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  • Front Bilstein insert gap

    Had to replace my front shocks as one was knackered.Bought some Bilstein B6 front dampers off Yaz here on the forum,(and have to say couldn't be more helpful)
    Just wanted to check that unlike the boge ones i had in the car which had a slight collar towards the top of the damper which made the shock seat in the strut tube,the bilsteins seem very loose in comparison.
    Have checked all relevant part nos with yaz and all match up.Was just wondering before i fit them that this was normal?
    Rob

    Ragussa green avant RS2+ spec
    Racing blue Octavia VRS mk2 estate-Remapped now to 250 bhp
    Audi coupe gt-slow as hell but loads of character-sold

  • #2
    Got a PIC or video, would be interested to see it
    sigpic

    1992 3b S2 Coupe

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    • #3
      I have the same "issue" - but I have driven quite a bit with them without problems. I'm still thinking a collar would keep the strut more stable. I had some noises from one side, but it went away. I'm hoping/thinking it was the H&R spring finding its final location

      I can't remember if the threaded top works as a collar?
      Cheers, Torben
      '94 B4 Avant S2

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      • #4
        They might be 50mm in a 55mm sleeve

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        • #5
          i'd thought the same but if i can't see how being that they've checked the p/n's. I have a low speed rattle....usually only heard when crawling in traffic and does cross my mind whether there is something allowing movent in the strut but they have been in for years and not ever got worse....who knows
          sigpic

          1992 3b S2 Coupe

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          • #6
            Mind the Gap(s)!

            In my case l've a 45mm O.D. yellow tube inside a 50mm I.D. Mac. strut body. I believe this gap is normal. Perhaps that air gap needs to be there to allow these upside-down style dampers to breathe? Bilstein could've built a bigger mouse-trap, they have a few. The reason I think that the gap exists is because it was deemed necessary . The damper's lower chamber works a lot like a bicycle's air pump and that pressure change is lessened by that air space; and with that space, perhaps Bilstein thought it wouldn't have to ask customers to mod their struts.

            One result of these dampers being so fat up top (it is a brilliant design, probably lower un-sprung weight, huge spread of forces over large area for longer life and stronger than otherwise) is that they're skinny (base plate and yellow tube removed) down below:

            https://patrickms.s3.amazonaws.com/p...3-5050-12K.jpg

            Having constructed their damper opposite to more usual practice put the skinny shaft at the bottom and created the unique cavity that operates like a bicycle tire air pump.

            The drilled drain holes in the strut bases, recommended on various forums where never part of Audi or Bilstein's instructions. With some of the water in dampers issues I've had, whenever I drive in the rain, I'll think of the construction of the Bilsteins as similar to an annoying child sucking on a straw in an almost empty milk-shake container, every time the suspension rebounds, it slurps up water from the spray in the wheel-well! Where does it go? It gathers in the strut bottom, but perhaps surprisingly it is sucked in at the top of the yellow tube at the circular interface with the big polished shaft! Ostensibly, the strut drain hole mod was conceived in response to, and to prevent; "Frozen Strut Syndrome", however it is hydro-lock that needs to be prevented; and by giving any water therein someplace downhill to go, we (by breaking the Mac. strut's seal) also make the Billy; a less effective water-pump.

            The earlier smaller diameter Billy's bottom cap (North American B3s) isn't obviously vented like the later larger diameter UrS style ones, which may be evidence of Bilstein attempting to deal with the issue. Here is a drwg. of one with a non-vented base:

            http://spiggs.sdf-us.org/pics/fiat_pics/P30-0032.jpg

            Attached below is VAP's photo of early small diameter non-vented; & larger UrS style damper bases.

            In the isometric drawing at the below link, you can more easily appreciate how the volume of that lower atmospheric chamber (also contains the bump-stop) must change radically with each damper movement, note also the description of the 100 micron vent; that is the kid with the straw:

            https://cdn.shopify.com/s/files/1/07...1x1024.jpg?243

            So that's my theory, without atmospheric venting of the Macpherson strut itself (i.e. a drain-hole) if one was to reduce the available air volume (2.5mm air space surrounding entire length of the yellow tube) between the exterior of the Bilstein and the interior of the Macpherson; you'd have an even more effective milk-shake slurper.

            MacSpring, perhaps it's customary & best for me to try to answer your Bilstein install questions in a new post, I don't see an existing thread of that sort, if you do, please let me know:

            "new post link title place-holder"
            http://www.s2forum.com/forum/showthr...178#post861178
            Attached Files
            Last edited by Lago Blue; 2 July 2015, 22:10. Reason: Moved Bilstein install discusssion to new post

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            • #7
              Lago,

              Please do expand your comments as I'm about to fit two new Bilstein front struts and naturally only want to fit them once and forget.

              Any BTDT comments, suggestions of would be gratefully received.

              If a small drain hole is to be drilled in the bottom of the oem strut housing, where exactly is it supposed to be drilled ?

              No instructions of any kind came in the box.

              Thanks.




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              • #8
                Anytime you choose a smaller diameter shock for your housing you are cheating yourself from capacity to dampen and possibly shortening a life of a shock that is designed to dampen less load.
                Always use the max you can, i.e. your tube is 55mm use 55mm shock, you have 50mm, use 50mm shock.
                Just my $0.02
                www.quattro.ca
                B2: 82 Urq into Sport quattro, 82 4000 2-door, 83 80q 2 Door, 83 Ur-q CDN, 85 Ur-q Euro with 3B, 86 4kq, 59,000km
                B3/B4: 91 CQ, 93 90q 2.5TDI, 94 80q avant 2.5tdi, 94 S2 Avant

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                • #9
                  I was under the impression that you definitely don't drill any holes in the shock housing so it can retain a little oil or anti-freeze (so it doesn't seize in-situ over time). This would probably help dissipate some of the heat out of the shocker too no doubt

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                  • #10
                    Mike,

                    that's right for a regular shock, but from reading another thread on here, the Bilstein front shock is apparently / allegedly inverted inside its own casing, so there is a possibility water can get in from the top of the oem housing and damage the internal workings of the shocks, hence the apparent need to drill a small hole in the bottom of the factory strut housing to allow any water to drain away rather than fill up oem housing and thereby be able to get into the 'top' of the shock.

                    As I say this is what I've read, just looking for more accurate info / confirmation of this info either way.

                    Thanks.

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                    • #11
                      I have a problem on one my struts with the bilsteins, it moves with a ominous clunk. All four have the same gap, its just the drivers front that moves, Ive had it out and I took it apart, cleaned the thread and tightened all back up. Seemed fine for about 10 day/700miles now its back and worse. I noticed a little damage on the top edge of the outer (yellow) tube, it was no longer sharp.

                      Im happy with the other 3 they dont seem to be moving but powering or braking in corners and the wheel moves and can be fairly shocking upset to the balance.

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                      • #12
                        Originally posted by mike74 View Post
                        I was under the impression that you definitely don't drill any holes in the shock housing so it can retain a little oil or anti-freeze (so it doesn't seize in-situ over time). This would probably help dissipate some of the heat out of the shocker too no doubt
                        No no no with Bilstein upsidedown dampers! Use search on this forum, then you know why not use oil in the housing with these shocks.

                        Audi UrS4 Avant 2.5 20vt - twincharged - Project
                        Audi 80q B4 Sedan 2.2 20vt - Daily user
                        BMW 320d Touring e91 M-Sport - Daily user
                        BMW 740iA e38 - Project

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                        • #13
                          Re: Clunk return

                          Hello Goodall,

                          From your 2nd paragraph, your steering wheel is moved when clunk occurs, correct? If yes, then perhaps Bilstein nut is now loose??

                          With spring removed, but prior to dis-assembling strut last time, could you get the damper shaft to rock in the strut and perhaps make noise? Did you find the Bilstein nut loose then?

                          Could the rounding-off of the yellow tube top, (more than paint damage?) which may have occurred due to unwanted yellow tube movement, or incorrect damper position on tightening, have been accompanied by slight damage to the underside tube-top recess of the Bilstein nut, such that its ability to restrain the tube-top radially, and/or maintain the applied torque; have been reduced?

                          Did you loctite the Bilstein nut? Did your install accomplish the aims of recent post titled "Bilstein into Macpherson"?

                          Hth

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                          • #14
                            Originally posted by Lago Blue View Post
                            Hello Goodall,

                            From your 2nd paragraph, your steering wheel is moved when clunk occurs, correct? If yes, then perhaps Bilstein nut is now loose??

                            With spring removed, but prior to dis-assembling strut last time, could you get the damper shaft to rock in the strut and perhaps make noise? Did you find the Bilstein nut loose then?

                            Could the rounding-off of the yellow tube top, (more than paint damage?) which may have occurred due to unwanted yellow tube movement, or incorrect damper position on tightening, have been accompanied by slight damage to the underside tube-top recess of the Bilstein nut, such that its ability to restrain the tube-top radially, and/or maintain the applied torque; have been reduced?

                            Did you loctite the Bilstein nut? Did your install accomplish the aims of recent post titled "Bilstein into Macpherson"?

                            Hth

                            I meant the road wheel moves, followed by me needing make a correction with the steering wheel.

                            However, the collar wasnt loose when I disassembled it and nor was the damper in the body, but taking the collar nut of showed had been moving as was more than paint damage it was pressed/formed all around a different shape. Looking at the collar istr it had a no or very little of a spigot to center the damper and I had considered turning a new one. But cleaned the threads and tighten it like crazy and was fine. Didn't use loctite seem like ideal area for it

                            Ill look for that thread, I havent seen it

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                            • #15
                              I've just installed some B6s and noticed this, hence finding this post through a search (yes, I know!) and so thought I'd share the pictures of what I found:
                              Attached Files
                              Cheers'en, AndyC
                              1994 ABY Coupe - Projekt Alpinweiss

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