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Thread: Thrust arm bolt torque under load? THE SHAFT!

  1. #1
    Join Date
    Apr 2004
    Posts
    517

    Default Thrust arm bolt torque under load? THE SHAFT!

    No wonder thrust arm bushing life is so short.

    Bad enough that many if not most are apparently torqued with no load on the suspension. The real deal is much worse.

    Bentley specs load of 150lbs on each front seat and center of back seat, 50 lbs in trunk and a full tank Assuming empty trunk and fuel 1/2 full, the "load", even if full load of empty car is on the suspension, is 575 lbs short. Do the math.

    One way to get the load is go to Lowes for eleven 50lb. bags of sand @ $2.67 each. If you don't think 575 lbs is significant, take it home in your car. Measure the ride height before and after loading and go for a rip on the way home.

    If your service shop doesn't have a stack of sand bags about 5 ft high, or a guarantee of four 150 lb people always in the shop to sit in the car, you're getting screwed.

    For DIY, c'mon, get with the program or tell me what's wrong with my analysis.

  2. #2
    Join Date
    Dec 2003
    Location
    PA
    Posts
    5,403

    Default

    Quote Originally Posted by Gene in NC
    No wonder thrust arm bushing life is so short.

    Bad enough that many if not most are apparently torqued with no load on the suspension. The real deal is much worse.

    Bentley specs load of 150lbs on each front seat and center of back seat, 50 lbs in trunk and a full tank Assuming empty trunk and fuel 1/2 full, the "load", even if full load of empty car is on the suspension, is 575 lbs short. Do the math.

    One way to get the load is go to Lowes for eleven 50lb. bags of sand @ $2.67 each. If you don't think 575 lbs is significant, take it home in your car. Measure the ride height before and after loading and go for a rip on the way home.

    If your service shop doesn't have a stack of sand bags about 5 ft high, or a guarantee of four 150 lb people always in the shop to sit in the car, you're getting screwed.

    For DIY, c'mon, get with the program or tell me what's wrong with my analysis.

    My opinion:

    If the OEM designed bushings require that kind of preparation to make a damned torque-spec, to hell with it! Grunt Urethane bushing... preload, nope. Weight in car, nope. Torque it and drive it.

  3. #3
    Join Date
    Dec 2003
    Location
    Eastern Tennessee USi
    Posts
    14,843

    Default

    if you drive with 4 people and a full trunk of luggage on a daily basis then thats the way to do it...if its only you in the drivers seat and you feel you have to be real anal about it I guess you could sit in the car during the alignment/torque process...I personally dont think its significant enough to harm parts since I am the primary person in there.
    95 E34 530I V2.37
    ===========
    Those who make peaceful revolution impossible will make violent revolution inevitable.

    John F. Kennedy

  4. #4
    Join Date
    Jun 2004
    Location
    Melbourne, Australia
    Posts
    1,305

    Default

    Quote Originally Posted by Gene in NC
    No wonder thrust arm bushing life is so short.

    Bad enough that many if not most are apparently torqued with no load on the suspension. The real deal is much worse.

    Bentley specs load of 150lbs on each front seat and center of back seat, 50 lbs in trunk and a full tank Assuming empty trunk and fuel 1/2 full, the "load", even if full load of empty car is on the suspension, is 575 lbs short. Do the math.

    One way to get the load is go to Lowes for eleven 50lb. bags of sand @ $2.67 each. If you don't think 575 lbs is significant, take it home in your car. Measure the ride height before and after loading and go for a rip on the way home.

    If your service shop doesn't have a stack of sand bags about 5 ft high, or a guarantee of four 150 lb people always in the shop to sit in the car, you're getting screwed.

    For DIY, c'mon, get with the program or tell me what's wrong with my analysis.
    As I rarely travel with passengers I put 4 x 20kg bags of cement on my drivers seat with 3/4's of a tank of fuel before I torqued up my 750 bushes.

    1990 E34 535iA, 215,000kms (130,000 miles).
    Dual Climate, Rear Headrests, Rollerblind, M-Tech Wheel,
    Memory Seats, EAT Chip, T-Stars.

  5. #5
    Join Date
    Apr 2004
    Posts
    517

    Default

    If Bently specs aprox. 600 lb added to chassis weight before torqueing control arm bushing does that indicate that factory uses that preload in original manufacture? At Spartanburg plant the x5 complete driveline and suspension comes in as a preassembled unit. Something is used for preload.

  6. #6
    Join Date
    Apr 2004
    Posts
    81

    Default

    The trick most mechanics use is: While the car is up on a frame holding lift,just jack-up the individual bottom side strut.High enough to carry the full weight off the front,and torque it then.

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