Now for the serious work. First, clean off all the dirt around the subframe mounting points. Then prep the metal for welding by sanding down the area completely down to the bare metal. Once the paint and undercoating is removed, you can see the damage clearly.
Apr 05, 2014 Hi Guys So after reading the updated Jezebel thread which mentioned subframe cracks, I decided to go and have a look at mine (2002 E46 330i). And to my surprise (probably believed like most owners that this would not happen to me) I found a crack on the left side: The previous owner. NOW WIDELY REGARDED AS THE WORLD’S BEST E46 SUBFRAME REINFORCEMENT PLATE KIT NEW. Our engineers has developed a kit to offer a cost effective long term solution to the well-documented problem of floor cracking which the BMW E46 series suffers. The company began in late 2016 to answer the growing problem of E46 BMW RACP/subframe cracks and failures. After discovering significant cracks in our low mileage E46 M3, we put our engineering abilities to the test and began developing what is now a comprehensive range of CMP reinforcement products for E46 BMW’s. Since the chassis' debut in 2000, the rear subframe issues have been a constant source of worry from owners. The subframe mounting points in the chassis are prone to cracking and have failed in some cases. BMW and aftermarket companies have all come out with weld-in reinforcement plating to help prevent this issue.
Before welding up the cracks, Precision German Performance recommends drilling tiny holes at the ends of every crack. These stop-holes will keep the crack from continuing on in the event that the welds don’t hold. Think of it like an anchor for the welds.
This is a good time to inspect the factory spot welds on the entire rear floor. The rear floorboard is made up of several sheets of metal all spot welded together. If you look closely you might even find that some of your spot welds have popped loose. We spotted some behind the driver’s rear wheel that had popped loose. We went ahead and drilled those holes out before welding.
Once the cracks and holes are all welded up you must grind down the welds in order for the reinforcement plates to lay flat against the car. Next, tack weld the BimmerWorld plates on to the undercarriage. You may need to hammer the plates to contour to the body first. Next, fully weld all the way around the plate so no moisture will get in. Also fully weld up the rosette holes in the plates to strengthen the plate. Then grind down any rosette welds that may keep the subframe from lying flat against the chassis. Lastly, spray paint everything to keep welds from rusting.
For badly cracked floorboards, you will have to go thru the cabin of the car, cut into the top side of the floorboard and then weld up more cracking. The kit comes with two rectangular plates for you to plug up the access holes you cut into the top. My car wasn’t that bad so we were able to avoid this.
Reinstall everything in the opposite order of removal; gas tank, subframe, driveshaft, then exhaust.
CONCLUSION
This feels like a different car. There’s no unwanted rear steering and no more thud noise when shifting and accelerating hard. Best of all, I now feel very confident launching the car and shifting in turns. It’s a horrible job. Probably the worst type of repair I’ve ever had to have done on any of my cars, ever. But it is an absolute must on any E46, whether you have the thud symptoms or not.
For those of you who prefer video, here’s a recent episode we shot doing this except job on our ’01 E46 M3 Cabriolet drift car project. Enjoy!
Product Description
These BMW E46 Rear Subframe Reinforcements weld directly onto the chassis – properly reinforcing the subframe mounting points to eliminate the possibility of a failure. An E46 rear subframe reinforcement kit is the only solution to prevent cracking and/or tearing of the sheet metal, caused by torque loads traveling up into the chassis through the inadequate mounting points. Those cars that are swapped, tracked and/or raced are guaranteed to experience a failure – prevent it with our E46 rear subframe reinforcement kit!
Our race-proven E46 rear subframe reinforcements are the thickest on the market and are engineered to properly reinforce the failure-prone mounting points. Unlike other kits, these E46 rear subframe reinforcements strengthen the area correctly, by utilizing extra-thick steel which is designed to precisely cover only the surface area of the chassis that is vulnerable to drivetrain torque loads. This provides for both stronger chassis mounting points AND an easier installation!
Precision CNC laser cut and bent. Set of four reinforcement plates and two spacers. Professional installation recommended – welding required.
Original AKG design. Learn more about Genuine AKG Parts.
Recommended Use: RACE / STREET
NVH Increase: NA
Designed for the following models:
BMW E46 (1999-2006) 323, 325, 328, 330, M3
Made in USA
$120.00
Bmw E46 Subframe Crack Symptoms
Out of Stock