As you all may know the E46 M3 has one major design flaw and that's weak rear sub frame mounting points. If your M3's suspension is heavily modified and you drag or track your car it could accelerate a major failure.

This is not to scare you but to reinforce the rear sub frame is a "preventitive" measure. I've been tracking and autocrossing my M3 since 2005 and yet to have an issue but who knows when and where it can happen.

I will be contacting Red Line in Pompano Beach to see if they will offer a discount if we bring them multiple M3's and the price will include all labor and sub frame reinforcement kit.

Also, I suggest to change the sub frame bushings to PowerFlex polyurethane. I can supply these as an option over keeping the OEM rubber. Cost is $214 for the set but a Group Buy price will apply to those who want them.

Post your interest here or contact me direct.

Click on the link below for more technical info. about the M3 sub frame.

E46 M3 rear sub frame info

Thanks.
Allan
AAK Motorsports

I've read a lot about the sub-frame issue with the E46 M3 and had a friend who had the reinforcements installed, but I didn't think it was that involved. Turner Motorsports sells the E46 rear chassis reinforcement kit for $146 and the front subframe reinforcement kit for $44.95.

I'm definitely interested in having this done to my M3 as I'm sure some of these other guys with M3s are as well. I'd like to hear what Red Line can do for us as a group.

Flat 6 Motorsports may also be able to do this for the guys down near Miami.

Carlos,
The parts are cheap compaired to the labor involved. The entire rear suspension, diff, gas tank (for safety reasons because of welding) and the removal of the sub frame all comes out. Here's a link to Turner's instructions.

E46 M3 sub frame repair instructions

Carlso, what happened to this group buy? Did any one talk to Rennie?

i AM IN! Carlos, lets re open this whole idea. If there is a weakness on my car, i will find/break it.
I love TMS products. Lets do this thing!

I can get us a discount from TMS for sure. Call me.

Hey guys, before we induce unnecessary panic - lift the car and check the condition of the rear subframe mounts, prior to doing anything -

Additionally, since I know a lot of folks with this issue, wanted to throw in my .02:

1- Keep in mind that there is no way to 100% prevent rust when you do reinforcements/welding in a patch way (much like the turner package). Reason is, the welding points will not have the necessary prime, so eventually they will rust. The difference with a factory prepped vehicle is that it is being dipped as a whole in a pool of prime when all frame components are welded/assembled (prior to adding everything else thereafter) - something that you can not do unless you completely disassemble the car and then perform the same technique (yes, impossible, unless you own/work for BMW A.G. ). So, if you do the re-enforcement, expect rust at some point down the road.

2- Obviously, it makes sense to compromise with future rust, rather than a) having the subframe completely come off from your car, or b)have the entire subframe and its mounts replaced. So, if you see cracks (even hairline ones) at the mount points in the undercarriage of the car, it will be time to weld the TMS parts.

3- As an alternative /compensating control, folks apply (or have tried to apply) structural epoxy. It is supposed to provide same -or better- re-enforcement distribution, as well as work without the rust effects. Problems are a)needs to be done prior to any visible damage (i.e. preventative), b) it is not cheap neither easy, and c) I don't even know if it has been done successfully...

So....currently suggested best approach:
Unless you have visible cracks at the subframe mount area, do NOT do anything; once you see such damage (even minor) re-enforce with the TMS kit. Check for damage every 2-3 months or so, depending driving conditions, style, and application (i.e. if you track every weekend, check way more often)

ON ANOTHER NOTE: Provided you do NOT have any structural modifications (read: suspension, aftermarket RTABs, sway bars, etc) there is a class action law suit that actually went through, and you are entitled for BMW to fix the problem, free of charge and even if you are out of warranty- here are the details:

http://www.girardgibb...

Obviously, if you do have AM parts, either you will have to fight a lot to get this done from BMW, or you will need to "magically" have the car back to stock...

First, you cannot see all four subframe connection points from underneath nor inside the trunk. The subframe has to be removed to be 100% sure. BMW must remove the subframe before they agree to do the structural foam system so they can totally inspect the car.

Second, BMW uses the structural foam method.

Third, once the sheet metal at the subframe is cracked it's too late and depending on how bad it is will determine the repair cost.

Fourth, if you had the subframe repaired prior to the class action then you will be reimbursed.

Again, the reinforcement kit is to prevent this failure.

I agree that in order to be 100% sure you will need to completely take out the entire subframe- however a) that costs, b) is time consuming and c) I have seen horror tears (i.e. you cant miss them) on the rear mounts of the rear subframe and they were still able to be fixed with the TMS plates. So, it is not too late if you can see the rear mount having cracks- it can still be fixed.

BMW will reimbursh you if you have already fixed the rear subframe mounts, or fix it for you if you show cracks- but again, provided that you do not have any mods- rtabs, suspension, and in some case even wheels with aggressive offsets.

The BMW structural foam is not (or has not confirmed as) being the same as an epoxy solution, and it will not work if you already cracks- so they will need to basically provide you with a new subframe. There is no proof that you will be bulletproof with the BMW structural foam.

The TMS kit is a great solution, and I don't know anyone that either didn't work for them or had to redo it. However, it has the drawback of inducing rust, so the point is, you don't gain anything by applying it earlier than just waiting to see if you get cracks at the rear subframe mounts.

Just got this email and wanted to share:

-------------cut here----------------------
We are pleased to report that the BMW 3 Series (E46) Sub-Frame Settlement has been granted final court approval. In response to allegations that 1999-2006 BMW 3 Series vehicles can suffer from sub-frame cracking that enlarges over time, BMW has agreed to provide the following benefits:
(1) If you paid for a sub-frame repair to your 1999-2006 BMW 3 Series vehicle, you can obtain reimbursement from BMW by submitting a completed claim form and proof of expenditure to the Claims Administrator. Claim forms can be downloaded from http://www.e46subfram... and should be mailed to the address listed on the claim form. The deadline to postmark you claim is September 9, 2010.
(2) If you currently own or lease a 1999-2006 BMW 3 Series vehicle, you can contact an authorized BMW dealer and make an appointment to receive a free sub-frame inspection. If the inspection reveals any sub-frame cracking, the dealer will provide a free repair as well. The deadline for free sub-frame inspections is September 9, 2010, for vehicles no longer under warranty. If your vehicle remains under warranty, you will have one year from the expiration of your warranty to receive a free sub-frame inspection.
To learn more about the BMW Sub-Frame Settlement, please visit http://www.e46subfram..., where you can download a claim form and read answers to frequently asked questions. Any extensions of the deadlines listed above will be posted on the website as well.
Many thanks to all of the BMW 3 Series owners and lessees who contacted us over the last few years to share their experiences. The relief provided through the BMW Sub-Frame litigation and settlement would not have been possible without the level of consumer involvement and concern that this issue received.
Girard Gibbs llp
601 California Street, Suite 1400
San Francisco, CA 94108
Phone: (415) 981-4800
Fax: (415) 981-4846
www.girardgibbs.com
-------------cut here----------------------

I know some m3forum.net and e46fanatics.com members got such email as well.

On that site there is an FAQ PDF, where the following are stated:
--------------------------------
Excluded from the Class are:
(1) BMW NA, its subsidiaries and affiliates, officers, directors, and employees;
(2) Insurers of Class Vehicles;
(3) All entities claiming to be subrogated to the rights of Class Members;
(4) Issuers of extended vehicle warranties;
(5) Individuals who validly opt out of the settlement;
(6) Any judge to whom this matter is assigned, and his or her immediate family;
(7) Any current or former lessee of a Class Vehicle whose Class Vehicle was modified for racing, whether sanctioned or not;
(8) Any current or former owner or lessee of a Class Vehicle that has been modified with suspension parts and/or wheels of a different size; and
(9) Any current or former owner or lessee of a Class Vehicle that has released his/her claims against BMW NA related to the Sub-Frame Condition.
--------------------------------

Soooo.....
That means that most of us are screwed, because we (a) Track our cars, and (b) Have modified suspensions.

indeed-I dont think the dealer will honor anything if you show up with your spanking new PSS10s and cool camber plates- however, if your car is in stock form they are obliged to take a look at it. I don't think participating in a track event per se (stock) would result to automatic disqualification, but if you modded the ride for racing, then obviously you will be left out.

I personally will not even bother, the day I get any cracks I will apply the TMS plates- but am thinking of doing it with the epoxy solution (read: glue for metallurgy) instead of welding, so to avoid future corrosion. Epoxy, if done correctly, can be as good as or stronger than welding.