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    RACP Failure After Plates

    Yes yes, we all know plates isn't the end all be all for RACP failure yaddah yaddah yaddah. I am by no means saying I was surprised, I just wanted to share an experience and with visual evidence - especially since M3F is no longer here and there were a lot of resources there regarding this matter.

    Anyway, my car has TMS reinforcement plates installed and previously had stock subframe/differential bushings. I've always kept an eye on the rear despite the fact for exactly this reason. My car is an '04 so it has the updated spot welds as well. And she is also tracked and driven (I think) like a proper M car. Here are the cracks which I initially found.

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    Once I took it to the shop and they took off the sound deadening and dropped the subframe they found additional cracks. The RACP was tearing itself apart!

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    As you can see, once the plates are installed the mounting points are no longer the weak spot and the stress continues to flex the RACP. I knew it would have additional cracks but I didn't think it was going to be this bad. The cracks were stitched up and I went with the Turner Delrin/Aluminum subframe bushings and AKG poly diff bushings. All in all I'm very impressed how well the car feels now. Solid, direct, and with a teeny weeny little diff whine - which I kinda like haha. The whine has actually attenuated since I first drove it to where I barely hear it even with windows up and stereo off.

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    Now that she's back on the road I'm thinking of preventative measures to prevent this from happening again. I have an xbrace which I bought and haven't had the time to install. But from my understanding, it only addresses the rear two mounting points. So if I install it, I have to somehow address the front two points. I'm sure the RACP will hold on until I figure out a solution, especially with the solid subframe bushings. I think that made the biggest difference in terms of reducing flex in the rear.

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    Attached Files
    Last edited by Dash1; 04-13-2020, 08:00 AM.

    #2
    How many miles did the car have when the plates were welded on, and how many does it have now? Did it have the same stock subframe bushings this whole time?
    '03.5 M3 SMG Coupe - Jet Black / Black

    Comment


      #3
      Originally posted by r4dr View Post
      How many miles did the car have when the plates were welded on, and how many does it have now? Did it have the same stock subframe bushings this whole time?
      ~90k miles between plates and now. Currently sitting at 190k. And no, the subframe bushings were replaced the last time with stock bushings.

      Comment


        #4
        Originally posted by Dash1 View Post

        ~90k miles between plates and now. Currently sitting at 190k. And no, the subframe bushings were replaced the last time with stock bushings.
        Oh wow I assumed the interval between plate install and now was much shorter. Honestly looks better that I though for having had plates and no topside reinforcement for 90k miles.
        2002 Topasblau M3 - Coupe - 6MT - Karbonius CSL Airbox - MSS54HP Conversion - Kassel MAP - SSV1 - HJS - PCS Tune - Beisan - MK60 Swap - ZCP Rack - Nogaros - AutoSolutions - 996 Brembos - Slon - CMP - VinceBar - Koni - Eibach - BlueBus - Journal

        2012 Alpinweiss 128i - Coupe - 6AT - Slicktop - Manual Seats - Daily - Journal

        Comment


          #5
          Climate where car was for those 90k?
          DD: /// 2011.5 Jerez/bamboo E90 M3 · DCT · Slicktop · Instagram
          /// 2004 Silvergrey M3 · Coupe · 6spd · Slicktop · zero options
          More info: https://nam3forum.com/forums/forum/m...os-supersprint

          Comment


            #6
            Originally posted by Dash1 View Post

            ~90k miles between plates and now. Currently sitting at 190k. And no, the subframe bushings were replaced the last time with stock bushings.
            thats a lot of cracks and after a 190k, the metal is pretty much fatigued. you may squeeze a little more life out of that RACP but im sure the cracks will come back. with that kinda, damage, its best to go with a whole new panel IMO

            2005 Phoenix Yellow M3 Coupe 6spd
            2013 Interlagos Blue M3 Coupe 6spd ZCP, CF roof
            2007 Imola Red Z4M Coupe

            Comment


              #7
              Plates are not a fix.

              2005 IR/IR M3 Coupe
              2012 LMB/Black 128i
              2008 Black/Black M5 Sedan

              Comment


                #8
                Originally posted by Tbonem3 View Post
                Climate where car was for those 90k?
                Southern California for its entire life. Dry heat, no ocean spray.

                Comment


                  #9
                  Originally posted by Obioban View Post
                  Plates are not a fix.
                  Did you read my post?

                  Comment


                    #10
                    Originally posted by Maxima SE View Post

                    thats a lot of cracks and after a 190k, the metal is pretty much fatigued. you may squeeze a little more life out of that RACP but im sure the cracks will come back. with that kinda, damage, its best to go with a whole new panel IMO
                    I wouldn't say a whole new panel. But definitely Vincebar/CMP type reinforcement is needed as it relieves the carrier panel from most of the stress from the subframe. I'd say its important to weld any existing cracks before installing one of the said components as well.
                    Last edited by Dash1; 04-12-2020, 02:50 PM.

                    Comment


                      #11
                      is it possible to inspect for crack just from the trunk? or do you have to remove the whole rear subframe to get a better look?

                      90k and driven the way it should have sounds pretty impressive for just plates.

                      Comment


                        #12
                        Originally posted by trudriv3r View Post
                        is it possible to inspect for crack just from the trunk? or do you have to remove the whole rear subframe to get a better look?

                        90k and driven the way it should have sounds pretty impressive for just plates.
                        If you have damage that can be seen from inside the trunk then there will be a lot more damage underneath. You need to remove the subframe to find all cracks, since most of the time there will be some around the subframe mounting points and these will be covered up by the bushings.
                        2002 Topasblau M3 - Coupe - 6MT - Karbonius CSL Airbox - MSS54HP Conversion - Kassel MAP - SSV1 - HJS - PCS Tune - Beisan - MK60 Swap - ZCP Rack - Nogaros - AutoSolutions - 996 Brembos - Slon - CMP - VinceBar - Koni - Eibach - BlueBus - Journal

                        2012 Alpinweiss 128i - Coupe - 6AT - Slicktop - Manual Seats - Daily - Journal

                        Comment


                          #13
                          Originally posted by heinzboehmer View Post

                          If you have damage that can be seen from inside the trunk then there will be a lot more damage underneath. You need to remove the subframe to find all cracks, since most of the time there will be some around the subframe mounting points and these will be covered up by the bushings.
                          +1

                          Comment


                            #14
                            Originally posted by Dash1 View Post

                            Did you read my post?
                            Literally the first sentence...

                            I think we need forum guideline to not post a response unless op's post is read in full and all the other posts that are part of the discussion also. Sometimes people read the title, think they know the question and come in guns blazing with a response. Unless you are just having fun and post nonsense (like I do sometimes).
                            Youtube DIYs and more

                            All jobs done as diy - clutch, rod bearings, rear subframe rebush, vanos, headers, cooling, suspension, etc.

                            PM for help in NorCal. Have a lot of specialty tools - vanos, pilot bearing puller, bushing press kit, valve adjustment, fcab, wheel bearing, engine support bar, etc.

                            Comment


                              #15
                              Originally posted by Dash1 View Post

                              I wouldn't say a whole new panel. But definitely Vincebar/CMP type reinforcement is needed as it relieves the carrier panel from most of the stress from the subframe. I'd say its important to weld any existing cracks before installing one of the said components as well.
                              Have you talked to Cayn from CMP? He is very knowledgeable and accessible and easy to catch in a chat on FB. He might be interested to chat about your case. He also has interesting materials published https://cmpautoengineering.com/pages/technical
                              Youtube DIYs and more

                              All jobs done as diy - clutch, rod bearings, rear subframe rebush, vanos, headers, cooling, suspension, etc.

                              PM for help in NorCal. Have a lot of specialty tools - vanos, pilot bearing puller, bushing press kit, valve adjustment, fcab, wheel bearing, engine support bar, etc.

                              Comment

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