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Thread: Thrust arm replacement question

  1. #1
    Join Date
    Dec 2003
    Location
    Los Angeles, CA
    Posts
    206

    Default Thrust arm replacement question

    I have the famous 60mph shimmy.
    my question is, should i replace just the bushings, or the entire things? the bushings are so much cheaper, so i'd rather do taht..
    how hard is the job? how long does it usually take?

    thanks!


    oh, and also, i put synthetic oil in my car 3000 miles ago. that oil is supposed to go for 10k, isn't it? the color is already getting dark, after about 3k miles. is that normal?

  2. #2
    Join Date
    Jan 2004
    Posts
    1,171

    Default

    there are many varied opinions on how to replace the thrust arms. The archives are replete with procedures etc. If you remove just the thrust arms, can leave pretty much the whole suspension intact. Your challenge will be breaking the bolts loose and dislodging the ball joint from each steering knuckle which can be done for the upper arms without removing each knuckle. Which begs the question if the ball joint should be removed at all. It is a judgement call. If the car has 100k miles on it, I recommend you change the entire upper arm. Personally there is a real pitfall with piece mealing your front suspension. I like to replace everything...shocks, sway bar links, idler arm etc at 100-120k miles. Then you are good for another 100k miles. Otherwise you are second guessing what is good and what is bad as you will be if you replace your bushings without replacing the arms/integrated ball joints. If your car has 60k miles on it...would suggest replacing just the bushings...go with 750 bushings. The bushings are the weak link and premature wear element relative to the rest of your suspension.
    As to changing from dino to synthetic engine oil....when ever first doing this, all the accumulated sludge from years of dino use will be dislodged and suspended into the bath of fresh synthetic...due to the excellent detergency and de-carbing capability of syn...part of its beauty...as a great safe cleaner of your internal engine components. Each successive syn oil change will become cleaner and cleaner as the engine is purged of contaminants over time. The early dark synthetic when first making the transistion is normal and nothing to be concerned with. Running synthetic in these engines is a very good thing.
    HTH,
    George

  3. #3
    Join Date
    Apr 2004
    Posts
    1

    Default

    About the shimmy. Having just conquered the "shimmy", I learned these things.

    -People on the forum will write what fixed the shimmy for them. The component that caused the shimmy is different for each person.
    -While I understand the argument that a bushing is cheaper and many people want to buy the 7 series bushing consider this: 1) You will have to remove the same amount of the suspension to get the strut arms off. Then you will have to drive somewhere to press the old bushings out and the new ones in. It's a hassle unless you have a 2-4 ton press at your house (which aren't real expensive) and can fixture the press up.
    - Now, having fully disassembled my front suspension 4 times (thats everything), I can tell you, this is no simple effort, I use air ratchets/guns/drivers and have gotten very familiar with all the bolts, but if your doing it the first time, even the E34 websight missed many steps which you'll no doubt learn....
    - The only real way to determine which strut (upper or lower) and on which side is really causing the shimmy is to pop all the ball joints loose, and move the arms left and right while they are still bolted to the frame. an arm that moves left and right (horizontally) is not acceptable. What you'll probably find is both the upper and lower move 2-3" so consider before doing this in buying both upper and lowers as you'll probably find after replacing one set, the car still shimmies, so to avoid taking the car apart again, I recommend (and this is from experience) buying them both. The upper requires you to drop the sway bar, dont worry, this is easier than it looks.
    -I agree with the last guys comment with the exception of the bushings, after you beat on the ball joints, etc, and go to all the trouble to press bushings etc. you could have been back on the road a day sooner by just buying the complete unit. I was all for rigid bushings when the car had 60k on it, but now realize I'm driving a 120k mile car and although I still love it, I must limit my investment in something that wont return it. I bought the uppers and lowers from BMA and being an engineer, would argue with anyone that you wont feel the difference between bushings. People perceive differences mostly due to the perception of quality. You'd be replacing a few very rigid bushings with urethane bushings that might be 20% more rigid when in fact, the whole car has 120k and you didnt touch the other 50 bushings, so really, would you be doing all the work just to say its got 750i bushings. The real mods are bigger sway bars, forget the bushings unless you'll be doing all the bushings.
    -TIME: I can do both sway bars in about 4-6 hours depending on kids, wife issues, temperature, etc. I use air tools, and a 3/4" 3ft pipe as an extension to my breaker bar for some bolts. I also leave the calipers connected and wire tied to the frame and the strut bolted up. Break loose the upper and lower ball joints, remove the lower strut arm frame bolts, then the 4 bolts per side holding the sway bar and upper strut arms on, and the whole front suspension will fall off. Pull it out and boom, your replace the uppers in no time, reinstall the new lower strut arm, and the whole assembly will bolt right up. Bolt the strut arms back to the wheel/brake/bearing assembly (3 bolts), reinstall the calliper, and your done. (sounds easy but each bolt is a challenge. Good luck

  4. #4
    Join Date
    Jan 2004
    Posts
    1,171

    Default

    I have been around these cars a long time and have never seen such convoluted logic...lol. Not only relative to how to change your thrust arms but your musings about solid bushings...whatever your point was. You can simply remove just the thrust arms if that is your agenda to change the bushings....without removing any other suspension components. The 750 bushings are the bushing of choice...they are not solid.
    I was "the guy" that posted the procedure including pictures for dropping the whole suspension down that created the firestorm of debate on this board some time ago.
    This does not include removing the struts from the car...not necessary to remove the struts, rotors or brake calipers unless changing shocks or springs.
    Dropping the whole suspension down is only beneficial if you are going to replace the lower control arms as well because the lower arm ball joint locknut is sandwiched between the strut housing and steering knuckle plate. If you want to remove the thrust arms to either replace the whole arm or bushing, all you have to do is remove the thrust arms...nothing else.
    George

  5. #5
    Join Date
    Feb 2004
    Location
    Missouri, USA
    Posts
    136

    Default Get the BMA or Racing King units for $90.....

    I recently replaced mine and, for the money, you can't beat a BRAND NEW arm with a BRAND NEW (installed) 750i bushing with a BRAND NEW ball joint on the end from BMA.
    No fuss, no muss.
    You have to remove the arm to replace the bushing anyway....
    Go ahead and do the whole enchilada, you won't regret it.

  6. #6
    jterrell Guest

    Default Thrust Arm replacement questions

    Your response to replacing the Thrust arms on your 525i sounded most simple, especially after reading the previous points of view expressed by others.
    Did you replace your Thrust arms due to shimmy?
    Did it correct the shimmy?
    Did you have the front end aligned afterwards?
    How long did it take you to do the work and did you need special tools?
    Thanks,
    John

  7. #7
    Join Date
    Feb 2004
    Location
    Missouri, USA
    Posts
    136

    Default The thrust arms corrected a LOT but....

    Quote Originally Posted by jterrell
    Your response to replacing the Thrust arms on your 525i sounded most simple, especially after reading the previous points of view expressed by others.
    Did you replace your Thrust arms due to shimmy?
    Did it correct the shimmy?
    Did you have the front end aligned afterwards?
    How long did it take you to do the work and did you need special tools?
    Thanks,
    John
    Not every bit of the "standard E34 front end ailments".
    If you read the list on the E34 web site, you can pretty much count on replacing all the parts that are listed there VERY soon or at the same time the Thrust Arms finally kick the bucket.

    My Thrust Arm replacement corrected a a HORRIBLE clunk sound (BAD Thrust Arm "ball joints") and the 50-60 mph shimmy.
    THEN I found another clunk (masked by the previous clunk), this was the swaybar end links.
    THEN I found a looseness in the wheel, and tightened the steering column nut.
    THEN I found more looseness, in the driver's side tie-rod ends.
    THEN I had the tires balanced....but the baboons didn't set my hubcentric rings in properly-another shimmy-so I fixed that myself.

    WHEW!
    All were easy to replace/adjust and inexpensive (THANK YOU BMA!!) and now the car drives like a DREAM!!!!
    BUT....the radiator shot craps.
    When will the repairs end?
    I hope VERY soon!
    I'd like to drive the car for more than two weeks without working on it!

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