2016 performanceIX Inc - privacy policy - terms of use