Foam subframe reinforcement - production date question - technical

[AggieBlake]

Now that I have begun tracking my ZHP, I thought I should go ahead and do the rear subframe reinforcement. I found the foam method on derbo's project thread (thanks derbo!) and was planning on doing that until I noticed something interesting in the pdf instructions he linked to...

http://www.zhpmafia.com/forums/attachment.php?attachmentid=9528&d=1374195971

On page 1 the foam/epoxy method (Procedure A) is limited by BMW to cars with production dates prior to 10/2004. My car is a 2005 with production date 12/2004. So does anyone have any idea what changed in 10/2004 on our cars? I can't find any information online. I'd love to know if BMW changed the design or performed the epoxy reinforcement in the factory. Sure would give me more peace of mind on track!!

According to the technical bulletin my only option is to replace the entire subframe if cracks one day appear. But based on the fact that I can't find any evidence of 2005 e46 sedans cracking rear subframes, maybe I can just ignore this issue. Any advice appreciated.

[slater]

filling the rear floor is, in my opinion, the best method for preventing rear floor failure (and it's the floor that fails, not the subframe!).

you can easily check to see if it has already been filling by removing the false floor in the trunk, then popping out one of the rubber grommets just ahead of the spare tire well and inspecting down inside. i would be really surprised if it was done at the factory, because i don't think BMW released the TSB for it until 2009-ish.

you can definitely fill it yourself! i filled mine.

[AggieBlake]

Yes, meant the floor :)

Good tip. I just checked. Here's a picture. There are some oddities with my car versus earlier models. The green arrow points to a hole that I can't access on mine. It's covered with that large piece of silver sound deadening material. It's tough. I could try to cut it away, but I hadn't seen it on other pictures. The red arrow points to the middle hole, and note that it is covered with a clear plastic or epoxy. Finally, you can see the two holes that epoxy would be injected into. I have used red lines to note that when i stuck my finger down through not just the top hole but the hole below it, the bottom cavity is bounded, or surrounded, by what feels like a solid plastic filler. The hole on the left, upon which BMW focused their repair efforts in the epoxy TIS, is completely bounded. If I injected epoxy, I believe I'd end up with about 1 cubic inch going in before it began going into the upper cavity. On the right it feels like it's only bounded on two sides, which would make sense if BMW was focusing their efforts on the left side. Anyways, it makes me think that the epoxy method would not work well on my car (the bad news) because it's probably already been taken car of by whatever BMW has added within the floor cavity (the good news).

Can anyone shed any light on this?

23719

[Sockethead]

I also have an '05 and I'm in the middle of a rear shock swap so I'll take a look at mine for you whilst apart

[Sockethead]

Looks like I won't get to this until tonight or tomorrow.

In the meantime, take a look at this thread. this will give you a much better understanding of what is going on in there...
http://m3forum.net/m3forum/showthread.php?t=450730&highlight=subframe

good info here too, including the structural foam:
http://www.redish-motorsport.com/E46M3FloorSubframeCrackRepairReinforcement.html

[AggieBlake]

That would be very helpful if you could take a look at yours and let me know! I've looked through the links you've sent. If I'm right, it seems like we've got something different going on that what's seen in these two images...

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23728

Note that if you stuck your finger through the right hole in the first pick into the cavity between the subframe floor and subframe floor upper panel (using terminology in http://m3forum.net/m3forum/showthread.php?t=450730&highlight=subframe) there's nothing you'd touch other than the subframe floor (if your finger's long enough you might be able to feel the corner of the internal mount). But on my car, that hole is totally bounded. You can feel stuff all around - feels like plastic filling the space between that subframe floor and floor upper panel. Let me know if you feel it, too. In contrast, I don't feel that on the right side.

[Sockethead]

Ok, yep I'll check it out... Hopefully this evening

[SoCalZman]

Would be very interesting if BMW implemented some fix for the last few months of the e46 run. My car was built in 11/2004.

[Sockethead]

This is the left rear hole. You can see all the way down to the internal mount.

http://uploads.tapatalk-cdn.com/20160116/7d38ac97ba23737cf0f9cf0db2927a35.jpg

There is some hard sealer in there but if it had the structural foam that lower cavity would be completely filled

Also I checked the build date of my car and even though it's an '05, the build date is 9/04

[Sockethead]

I just checked the right one and it's the same.
I don't have a copy of the official instructions for filling that void with structural foam but I can't imagine that they would only indicate one side.
The left side is the one that fails on our cars due rotational force of the drive line and the design of the rear diff mount. On the Ms it's the front mounts that fail because the diff mounts are a different design.

[AggieBlake]

Thanks for checking!! Sounds like our cars are different, which would confirm that something did change after 10/2004. When I feel inside the two holes, they are not the same once you get down into the second cavity. The one on the driver's side is surrounded by plastic. The one on the passenger side is not. If yours are the same, then BMW did add something in cars built after 10/2004.

Here's the official instructions (http://www.zhpmafia.com/forums/attachment.php?attachmentid=9528&d=1374195971). Note that the epoxy reinforcement done by BMW was only for the driver's side, not the passenger side. It seems that was where the vast majority of failures occurred.

So this leaves me wondering if my car is safe as-is to track. I've yet to find any evidence of any subframe failures in e46 non-M's built after 10/2004. But I sure wish BMW would have been more forthcoming on this issue and on their design modifications!

NorCalZman, any chance you want to pop those two rubber plugs and look inside yours. It would be interesting to see if your car's the same as mine.

[Sockethead]

Yea there is nothing in the second cavity in mine.
Any chance you can take a picture of the inside of the left like I did? I used my iPhone and a flashlight.
I'm really interested to see what's in there...

[AggieBlake]

This is the best I could do. Pretty poor pic. This is a time when I really need a camera scope!

This is on the driver's side looking all the way down through the second hole into the subframe floor/subframe top panel cavity (the bottom cavity). You can see a little of the black plastic. The rest is out of view but totally surrounds that hole. So as best I can tell, if I inject epoxy I will only get about a cubic inch of it in the bottom cavity before it overflows into the top cavity, which does not help me. The other side (passenger) is open, and would therefore possibly be good to epoxy.

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[AggieBlake]

Also, just so I'm clear, when you say "left" are you talking about from the driver's seat, so the driver's side? Or looking at the front of the car (so passenger's side)?

[Vas]

Very interesting. Makes me want to look at both of my zhp sedans

[AggieBlake]

Appears there's a similar discussion going on across the pond among some M3 guys who noticed that unusual piece of plastic in the bottom cavity of their 2005 cars: http://forums.m3cutters.co.uk/showthread.php?t=138030&page=2

If interested, read posts 9, 10, 12, 20, 21, 22, 23. Maybe they'll find out some more info.

[Sockethead]

Interesting, yep looks like you got something there.... Good find!
I'm going to have to check mine from another angle... Being built in 9/04 mine probably doesn't have it...
If structural foam was pumped in there, you wouldn't be able to see the bottom of the inner mount at all....let a lone a black plastic structure

This is all very interesting and important to know as is the first I've heard of proof that BMW did something to alleviate this problem.

[SoCalZman]

NorCalZman, any chance you want to pop those two rubber plugs and look inside yours. It would be interesting to see if your car's the same as mine.

Im sick and not feeling like getting up off the couch for another day or two but Ill get to it. So how did you get the rubber plugs out? I don't want to scrape at anything if possible.


Interesting, yep looks like you got something there.... Good find!
I'm going to have to check mine from another angle... Being built in 9/04 mine probably doesn't have it...
If structural foam was pumped in there, you wouldn't be able to see the bottom of the inner mount at all....let a lone a black plastic structure

This is all very interesting and important to know as is the first I've heard of proof that BMW did something to alleviate this problem.

taking into consideration BMW had been implementing fixes ever since the LCI, in my mind if the foam is not needed for the last few E46s, they had to have done something else to keep the subframes from ripping.

[AggieBlake]

Hope you feel better soon, man. No rush on any of this.

The plugs are super easy to remove. You won't scrape anything. Just use a small flat screwdriver, or better yet a flat plastic tool like a plastic putty knife. They come out with little pressure.

[Sockethead]

I just checked mine again and it does have the plastic filler piece like yours. I can also see a white plastic barbed fastener holding it in place on the subframe floor upper panel. I can also see blue epoxy glueing it to the subframe floor.
Sorry the pics are a little blurry. It was really hard to get the phone to focus that close

http://uploads.tapatalk-cdn.com/20160118/f19a2810b417397d2aa509459432e251.jpg

In this pic you can see the black plastic structure that's sandwiched in there

http://uploads.tapatalk-cdn.com/20160118/b8e60c3382105fbb8b6823d09435ccb4.jpg

And you can see the blue glue here

http://uploads.tapatalk-cdn.com/20160118/f40e0dc934e311956c8bf99253978fb8.jpg

[ELCID86]

Hmm the mystery deepens. Makes me want to rip all the crap out of my trunk to. Well almost. I'm lazy (and sick).


---
"ZHP is a garbage option anyway- just some cosmetic upgrades with a different cam and diff to claw back some of the performance lost fitting those hideous and heavy wheels. Any 330 with a 3.46 diff will smoke a ZHP every time. The whole Mafia thing reeks of childish behavior." - an e46fanatic

[Sockethead]

You only have to take out the floor liner and the floor over the spare tire... if you get around to checking it, can you post your build date and whether the plastic filler is in there or not?

I'm getting down with the sickness too...:eyetwitch must be going around...

[derbo]

Pretty interesting. My car is 10/03 so I followed the instructions. :)

[AggieBlake]

Ok, here's some new information! I contacted Redish Motorsport in England. They're experts at repairing and reinforcing e46 chassis that have cracked where the subframe mounts. They were kind enough to send me a link to a video they recently put together outlining the two major changes BMW made to the floors of our cars in the later model years (approx Oct '04 production onward, but may have started a little earlier). Here's the video describing the new plastic insert a couple of us have found in our cars, as well as a change in the spot welding location to lower the risk of subframe cracking...

https://www.youtube.com/watch?v=XxLW-ZnHk50&feature=youtu.be

I'm going to contact them back and try some other leads as well. I'm not convinced that their guess is correct about why BMW added the plastic piece. Why would they add a plastic dam to make epoxy filling easier if they forbid their techs from doing the epoxy fill on post 10/2004 cars? The first suggestion in the video seems more likely - that it's there to stiffen the sheetmetal (stiff plastic can be an effective middle layer in a "composite" type structure since it can have high compressive strength). Anyways, I'll let you all know if I can find out any more info.

[BMWCurves]

Very interesting. I'm impressed with your diligence. I'll take a look at my coupe tomorrow and see what's going on all up in dat trunk (build date 02/05).

[SoCalZman]

Is there a way to find out what this plastic piece looks like? From a part number diagram maybe?


Sent from my iPad using Tapatalk HD

[ELCID86]

Nice investigating.

Did you see this one??
http://youtu.be/fH1MqZ3ncMQ


---
"ZHP is a garbage option anyway- just some cosmetic upgrades with a different cam and diff to claw back some of the performance lost fitting those hideous and heavy wheels. Any 330 with a 3.46 diff will smoke a ZHP every time. The whole Mafia thing reeks of childish behavior." - an e46fanatic

[AggieBlake]

Wow, Shawn, that's a nightmare! The e46 M3's do seem to suffer the worst of it, don't they.

I've sent emails to a couple BMW divisions to see if anyone will clarify, but I'm not holding my breath. I talked to another friend who wrenches with Bimmerworld's race team. He says they just weld the crap out of everything in the rear on their track e46's - not just the subframe mounts, but every suspension point gets significant plate reinforcements. It's almost a custom rear chassis by the time they're done.

[slater]

Ok, here's some new information! I contacted Redish Motorsport in England. They're experts at repairing and reinforcing e46 chassis that have cracked where the subframe mounts. They were kind enough to send me a link to a video they recently put together outlining the two major changes BMW made to the floors of our cars in the later model years (approx Oct '04 production onward, but may have started a little earlier). Here's the video describing the new plastic insert a couple of us have found in our cars, as well as a change in the spot welding location to lower the risk of subframe cracking...

https://www.youtube.com/watch?v=XxLW-ZnHk50&feature=youtu.be

I'm going to contact them back and try some other leads as well. I'm not convinced that their guess is correct about why BMW added the plastic piece. Why would they add a plastic dam to make epoxy filling easier if they forbid their techs from doing the epoxy fill on post 10/2004 cars? The first suggestion in the video seems more likely - that it's there to stiffen the sheetmetal (stiff plastic can be an effective middle layer in a "composite" type structure since it can have high compressive strength). Anyways, I'll let you all know if I can find out any more info.

very cool stuff. seeing that it's held in with two skimpy plastic plugs, does it move around at all when you touch it? i can't say at that would do much for the structure. filling still seems like the best method overall as it "locks" the threaded sleeves for the subframe bolts down and keeps them from moving, and also keeps the floor panels stable.

my car is a 6/04 sedan and did not have the plastic piece (not surprising given your research).

are you going to fill it? i would.

[AggieBlake]

It is held in place tightly by the clips - it can't be moved. And if it is a structural filler piece, then it would be effective even without more attachment points - it's just a spacer preventing the sheet metal plates from buckling towards one another under load (if that theory is correct).

Yes, I am still expecting to fill both sides with epoxy. The problem is that the BMW technical article on the epoxy method says not to do this. I want to know why before I fill it. There's got to some reason they wouldn't let their techs do it. I just hate working in the dark (I was an engineer by training - I like to understand something before I do it). Furthermore, if the Reddish theory is correct, then my method will need to be adjusted - no foam filler before the epoxy. Or perhaps just foam filler on one part.

[AggieBlake]

NorCalZman, I've looked all over the internet and can't find either a picture or part number for it. Neither RealOEM nor Pelican have anything on it. Not surprising though since it's not a user-serviceable part. It seems to be a permanent part of the unibody since it's trapped within the welded sheetmetal. We'd need a manufacturer's drawing showing how the chassis was put together, which we are very unlikely to get.

[Sockethead]

The black plastic in my car looks like it's epoxied in on the bottom so I don't think there is any chance of it moving. I'm at work so I can't spend too much time on the internet looking at everything.

Blake, Thanks for researching and actually calling Redish.
I'm really paranoid about the subframe cracking. I drive my car hard and have been to the track and the drag strip. It's good to know that, at least, there is some additional support in there. We would never have known about that if you hadn't posted.

In my research, I stumbled across redish and read everything I could on the issue. The Redish kit is the way to go. I'll be going this route eventually as I plan on having my car for a really long time.

As I said previously, my build date is 9/04 so it looks like they may have started a little earlier as you speculated.

[ELCID86]

Is Redish here in the US? Or do they make their kits available? (Or is this an excuse to ship our cars to Europe for a bit...!)


---
"ZHP is a garbage option anyway- just some cosmetic upgrades with a different cam and diff to claw back some of the performance lost fitting those hideous and heavy wheels. Any 330 with a 3.46 diff will smoke a ZHP every time. The whole Mafia thing reeks of childish behavior." - an e46fanatic

[AggieBlake]

Reddish is only in England as far as I know. I think they'd sell you their plates even if they couldn't do the work themselves. They are much more elaborate and look much stronger than the typical plates you'd see (e.g. the ones Turner sells). They provide a much longer welding seam that better encompasses stress points. You would, however, need to know someone who is very good at welding. Can't be cheap to get this all done. I'd guess well over $1000 by the time you add parts and labor. If the epoxy method works on our cars, it will be a dramatically less expensive way to go IMO.

[Sockethead]

You can buy the Redish plates on eBay http://www.ebay.com/itm/Redish-Motorsport-BMW-E46-V2-Chassis-Subframe-Repair-Reinforcement-Plate-Kit-/291650279463?hash=item43e7b61827:g:ly8AAOSw~bFWL0j p

Redish doesn't recommend epoxy on their plates and it would next to impossible due to some of the bends required on their pates (weld then bend)

Welding process/procedure is basically the same as the TMS plates for instance. There is just more to weld

[AggieBlake]

Good find!

I wasn't clear: I don't mean epoxying the plates, I mean the epoxy injection method for strengthening the floor. If that alone is sufficient and we can avoid welding entirely, then we save a lot of money.

[slater]

It is held in place tightly by the clips - it can't be moved. And if it is a structural filler piece, then it would be effective even without more attachment points - it's just a spacer preventing the sheet metal plates from buckling towards one another under load (if that theory is correct).

Yes, I am still expecting to fill both sides with epoxy. The problem is that the BMW technical article on the epoxy method says not to do this. I want to know why before I fill it. There's got to some reason they wouldn't let their techs do it. I just hate working in the dark (I was an engineer by training - I like to understand something before I do it). Furthermore, if the Reddish theory is correct, then my method will need to be adjusted - no foam filler before the epoxy. Or perhaps just foam filler on one part.

it is perhaps possible that the epoxy and the plastic filler piece will not behave together chemically, but i don't see why.

filling that cavity, to me, makes more sense than welding in plates - if you have no cracking now. because the fill would prevent the sheetmetal from cracking... and as you suggested, it's a much easier and more economical approach.

[Sockethead]

Any time a Manufacturer starts a warranty program, they have to pay their dealerships parts and labor for the warranty work.
Maybe BMW doesn't want to pay the dealerships for the epoxy and labor when they believe the problem is resolved with the floor modifications

[Vas]

I would fill them if there is no issue with cracking.

What is the cost difference just for the parts to fill vs weld? BMW still sells the material to fill I assume?

[SoCalZman]

It is held in place tightly by the clips - it can't be moved. And if it is a structural filler piece, then it would be effective even without more attachment points - it's just a spacer preventing the sheet metal plates from buckling towards one another under load (if that theory is correct).

this is exactly what I was imagining when this piece was described. (Theory and wishful thinking) It's a little plastic brick in between the two plates of sheet metal that keeps one from bending into the other during load. If it works that way then what would be the point be of using the filler if the bottom sheet is kept stable?

[AggieBlake]

Any time a Manufacturer starts a warranty program, they have to pay their dealerships parts and labor for the warranty work.
Maybe BMW doesn't want to pay the dealerships for the epoxy and labor when they believe the problem is resolved with the floor modifications

Now that makes some sense! Perhaps this does ultimately come down to a financial issue related to warranty repairs.

[slater]

Now that makes some sense! Perhaps this does ultimately come down to a financial issue related to warranty repairs.

that seems the most logical reason, yeah!

[AggieBlake]

I would fill them if there is no issue with cracking.

What is the cost difference just for the parts to fill vs weld? BMW still sells the material to fill I assume?

Good question. As best I can tell, I would need 2 of these kits (https://www.ecstuning.com/ES1898189/) per side, or 4 total. But I could be wrong - maybe it's one per side. Hard to tell b/c the part # and quantity of epoxy has changed over the years. Worst case, 4, would put us at ~$350, plus $100 for the gun (unless I can get one used or find a cheaper alternative), plus another $20 for supplies. So a little under $500 total. If it's just 2 tubes and I can find a used gun, it would be closer to $200.

The Reddish weld plates are only ~150, but labor for that job must be in the $800+ range. I can't weld (on the list of life goals, but ain't going to happen at the moment). So that option is at least twice the epoxy option if not more.

I haven't heard back again from Reddish, and no luck with BMW either. I still think it's likely that the plastic is meant to add stiffness to the floor. But it may still be worth doing the epoxy method. The rub is that we don't have instructions for how to do it when that plastic piece is present. What volume do we use? Where do we need to inject cavity foam to dam up the void we'll fill with epoxy? We'll be doing the repair in the dark. The good news: it's hard to imagine the epoxy hurting anything. I think it's unlikely it will react chemically with the plastic piece since it's packaged in plastic and is dispensed through a plastic nozzle (though, to be fair, there are many different variants of plastics).

[AggieBlake]

Found a camera scope. When I get home tonight I'll try to thread it into the cavity in the floor and see if I can get better pictures of that plastic piece.

[Sockethead]

I think it all depends on the expansion properties of the injected material... too much expansion and it could warp the floor

A lot of the labor cost for the welding is the removal of the subframe and gas tank. With the epoxy, obviously all you'd be doing is injecting it in couple of holes... nothing needs to be removed

I can weld the Redish plates but I don't have a lift and it would be impossible to do those welds laying under my car

[Sockethead]

Found a camera scope. When I get home tonight I'll try to thread it into the cavity in the floor and see if I can get better pictures of that plastic piece.

Awesome!

[Vas]

Looks like the cheapest place right now for the foam is from The BMW Parts Store at $74.23 per cartridge. You do need 4 of them to do both sides.

Plus this gun
http://www.grainger.com/product/COX-Applicator-3EPT5?cm_mmc=PJX-_-GraingerBrand-_-43737-_-Generic

Basically comes out to right around $500 to do this.

[ELCID86]

Looks like the cheapest place right now for the foam is from The BMW Parts Store at $74.23 per cartridge. You do need 4 of them to do both sides.

Plus this gun
http://www.grainger.com/product/COX-Applicator-3EPT5?cm_mmc=PJX-_-GraingerBrand-_-43737-_-Generic

Basically comes out to right around $500 to do this.

$138 caulk gun :facepalm I like buying tools, but this one has Barry limited use.


---
"ZHP is a garbage option anyway- just some cosmetic upgrades with a different cam and diff to claw back some of the performance lost fitting those hideous and heavy wheels. Any 330 with a 3.46 diff will smoke a ZHP every time. The whole Mafia thing reeks of childish behavior." - an e46fanatic

[slater]

I think it all depends on the expansion properties of the injected material... too much expansion and it could warp the floor

A lot of the labor cost for the welding is the removal of the subframe and gas tank. With the epoxy, obviously all you'd be doing is injecting it in couple of holes... nothing needs to be removed

exactly.

the stuff BMW uses has almost zero expansion (and a very high tensile strength), which is likely why they chose it.

[slater]

$138 caulk gun :facepalm I like buying tools, but this one has Barry limited use.

perhaps a few folks could go in together and amortize the cost of the gun?

[AggieBlake]

perhaps a few folks could go in together and amortize the cost of the gun?

Good thinking! If I end up going this route, count me in. I hate buying a tool that doesn't see much use.

Here's another somewhat odd option that's being floated around e46fanatics - you epoxy or weld a 7"x7" plate into the trunk, remove the rear subframe bolt and replace it with a longer bolt that comes all the way through the new plate. Anyone see this or know anything about it? It theoretically makes sense to me since it would distribute the bending loads and reduce warping. It would be WAY cheaper than any other method.

Here's a picture of a really crappy implementation of that idea. Ignore the crappiness and just consider the basic idea.

[AggieBlake]

Here's another picture of the method done by Active Autoworke

http://forum.e46fanatics.com/attachment.php?attachmentid=569486&d=1408159156

[slater]

Good thinking! If I end up going this route, count me in. I hate buying a tool that doesn't see much use.

Here's another somewhat odd option that's being floated around e46fanatics - you epoxy or weld a 7"x7" plate into the trunk, remove the rear subframe bolt and replace it with a longer bolt that comes all the way through the new plate. Anyone see this or know anything about it? It theoretically makes sense to me since it would distribute the bending loads and reduce warping. It would be WAY cheaper than any other method.

Here's a picture of a really crappy implementation of that idea. Ignore the crappiness and just consider the basic idea.


Here's another picture of the method done by Active Autoworke

http://forum.e46fanatics.com/attachment.php?attachmentid=569486&d=1408159156

my problem with that is that the 'drawing' is not accurate. there is space between the top of the subframe bolt carrier/receiver and the uppermost trunk floor sheetmetal. you would end up collapsing the trunk floor onto said carrier/receiver.

filling, to me, makes the most sense - it's non-destructive (so to speak - nothing changes in vehicle operation or appearance), it's easier to do, and it's cheaper. and from a technical perspective it makes the most sense to address the issue at hand - to me, anyway.

i filled. :cheers

[Sockethead]

my problem with that is that the 'drawing' is not accurate. there is space between the top of the subframe bolt carrier/receiver and the uppermost trunk floor sheetmetal. you would end up collapsing the trunk floor onto said carrier/receiver.

filling, to me, makes the most sense - it's non-destructive (so to speak - nothing changes in vehicle operation or appearance), it's easier to do, and it's cheaper. and from a technical perspective it makes the most sense to address the issue at hand - to me, anyway.

i filled. :cheers

I agree. The bolt/plate would have to terminate on top of the second layer... easy enough to do by cutting a hole in the top layer to get access. Most welding repair kits have you cutting an access hole there and adding welds to that area as the spot welds between the second layer and bracket are what fails.... the bolt would take the place of the welds and you could epoxy a plate over the hole... That method would require no welding at all but you are still cutting into the structure...

[AggieBlake]

Yep, I see that now. You're both absolutely right. This would be pointless without removing the upper sheetmetal, meaning that this method requires cutting, which I'm not super excited to do. I'm surprised the Active Autowerke drawing is wrong. Those guys typically know their stuff.

One other issue with this method: if it is mounted on the middle sheetmetal, it won't actually have much contact area since that sheetmetal has divets in the pictures I've seen. It's not flat like the top sheetmetal. So another reason to go with the epoxy method. Just wish BMW would write me back with a clarification :)

[slater]

Yep, I see that now. You're both absolutely right. This would be pointless without removing the upper sheetmetal, meaning that this method requires cutting, which I'm not super excited to do. I'm surprised the Active Autowerke drawing is wrong. Those guys typically know their stuff.

i would be surprised if that was their actual 'drawing' - looks like someone made it in MS Paint. another interesting thing is that they have zero information about this on their website. so who knows where it came from?



One other issue with this method: if it is mounted on the middle sheetmetal, it won't actually have much contact area since that sheetmetal has divets in the pictures I've seen. It's not flat like the top sheetmetal. So another reason to go with the epoxy method. Just wish BMW would write me back with a clarification :)

yep, exactly.

also, you should heavily consider replacing your subframe mounts with units like the AKG poly ones - they have a flat face (and harder durometer than powerflex, if i remember correctly), which helps distribute subframe load on the rear floor a lot better than the stock ones (which just concentrate it on a very small area surrounding the bolt). i used these... fitment was very good. there's a pic or two here in my build thread: http://www.zhpmafia.com/forums/showthread.php?12602-peter-s-canadian-imola-ZHP-project&p=459844#post459844

[AggieBlake]

Ok, I finally got a chance to put a borescope down the hole and take some video for you guys. The video quality's not great (had to improvise with my iPhone b/c the scope had no record capability). But it did the job. You can clearly see the plastic piece that's been added. It's substantial and it is epoxied in place. There is virtually no room for liquid epoxy to be injected into the driver's side cavity unless the viscosity were very low, which I doubt to be the case. There is no such plastic piece on the passenger side, meaning it would be easy to do the epoxy reinforcement on that side.

Here's a link to the video...
https://dl.dropboxusercontent.com/u/1773194/ZHP%20Subfloor%20Video%202.mov

Having studied this, I am now 95% sure that the purpose of the piece is to reinforce the subframe and prevent cracking. Keep in mind that the piece was added into production 5 years before BMW released the epoxy repair protocol (in 2009). So it can't be a dam to make the epoxy method easier (contra Reddish) b/c no one was injecting epoxy into these cars back in '04. Instead, I believe BMW added this piece to stiffen the floor (a metal/plastic/metal composite sandwich) because they were hearing about more failures in earlier cars. Years later, as the failure rates of older cars increased, BMW began to look for a way to mimic the effect of the plastic piece in existing cars (obviously you can't add the plastic piece in to a chassis that's already welded together). The epoxy was the best available option. With the expanding foam barriers in place, you are effectively creating a plastic-like block between the sheetmetal layers, creating a metal/epoxy/metal composite sandwich. This would explain why they did not allow their techs to do the epoxy method on cars produced after 10/2004 - the plastic piece has the same benefit as the epoxy. If the subframe still failed, there was nothing left to do but replace the whole thing. This would also explain the much lower rate of failure of post-10/2004 cars. I only found 1 instance online of a post 10/2004 failure that I could verify, and even then there were no pictures or details to explain where it failed.

Summary: for e46's produced after 10/2004 (or thereabouts) that include the plastic block reinforcement in the chassis floor, there appears to be no way to fill the driver's side cavity with epoxy and no need to do so. That location has already been strengthened. However, it's still worthwhile to reinforce the passenger side mount with epoxy injection on a car that will see hard driving, especially one on a stiffer aftermarket suspension. That's what I plan to do at some point in the near future.

[Vas]

I need to check both of my vehicles

[Johnmadd]

Great thread, I enjoy the your research. I am now Paranoid... thanks bro.

[slater]

Ok, I finally got a chance to put a borescope down the hole and take some video for you guys. The video quality's not great (had to improvise with my iPhone b/c the scope had no record capability). But it did the job. You can clearly see the plastic piece that's been added. It's substantial and it is epoxied in place. There is virtually no room for liquid epoxy to be injected into the driver's side cavity unless the viscosity were very low, which I doubt to be the case. There is no such plastic piece on the passenger side, meaning it would be easy to do the epoxy reinforcement on that side.

Here's a link to the video...
https://dl.dropboxusercontent.com/u/1773194/ZHP%20Subfloor%20Video%202.mov

Having studied this, I am now 95% sure that the purpose of the piece is to reinforce the subframe and prevent cracking. Keep in mind that the piece was added into production 5 years before BMW released the epoxy repair protocol (in 2009). So it can't be a dam to make the epoxy method easier (contra Reddish) b/c no one was injecting epoxy into these cars back in '04. Instead, I believe BMW added this piece to stiffen the floor (a metal/plastic/metal composite sandwich) because they were hearing about more failures in earlier cars. Years later, as the failure rates of older cars increased, BMW began to look for a way to mimic the effect of the plastic piece in existing cars (obviously you can't add the plastic piece in to a chassis that's already welded together). The epoxy was the best available option. With the expanding foam barriers in place, you are effectively creating a plastic-like block between the sheetmetal layers, creating a metal/epoxy/metal composite sandwich. This would explain why they did not allow their techs to do the epoxy method on cars produced after 10/2004 - the plastic piece has the same benefit as the epoxy. If the subframe still failed, there was nothing left to do but replace the whole thing. This would also explain the much lower rate of failure of post-10/2004 cars. I only found 1 instance online of a post 10/2004 failure that I could verify, and even then there were no pictures or details to explain where it failed.

Summary: for e46's produced after 10/2004 (or thereabouts) that include the plastic block reinforcement in the chassis floor, there appears to be no way to fill the driver's side cavity with epoxy and no need to do so. That location has already been strengthened. However, it's still worthwhile to reinforce the passenger side mount with epoxy injection on a car that will see hard driving, especially one on a stiffer aftermarket suspension. That's what I plan to do at some point in the near future.

awesome, awesome work blake! thanks for taking the time to scope (ha) that out, and post the video. i definitely agree, there is some room to fill the cavity on the driver's side - i would do that and also the passenger side.

cool stuff. mine was produced in 6/04 and did not have the plastic piece.



I need to check both of my vehicles

LOL. what's the build date on your 2004?



Great thread, I enjoy the your research. I am now Paranoid... thanks bro.

ha!! if you have no cracks, filling is easy. cheap insurance. also, i highly recommend the AKG subframe mounts - insurance and better feel/feedback.

[AggieBlake]

also, you should heavily consider replacing your subframe mounts with units like the AKG poly ones - they have a flat face (and harder durometer than powerflex, if i remember correctly), which helps distribute subframe load on the rear floor a lot better than the stock ones (which just concentrate it on a very small area surrounding the bolt). i used these... fitment was very good. there's a pic or two here in my build thread: http://www.zhpmafia.com/forums/showthread.php?12602-peter-s-canadian-imola-ZHP-project&p=459844#post459844

I'll definitely check on those subframe mounts. I've got M3 engine mounts, UUC transmission mounts, Powerflex black FCABs, RE rear shock mounts, and front shock tower reinforcements on the way. This will be my first time replacing suspension bushings, so lots to learn. But I'll definitely put subframe bushings on the list of future parts to order, too. Thanks for the suggestion.

[Sockethead]

Good call on the RE shock mounts. I put Meyle heavy duty shock mounts 4 years ago and I changed them the other day... they both punched through.

http://uploads.tapatalk-cdn.com/20160119/a0a53db475f59f17c26037ea8992996f.jpg

http://uploads.tapatalk-cdn.com/20160119/f20916ea864aa87eb6e0bfdb4375dbbe.jpg

[slater]

I'll definitely check on those subframe mounts. I've got M3 engine mounts, UUC transmission mounts, Powerflex black FCABs, RE rear shock mounts, and front shock tower reinforcements on the way. This will be my first time replacing suspension bushings, so lots to learn. But I'll definitely put subframe bushings on the list of future parts to order, too. Thanks for the suggestion.

no problem. check out my build thread for pics and install notes too. installation of all of those bits is very easy.

i'm running the M3 engine mounts, UUC trans mounts, RE RSMs, and front shock tower reinforcements as well! i'm using AKG FCABs (nicer and more durable than powerflex in my opinion). i highly recommend the bimmerworld sealed spherical RTABs too!

[Vas]

Production date on the wife's zhp is 12/13/2004 and her car is a 05 model. Need to see what the date is on my 04 sedan

[ELCID86]

Good call on the RE shock mounts. I put Meyle heavy duty shock mounts 4 years ago and I changed them the other day... they both punched through.

http://uploads.tapatalk-cdn.com/20160119/a0a53db475f59f17c26037ea8992996f.jpg

http://uploads.tapatalk-cdn.com/20160119/f20916ea864aa87eb6e0bfdb4375dbbe.jpg

Another strike against Meyle in my book.


---
"ZHP is a garbage option anyway- just some cosmetic upgrades with a different cam and diff to claw back some of the performance lost fitting those hideous and heavy wheels. Any 330 with a 3.46 diff will smoke a ZHP every time. The whole Mafia thing reeks of childish behavior." - an e46fanatic

[ELCID86]

*** Sub frame Damage *** Sign here if you have this Problem (Letter to BMW)
http://forum.e46fanatics.com/showthread.php?t=195602


---
"ZHP is a garbage option anyway- just some cosmetic upgrades with a different cam and diff to claw back some of the performance lost fitting those hideous and heavy wheels. Any 330 with a 3.46 diff will smoke a ZHP every time. The whole Mafia thing reeks of childish behavior." - an e46fanatic

[Sockethead]

I don't think that list is going to lead to anything from BMWNA as this issue has already been settled and closed with the NTSB with the recall letter and inspection a few years back.

[cakM3]

I don't think that list is going to lead to anything from BMWNA as this issue has already been settled and closed with the NTSB with the recall letter and inspection a few years back.

You're probably right on this one Rob.... unfortunately...

[s14realm3]

I am going to have to redo my rear subframe bushings anyways on my 03 sedan so the subframe is coming out. I am going to do the weld plates

[SaltyNC]

I know this is an old thread, but in case others happen to find it looking for information, I wanted to add an update.

I have a very early production 2005 330Ci coupe. My production date is listed as 09/01/2004 on the VIN decoders. It is commonly thought that BMW began adding a factory reinforcement in 10/2004, but at least in my case, it appears that it was done as early as Sep 1, 2004.

You can see the reinforcement block and blue epoxy in the photos in my restoration thread here:
Salty's 2005 330Ci ZHP Jet Black Coupe Restore - Factory Reinforcement (http://www.zhpmafia.com/forums/showthread.php?21026-Salty-s-2005-330Ci-ZHP-Jet-Black-Coupe-Restore&p=551862#post551862)

Salty

[nsk040]

I have a mid-04 production and I noticed that I have a third hole (circled in red) b/w the two large, plugged holes, however it's not precisely b/w the two. When I peer into the third hole, or when I look into the driver's hole that's plugged, I can see two layers of metal and it doesn't appear that there's any foam that has hardened in there. That the third hole exists make me thinks a prior owner had this done, however, it doesn't seem to be in the right place based on the BMW bulletin. Also, I'm the only owner of the car out of warranty so if this was done it would have been done by a dealer. Further, the other hole that's supposed to be accessed under the sound deadening material (not visible but would be far top left of my photo) does not exist - all the sound deadening material is intact.

Any ideas?

32470

[Sockethead]

If you don't see it, it's probably not there. Looks like they might of started with it in September of '04 since me and Salty both have September '04 production dates and the modification is there... Perhaps BMW said October 04 to cover cars already in production...

Do you know the month of production on your car?

[nsk040]

Realoem has mine as a July '04 production date - but I will try to confirm this elsewhere.

Salty seems to have a similarly located "third hole" which can be seen to the right of the red square in post #50

http://www.zhpmafia.com/forums/showthread.php?21026-Salty-s-2005-330Ci-ZHP-Jet-Black-Coupe-Restore&p=551862#post551862

Does the existence of this third hole mean that someone at some point drilled it, or did it come that way from the factory? In the BMW service bulletin (the pdf), it says that this hole does not exist and must be drilled...but it also says that it should be drilled half-way b/w the left and right side of the vehicle...mine is clearly more towards the left side.

Salty - In that post you seem to conclude that BMW did do the reinforcement. I thought that the foam reinforcement (assuming this is what you're talking about) would literally have filled up the lower cavity and likely spilled somewhat into the upper cavity as well - I don't see this when I look at the 2nd photo in your post. Can you clarify and explain what you mean by Blue Epoxy and Black Plastic Reinforcement Block?

[Sockethead]

The support we are taking about is hard composite added between the layers during production. The foam reinforcement is preventative maintenance done at the dealership

[SaltyNC]

^ This. The factory production modification of gluing in a hard plastic/composite piece with blue epoxy to prevent flex didn't come into play until late in the lifecycle of the E46's production. The reinforced epoxy fill of the cavity was an in-field solution.

[nsk040]

Got it - mine is not reinforced in any way. Odd that the third hole exists, however.

I'll create a separate thread seeking to clarify a few items from the BMW pdf bulletin b/c I do want to do the foam.