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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 Fri, Jan-24-2020, 07:07:41 PM   #11
kusiobache
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Default Re: Subframe reinforcement

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Originally Posted by Drewster View Post
The consensus is that a reinforcement from the top is the best solution.

This isnít necessarily a one-time permanently successful solution like the guy asked for.

For example, Iím pretty sure that many years ago if someone asked for the best solution most answers would not have said anything about reinforcement from the top.
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Old Fri, Jan-24-2020, 07:39:44 PM   #12
Drewster
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Default Re: Subframe reinforcement

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Originally Posted by kusiobache View Post
This isnít necessarily a one-time permanently successful solution like the guy asked for.

For example, Iím pretty sure that many years ago if someone asked for the best solution most answers would not have said anything about reinforcement from the top.
It is the best solution that addresses root cause. Unfortunately it's complicated and wasn't really commercialized until the past few years
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Old Fri, Jan-24-2020, 08:21:04 PM   #13
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Default Re: Subframe reinforcement

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Originally Posted by Aeko View Post
These videos actually did an awesome job showing the issues with just a plate reinforcement (even though they did try to do an early topside "fix") and how to properly address the RACP issues
What I see is a M3 that had a V10 put in it, reinforced 10 years ago with whatever they had for a solution back then, subsequently tracked HARD, and then sold to someone who clearly didnt care for the car at all and probably thrashed around in it doing lord knows what.

These cars have subframe problems, no doubt. I'm getting mine reinforced before April. But I think it's a little extreme to suggest this video is indicative of the extent of the problem.

Thoughts? I'm open to adding more on to the repair, but I would need some more examples of your typical M3 falling apart as much as the one in this video. At that point I'd just sell the thing.
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Old Fri, Jan-24-2020, 09:35:28 PM   #14
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Default Re: Subframe reinforcement

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Originally Posted by Seagull View Post
But I think it's a little extreme to suggest this video is indicative of the extent of the problem.
Then go look at any number of other threads and videos with varying degrees of issues in cars that have only been street driven. All of these chassis were made virtually the same way, they all suffer the same problems.

Yes, there is a higher incidence with higher horsepower and abuse, but the point is this is a design flaw endemic to the e46 and they all suffer it, no exceptions. Whether or not it will develop into a serious issue on any particular car is a matter of time. M3s and even 330s with high miles and no RACP issues are starting to become the exception and not the rule.




Edit: Here's a *318i* with suframe cracks. A 318!!

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Last edited by Aeko; Fri, Jan-24-2020 at 09:48:17 PM.
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Old Sat, Jan-25-2020, 12:54:13 AM   #15
Seagull
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Default Re: Subframe reinforcement

Poor wording on my part. I should have elaborated more where you quoted me. In your OP it sounded like you were saying that the video shows that a plate reinforcement alone is clearly not enough. I was only trying to make the point that the video in question isn't a good example to use. If there were more typically driven cars coming in after getting the plate reinforcements with cracks spreading, then yeah that would be a serious problem! But I havent seen much of that. Not saying it's impossible and not out there, but from what I've heard around it seems the plates are a reasonable solution for your average driver. Add in some top bar support for the track and keep it corrosion free and you're set.

But maybe you know of some examples of people getting the plates welded in and the RACP still falling apart?

I completely agree that the way the RACP is put together is absolutely shameful. I'm scratching my head as to how there isnt a class action on this. Clearly the subframe cracking is as sure as the sun rising in the east. I just hope I didnt miss something about the plates not being enough.
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Old Sat, Jan-25-2020, 04:53:07 PM   #16
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Default Re: Subframe reinforcement

Here is what HMB here in Sacramento told me they do and runs about 3k based on what Josh quoted me recently:

"These cracks always start at the forward passenger side mount. We always check that area first for the crack the leads from the mount stud out and up over the curve of the sheet metal. Exactly where yours is cracking. Once you can see the crack going up and over, like yours is, damage is already done. We remove the whole rear suspension, clean the underside really well, inspect for all cracks and failed spot welds, drill holes in the end of each crack to prevent them from spreading, Weld all cracks and around each mount stud hole, grind it flat, weld in the reinforcement kit, epoxy prime it, add seam sealer around the welds, then use undercoating on top of that then paint it to match the factory undercoating color. It is very lengthy process to do it correctly. When the whole rear suspension is down, we highly recommend replacing all the subframe bushings, differential bushings and rear trailing arm bushings. We also recommend resealing the differential, which just like yours, is leaking from the front pinon seal (see attached photo). We call this bulletproofing the rear end."
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Old Sat, Jan-25-2020, 07:14:48 PM   #17
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Default Re: Subframe reinforcement

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Originally Posted by mixxalot View Post
Here is what HMB here in Sacramento told me they do and runs about 3k based on what Josh quoted me recently:

"These cracks always start at the forward passenger side mount. We always check that area first for the crack the leads from the mount stud out and up over the curve of the sheet metal. Exactly where yours is cracking. Once you can see the crack going up and over, like yours is, damage is already done. We remove the whole rear suspension, clean the underside really well, inspect for all cracks and failed spot welds, drill holes in the end of each crack to prevent them from spreading, Weld all cracks and around each mount stud hole, grind it flat, weld in the reinforcement kit, epoxy prime it, add seam sealer around the welds, then use undercoating on top of that then paint it to match the factory undercoating color. It is very lengthy process to do it correctly. When the whole rear suspension is down, we highly recommend replacing all the subframe bushings, differential bushings and rear trailing arm bushings. We also recommend resealing the differential, which just like yours, is leaking from the front pinon seal (see attached photo). We call this bulletproofing the rear end."
Thank you Drew & Mixxalot. What you both provided is very helpful to new members.
$3K is a substantial amount I don't see we have much choice to safely enjoy our cars.
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Old Sat, Jan-25-2020, 07:44:15 PM   #18
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Default Re: Subframe reinforcement

Used to have nightmares of RACPs until I finally did CMP topside with front extension.

And that was with the car already fully plated & seams welded, as a preventative measure, from underneath.

If you are planning to keep the car around for a while, just get it done..
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Old Sun, Jan-26-2020, 02:47:03 AM   #19
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Default Re: Subframe reinforcement

FWIW on my first M3 I only used a Turner reinforcement kit at 46k miles. Tracked the car hard for 6 years. Never had any cracks or issues for 40k additional miles. My second M3 is getting Reddish plates and only the bottom plates.

Top side reinforcement may seem like a good idea but I guess I need to have it fail on me before I believe in it.
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Old Sun, Jan-26-2020, 05:04:52 AM   #20
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Default Re: Subframe reinforcement

I purchased the entire CMP catalogue for my M3. Including the 6-point brace. Rear end is stiff as fark now. At least I know the RACP issue is permanently fixed!

OEM rubber all throughout the rear end (including oem diff bushings), poly black rtabs and CMP solid aluminium subframe mounts.

Have a look at my thread. Best kit available IMHO

http://www.m3forum.net/m3forum/showthread.php?t=604018
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Discussing Subframe 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)