Subframe Reinforcement Status Thread

[scubastove]

Just picked up my new (to me) 2002 M3. I brought it to my shop (VAC motorsports in Philly) for a subframe analysis. The tech mentioned that since he saw no cracks or any signs of stress to the area, he recommended the foam injection remedy that BMW offered back in the early 2000's. According to him, if the subframe mounting points are in good shape and show no signs of cracking, he stated that he did not want to drop the rear subframe, galvanize the steel and weld in the plates. Mind you this is coming from VAC motorsports, they specialize in these cars and know their stuff.

Has anyone had any experience with the foam injection process for subframe reinforcement? And what have your results like? Eventually I'll wind up reinforcing it, I just want to only have to do it once. Thanks!

[Stepstools]

Interested to hear something on this as well. The shop that did my PPI back in November said the subframe was clean and I checked personally last week when I had the rear end up for shock mounts and diff bolts. What is recommended for a car with an undamaged subframe that might see some occasional track time in the near future?

[eacmen]

Watch the videos online from Reddish. Most of the subframe damage is typically covered by the subframe when its mounted to the vehicle. Once you see cracks without dropping the subframe then it has gotten quite bad.

I would recommend at the very least lowering the subframe enough to see above it.

If you plan to keep the car you need to start budgeting for a real solution. Redish, VinceBar, CMP, Mason all have good solutions with their own pros and cons.

[liam821]

Mine was visibly cracked without having to drop the subframe, once I did it was even worse under. I ended up having all the cracks welded and fixed, welded plates on, and will do the foam on top. The foam is fairly cheap, easy to do, and works well so why not. My car had 110k miles without any sort of reenforcement done - i brought it broken.

I guess it depends on if you track your car, the type of suspension etc, but I'd have plates welded on and do the foam, but I track my car so I'm probably harder on my car than most.

[clawhamm3r]

I DIY'd mine and was involved in another DIY. What I saw was enough to convince me there is no such thing as one of these cars with no subframe mounting cracks. And you won't know until you drop the subframe and grind it down to the bare metal, at which point you might as well weld in the plates. By the time you can see the damage from a visual inspection, it's probably the passenger front which means the driver rear is toast.

Census on the old forum was that welding with foam in place was a fire hazard. Wouldn't do it if you're planning on reinforcing later.

[PerformanceEurowerks]

We have reinforced numerous E46s and E36/8 Z3s and highly recommend doing it whether you see a crack or not. As other's have mentioned, you won't really know the full extent of things unless you lower the whole rear assembly and grind down the undercarriage coating.

What is just as important is that you weld with a clean surface and take necessary precautions to minimize any type of inner cavity or external corrosion after the reinforcement. With us being in the Midwest, many of our clients drive their cars all year round. We are often exposed to a lot of salt on the road. So when we reinforce our client cars, we go through extensive measures to minimize the risk of corrosion.

Our general undercarriage sealing consists of the following; weld through primer before/after welding, seam sealer, rubberized coating, paint, and inner cavity sealer.

[wahsm]

I DIY'd mine and was involved in another DIY. What I saw was enough to convince me there is no such thing as one of these cars with no subframe mounting cracks. And you won't know until you drop the subframe and grind it down to the bare metal, at which point you might as well weld in the plates. By the time you can see the damage from a visual inspection, it's probably the passenger front which means the driver rear is toast.

Census on the old forum was that welding with foam in place was a fire hazard. Wouldn't do it if you're planning on reinforcing later.

Mine didn’t have cracks. Not all of these cars do do and this was after tracking the car for 2 years. Reinforced anyway since I was replacing all the bushings and upgrading the suspension

[karter16]

If you don't drop the subframe and completely clean the RACP then you don't know for sure if you have cracks or not. Period.

Mine had cracks (approx 15-20mm) which I elected to drill and weld. I then bonded plates with structural epoxy. The rear mounting points of my RACP had previously had the foam done by BMW. There was no cracking in the rear mounts. The front mounts (which weren't part of BMW's foam procedure) had cracks. I plan to do the foam on the front mounts in the near future.

[aapilcher]

I had the CMP stuff (Topside Beam Kit, Plates, and Frontside beam kit, underside plates) installed a couple months ago. My M3 has 72K miles, and the shop (SCR Performance in Loveland, CO) reported that no cracks were found

[Deen HK]

After purchasing I found out that mine had a hairline crack, after dropping the subframe there were a few more that were hidden. I decided to go with the Redish Motorsport plates as they have a good amount of surface area. I got them welded on instead of epoxied, with my previous cracks drilled and welded too.

[timmo]

Drove my car around for a couple of years, and hairline cracks in the seam sealer in the LH wheel well caught my eye. Went underneath the car and found this:



Had Redish Motorsport plates installed along with new poly bushings. Then DIY'd the Vincebar to 100% bulletproof it for autox & track:

[Dash1]

OP, I recommend getting it reinforced. I had to persuade my friend to get it done with no visual cracks. Once the shop dropped the subframe and removed the weather coating there were huge visible cracks that had to be welded.

[BMWahba]

Vincebar or CMP are the best solutions right now.

Any underside reinforcement plate only is job half done, as it does not solve the inherent issue which causes the fracturing.

Important to note that the CMP Kit and the Vincebar Kit both offer the front mount reinforcement as well. This is often overlooked especially when only reinforcing only the underside.

I have a vincebar sitting in the box waiting to be installed alongside the PSDesigns underside plates.

Although, my experience has been that not many shops even know or care what the Vincebar or CMP solutions are, and so I’m having a hard time finding a trusted installer to carry out the work. Many shops just want the easy way or sticking to what they think has historial precedence. I’ve been contacting race shops and other similar fabricators who have the technical know-how. The thing is, it doesn’t require a rocket scientist to understand why these things work.

[jowo]

Vincebar or CMP are the best solutions right now.

Any underside reinforcement plate only is job half done, as it does not solve the inherent issue which causes the fracturing.

Important to note that the CMP Kit and the Vincebar Kit both offer the front mount reinforcement as well. This is often overlooked especially when only reinforcing only the underside.

I have a vincebar sitting in the box waiting to be installed alongside the PSDesigns underside plates.

Although, my experience has been that not many shops even know or care what the Vincebar or CMP solutions are, and so I’m having a hard time finding a trusted installer to carry out the work. Many shops just want the easy way or sticking to what they think has historial precedence. I’ve been contacting race shops and other similar fabricators who have the technical know-how. The thing is, it doesn’t require a rocket scientist to understand why these things work.

Agreed. Anyone know of any trusted shops/mechanics in Canada (particularly west coast) that has done a CMP subframe reinforcement?

[clawhamm3r]

Mine didn’t have cracks. Not all of these cars do do and this was after tracking the car for 2 years. Reinforced anyway since I was replacing all the bushings and upgrading the suspension

That'd be amazing if true, but send me pics of your front mounts and all those little spot welds that have tiny cracks radiating off of them before I believe it. How many miles?