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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 Tue, Aug-04-2015, 06:27:54 PM   #1
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Default A few pics from a major overhaul. Reedish plates and lots more

Edit: Ideally the title of this thread should be changed as there is a lot more detail than I initially planned for. Can a Mod assist me please?
And perhaps I should brake this up into several thread as it has become a set of mega posts?

After three + months on jack stands I got to drive the M today (this was early August). What a blast!

My plan is to ad a number of write ups in this thread later on.

Until then I uploaded some teaser pics in post #5 of this thread:

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Last edited by VinceSE2; Fri, Nov-06-2015 at 02:27:46 PM.
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Old Tue, Aug-04-2015, 06:28:14 PM   #2
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Default A few pics from a major overhaul. Reedish plates and lots more

RACP repair and reinforcement

I'll start with some definitions, theory and background of how and why I believe we are seeing the " subframe failures".

Firstly I really wish our community could stop referring to this as the "subframe". The subframe is the frame to which the diff and control arms are bolted, and I have yet to see a subframe fail. It's the chassis/body panel which BMW has chosen to call "Rear Axle Carrier Panel" (I'll hereafter refer to it as the RACP) that cracks and/or pulls away from the rest of the body/chassis.

The video below shows what the RACP looks like.
For some reason James Reedish (from whom I learnt the term RACP) calls the RACP "floor" in this video. Even though the top most side of the RACP is part of the floor, I still prefer to call it the RACP to avoid confusion.

So why are these failures seemingly randomly found in very different stages?

To answer this we must understand what causes the failures.

It's not a single large load that brakes the RACP. At least not the predominant majority of failures.

In short it's metal fatigue that destroys the rear chassis/RACP (think of it as bending a nail back and forth many times). Specifically fatigue of the sheet metal that is absorbing, and/or distributing, the load from the rear axle.
The fatigue in turn is due to the load cycles (think on and off the throttle) applied to the rear axle.
And more specifically the amplitude (size), the frequency (how often) and how "spiky" (how rapidly) the load cycles are.

Someone who smoothly and progressively rolls on and of the gas, and to some degree even the brakes, may never see a RACP failure.
While someone who slams the gas pedal ,and to some degree the brake pedal, to the floor and equally violently and momentarily takes his foot completely of the gas pedal, may see failure very soon.

So I'm saying that ones DRIVING STYLE has much more bearing on the failure than WHERE you drive (street or track etc).
And this also applies to a launch. Some can launch very smoothly while others really can't, or choose not to, or are ignorant about it.

If you never track or launch, but violently and repeatedly "telegraph" (on/off) your gas pedal, you will still see failure.
But yes, multiple and violent launches will significantly expedite the failure.

So shouldn't the chassis of an M3 be able to take this kind of load? Of course it SHOULD!
But the RACP is simply:
•To week (it's s the same as for a base E46)
•AND the attachment of the RACP to the rest of the body/chassis is far from ideal.

Design flaws which I believe are due to cost control and production constraints.
We will be looking into some more details further in this post.

I hope that was understandable, English is my second language.

Anyway, thanks to this video:

I caught the failure of my RACP in a very early stage (although I had about 87 000 miles on the clock).
The last couple of years I have been monitoring this area on a regular basis.

It's the reaction torque of the drive axles that pull the rear of the RACP downwards (and in the extreme cases away) from the rest of the chassis. This video (of an extreme case):

clearly illustrates the downward force.

A bit simplified, the vertical cross section of the RACP - which runs through the threaded receivers of the rear subframe mounts - acts like a beam that takes the downward load and applies it to the OUTER MOST part of the chassis legs.

Due to the shape of this "beam", AND the distance from the subframe mount to the part of the chassis leg it is attached to, there are "hot spots" (concentrated areas of stress) as illustrated in the sketch below:

EDIT: The numbering of the different sheet metal pieces follow this numbering scheme:

Hot spot #1 is in the area where most/all RACP cracks start. The hot spot is due to the hight of the "beam" being reduced (to fit the subframe mount) and the affect of the hot spot is worsened because the sheet metal is stretched thin (weakened) in the process of forming the underside of the RACP (our "beam").

Hot spot #2 is where Reedish motorsport have identified spot welds start popping and where the RACP starts pulling loose from the rest of the chassis.
There are great videos of this on Reedish Motorsports YouTube channel, I highly recommend watching all of them.

This video gives a pretty detailed picture of the bottom side, and at about 3:55 into it it provides a glimpse of the inside as well.

I noticed a couple of these spot welds had popped before my RACP cracked.
So when I learnt that this separation is believed to initiate the crack in hot spot #1, and I was still trying to avoid welding (my RACP had no crack at this time), I strengthened the joint with screws per CCE46M3's method:

Unfortunately this didn't stop my RACP from cracking. Perhaps because it was already too far gone, or perhaps because there was still movement in the joint because I chose to leave the factory seam sealer to avoid rust issues (the screws sunk into the seam sealer).

Unfortunately I have no pic of the screw fix, but this pic partially shows what it looked like when I later cleaned up the joint prior to welding it:

Once I found the crack and had studied the benefits of welding on the Reedish plates I ordered the plates. And decided to weld the crack, ad the plates as well as weld in my rear cross bar design and my reinforcement of the top side of the front mounts.

My opinion is that, IF one has found cracks, one should absolutely have plates mounted to the underside of the RACP, AS WELL AS adding a brace/bar, AND address the top side of the front mounts (please find more on bar and front mounts further down in this post).

I chose to WELD on the Reedish plates as:
•They spread the load to a larger area than other plates
•Tie into the threaded reciever (via the plug and rosette welds)
•Are formed (during the weld process) to fit snugg against the RACP (and this is easy when you tack weld the edges of the plates that are touching the RACP, and then alter hammering the edge with a gap closest to a tack weld and then ad a new tack weld. And repeat many times).
--I don't see how this could reasonably be achieved using epoxy (as it needs to cure between the steps). And I'm not sure the epoxy bond will handle the hammering and bending.

Side note. I chose a bar/brace at the rear mount (rather than the structural resin (aka foam) as the bar not only ads even more strength than the structural resin and improves the load path (bringing the load from the rear mounts the most direct way to the chassis leg), it also doesn't limit potential future additional fixes/revisions.

Once you inject the structural resin you limit what and where you can weld.

Anyway, lets dig into STEP 1, installation of the Reedish plates.

Unfortunately I took very few pics of this part of the project.
But you don't really need these from me as Pete has done a great job with the instructions that come with the plates, and James has posted several excellent videos on YouTube well.

As I have fabricated other parts you might wonder why I bought the Reedish plates rather than creating my own plates.
I simply wanted to pay for the excellent work and information Pete and James has provided.
And it saved me quite a bit of time!

Here is how the car looked once jacked up and all the components where removed.
Notice I built rugged wooden "spacer boxes" to get it up higher so I could sit while welding the plates.

And here is what the mounts looked like after I cleaned the underside.

Left rear mount viewed towards the rear of the car. Notice the small hairline crack to the left.

Right rear mount viewed towards the rear of the car. No cracks there (as expected when finding the crack on the left rear while still so small)

Right front mount viewed towards the front of the car. No visible crack, but a clearly visible indentation to the right of the mounting hole (as expected since the subframe is tilted and pushed up against the RACP)

Left front mount viewed towards the front of the car. No visible damage,

Close up of right front mount. Hard to tell if there was cracks or just scratches and/or small indentations from the aluminum sleeve of the OE bushing.

Close up of the left rear crack after stop drilling

Close up of the right front after sanding off the paint and stop drilling just in case they are cracks.

The pic below could be seen as premature as it's part of the front mount reinforcement section further down. BUT I wanted to take this opportunity to show you that the top side of the right front mount was cracked. EVEN THOUGH the bottom side doesn't really look like it's damaged.
So if you are looking to "bulletproof" your RACP, Do Not assume your front mounts are OK.

As previously mentioned I don't have any pics of the installation of the plates, apart from these two of the bottom side of the front mount plates.

I took them because I wasn't sure if the section protruding past the underside of the RACP should be cut off or bent/formed around the edge. It should be bent/formed, no cutting of the plates should be done.This was one of very few not obvious parts of the installation.
These pics also illustrate some of the forming I don't really believe can be efficiently done if the plates are epoxied to the RACP.
I tac welded the edges that touched the RACP, hammered the protruding edge of the plate, tac welded again and so on and so forth. Oh and before welding the plates I had obviously removed the paint underneath the plates and then sprayed weld through primer.

I mostly used the dark gray looking wheel, to the left in the picture below, mounted on a power drill to remove most of the paint

Once welded and grinded I applied two coats of a POR15 self etching primer followed by two coats of POR15 Flex coat and finally two coats of Wurth seam sealer. All applied with a brush.

The Wurth seam sealer is not pictured as I had thrown away the tubes before I thought of snapping a pic.

This is how it turned out.

Left rear. Notice the small bumps on the joint between the RACP and the wheel arch. They are from welding the joint and filling the holes I had there as a result of the screw type reinforcement

Right rear

Right front

Left front

A mistake i did was applying seam sealer to the mating surface between the subframe bushings and the RACP. Because of this I had to re torque the subframe bolts as the seam sealer was "squished out" from the contact area after some driving. And getting to the left rear bolt is a PITA once the exhaust is installed...

Now lets look at STEP 2, fabricating and installing my stealth REAR MOUNT CROSS BAR.

First lets revisit my sketch.
Remember how I said that the cross section of the vertical plane going through the rear mount threaded receivers only connect to the outer most part of the chassis leg? And how this puts a lot of stress at the hotspots?

While the structural resin, aka "foam", does help relieve the stress at hotspot #1 (by stiffening the "beam" within the area enclosed by the cavity highlighted in grey)... does nothing to improve the load path from the mount to the chassis, nor does it improve how the load is dissipated to other parts of the chassis leg.
Hence my idea of improving just that. In this image I have conceptually made that connection.

But in order to avoid bending the connection and/or the vertical wall of the chassis leg one should create something that is rather rigid such that it "cleanly" applies a vertical force to the chassis led. Something like this:

Apart from providing this rather "clean" vertical force, the bar also strengthens the factory "beam" and the bolt through design also relives the "beam". In addition the bolt through design relieves the spot welds, in the vertical plane as well as the bending, attaching the threaded receiver.

Very similar to the Mason Engineering rear strut bar with the cross brace. This design is however nearly completely hidden, and does not affect the luggage space, or the ability to load larger items with the rear back rests folded down. It doesn't negatively impact the usability of the car.
Just the way I like it!

Here is how I solved it.

Using chisels I started by removing the polyurethane seam sealer to expose the spot welds and stitch welds connecting the trunk floor to the RACP.

EDIT: I've been asked if one could perform the rear bar reinforcement and the front "gusset pipe" reinforcement without completely removing the rear axle assembly (subframe and diff etc). I believe (but have not tried this) it could be done if the subframe is lowered enough to cut off the hex part of the front bolts and the drop the remaining bolts parts through the subframe bushings.
It should however be noted that when reapplying the "lid" the front spot welds will burn off the under coating right above the rear diff. With the rear axle assembly in Place it would be very difficult to repair that rust protection due to space limitations.

If you choose to perform this reinforcement without completely removing the rear axle assembly you might want to cut the "lid" right behind the elevated "ridge" rather than drilling out the front spot weld. That way welding that that seam should not burn off any under coating.
But please note that I have not tested this theory.

Then I started drilling out the spot welds, cutting the stitch welds and cutting loose the part of the trunk floor right above the aforementioned vertical cross section. This part of the trunk floor I will be calling "the lid" moving forward.
But then I realized I will need to know where to cut open the lid later on, so, from underneath the car, I drilled a hole through the top part of the threaded receiver, the top sheet metal of the RACP and finally through the lid. On both sides obviously.

Then I continued cutting loose the lid. Using a Dremel in order to minimize the width of the cut (as this would later need to be welded)

Once the lid was off I threaded the new part of the holes with a M12x1,5 (this is a bit finer pithed than the standard M12x1,75) tap (EDIT: taping the new part of the holes is probably overkill. You should be fine simply enlarging that new part of the hole be drilling a 12mm clearence hole from the top. It would be a good idea to insert the OE bolt as a "drill stop" such that you won't unintentially drill out the exsisting thread). And then measured the distance from the top surface of the RACP to the bottom lip of the chassis legs inner wall. Excluding the formed stiffening "T" there was a perfect 25 mm! This meant I could use a 25x25 mm square tub if I took care of the protruding "T" (which would no longer be needed once the bar was in place.

So I cut slots in the "T" using the Dremel. And then hammered down the "T" towards the threaded receiver.

And welded the slot and ground it off. And ran the thread tap through the holes again.

Now I cut a slot in the horizontal "lip" of the inner chassis leg wall, and bent the remaining thin sheet metal walls upward to make room for a 2 mm sheet metal plate connecting the 25x25x3 mm square tubes to the chassis leg.

As I created a bolt through design both front and rear, I now needed longer bolts. That turned out to be difficult to find (especially the front design). So I designed my own and had them made along with the two "cups" I needed for welding into the square tubes.

To keep it simple, and not too expensive, I used OEM "collar nuts" as the hex head of the rear bolts, and had the large hex spacer/nut kind of thing made as a separate item. Both the "collar nut" and the spacer/large nut are screwed on to the bolts and secured using Loctites green 648 retaining compound.

Here are the assembled bolts next to the factory bolts.

EDIT: I'm offering the bolts for sale in this thread

In this picture you can see one of the rear bolts protruding up through the rear mount

The bars and plates added and tack welded

And the cups added and ready to be tack welded

The welded bar

Test fitted

Rounded edges and holes drilled for plug welds

Holes drilled in the chassis legs to allow the plug welds to connect the inner sheet metal layer to the outer layer and the bar

The plug, perimeter and stitch welds done and excess material ground off. Prior to welding, the surfaces where sanded and primed using Wurth weld through primer. EDIT: Please note that the plates are welded to the chassis legs though plug welds in the holes, AS WELL AS with a continuos fillet weld around all of the perimiter that the plate has against the chassis leg. The reason it doesn't really show is that I ground off excess weld beads to make it look better. It's probably a better idea to leave the weld as is.
And any surfaces of the bar that would not be welded where primed with Wurth self etching primer.
Once welded the rest of the bar was primed in place.

Testfitting and adjusting the lid to fit over the bar. The area originally recessed is now "lifted" and the large hole cut out.
Unfortunately I dont have a pic of the patched up lid

Two coats of the POR flex coat paint added. And I decided to glue the side perimeters of the lid and glue the lid to the bar, a black seam sealer/adhesive is applied to the bar and side surfaces

The front perimeter plug and stitch welded. And the rear perimeter tack welded more "spots where added later).

Adhesive/seam sealer added to the perimeters.
Weights added to press the lid against the cross bar while the adhesive/seam sealer cures.

Sanded and smoothed the outside of the lid.

Another coating of etch primer and preparation for spraying carbon black

The final result

And the interior back in

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Last edited by VinceSE2; Fri, Nov-27-2015 at 09:40:44 AM.
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Old Tue, Aug-04-2015, 06:28:35 PM   #3
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Default A few pics from a major overhaul. Reedish plates and lots more


Regarding the front mounts I would say the critical aspect is the bending/twisting/tilting (depending on what you call it) rather than the compression or even the lateral force (if isolated).

And specifically the twisting/tilting of the front right mount. Partly from lateral force, but probably more so from the combination of the drive axle torque and the prop shaft torque.

Vastly simplified, imagine removing all the subframe studs/bolts except the front right (passenger side). And now pulling down at the rear left subframe mount. The front left stud/bolt will now be trying to bend the threaded receiver loose from it's position between two sheet metal layers (the top and bottom of the RACP). In addition imagine a lateral force from cornering your M and finally imagine this being repeated over and over again.

What happens is the threaded receiver starts to come loose inside the RACP. And it can look something like this:

My car (notice the small hairline crack to the bottom of the picture, adjacent to the plug weld)

Member EricSMG's car

Member CCE46M3's car

Viewing the pic of my front mount, notice the crack that has started around the weld (the one at the bottom in the pic. Towards the middle of the car in reality).

The threaded hole in the middle is part of my procedure (drilled diameter 10 mm from under the car and then threaded M12x1,5) and is not there originally. I have also exposed the top of the RACP using a 51mm hole saw.

EDIT: You can save your self some work and the need to buy a M12x1,5 tap by drilling a 12mm clearence hole from the top rather than threading that new piece of the hole. You might however want to be careful to not drill out to much of the factory thread.

Here is how I carried out this reinforcement

Drilled a 10 mm hole from the underside of the car (subframe removed).

This takes us through the top of the threaded receiver, the top of the RACP, and finally through the "floor pan" behind the rear seat.

Perfectly centered by the ID of the threaded receivers M12 thread.

Here you can't really see where the drill exits as the hole is covered by the bracket. (BTW this is the left front mount. The following pics can alter between left and right).

And here I have used a spot weld drill to remove the bracket exposing the hole.

In hindsight it would have been better to remove the bracket first, but I wasn't quite sure where the drill would exit.

Next I bought a kit of hole saws and replaced the 6 mm center drill with a dia 10mm rod with a dia 6 mm piece (welded on as I don't have a lathe myself) with which I could attach it to the hole saw.

EDIT: I'm now offering properly turned "drill guid rods" for sale.

And then it was pretty easy to get a nice clean cut!

Back to the close up of the right front mount, notice how perfect the OD 51mm hole saw met the top of the RACP (the cut mark on the RACP)

Here I have stop drilled the crack:

Welded the holes:

A bit of grinding:

And then my reinforcement "pipe" which has 2mm wall thickness as well as a 2mm "bottom" (cut using the same hole saw) that is welded against the top of the RACP and the pipe and later welded to the top of the threaded receiver (via the original welds)

What you cant see here is that I ground of a "step" from the front most of the "pipe floor" so it would sit flush against the top of the RACP (which has a small step on it's front most part).

I then welded the reinforcement "pipe gusset" to the top of the RACP (through the holes) as well as welding it to the wall/floor pan behind the rear seat. This acts as a structural gusset. And distributes some of the twisting/tilting force, and compression force to the sheet metal layer above the RACP.

And finally it's all tied together using using my custom, extended bolt, a 3mm thick washer and the OE nut which has, what I call, a collar:

And on the bottom side of the RACP I have, as previously shown, the 2mm thick Reedish plate welded to the RACP as well as to the threaded receiver inside the RACP. Reinforcing that end of it.

And here are a couple of pics tidying it up with POR15 etch primer and the OE Carbon black without clear coat.

And once the carpet and sound insulation is put back on you can't see it at all.

So there is more to this than a washer and a nut. This ads the structural support I believe is needed.

And there isn't really all that much space to do a lot here. Unless you go for the brace/cage sort of idea member HassanEido had made (Which I believe is an excellent, albeit space consuming, solution) in this thread :

STEP 4, rust protection of the cavities and treating the under body.

In the last pic of the front mount reinforcement you can se one 10 mm hole on each side of the top of the "pipe gussets". These are 4 of the holes I drilled and/or used to spray a thin bitumen/oil/wax rust protection product all around the inside of the cavities where I had welded.

I also took the opportunity to spray all other cavities of the body as the climate here leads to salty roads in the winter (yes, I do drive it all year around).

The yellow can on the left

Using this handle/tube:

With a multi hole nozzle at the end

Due to the North East US winters and the winters here in Sweden there where quite a few rust spots uncovered on the underbody once I had it all cleaned up (it was very greasy and dirty).

To make a long and rather messy story short, I grounded off any loos rust, degreased those areas, treated the areas with POR15 metal prep and then applied 2-3 coats of the excellent POR 15 rust preventative paint.

This how it looked:

I then applied the Wurth seam sealer:

And finally a few coats of a really cool, water based, synthetic latex product called "Body elastic". The right most can in this pic:

Gearing up for spraying the underside. My youngest daughter keeping me company while decorating the floor. She was very happy about such a large piece of paper

It's initially blue when sprayed, but turns black once it dries. Making it easy to see when and where to spray once on the second and third coat.

Once the underbody was sprayed I cleaned out all the threaded holes by running the appropriate tap through them. When installing the components I also cleaned the threads of the bolts and applied Loctite where appropriate.

But prior to spraying the Body elastic spray I made the mistake of spraying a thicker (than the cavity spray) bitumen/wax product (the red can). It never dried, leaving a rather unpleasant sticky kind of asphalt surface. Needless to say I was not happy with this and had to clean the underbody with paint thinner. I do not recommend making this mistake!

STEP 5, refresh of subframe, trailing arms, brackets and braces etc.
Plus cleaning the plastic under panels.

While having everything apart I took the opportunity (and extra time) to grind of rust and use the POR 15 products to treat most of the steel components of the rear axle and bracings/brackets. AND clean the waxy stuff off the plastic under panels.

I did however notice something that I had previously not realized (even though I should've realized this as its quite light for it's size).

The large V-brace supporting the rear axle has hollow rectangular steel profiles, and NOT homogeneous steel bars as I thought.

So what I thought was surface rust was in fact serious rust damage to the structural integrity of the V-brace. Rust starting from the INSIDE of the rectangular profiles and expanding such that the rubber coated outside of the profile is pushed outwards.

Because of this I ordered a new V-brace and treated it by sealing the holes where salt and water makes it's way into the hollow profiles as shown below.

The underside of the V-brace (what i had mistaken for surface rust):

The top side where the welded seam has been severely damaged by rust:

And these pics show the holes I believe are the culprits of this rust damage:

The center bracket that bolts to the subframe. Notice the rectangular holes showing that the V brace uses hollow profiles.

And a view from the center, looking outwards, showing the rust damage. Please also notice the small area where I pealed off some of the factory rubber coating (under which the rust had flourished)

And a view from the outside facing inwards. Notice the smaller hole located just next to the mounting hole

Both of the pics above are on the underside of the V brace

So as it obviously wasn't going to be enough grinding and painting this V brace I bought a new one and treated it.

And here is a pic of the new, treated, V brace installed against the rest of the restored components.

You can just about see that the rectangular holes are covered with a flexible seam sealer product (same as I used to "glue" the trunk floor piece back on top of the RACP reinforcement bar).

I did the same to the smaller holes on the outer ends as well.

(this pic is taken after a few months of driving after the overhaul)

These pics lead us to the restoration of the subframe itself, trailing arms, brackets, diff (outer surface + seals) and other rusty steel components (my car has done several winters in the north east of the US as well as here in Sweden).

The pic below shows just a few of the components I took care of, but shows the starting condition.

I ground off the rust using several different tools, here are the ones I mostly used:

As I've mentioned I used POR 15 products.

First their de greaser, followed by their metal prep, and two layers of their rust preventative paint and finally two layers of their flex coat. The last two layers because I wanted to maintain the glossy (non sticky) surface and the rust preventative paint is affected by sun light

Here are some of the components after the metal prep step. Notice how the bare metal surface is etched and dull:

I also thoroughly cleaned the plastic under panels and the aluminum heat shields several times using Turtles extreme prewash

(which is great as its more of a gel than a liquid, and thus sits there working rather than just slides off or evaporate)

and a stiff brush. Apart from removing all the oil, grease and other gunk build ups, this also took care of the waxy yellow stuff on the plastic panels.

I didn't take very good pics of the result of the painted components and the and cleaned plastic and aluminum panels, but here are a few pics where you can see some of it:

Last edited by VinceSE2; Tue, Dec-08-2015 at 09:08:18 PM.
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Old Tue, Aug-04-2015, 06:29:02 PM   #4
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Default A few pics from a major overhaul. Reedish plates and lots more

Bushings and transmission

When the body flexes (which it does) I believe the stock and poly bushings will allow the body and the tubular subframe to flex more or less independently without adding extra, concentrated, stress to the bolts -> threaded receivers-> the threaded receivers connection to the RACP (which is an issue withe the front right mount specifically).
An OE bushing should minimize this, but the stock bushing has the "lip against the spot weld issue".
A poly bushing ads a bit more of the stress I described above, but has a significantly larger area distributing the upward stress of the front mounts to the Bottom surface of the RACP.
This is why I chose the yellow Polyflex poly bushings rather than solid aluminum ones.

I also replaced the front diff bushing (in the subframe) with a new OEM bushing. I didn't however replace the rear diff bushings as I wanted OEM's and you need to replace the diff cover to get them. They also looked to be in good shape.

I replaced the outer control arm bushings with new OEMs, but chose to not replace the inners(even though I had bought them) as they looked brand new.
I also replaced the rear wheel bearings and the RTABs. Removing the Polyflex units I've had for about 7 years (they looked great BTW) and installing the BW bearing style ones.

As discussed in this community, the tolerances of the bore diameter of our trailing arms, as well as the width (at the bore), are wider than desirable for a press fit metal bushing/bearing (it's designed for a compressable rubber unit). After cleaning my bores with this:

I found I had a proper press fit in one of the arms, but more of a finger tight press fit on the other. I also found that I had a small gap between the sides of the arm and the flanges of the bearing house. So I asked BW for the shims, and once I had them, I used Loctite 648 in the bores and the shims on both sides. In this image you can just about see the aluminum shim on the left side.

I'm very happy with these bearings so far!
I do experience a "tighter" and more predictable rear end, and believe some of the crisper cornering stems from these bearings as well.

But it is a bit hard to tell as i also replaced the original OEM FCABs with BW's TrackCAB's

When checking them out prior to the installation there was noticeable play between the delrin bushing and the aluminum housing. So I was a bit worried that there would be clatter and/or other noises. I also found that the hex ends of the control arms (that go into the delrin bushing) has a longitudinal "ridge" that look like the result of the casting/forging tooling. And even though I filed off the "ridges" and lubricated with copper paste, it was pretty tight getting the bushings on to the control arms. But once on, the play between the bushing and housing was gone.

I also had to cut the bosses that support the aluminum under tray. Without doing so I would have bent the aluminum under tray which is not something I'm willing to do. This boss is BTW a benefit of BW's design compared to the Tree house version

These are videos I made to show/explain the issue to the BW technician. I ended up cutting about 4-5 mm off the boss (I call it "the stud" in the video), which made him very surprised.
But, as seen in the videos, it needed that much modification.

Other than a bit more modifications during the installation than I expected, I'm VERY happy with BE TrackCAB's as well!

As the prop shaft was down I took the opportunity to replace the flex disc (guibo)and center bearing with a new OEM parts.

As for the engine/transmission mounts I chose a moderate upgrade (as in firmer, but not crazy so).
I went with Bimmerworlds performance/track engine mounts (the group N replicas)
(Love these BTW! Some complain about the vibrations, but I find it to be very involving and exciting with the vibrations).

And the Rouge Engineering transmission mounts

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Old Tue, Aug-04-2015, 06:29:27 PM   #5
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Default A few pics from a major overhaul. Reedish plates and lots more

Water/Meth injection

As I desired a stealth installation I decided to mount the tank where the CD changer and navigation unit would sit if you have those ("stole" this idea from member Tscleung although he has a custom tank). As I don't have those options I pulled out this:

And fabricated this bracket to fit the Harman Kardon amp and the AEM tank

Welded these two (bottom right corner of the pic below) 6mm rods (with approx 15 mm M6 thread at the top) to the boot floor while doing the RACP reinforcements.

Painted with CB base coat (no clear) for Factory look

Cut out some of the styrofoam and mounted the pump with part of an exhaust clamp

Routed the hose from the tank through the chassis leg

To the filter (which I placed recessed in the styrofoam)

And further through the styrofoam to the pump

And up through the right chassis leg

Followed the battery cable forward through the drug bin and further in the engine compartment. Conveniently there was a factory hole in the sheet metal below the cable harness.

I just needed to replace the right rubber plug with the left one which has a hole in it.

And finally looped over from the right side to the left side

I placed the control unit in the center console by the e-brake and will have it concealed using the Euro tray

EDIT 01/12 2016: finished concealing the control unit in a Euro tray.

I started by cutting openings on the sides to allow the broadest part of the control unit to protrude through the opening. At first I planned on having the unit lay flat against the bottom surface of the tray. But I soon decided to have it sit a bit slanted, so I build a wedge, or slanted surface using a silicon like seam sealer.

And to close the gap, due to the angle, at the top of the control unit I had a strip of sheet metal formed around the top of the control unit

Prepped one side with lip balm (I believe you call it chap stick in the US) to have it release from the seam sealer

And used it to mold a wedge that would follow the contour of the control unit.

I later trimmed it a bit and also cut a hole in the bottom surface of the tray

And test fitted the control unit

While the seam sealer was drying I enlarged the bottom hole in the center console as well as drilled a hole for the vacuum hose

And here's the unit and the tray assembled to the console

And hidden once the tray is closed!


And placed the LED in the left vent next to my P3cars gauge

So all in all a pretty concealed and stealth installation which works very well.

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Old Tue, Aug-04-2015, 06:29:50 PM   #6
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Default A few pics from a major overhaul. Reedish plates and lots more

The faster yellow tag 712 "ZHP" steering rack

As my high pressure power steering hose had (like most do) been leaking, or rather "sweating", for some time, AND I had the car sitting on high jack stands, I felt like I might as well swap the steering rack while replacing the HP hose (with a new OE hose).

Having done some research on this excellent forum I understood that there are two important factors when choosing a quicker rack:
• The ratio obviously
• The amount of power assistance

The ratio of the:
- Standard M3 rack is 15,4
- CSL/ZCP rack is 14,5
- ZHP (yellow tag) rack is 13,7
So the yellow tag is significantly quicker.

The difference in the amount of power assistance was new to me. But apparently there are some 330 racks (purple tag IIRC) that are as fast as the yellow tag, ".712" or "ZHP" rack, but they have more power assist and therefore don't supply the excellent feedback the yellow tag rack does.

Having done some more research knowing the ZF part number (7852 974 712) of the rack I desired I found that these racks where installed on the -02 and beyond Diesel E46's. Both the 330d, AND the more common 320d. So I found a nice low milage yellow tag off a 320d.

Through my research I had learned that it fits bolt on to the M3 reusing the M3 tie rods and dust boots (I reused the M3 dust boots, but as far as I could see the dust boots are the same).

I soon found that the two bolts holding the rack to the front subframe where not going to give in without a serious fight. So because the nuts are on the top side and pretty difficult to get to I decided to release the front subframe from the chassis legs (this also helped when replacing the engine mounts).
So I improvised a bit and built a wooden engine support beam.

Here you should see the front subframe tilted and the holes for assembling the rack are pretty much in the center of the pic.

And here the "new" rack is going in.

This is an awesome mod that should be a must for anyone who enjoys spirited driving, auto cross or track events!

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Old Tue, Aug-04-2015, 06:31:22 PM   #7
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Default A few pics from a major overhaul. Reedish plates and lots more


For the exhaust I had planned work in three areas. One repair out of necessity, and two modifications that falls in the performance/vanity category.

Repair of muffler flanges.

When removing the exhaust I noticed that one of the muffler flanges had cracked completely off. And the other one was in very bad shape.

Even though there are new OEM flanges available, these are meant for the section two pipes. Or rather one of the two section two pipes. The other pipe has a cone (like both the muffler inlet pipes) and thus it's flange can't be removed/replaced.

But as I had an idea of how I could replace the flanges on the muffler inlet pipes I ordered two of the section two flanges.

Then I cut off the coned tip of the inlet pipes and easily slid one of the flanges onto the pipe. The other one would however not fit!

This is when I realized that one of the section two pipes slide into one of the muffler inlet pipes. Whereby one of the muffler inlet pipes has a larger OD. The one to the right in this pic.

So I had to spend a lot of time enlarging the flange ID using the Dremel, with multiple disks stacked against each other, and running it in a circular motion.

This pic shows the amount of grinding dust generated from this exercise.

Once the flange fit, it was just a matter of welding the cone parts back on. Because of space limitation (the short length of the inlet pipes had the flanges cover too much of the area I needed to weld) I welded from the inside of the pipe and then ground of the excess weld bead using the same method as when enlarging the ID of the flange.

Modification for "OEM+ sound"

Just like most of us in this community I do believe the stock exhaust is a bit to quiet and toned down. But I utterly and completely hate drone and I wouldn't even think about driving around in a load mouth kind of ride. And unlike most of us, I love the rasp as I find it to one of the defining things about the E46 M3 and the S54 (as well as the Euro E36 M3and it's S50).

So, apart from almost getting a Dinan muffler some 6 or so years ago, I have chosen to stick with the stock muffler.

However, after have replaced the US headers and section 1 with the Euro headers and catted section 1, I did find that to sound a bit deeper and louder. And I liked it. That's when I started looking into modifying the stock muffler, and perhaps running cat less.

Having read this thread:

My conclusion is that removing the sound damping fiberglass out of chambers 1, 2, 3 or 5 doesn't really do much.

To make a difference one needs to address chamber 4. This is where the deeper tones are muffled by reflection (I think).

So by studying this pic:

for a long time I came to the conclusion I would try bypassing the reflection chamber by connecting the inlet pipes with the outlet pipes. But not side wise as others have done, I wanted to have all the noise mixed and coming out on both sides of the muffler.

The first step was to open up chamber 4 and make sure I could patch it back together later on.

Once open I measured the inlet and outlet pipes and the distances to figure out what could be done.

Chickening out a bit I decided to only bypass chamber 4 with one of the pipes. I was worried it would be too loud for my liking.

So I ordered three (what we call) weld (in) bends with tight radiuses. One 2 1/2 inch and two 1 3/4 inch.

After I cut one of the inlet pipes and tested the embryo for my "Y-pipe", I decided to go with the "pair" with the furthest distance.

So I measured, test fit, adjusted and repeated this a few times. Ending with the basic shape I wanted.

Then I focused on achieving a nice looking flow between the different sized bends.

But once welded in place I chickened out again... I thought maybe I would screw something up by having one pipe flow more freely than the other. So I improvised and drilled a bunch of holes that could allow some sort of pressure equalizing.

Once this was done i welded the other inlet pipe back in.

And weld it shut.

Here is a short video sound clip of idle and varying revs. Will add a drive by when I have some assistance.

Cat less section one with EGT and O2 bungs

As I had the US section one, and the US headers, laying around, I decided to cut the bungs off the headers and weld them to the US section one. That way I could correctly attach the O2 and EGT sensors while running cat less.

This, along with the muffler mod, did in fact produce the OEM + sort of sound I desired! And it had a cool kind of snarl slowly moving away from a stand still (this could however have been a leak from a crack in the section one flange).

And the first impression regarding the smell, from running cat less, was that it wasn't all that bad.

But fast forward a couple of weeks and it got pretty old and embarrassing with the smell. Especially as it made the car feel old and the smell "stuck" to my clothes.

So when the section one flange broke loose:

I took that as an excuse to go back to the catted section one. Which also made it a bit quieter again. But still a nice OEM + kind of sound.

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Last edited by VinceSE2; Mon, Jun-26-2017 at 01:32:22 AM.
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Old Tue, Aug-04-2015, 06:45:09 PM   #8
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Default Re: A few pics from a major overhaul. Reedish plates and lots more

Impressive amount of work!

What's going on with that steering rack?

Also, you know they make engine supports out of metal that you can buy these days :P
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Old Tue, Aug-04-2015, 07:40:03 PM   #9
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Default Re: A few pics from a major overhaul. Reedish plates and lots more

Originally Posted by Drewster View Post
Impressive amount of work!

What's going on with that steering rack?

Also, you know they make engine supports out of metal that you can buy these days :P

It's the yellow tag "ZHP" rack. Quicker ratio and no over boost kind of feeling ( which some other fast ratio racks have). It turned out that -02 + European Diesels have that rack. I found a nice low mileage one.
When I was in there I also cleaned up and replaced the motor mount with Bimmerworlds OE looking stiffer ones as well as their Tree house style lollipop FCABs. The front end feels great now

so their are steel bars.
I simply wasn't planning for that job so I took some stuff lying around and built a support. It worked pretty well.

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Old Tue, Aug-04-2015, 10:04:37 PM   #10
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Default Re: A few pics from a major overhaul. Reedish plates and lots more

Originally Posted by VinceSE2 View Post
My plan is to add a number of write ups in this thread later on
Nice build. Hope to see that!

Really like what you need for the methanol setup.

Photos of My ///M3
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Discussing A few pics from a major overhaul. Reedish plates and lots more 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 (E30 M3 | E36 M3 | E46 M3 | E92 M3 | F80/X)