welding plates is the way to go.
Go to a BMW specialist shop, they tend to be more time efficient and careful and possibly charge less hours.

 

Are uuc plates different than tms ones? Also what else should I have done when I'm in there? Subframe bushings? Rtabs? Diff bushings?
And poly or oe

 

If it ain't broke don't fix it (edit: unless you plan to change the use of the vehicle). If you decide to fix it anyway, weld in steel. Might as well use the foam as well,
but, likely it only helps a little bit.

 

Having been through the process, I'd agree with this... so long as you're getting it checked when your car is in for work.

The cost of repairing a slightly cracked subframe is negligibly more expensive then doing the work as preventative maintenance. So you might as well just continue as is (unless you hardcore track your car) and do it only after minor cracks have been found.

 

I'd replace every rubber bushing that had to be touched. You could use stock parts if you like the way bmw made them, or you could try something different.
It is the mounting points that might fail. If you are going to pay for labor to have this done, you might as well have new rubber parts put in

 

When you do the rear subframe and differential bushings, which you should for preventive maintaince, you can easily check the subframe then.
The subframe cracks largely as result of failed bushings from the lack of cushioning.

 

When I have my subframe out to do the bushings wouldnt it be worth it to just have them weld in the plates? I can't imagine it being much more in labor costs.

 

Injecting a structural foam into the mounting point cavities was the only reinforcement method the average DIYer could do in his garage.
Unfortunately, both structural foams suitable for this process (BMW 83190445721 and Lord FUSOR-1908) are no longer available. Henkel may have a terocore foam with comparable specs, but I haven't found a way to order their products.

 

Inspect your car at 30,000 mile intervals like what BMW does if you took your car to BMW for servicing. If you see cracks starting, repair, if not, don't waste money.

 

there is a 3rd way you forgot which is to use the epoxy/cement to adhere the plates to the car. this is an industrial aircraft grade adhesive so it's not only super strong but does not fatigue the metal like welding can.

i would NOT say if it's not broke don't fix it. to the extent if it's an earlier model i would preventively add the epoxy foam to the cavity which is to keep it from flexing and cracking. this was the first method bmw used to fix the cars in europe from their TIS bulletin back in like 2002. much easier to do and one does Not have to drop the subframe, the gas tank, or get a complete alignment. just a couple of access holes in the trunk floor and inject the expoxy foam and cavity filler. allow to cure to hardness 24hr without moving and then you're done.

if the frame is cracked i would do the plates if not a whole section of the floorboard. some places now suggest to weld in the mounting block from the inside trunk area to reinforce aswell when ever doing plates to fix those that have pulled through the bottom.

much of the labor to do the bushings is done. but there is So much more work to weld in the plates. not to mention you have to drop the whole gas tank aswell to weld. geometry changes whith the plates so things have to be all re-aligned.

 

If we already have the TMS Reinforcement plates and subframe is okay for now.

What's the easily way to make use of these plates without going to a shop for welding?

 

Alex was referring to this method for epoxy-gluing the TSM plates to the floor. It's not easy by any means, but at least there's no need to drop the gas tank, cut holes in the trunk, weld... If only JeppeJ had made this thread a year earlier (when I had the subframe and the differential down to replace the bushings) I would have done it.

On the brighter side, the BMW structural foam still can be ordered. A few weeks ago I was told by a dealer that the foam is no longer available in USA and Germany. However, Tischer apparently still has it. They just shipped one my way.
I already have FUSOR-1908 into the driver side cavity, the BMW foam will go into the passenger side once I find an applicator gun.

 

I have a 2000 E46. It is not broken and therefore, I am not fixing it. If you are into PM on the subframe, how about changing all your window regulators this weekend as part of your PM program, and clips on the moon roof.

 

I say the welding of re-inforcement plates is a superior approach to injecting epoxy. And I would not do anything until a crack appears.

I waited until a very small crack appeared on my subframe mount. A crack appeared on the left side at about 150,000 miles. I had the Turner re-inforcement kit welded in for a total cost of $1200 including parts and labor. Some have had the job done for a lot less, but I would say around $1000 for the job is fair.

 

This issue has been fought over many time between epoxy and welding. I was on the epoxy bandwagon myself because I use them often at work and see the strength and reliability of epoxy. BUT the issue of subframe re enforcment isn't just to fasten the load distributing plates to the sheet metal,but also to drill through the sheet metal and weld the actual mounting plate to the new plates. The existing spot welds fail allowing fatigue and then cracking. I strongly recommend anyone concidering this repair to download the Turner Motorsports PDF installation instructions to see how this is addressed. Also the foward mount is to be beefed up by cutting acess panels in the trunk and further welding the structural mount to the sheet metal because the existing spot welds are insufficient. This can not be properly addressed with use of epoxy.
Op,do it for piece of mind before it cracks. Working with good clean solid metal is much easier than beating and welding torn and fatigued metal.

 

megal, hope you'll take some photos for us of this.

I had my subframe done 'officially' so I'm good, but if I was in OPs situation, with concerns but no cracks yet, I think I would use the foam filling. That said, I'm not sure how that would then react if later you needed to do the reinforcement. As I understand it, bmw only used the foam filling if the crack was slight...as in not protruding beyond the bushing...admittedly, that was probably a cost saving effort, but this foam, fyi, isn't like Great Stuff...it's a seriously hard expanding epoxy foam...and when contained in the area you make with the 'cavity forming foam' I believe it adds a bit of stability...not allowing the sheet metal to flex and then tear.

This 'gluing' the reinforcement plates sounds dicey, but since it comes from Alex, I'd believe it to be a suitable alternative to welding.

 

megal, hope you'll take some photos for us of this.

Can't promise this DMAX. The process of injecting the foam is a kind of job you want to do fast. The foam is very viscous, should be prewarmed to be able to push it trough the mixer (LORD Fusor-1908 manual specified- at 65 C, The BMW product says 'under hot water').
I used a manual injection gun (can't inject fast with it), not the recommended pneumatic one and was scared the FUSOR-1908 foam will cool down and will become too viscous before I manage to inject the entire cartrige. Not much time to take photos by myself.
The BMW foam will be more challenging since the cartrige is almost twice larger - 420 vs 220 ml.
Anyway, JeppeJ's pics are excellent and the two component cartrige he shows is still the same, even though the epoxy formula may not have been the same as the current one (they have different BMW part numbers).

 

F*ck it.
Since Canadian 2000 E46s are mostly built in mid-year 2000. These cars' subframe are considered to same as 2001+ models.
I have personally asked a few 400,000+ km 2000 323ci and 328ci local owners and they all said there was never any subframe repair needed.
So I am guessing there is no need to preventively spend $1000 if you do have a mid-year 2000+ e46.
Put that $ in a bank instead.

I'll just put that bag of $150 steel plates in the dungeon incase some sh1t do happen 5 years from now.

 

Have fun Merc. Maybe photos afterwards of where you drilled the holes.

I read the TIS for this and I know it was very exacting about the holes and time of injection...sort of stuff.

Anyway, your repair comes first, of course, but afterwards, pics?

 

My car is very bad off. Trunk floor seams have separated, upper spring perch"s are almost torn from the body and the cracks are also going from the forward most subframe mounts towards the back seats. People install the reinforcement plates/kits and still develop cracks later down the road. They start cracking around the welds of the plates. Anyone that is going to fix their car should check out this thread. http://forum.e46fanatics.com/showthread.php?t=909256 It seems the like the only proper way to fix it. This is how my car is getting fixed this week. Ordered all new metal from BMW and installing AKG subframe and differential bushings and new OEM bushings for the rest of it. Goodluck :thumbsup: