Front Sway Bar Mount Torn Out

[sc_tr0jan_m3]

Yikes. Might need to do this since my car’s now 90% track.


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[beefaroni]

I have not seen any pre-made reinforcement plates for the E46 M3 rear sway bar. Only non-M. Before I make my own i’d like to determine if this is a problem area like it is on the E30/other cars.

[foolio]

Due to all the stories I read on the old m3forum I had mine reinforced. Seems like cheap insurance considering loss of a track day. I think I paid like $250 for a shop to do it.

[beefaroni]

Just as a followup. The repair was actually pretty painless and easy.

The loading on these points should primarily be vertical up and down movement resulting in fatigue fractures between the pressed in studs and what appears to be either drain holes or fixturing holes. In my case I believe over-tensioning of the sway bar bracket hardware and dry sway bar bushings lead to compressive and bending stresses that caused the failure to happen much sooner than it may have otherwise.

I bought the reinforcements mentioned byObioban
which upon receiving them I thought maybe they wouldn’t be thick enough. They measure in at 0.114” (11 ga.) the frame rail sheetmetal is a surprising 0.053” (17 ga.)

The drivers side was 100% intact.




The passenger side was slightly worse off.


The metal was mushroomed and had a few cracks. The metal was hammered/pulled flat then the ends of the cracks were drilled, welded, then ground flat.








M8x1.25 Grade 8.8 flange bolts (for better surface area/load distribution) were attached to the reinforcement plate with a nut. The metal was cleaned with a wire wheel drill attachment then preheated to 300 F then slow cooled (wrapped in alum. foil inside of a blanket) to help reduce the chance of brittleness.


Once the plates were ready for install, the mounting points were given a final cleanup with a wire wheel and heated to 220 F with a torch to burn off any moisture on the surface before welding. The welds were ground smooth where needed and the repair work was sprayed with a Duplicolor rust barrier rubberized coating, then top coated with black spray paint.






Glad to be clunk free once again!

[Obioban]

I used these:

https://www.moreheadspeedworks.com/product/e46-full-reinforcement-kit/

$18 is cheap enough that putting effort into fabbing didn't make sense to me.

[elbert]

Typically it happens when one is using springs on the softer side and with big bar the forces
increase and wants to pull the bracket due to lean

Track people doing Flat Ride should take note.

[chalaka]

Exact same thing happened to me as well ..
making quite some noise, and car pulls all over the places on rough road surfaces ..

i just asked for help to weld those 2 studs back to those holes and spray paint on them ..

[BBRTuning]

I did the same thing at T6 at Laguna.. ripped it right out. Techcraft Performance in SoCal welded a new ~1/4" thick pad with new studs. I believe he sells these as a kit as well.

[timmo]

If the sheet metal isn't too mangled you can probably get away with fab'ing a plate with a couple studs welded to the bottom, then weld that on top of the existing ARB bracket mounting surface.

I have a 30 mm front sway I will be installing this spring - before doing so I plan to epoxy reinforcement plates to prevent this from happening. I designed a plate based off some dimensions I found online, but have yet to actually verify fitment on my car since it's still in winter storage:

[Anri]

I have GC Race sways but no reinforcements on the mounting points. I guess its time, yeah? I love this car but the suspension sure seems to want to divorce itself from the chassis a lot

I blame the articulation of pulling in my ridiculous driveway entryway. And COVID.

If anyone else has experience here i’d welcome some feedback. I do see that the mounting points are available for sale (yes, I took a picture of my computer screen, calm down) if I wanted to have the spot welds drilled out and have fresh steel with new studs.

Hi,

Very typical for cars which are driven mostly on track with sticky tires and big sway bar up front.
I have seen bunch of cars with torn sway brackets.

Typically it happens when one is using springs on the softer side and with big bar the forces
increase and wants to pull the bracket due to lean, also when the bushings are firmer than
oem it also puts stress on the bracket.

It takes few hours to fix. Make sure you put some rubber coating so welds don't rust !

Regards,
Anri.

[beefaroni]

I have GC Race sways but no reinforcements on the mounting points. I guess its time, yeah? I love this car but the suspension sure seems to want to divorce itself from the chassis a lot

I blame the articulation of pulling in my ridiculous driveway entryway. And COVID.

If anyone else has experience here i’d welcome some feedback. I do see that the mounting points are available for sale (yes, I took a picture of my computer screen, calm down) if I wanted to have the spot welds drilled out and have fresh steel with new studs.