Announcement

Collapse
No announcement yet.

Subframe bush inserts

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • #46
    LOL!

    Fit all 4 if you want, I'm just peculiar about NVH so took the front most inserts back out - I just found this a happy medium (I have also pack the gap between the top of the subframe and the car body though (there is a void above the bush/subframe at the mounting points). This stops the float and also reduces subframe twist ("horizontally"/x-axis) further. The bushe inserts contribute to his but also on what I can best describe as z-axis too (forward and back).

    I can never decide whether it's better for subframe issues or not! If you tighten up the subframe movement at the front points then it could be suggested that the movement/energy is just then transferred to the rear diff mount.

    It's seems the rear boot floor failures cannot be correlated though to how the car has been driven so I wouldn't worry either way. Some cars with lowish miles and an easy life have failed spectacularly but others like mine which have been tracked with semi slicks merely had a couple of spot welds fail and no obvious failure until the boot was stripped of it's matting.
    Last edited by c_w; 08-03-2011, 03:45 PM.

    Comment


    • #47
      Thanks. I dont want a rock hard ride so 2 inserts will be fine for me. I must confess I have never checked the boot floor, so I really must do that when working on the car next week.

      Comment


      • #48
        Hey guys,

        I've got a short question. I want to put PU bushings in the rear axle of my M-Coupé (which is not a dedicated track tool) but I am not sure which version I should install in the rear trailing arms. There are the hard 75D shore AKG bushings (70€) and the Powerflex 80A (100€). Do the harder AKG bushings increase n/v/h noticably?
        The subframe bushings will be the violet Powerflex with 80A shore.

        Thanks in advance.

        Best regards,
        Phil

        Comment


        • #49
          Originally posted by RST Driver View Post
          Hey guys,

          I've got a short question. I want to put PU bushings in the rear axle of my M-Coupé (which is not a dedicated track tool) but I am not sure which version I should install in the rear trailing arms. There are the hard 75D shore AKG bushings (70€) and the Powerflex 80A (100€). Do the harder AKG bushings increase n/v/h noticably?
          The subframe bushings will be the violet Powerflex with 80A shore.

          Thanks in advance.

          Best regards,
          Phil
          Phil,

          I did this mod myself a few years ago and would strongly advise you against it. Those damned things squeak like mad and it is VERY irritating. I tried all manner of tricks and lubricants to stop the squeaking, which always returned a short time after attempting to cure the problem. In the end, I'd had enough and fitted some new OEM TA bushes.
          /// Exdos ///
          "Men who try the impossible and fail spectacularly are infinitely superior to those who reach for nothing and succeed" --Napoleon Bonapart

          Comment


          • #50
            Ouch, I didn't want to hear that.

            Anybody else who had problems with sqeaking Powerflex rtabs?
            A buddy has the violet ones in his 2.8 Z3 roadster, no complaints so far.

            What exactly causes the noise exdos? The inner metal part or the urethane surface which is in contact with the subframe?

            Best regards,
            Phil

            Comment


            • #51
              I have some Ireland Engineering subframe bushes myself to go in next week hopefully, they have been sitting inmy garage for a couple of weeks now!

              I'm prepared for a bit of noise just doing it really to help preserve the subframe as I am of the same opion of some of those mentioned in this thread. Randy Forbes afaik fits this as well as part of his subframe repairs.

              Will report back once I have them fitted..
              KW V3, H&R arbs, H&R 12mm Spacers, Weichers Strut Brace, Ireland Engineering Bushes, Uprated rear top mounts,swapped front top mounts, EBC Yellows, Simota CAI, Supersprint Exhaust, Shadow chrome Roadstars

              Comment


              • #52
                Originally posted by RST Driver View Post
                Ouch, I didn't want to hear that.
                I'd read about the squeaking before I decided to fit the Polyurethane bushes, and I decided to ignore the warning


                Originally posted by RST Driver View Post
                What exactly causes the noise exdos? The inner metal part or the urethane surface which is in contact with the subframe?

                Best regards,
                Phil
                The TA bush has a metal tube insert which is clamped tight between the sides of the trailing arm brackets on the rear subframe and the poly bush fits then fits between the metal tube insert and inside the metal sleeve of trailing arm bush holder. In the case of the OEM rubber TA bush, the TA can rotate by stretching and compression of the rubber bush, but in the case of a polyurethane bush, for the TA to rotate, the metal sleeve of the TA bush holder must move over the face of the polyurethane TA bush, and/or the the bush must move around the metal sleeve insert and this creates friction. The bushes come with some silicone lubricant, but the fit of the polybushes is so tight, that there's nowhere for the lubricant to remain. Obviously, heat is generated by the frictional movement of the TA, so what little of the lubricant remains in place after fitting, soon burns away and then you get the sound of polyurethane sliding across metal creating the squeaking noise.

                I tried using different lubricants and also making little reservoirs on the fitting surfaces of the polyurethane bushes, to help lubrication to remain in place, but nothing worked for long. It's such a hassle messing around with the trailing arms, that I decided to revert to OEM TA bushes and be finished with the problem once and for all. It was the only mod that I regretted doing.

                You've been warned!

                OTOH, fitting polyurethane subframe bushes is a worthwhile mod.
                /// Exdos ///
                "Men who try the impossible and fail spectacularly are infinitely superior to those who reach for nothing and succeed" --Napoleon Bonapart

                Comment


                • #53
                  Originally posted by UJM3 View Post
                  I have some Ireland Engineering subframe bushes myself to go in next week hopefully, they have been sitting inmy garage for a couple of weeks now!

                  I'm prepared for a bit of noise just doing it really to help preserve the subframe as I am of the same opion of some of those mentioned in this thread. Randy Forbes afaik fits this as well as part of his subframe repairs.

                  Will report back once I have them fitted..
                  Subframe bushes don't move in the same way that TA bushes do, so you'll have no problem.
                  /// Exdos ///
                  "Men who try the impossible and fail spectacularly are infinitely superior to those who reach for nothing and succeed" --Napoleon Bonapart

                  Comment


                  • #54
                    Originally posted by exdos View Post
                    Subframe bushes don't move in the same way that TA bushes do, so you'll have no problem.
                    Ah mixed them up..

                    That's good to hear! this is the set I bought
                    http://store.nexternal.com/ireland/r...pair-p545.aspx
                    KW V3, H&R arbs, H&R 12mm Spacers, Weichers Strut Brace, Ireland Engineering Bushes, Uprated rear top mounts,swapped front top mounts, EBC Yellows, Simota CAI, Supersprint Exhaust, Shadow chrome Roadstars

                    Comment


                    • #55
                      Originally posted by exdos View Post
                      The TA bush has a metal tube insert which is clamped tight between the sides of the trailing arm brackets on the rear subframe and the poly bush fits then fits between the metal tube insert and inside the metal sleeve of trailing arm bush holder. In the case of the OEM rubber TA bush, the TA can rotate by stretching and compression of the rubber bush, but in the case of a polyurethane bush, for the TA to rotate, the metal sleeve of the TA bush holder must move over the face of the polyurethane TA bush, and/or the the bush must move around the metal sleeve insert and this creates friction. The bushes come with some silicone lubricant, but the fit of the polybushes is so tight, that there's nowhere for the lubricant to remain. Obviously, heat is generated by the frictional movement of the TA, so what little of the lubricant remains in place after fitting, soon burns away and then you get the sound of polyurethane sliding across metal creating the squeaking noise.

                      I tried using different lubricants and also making little reservoirs on the fitting surfaces of the polyurethane bushes, to help lubrication to remain in place, but nothing worked for long. It's such a hassle messing around with the trailing arms, that I decided to revert to OEM TA bushes and be finished with the problem once and for all. It was the only mod that I regretted doing.

                      You've been warned!
                      Quite reasonable explanation - thanks for that.

                      Have you tried ATE plastilube (or something like that), which is usually used for brakes? Could be worth a try since this is a long lasting high temperature lubricant.

                      Best regards and again thanks for saving my money ,
                      Phil

                      Comment


                      • #56
                        Originally posted by RST Driver View Post

                        Have you tried ATE plastilube (or something like that), which is usually used for brakes? Could be worth a try since this is a long lasting high temperature lubricant.

                        Phil
                        For any lubricant to work there's got to be a space for the lubricant to remain. In the case of the polyurethane TA bushes, they're slightly compressible and over-sized, so when they're inserted in the trailing arms, they obliterate all the free-space and force out any lubricant that you try to use!

                        I decided my life's too short to mess around anymore with these things. I should've heeded the warning of others and never bothered fitting the damned things in the first place!
                        /// Exdos ///
                        "Men who try the impossible and fail spectacularly are infinitely superior to those who reach for nothing and succeed" --Napoleon Bonapart

                        Comment


                        • #57
                          So they would definately need a modification. What abound putting them onto a lathe and cutting off some material in a v-shape where lubricant can remain? Is that pretty much what you tried?

                          Best regards,
                          Phil who will insert new OEM bushings.

                          Btw, did the Powerflex rtabs make a huge difference compared to the stock rubber ones?

                          Comment


                          • #58
                            Originally posted by RST Driver View Post
                            So they would definately need a modification. What abound putting them onto a lathe and cutting off some material in a v-shape where lubricant can remain? Is that pretty much what you tried?
                            I did something similar, but if you start cutting into the bushes, then you reduce the compressibility of them, thus you start to defeat their effectiveness of greater stiffness. Also, nobody seems to know the effect that different lubricants might have on polyurethane. I have noticed that after a few years of use, the poly bushes are now softer than they were when new, so either, they've softened with use and/or reacted with the lubricants that I've used.


                            Originally posted by RST Driver View Post
                            Btw, did the Powerflex rtabs make a huge difference compared to the stock rubber ones?
                            I fitted the polyurethane subframe bushes at the same time as poly TA bushes, but I'd already got a butt-strut on the car. They definitely made a difference to handling near the limit which I noticed at my last visit to The Ring, after I'd removed the poly TA bushes and reverted to OEM bushes. I found that on the sharp right-hander at Hohe-Acht -> Hedwigshohe I was getting a rear-wheel steer effect which I'd not had with poly bushes and my ECU data-logger shows that I was going around that bend (radius of around 46metres) at around 55mph. Otherwise, I haven't really noticed any loss of performance, only the benefit of the squeaking has gone!
                            /// Exdos ///
                            "Men who try the impossible and fail spectacularly are infinitely superior to those who reach for nothing and succeed" --Napoleon Bonapart

                            Comment


                            • #59
                              I've found several other complaints on bimmerforums.com about poly-bushings.
                              Thanks for your warning, I'll definitely install new oem rubber bushings.

                              Best regards,
                              Phil

                              Comment

                              Working...
                              X