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Experience of the Z4 M Coupe

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  • #16
    TMS Rear Trailing Arm Bush Limiter Kit


    Two TMS discs are fixed to the inside of each RTA bracket.




    Two holes are drilled through both sides of the bracket (using a template supplied with the kit) and the discs are screwed in position.




    The discs reduce the lateral space within the brackets by 14mm.




    The OEM RTABs protrude from the trailing arms and the sides of the bushes will now make contact with the limiter discs when installed.




    This photo shows the trailing arm housed inside the bracket with the limiter discs in situ.




    This shows the RTA bracket installed.

    /// Exdos ///
    "Men who try the impossible and fail spectacularly are infinitely superior to those who reach for nothing and succeed" --Napoleon Bonapart

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    • #17
      Exdos,

      I applaud you....

      Great info.....

      Any chance of prices of mods and places where your bits were sourced?

      Can E46 M3 roll bars be fitted and is there any point in doing so ?

      Edit.... Regards the exhaust mod,is the box now empty ? Is there anything to "encourage" exhaust gas glow to the twin outlets ? How have you found the exhaust now for noise and drone ?
      Last edited by Alpinaman; 01-08-2012, 04:53 PM.

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      • #18
        Originally posted by Alpinaman View Post
        Exdos,

        I applaud you....

        Great info.....

        Any chance of prices of mods and places where your bits were sourced?

        Can E46 M3 roll bars be fitted and is there any point in doing so ?

        Edit.... Regards the exhaust mod,is the box now empty ? Is there anything to "encourage" exhaust gas glow to the twin outlets ? How have you found the exhaust now for noise and drone ?
        I've done a lot of mods on my MC so I've just set about doing the same thing to my Z4MC so that I can enjoy the car at its best ASAP.

        The brake cooling cost me just the price of 2m of 50mm neoprene ducting at approximately £24 plus a few quid for the stainless jubillee clips and plastic cable ties.
        The air intake mods cost me nothing because I already have a store of aluminium sheet.
        I bought the ACS Racing suspension secondhand for an absolute bargain price and it had only done about 2k miles. You can get the kit from Rossiters for around £2.3k.
        StrongStrut strutbrace for £299 including freight + £38 import duty. This part is expensive relative to others but I think the StrongStrut is the best strutbrace by far.
        4 of H&R Trak 10mm spacers circa £135 from Larkspeed + the cost of a set of Locking wheel nuts
        H&R ARB 30mm for E46 M3 front £230 from Evolve
        TMS RTAB Limiter kit £109 from Simpson Motorsport
        Goodridge stainless braided hoses at £90 from CA Automotive.
        Yellowstuff pads all round off ebay £150


        The E46 M3 actually has a front ARB which is 26mm whereas the OEM ARB for the Z4MC is 27mm.


        With regard to the silencers: the middle only section is empty and I've welded plates to encourage the gases to go straight out through the tailpipes. There's a bit of drone at 2000rpm but the rest of the rev range it sounds so much better. This was the first time I'd modded the Z4MC silencers and I might reopen them and tweak them some more.
        /// Exdos ///
        "Men who try the impossible and fail spectacularly are infinitely superior to those who reach for nothing and succeed" --Napoleon Bonapart

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        • #19
          Very interesting John.

          What do the limiter discs do, remove what looks like a huge amount of play?
          2002 '52 S54 - Titanium Silver with 18" BBS LMs, AP Racing BBK, KW V3, H&R anti roll bars & ACS flippers (previously 2000 'X' S50 - Arctic Silver)

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          • #20
            Originally posted by Spooks View Post
            What do the limiter discs do, remove what looks like a huge amount of play?
            The OEM bracket is a very bad design. The limiters considerably reduce any lateral movement of the bushes thus maintaining the toe angles. Alternatively, you can fit polyurethane bushes which will fill the void, but from my experience of poly trailing arm bushes on the MC, there's no way that I want those again when they have to move because they squeak.

            Likewise, the Z4MC is a VERY stiff chassis and it's easy to increase NVH. I had to reinstall the upper rear spring pads after fitting the ACS suspension because without them (as per ACS instructions) the cabin was turned into a resonator for the exhaust!
            /// Exdos ///
            "Men who try the impossible and fail spectacularly are infinitely superior to those who reach for nothing and succeed" --Napoleon Bonapart

            Comment


            • #21
              Some interesting mods there.

              Interesting to read that you think the Z4MC doesn't handle as well as the Z3MC, your Z3 must have been heavily modified because my S54 MC certainly didn't handle anywhere near as well as my Z4MC.

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              • #22
                Originally posted by Wallachie View Post
                Interesting to read that you think the Z4MC doesn't handle as well as the Z3MC, your Z3 must have been heavily modified because my S54 MC certainly didn't handle anywhere near as well as my Z4MC.
                An OEM Z4MC does handle a lot better than an OEM Z3MC but certainly not as well as my heavily modded Z3MC. But I find the ride of an OEM Z4MC dreadful and I couldn't live with one in OEM state. So when I bought the Z4MC it was my intention to get it to the same level of handling as my Z3MC and to improve the ride without delay. The handling of my Z4MC is now superb and with a good ride and a great improvement on what it was like when I bought it.
                /// Exdos ///
                "Men who try the impossible and fail spectacularly are infinitely superior to those who reach for nothing and succeed" --Napoleon Bonapart

                Comment


                • #23
                  Thank you Exdos for such a great journal of what you have done. Have been following your writeups here and on the z4 forum

                  I too have a z4m coupe and would like to do a few modifications. I agree the suspension is uncomfortable and bouncy. I also find changing direction at high speed scary. We have crap roads in Malta that are definitely worse than what you are used to in the uk. I would definitely like to find a setup that doesn't really lower the height, makes everyday driving more comfortable but also makes the car handle better. I thought it was impossible to have all these things together, however your writeups say it is.

                  Also like your other mods to the exhaust and intake. Does the exhaust sound too loud after you gutted them? By interested in this one. Will a normal silencer shop be able to this?

                  Enough questions for now. Keep up the great work

                  Kerstien

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                  • #24
                    Originally posted by kerstien View Post
                    Thank you Exdos for such a great journal of what you have done. Have been following your writeups here and on the z4 forum

                    I too have a z4m coupe and would like to do a few modifications. I agree the suspension is uncomfortable and bouncy. I also find changing direction at high speed scary. We have crap roads in Malta that are definitely worse than what you are used to in the uk. I would definitely like to find a setup that doesn't really lower the height, makes everyday driving more comfortable but also makes the car handle better. I thought it was impossible to have all these things together, however your writeups say it is.

                    Also like your other mods to the exhaust and intake. Does the exhaust sound too loud after you gutted them? By interested in this one. Will a normal silencer shop be able to this?

                    Enough questions for now. Keep up the great work

                    Kerstien
                    Kerstien, I'm glad you find the info useful.

                    I've modded quite a few sets of Z3MC silencers and the one set of Z4 MCs and not of them are too loud because I retain the OEM outlet pipes and follow a few "rules" that I've worked out need to be followed. Anyone with the right cutting and welding kits should be able to modify silencers for you using the photos I've posted, but you do so at your own risk that they get the sound right for you.
                    /// Exdos ///
                    "Men who try the impossible and fail spectacularly are infinitely superior to those who reach for nothing and succeed" --Napoleon Bonapart

                    Comment


                    • #25
                      Does this really help the performance in any way? Should be less restricted right?
                      Would you have any sound clips by any chance? I woud still like to keep the same character of the engine if you know what i mean.

                      Also can you amplify on the rules part? Is there more than one way of modifying them?

                      Thanks

                      kerstien

                      Comment


                      • #26
                        Originally posted by kerstien View Post
                        Does this really help the performance in any way? Should be less restricted right?
                        Derestricting the silencers makes it easier for the engine to "breathe" which allows the engine to function better as an "air pump", allowing it to produce more power. Take a look at the graph that I've produced showing before/after results for both my Z3MC and my Z4MC comparing OEM (before) with my "after" air intake and exhaust mods.

                        Originally posted by kerstien View Post
                        Would you have any sound clips by any chance? I woud still like to keep the same character of the engine if you know what i mean.
                        I haven't bothered making any sound clips from my Z4MC but there are some around of my S54 Z3MC with modded silencers. The character doesn't change: it's just more vocal and it really does make the driving experience a lot more "involving".

                        Originally posted by kerstien View Post
                        Also can you amplify on the rules part? Is there more than one way of modifying them?
                        There are lots of different ways of modifying silencers and each one will produce different noises: some nice and others just noisy. The "rules" that I mention are similar to the sort of "rules" that violinmakers have to follow to make a violin sound like a Stradavari rather than a Crapolotti.
                        /// Exdos ///
                        "Men who try the impossible and fail spectacularly are infinitely superior to those who reach for nothing and succeed" --Napoleon Bonapart

                        Comment


                        • #27
                          Originally posted by exdos View Post
                          Derestricting the silencers makes it easier for the engine to "breathe" which allows the engine to function better as an "air pump", allowing it to produce more power. Take a look at the graph that I've produced showing before/after results for both my Z3MC and my Z4MC comparing OEM (before) with my "after" air intake and exhaust mods.
                          I would caveat this by saying that the engine management is designed to cope with backpressure, and there is an ideal level for a given engine. As an extreme example, if you just took the exhaust back to headers you'd be WAY down on power.

                          If you're significantly altering back pressure, you should get an active remap done too really. Ditto playing around with the intake.

                          At the end of the day, BMW spent a lot of money making sure all these parts run in harmony.

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                          • #28
                            Originally posted by breezer View Post
                            I would caveat this by saying that the engine management is designed to cope with backpressure, and there is an ideal level for a given engine. As an extreme example, if you just took the exhaust back to headers you'd be WAY down on power.

                            If you're significantly altering back pressure, you should get an active remap done too really. Ditto playing around with the intake.

                            At the end of the day, BMW spent a lot of money making sure all these parts run in harmony.
                            I totally agree that BMW must have spent a huge amount of time and money in developing its engine management systems, therefore I can't see how spending just a few hundred £s for an aftermarket remap will actually confer the benefits you suggest.

                            The one thing that the majority of owners just don't seem to understand about BMW's air intake systems is that they harness "ram-effect", which causes a variable increase in pressure within the air-intake system which is related to speed. This occurs at ALL speeds and not just at speeds over 150mph, as the doubters might suggest. As such, BMW's engine maps are more than capable of dealing with a wide range of air-intake pressures/volumes, and exhaust pressures. Over the past few years, I've spent a fair amount of time with an ECU datalogger, and analysing its recordings, and it's amazing to observe the variability that ordinarily occurs within the air-intake/exhaust systems (of both my S54 MC and Z4MC). The OEM maps are more than capable of coping with the fuelling that is required with modifying the air-intake/exhausts systems, in the same way that the maps cope with a wide range of air volumes at all speeds from 0 - 155+mph and in all climatic conditions. All my air-intake and exhaust mods have been monitored by ECU datalogging, which shows precisely what occurs, if anything, with every mod configuration. I have yet to see anything which suggests that any of my mods have touched the limits of the OEM ECU maps or been detrimental to the car.

                            I've posted a lot of information about this subject on this forum in the past.
                            Last edited by exdos; 12-08-2012, 09:46 AM. Reason: More information
                            /// Exdos ///
                            "Men who try the impossible and fail spectacularly are infinitely superior to those who reach for nothing and succeed" --Napoleon Bonapart

                            Comment


                            • #29
                              Originally posted by exdos View Post
                              Derestricting the silencers makes it easier for the engine to "breathe" which allows the engine to function better as an "air pump", allowing it to produce more power. Take a look at the graph that I've produced showing before/after results for both my Z3MC and my Z4MC comparing OEM (before) with my "after" air intake and exhaust mods.


                              I haven't bothered making any sound clips from my Z4MC but there are some around of my S54 Z3MC with modded silencers. The character doesn't change: it's just more vocal and it really does make the driving experience a lot more "involving".



                              There are lots of different ways of modifying silencers and each one will produce different noises: some nice and others just noisy. The "rules" that I mention are similar to the sort of "rules" that violinmakers have to follow to make a violin sound like a Stradavari rather than a Crapolotti.

                              I had heard clips of your m coupe and I like the sound I think I'll try this mod out!
                              Ok so looking at your back box with connecting pipes still in place I woul need to block off the left and centre one at the top and the holes furthest to the right of the bottom holes right?

                              What about the cats? On my other car I had removed them and placed an open pipe in their place. However on the z4 there's the sensor with a wire going to it. Is it possible to get a decat pipe don't by my local shop or will I get some errors? This should also help her breath more no? I had felt a great difference with my other car.

                              With regards to the intake, if I understood correctly you are also getting air from the other grill to increase the volume right? I think on your z3m you had used a k&n filter also right to help. Does this also help slightly?

                              Thanks once again for all the help. I would like to try out your mods as they seem well Investigated and I like the fact that they don't include splashing out a lot of money as many seem to do.

                              Thanks

                              Kerstien

                              Comment


                              • #30
                                Originally posted by kerstien View Post
                                I had heard clips of your m coupe and I like the sound I think I'll try this mod out!
                                Ok so looking at your back box with connecting pipes still in place I woul need to block off the left and centre one at the top and the holes furthest to the right of the bottom holes right?
                                Just cut out everything in the centre section and remove all unnecessary pipework, and then stuff some of the glassfibre into the two end sections to fill the voids, but leave the centre section completely empty.

                                Originally posted by kerstien View Post
                                What about the cats? On my other car I had removed them and placed an open pipe in their place. However on the z4 there's the sensor with a wire going to it. Is it possible to get a decat pipe don't by my local shop or will I get some errors? This should also help her breath more no? I had felt a great difference with my other car.
                                I tried modding the cats on my Z3MC after I'd already modded the silencers and my datalogging showed that this lost some of the gains I'd made from modding the air-intake and the silencers, so I won't be bothering attempting any further exhaust mods for the Z4MC than what I've already done. I agree with the point that Breezer made, that engines do require some back pressure in the exhaust system and my datalogging showed me when I'd gone too far. I suspect that decatting on its own, without modding the silencers, would also yield gains.


                                Originally posted by kerstien View Post
                                With regards to the intake, if I understood correctly you are also getting air from the other grill to increase the volume right? I think on your z3m you had used a k&n filter also right to help. Does this also help slightly?
                                I use the lower grill area for my brake ducting, but this could be used for the air-intake.

                                Originally posted by kerstien View Post
                                Thanks once again for all the help. I would like to try out your mods as they seem well Investigated and I like the fact that they don't include splashing out a lot of money as many seem to do.
                                It's my objective to use my ingenuity rather than money to devise simple and cheap ways of increasing engine performance because this is possible due to my understanding of the OEM air-intake system and ram-effect from my own personal investigation of how it operates and works.
                                /// Exdos ///
                                "Men who try the impossible and fail spectacularly are infinitely superior to those who reach for nothing and succeed" --Napoleon Bonapart

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