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Interesting Bilstein Discovery

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  • Interesting Bilstein Discovery

    So here is an interesting tidbit. I recently ordered a full set of Bilstein B8 Performance Plus shocks and discovered something interesting when comparing the rear B8 shock against the rear Bilstein Group N Motorsport shock. Respective part numbers are B8 = 24-020275, Bilstein Group N = 24-000642.

    When comparing the length of the two shocks the Group N shock shaft is about 1.5 inches shorter than the B8. I find this interesting as the B8 shocks are supposedly shorter and designed to be paired with lowering springs (according to Bilstein). Seems to me the Group N shock DESIGN would be a better match due to the shorter shaft. Unfortunately the Group N shock is valved at 200/200 which is likely incompatible with a typical replacement spring (i.e. H&R Race spring whose spring rate = 570 lbs/in or the H&R Sport spring whose spring rate is 380 lbs/in ). Probably better paired with a spring with a much higher spring rate such as the TMS J-Stock spring whose spring rate is 1026 lbs /in. When compressed, both shocks are the same length.

    I also compared the front strut inserts between the B8 and the TMS modified J-Stock Bilstein. In this case both shocks have the same overall length (both compressed and uncompressed). This leads me to believe that other than a valving change, the J-Stock Bilstein is the same internally as the B8.

    Finally, the rear B8 shock is crimped thereby negating the ability to re-valve the shock (this has been discussed in another thread). Interestingly enough the Group N Bilstein is not crimped thereby allowing for future rebuilding and / or re-valving.

    PICTURES:

    Side-bySide Comparison

    Click image for larger version  Name:	Shock 1.jpg Views:	0 Size:	231.1 KB ID:	1283362

    Close-up of shaft differences

    Click image for larger version  Name:	Shock 2.jpg Views:	0 Size:	225.8 KB ID:	1283363

    Crimped vs. non-crimped

    Click image for larger version  Name:	Shock 3.jpg Views:	0 Size:	178.6 KB ID:	1283364

    Thanks,

    Mark
    1990 M3

  • #2
    I'm going by memory here, and I'm not a "shock guy" by any means, but I thought that back in the day the Gruppe N dampers were available in a few different valvings along the lines of the Gruppe A inserts (so they could be better matched with the various Gruppe N springs available).
    jimmy p.
    87 E30 M3 Prodrive British Touring Car
    88 E30 M3 Zinnoberot - Street
    88 E30 M3 Lachsilber - Race (#98 SCCA SPU)
    92 E30 M Technic Cabrio - S14 POWERED!
    98 318Ti M44, Base - Morea Green
    04 Ford F350 - V10

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    • #3
      Originally posted by jimmy p. View Post
      I'm going by memory here, and I'm not a "shock guy" by any means, but I thought that back in the day the Gruppe N dampers were available in a few different valvings along the lines of the Gruppe A inserts (so they could be better matched with the various Gruppe N springs available).
      Your memory is correct, there were different valving specifications. In the case of Bilstein part number 24-000642 the valving is 200/200.
      1990 M3

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      • #4
        Original J stock rears were revalved Ford E250 shocks.
        Who knows where I'll be, changes from day to Continent.

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        • #5
          Originally posted by M-technik-3 View Post
          Original J stock rears were revalved Ford E250 shocks.
          Correct. Complete discussion regarding J-Stock springs and dampers here: https://s14net.vbulletin.net/forum/s...rings-are-back
          1990 M3

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          • #6
            Gr. N Wet set-up and dry set-up respectively are:

            31 32 2 221 922 Dämpfereinsatz VA / shock absorber FA 235/270
            2 31 32 2 483 088 Dämpfereinsatz VA / shock absorber FA 300/300
            33 52 2 221 909 Stoßdämpfer HA / shock absorber RA 165/170
            2 33 52 2 483 087 Stoßdämpfer HA / shock absorber RA 200/200


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            • #7
              The Bilstein Group N rear shock (24-000642) would be equivalent to BMW Motorsports part number 2 33 52 2 483 087.
              1990 M3

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              • #8
                some additional info

                Tarmac Rally

                Front: 34-236406 280/150 Length: 597 mm

                Rear: 24-233637 260/120 Length: 533 mm

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