Subframe Reinforcement Status Thread

[jowo]

turn3autosport did an excellent job on mine. Also Nixon and CG Motorsports are great shops as well, but don’t have first hand experience on subframe reinforcement from those two.

Thanks! Can you tell me what you had done and approximately how much $$$ it was?

[BigDave]

Thanks! Can you tell me what you had done and approximately how much $$$ it was?

I had my 2005 Cabrio done in 2010. It had 20K miles on it at the time. No cracks at the time.

I supplied my welder at Redline BMW in Pompano Beach FL with two sets of plates. One from HPF and one from Turner Motor Sports. The welder mixed and matched the plates and used the ones he thought were best. He did extensive welding. Opened up sections, welded and stitched them closed.

The paint shop on site did a full metal prep and a two part urethane sealer paint. Man, did it come out nice! "Only" $1,100 in 2010 for all that work. I thought it was money extremely well spent.

I just dropped the rear subframe two weeks ago to install new OEM bushings. The chassis surfaces were immaculate. Zero rust, zero cracks and still shiny paint underneath. Low mileage still, however. Only 45k miles on chassis. However, I have done many hard launches and snapped a few rear half shafts in the process. I have not babied the car. The welder said the rear was good to over 1,000 HP should I ever go Forced Induction.

[wsybert]

Just did my reinforcement this weekend. Got the underside done yesterday and waiting on new bushings. Once it is back together, I will do the trunck area. This is my second time doing this... first was a 1999 E46 328 I turned into a track car... forgot how my much of a PITA this was.
Mine is a 2003 with 55k. Not a crack or issue when looked it over... now it's good for a long time!

[Titaniu//M]

Just had mine done at 54k miles. No cracks found at all, but both rear springs were cracked. Had it reinforced anyway for piece of mind since the subframe was already off. New bushings and springs as well.

[Silbergrau metallic]

Curious! if you have a E46 M3 or in the Market for one and you're concerned about re-sale value or looking for a Car that's had the work done as far as Subframe re-inforcement, which would you prefer, No Cracks, No Cracks, but re-inforced plates either epoxed or welded in or a brace installed either Mason Engineering or DMG Autosport.

[newton22]

Mine had 120k miles. Zero cracks even after removing subframe and grinding it down. Not even hairline cracks. Obviously I went ahead and welded in plates at that point.

My car has never seen snow/the north though.

[ecwx215]

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!

Your first mistake was going to VAC. They half ass the process and will charge you an arm and a leg. Since it sounds like you're in PA, reach out to Matt @ Kassel Performance. He's the guy that you want to work on your m3.

[Syfon]

As a few have already said, if cracks are no visible under the car, they will be once the subframe has been removed.

We all know its a matter of when, not if, with these cars.

If you drive your car hard or track it, I'd be doing a full underside & topside reinforcement (with a 6 point brace like mine if you so desire).

I acquired my car at 50k km (31k miles) and cleaned/checked the underside. I found no evidence of cracks, however after 40k km (some of which was pretty hard), the rear right mount pointhad a tear in the metal. I went the whole 9 yards and reinforced everything so it won't fall apart. Rear end is tight as now!

[TexaZ3]

Do it the right way.

[mrgizmo04]

Take a look at 4 articles from CMP here. https://cmpautoengineering.com/pages/technical

There are a lot of parts to the failures. To do it properly, you need to not just lower/remove the subframe to see if any cracks are hiding behind the surface of the bushing (why PPI are worthless here with their visual inspection without at least removing the subframe), but also remove the underbody weather coating (this is probably 80% of the total time of the job, cleaning that and the black cover in the trunk). You also need to cut into the metal and expose parts of the trunk and floor to see if some of the spot welds have popped and to reweld them with reinforcements. You also need to seam stitch the wheel arches, tie front and rear mounts together, etc.

I went to CMP kit because I spoke with Cayn extensively about the problems and his solutions. He is an engineer (as I used to be), so his solution seemed sound and well thought out. I got the full kit with front extension but without the strut brace part. It is definitely a huge job overall and to strip the entire rear end to clean/prep and do correctly and address all modes of failure.

[mugm3]

Does anyone know of a good place in Indiana that does RACP repairs? I know of one place Northwest Frame and Alignment. I think they don't want to do it though cause he quoted me 2600 bucks. To me that seems pretty high for just welding in plates. I can see that with doing the cmp front and top bars plus plates which I will probably end up doing. Just seems really high to me. I am half tempted to do it myself but would have to add a 220 socket and breaker at my house then also get a welder. Or am I just overreacting?

[Keyser Soze]

I had this job done about a month ago on my 06' with approximately 104k. I opted for the Redish plates based off of their reputation and quality. I had a local shop perform the job (I don't weld) and replace my rod bearings while everything was off the car. I think the choice of product that you use it is less of a structural integrity issue than an insurance policy. I haven't heard of any RACP failures with a welded vehicle, although I am certain that someone will correct me if I am wrong. That being said, I considered the CMP topside solution and am still looking at it for additional insurance. IMHO ,I would discourage solid bushings, and even super hard delrin bushings when you have them replaced unless the vehicle is exclusively a track or race car, otherwise you will be absolutely punished on the road. The car is significantly tighter after a plate reinforcement and poly bushings. I don't think you can go wrong with any of the choices.

There has been instances of failure after Turner plates were welded in on some cars.

[mrgizmo04]

CMP topside beam and extension can be done from the top without needing to drop the subframe again. So if you had plates previously welded or epoxied, there is some time/work saved. However like I mentioned before, 80% of time is spent on prep - scraping off sound deadening, paint, etc to get a clean area to have clean welds. The amount of prep for topside portion is still non-trivial with everything that has to be cleaned up in trunk and around rear seats.

[Jersey_M3]

CMP topside beam and extension can be done from the top without needing to drop the subframe again. So if you had plates previously welded or epoxied, there is some time/work saved. However like I mentioned before, 80% of time is spent on prep - scraping off sound deadening, paint, etc to get a clean area to have clean welds. The amount of prep for topside portion is still non-trivial with everything that has to be cleaned up in trunk and around rear seats.

Respectfully, I would like to disagree about the ability to install the topside beam and front extension without dropping the subframe. Having just installed the kit myself, you would have to be an incredibly skilled welder to be able to install these kits without causing damage to the underside of the car in the form of weld through heat blistering up the undercoating. Not to mention the welds proximity to the gas tank.

[mrgizmo04]

Respectfully, I would like to disagree about the ability to install the topside beam and front extension without dropping the subframe. Having just installed the kit myself, you would have to be an incredibly skilled welder to be able to install these kits without causing damage to the underside of the car in the form of weld through heat blistering up the undercoating. Not to mention the welds proximity to the gas tank.

It's not easy, but I got this kit only after speaking with Cayn (owner of CMP) about my situation, which was - I already did the rear subframe rebush work a year prior to engaging with him in a conversation about his solution, and was not looking to drop it again, and, especially since I already had plates welded on the car from po. He confirmed that it could be all done from the top. His instructions were even modified for that case (rather than assuming that someone was doing everything including plates as part of the job and the subframe would be down anyway).