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Thread: Front eng thunk when going over small bumps

  1. #11
    Join Date
    Oct 2004
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    3,395

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    Actually, you can just use a hex key and an open ended (or crow's foot if available) wrench to tighten the strut nut. Every strut insert I've ever seen made for the e34 has had a hex female machined into it.

    And also: you do *NOT* want to hold any part of the strut insert's shaft with a monkey wrench...You don't even want to touch it, as it will remove any grease on it that's on there to protect it...Sticking a monkey wrench on it is a quick and easy way to destroy it: if it's correctly installed in the mount, there won't be anything to grab onto except for the shaft.

    I still think it's the sway bar links. If the collar nut were loose, you'd be able to see and hear the problem when you jacked up that side of the car.

    It may also be a bent dust shield. One of mine is still badly messed up from my front end rebuild. I keep on bending it so it doesn't bang against the rotor (which it does, over some bumps) because replacing it is a pain (have to remove the hub). You'll probably be able to see evidence of it ON the rotor if this is your problem. Mine sounds like a metal "clink" when it happens. Also, (I guess because of suspension geometry) it's much harder to reproduce when the front of the car is up in the air...I guess the shield is closer to the rotor when the sucker's on the ground. But again, this happened because I pulled the strut housing, then stood it up on the dust shield (which bent it).

    best, whit

  2. #12
    Join Date
    Feb 2005
    Posts
    14

    Default You lost me.

    I think I understand what nut you are talking about... the nut on the very top of the shock shaft that connects it to the upper mounting bracket? If so, I used an allen wrench to turn the shaft while I held the nut with a gerry-rig'd socket and channel locks. How tight is tight? I was able to get a pretty grip......but maybe not enough.

    You description discribes the problem pretty good. I will get the proper tools and try tightening it. thanks, Paul

    Quote Originally Posted by emw525E34
    It is *most likely* the 22mm nut that secures the strut to the mount is NOT tight. It looks tight when the car is set flat without ramps or jacks. But if you use a big wrench to turn it, the whole middle rod will turn. How to hold it ?.

    Special monkey wrench below to hold it when you get a few turns in the 22mm nut. When new springs/struts were installed, this is usually the case. This nut need to mildly compress the springs a little during rest. If not, the rebounded spring will raise the front a little. The car, when loaded has about 3 to 6 mm play due to that "raised" REBOUND , so clunk. Then it stays there cos the car is loaded and that play is going. When you park and get off, it rebound and raises again!. This repeats and gets annoying.

    Another possiblily is the steering link below the driver side, its about 2 mm lose (needs 2 or 3 turns more), this causes a minor clunk on bumps.

  3. #13
    Join Date
    Feb 2005
    Posts
    14

    Default Thanks for the feedback.

    Thanks for the feed back everyone. I will double check everything you've mentioned tomorrow. I will update tomorrow. Paul

    Quote Originally Posted by lowell
    Actually, you can just use a hex key and an open ended (or crow's foot if available) wrench to tighten the strut nut. Every strut insert I've ever seen made for the e34 has had a hex female machined into it.

    And also: you do *NOT* want to hold any part of the strut insert's shaft with a monkey wrench...You don't even want to touch it, as it will remove any grease on it that's on there to protect it...Sticking a monkey wrench on it is a quick and easy way to destroy it: if it's correctly installed in the mount, there won't be anything to grab onto except for the shaft.

    I still think it's the sway bar links. If the collar nut were loose, you'd be able to see and hear the problem when you jacked up that side of the car.

    It may also be a bent dust shield. One of mine is still badly messed up from my front end rebuild. I keep on bending it so it doesn't bang against the rotor (which it does, over some bumps) because replacing it is a pain (have to remove the hub). You'll probably be able to see evidence of it ON the rotor if this is your problem. Mine sounds like a metal "clink" when it happens. Also, (I guess because of suspension geometry) it's much harder to reproduce when the front of the car is up in the air...I guess the shield is closer to the rotor when the sucker's on the ground. But again, this happened because I pulled the strut housing, then stood it up on the dust shield (which bent it).

    best, whit

  4. #14
    Join Date
    Oct 2004
    Posts
    3,395

    Default

    talking about this one:



    (center nut)

    You want to use a hex key and a 19/22mm (depends on the car -- mine's 19mm, yours is probably 22mm) C wrench on the top. Also, be sure to use either a new nylocker nut or some red loctite on it so that it doesn't come loose. It'll be snug when set correctly.


    best ,whit

  5. #15
    Join Date
    Oct 2004
    Posts
    3,395

    Default

    Hey Paul...also, check this out:



    there's me actually doing what I'm talking about here. read http://www.bmw4life.com for the whole shebang.


    EDIT: the wrench I'm using is even the Heyco that's included in the trunk tool kit.

    best, whit
    Last edited by Kalevera; 04-06-2005 at 10:20 PM.

  6. #16
    Join Date
    Feb 2005
    Posts
    14

    Default The 22mm is more difficult

    Lowell, The 22mm nut I have is set down inside the upper mounting bracket making it difficult to access. I plan to get a spark plug socket that will fit it so I can run the allen down the middle and have some to put a wrench on to tighten it. I really think they are snug, but it has been difficult to get much leverage with my current setup.

    Nice pictures! I headed to the link now.


    Quote Originally Posted by lowell
    Hey Paul...also, check this out:



    there's me actually doing what I'm talking about here. read http://www.bmw4life.com for the whole shebang.


    EDIT: the wrench I'm using is even the Heyco that's included in the trunk tool kit.

    best, whit

  7. #17
    Join Date
    Feb 2004
    Location
    Bellingham
    Posts
    380

    Default

    Quote Originally Posted by pshirley
    Lowell, The 22mm nut I have is set down inside the upper mounting bracket making it difficult to access.
    Bah.

    I should mention that with that stupid hex key I could get nowhere near the torque I needed to break the bolt free. I later used a hex socket and adapted it to a nice long 3/4" ratchet. With a friend of mine holding the socket still, and me leaning on the 22mm wrench, it finally broke.

    Torque spec on this bolt is pretty high - something like 90 ft-lbs, if I'm remembering correctly. I don't know how you're going to measure that, but going as tight as you can should be good.
    Last edited by Mobius; 04-07-2005 at 11:17 AM.

  8. #18
    Join Date
    Feb 2005
    Posts
    14

    Default Nothing found

    I put the car up on ramps last night and checked, and double checked for anything loose. Nothing found.

    I also bought cheap 22mm socket and grount to flat spots on the ratchet end that allowed me to get an 22mm open end wrench on it. I cranked as hard as I could hold the allen wrench with a long cresent wrench. These babies are tight, no movement.

    I started to wonder if the upper shock mounts are shot. They physically looked okay (nothing broken), but they are extremely stiff/hard maybe even brittle. What are your thoughts? I know the new back mounts I put on were soft and actual flex when weight is put on the rear of the car. The fronts don't move, almost like hard plastic. Is this normal?

    thanks again for your help. Paul
    Quote Originally Posted by Mobius
    Bah.

    I should mention that with that stupid hex key I could get nowhere near the torque I needed to break the bolt free. I later used a hex socket and adapted it to a nice long 3/4" ratchet. With a friend of mine holding the socket still, and me leaning on the 22mm wrench, it finally broke.

    Torque spec on this bolt is pretty high - something like 90 ft-lbs, if I'm remembering correctly. I don't know how you're going to measure that, but going as tight as you can should be good.

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