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Thread: Dinan spring question

  1. #1
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    Dinan spring question

    I noticed a blown shock on my 540i a couple weeks ago, and while taking the shock assembly apart I noticed a spring end was broken off. I happen to have a set of Dinan springs in my parts stash that I got from another forum member years ago, so I figured why not go whole hog and redo the dampers all around.

    I'm scratching my head a bit while reassembling. I don't need the spring compressor while putting the shock assembly together. The threads from the shock are sticking fully out of the shock mount, and I threaded the nut on with no resistance until it was fully tightened. I can even rotate the spring slightly in the assembly by hand with the nut fully cranked down. Nothing is flopping around, but I've never seen a coil spring that wasn't under some pressure when installed.

    These springs are supposed to maintain full ride height, I believe; in fact, I set the fresh shock assembly next to the old one and the assemblies are exactly the same length.

    The springs have no markings on them, so I suppose they could be for a model other than the E34 and may not even be Dinan. They look exactly the same as the Dinan springs on the Turner Motorsport webpage, though.

    Any insights out there? I will add that these springs are STIFF. Good thing I don't do a 90-mile daily commute anymore.

  2. #2
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    Measure the coil wire diameter, I'll bet they are made from thicker wire. I've just used a pair of E34 rear coils on one of my E39s when I also found one spring broken.
    The E39 coils were 12mm the E34's I used(from a 540) are 12.5, had fewer turns and a shorter free length. Re-assembly was as you described.
    If any difference in ride height I don't notice it. Ride seems firmer but I've also replaced worn shocks.

    If you can leave two black stripes from the exit of one corner to the braking zone of the next, you have enough horsepower. - Mark Donohue

  3. #3
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    So the E34 springs were shorter than E39 -- that's reassuring, because I feared these might have come off an E39.

    They have the same number of coils as stock, but the wire is 13mm thick and the coils, obviously, are a little tighter.

    I guess I'll go ahead and install them and see how it goes. The worst that can happen is they make some noise.

    BTW, the symptom I was experiencing was that the back end of the car would jitter to the right on rough roads. Guess I should have suspected a bad spring all along.

    Thanks for the insights, Ross -- they were very helpful.

  4. #4
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    I've examined the E39 spring remaining and corrected my post above. Nearly 2" difference in free length which accounts for the ease of assembly.

    If you can leave two black stripes from the exit of one corner to the braking zone of the next, you have enough horsepower. - Mark Donohue

  5. #5
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    moroza is offline MORΩN ΛABIA BMW CCA Member
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  6. #6
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    Quote Originally Posted by moroza View Post
    What's the free length?
    Free length of the E34, 540 coils is 13 1/4", the E39, 528 coils are 15 7/8".
    I have two E39 528s, the one on the E34 coils rides 3/8" lower in the rear. The car which sits lower also has rear tires very near the wear bars while the other has near new ones. Otherwise tires and wheels are identical.

    If you can leave two black stripes from the exit of one corner to the braking zone of the next, you have enough horsepower. - Mark Donohue

  7. #7
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    Quote Originally Posted by moroza View Post
    What's the free length?
    Yep, the new springs are 13 inches ...

    Edit: I thought the old ones were longer, though. I'll measure the unbroken one tomorrow.
    Last edited by mrgraybeard; 06-04-2019 at 11:54 PM.

  8. #8
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    moroza is offline MORΩN ΛABIA BMW CCA Member
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    Standard units, please, to within 5mm or better. Stock non-sport springs are 385-400.

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    USA, sir. Inches ARE standard units. X 25.4, as if you don't know
    Last edited by ross1; 06-06-2019 at 10:50 AM.

    If you can leave two black stripes from the exit of one corner to the braking zone of the next, you have enough horsepower. - Mark Donohue

  10. #10
    moroza's Avatar
    moroza is offline MORΩN ΛABIA BMW CCA Member
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    Earth, sir. Metric IS standard, and the US is a deviant exception with its archaic folk units that are based on nothing and are harder to work with.

    My data hoard has 279mm for Eibach and H&R, 335mm for Vogtland. IIRC both Eibach and Vogtland needed to be compressed to fit a v.2 Bilstein HD strut.
    Last edited by moroza; 06-06-2019 at 04:12 PM.

  11. #11
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    I finally got these installed. The car rides fine, maybe sits a smidgen lower than stock. While I was back there I spotted a leaky brake line, so got sidetracked a bit. I'm usually pretty good with brake line fittings, but these would not let go -- I ended up sawing the fittings off and replacing the inner and outer hoses. Cunifer brake line FTW!

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