TMC is an independent, primarily volunteer organization that relies on ad revenue to cover its operating costs. Please consider whitelisting TMC on your ad blocker and becoming a Supporting Member. For more info: Support TMC
Start a Discussionhttps://teslamotorsclub.com/tmc/tags/

Replacing front upper A-arms

Discussion in 'Model S: Driving Dynamics' started by scottm, Oct 10, 2017.

  1. scottm

    scottm Active Member

    Joined:
    Jun 13, 2014
    Messages:
    1,990
    Location:
    Canada
    Turns out it's possible to do this yourself in your garage with one jack, but two jacks makes it better.

    I had upper ball joint play on one side (passenger), called while checking alignment. The ball joint is part of the A-arm and not separately replaceable so I ordered 2 new A-arms, and associates hardware bolts.

    These are bolt-out bolt-in replacement parts, so did the work in my garage. And since there's no adjustability of these parts there's no fear of changing your alignment.

    Here are some tips / tricks I can pass on, this coming from my RWD car vintage August 2014 build, air suspension...

    - observe direction of ball joint bolt, and forward bushing bolt, replace in same direction
    - put suspension in "standard ride height" and make a marking with a line of where the A-arms are resting with respect to chassis. I marked the strut tower as seen from the frunk bin area, when the car was level and on the ground at this setting.
    - put the car in jack mode

    - 15mm wrenches and sockets for all, plus you'll need a T50 torx for the ball joint pinch bolt
    - 10mm for moving the air suspension link ball connector from old arm to new arm (it doesn't come with it), pay attention to mounting direction of the ball and replicate on new arm
    - frunk tub out, windshield cowl and wipers off... you need to pull the 12v battery for access in that side of car (ugh!)
    - jack up car on front jack point one side at a time, and then either lower the wheel carrier onto a raised block to load up the spring, or raise the wheel carrier up with a second jack (what I did)
    - leave the strut mounted as it is in the car normally
    - wheel off on side you're working on. For the driver's side, undo the rear half of the wheelwell liner and let it dangle in place, you just need to reach behind it with a wrench. For passenger side, access is different, read on.
    - remove the air suspension link from the A-arm but can leave other end of this link connected to the sensor arm
    - get a flat wrench on the A-arm forward bushing bolt head, reaching in through the strut tower around the strut for access and undo the nut from where the frunk bin was
    - this forward bolt back out in the strut tower behind the strut and can *just* clear obstacles in there... I used a punch to knock the bolt out from the frunk direction backward
    - the A-arm rear bushing bolt head is accessed by reaching behind the fender liner on the driver side.. these bolts are screwed into the frame, no nut... don't strip it! Driver side is easy out... Passenger side you must remove the 12v battery. Since the battery is out, you can reach this rear bolt head from where the battery was - instead of playing with the wheel liner on that side.
    - the ball joint comes out last, it is a pinch bolt (T50/15mm), take the bolt out completely before hoping to pull the ball joint peg from the wheel carrier. Once the bolt is out the ball joint should easily be freed from the arm with a few taps.
    - the wheel carrier will "flop" around a bit when the ball joint is freed... tension and pressures on the coil spring and anti-sway bar will force this arm one way or the other, be ready for that
    - pull the A-arm out, move the air suspension link ball over to the new arm
    - put new arm in its place,
    - it is a bugger trying to get the forward bolt back up behind the strut tower to poke it forward into its hole through the new part with threads facing forward... My wife with skinny hands saved the day for me by doing this. It helps to line that hole up with the new part by using the old bolt, then pull it out... ready to receive the new bolt.
    - then do the rear bushing bolt.. bushing bolts get finger tightened until suspension is leveled to standard ride height again, then get torqued down
    - put the ball joint and pinch bolt back in, you can torque this on fully with car up in air. I used 35 ft/lbs.
    - connect the air suspension control arm link
    - wheel back torqued to spec, lower the car, do what is necessary to restore standard drive height getting the arm back to the level where you marked it. THEN torque down both bushing bolts for that arm.
    - I torqued the rear bushing bolt 45 ft/lbs, scared shitless of stripping that frame nut
    - torqued the front bushing bolt 50
     
    • Helpful x 1
  2. scottm

    scottm Active Member

    Joined:
    Jun 13, 2014
    Messages:
    1,990
    Location:
    Canada
    The price of 2 new A-arms and misc hardware to go with is about CAD $500

    I have the parts list and will append it here.

    Several hours of labor all told... removing frunk was expected, but removing cowl parts, fresh air intake duct work, and the 12v battery pull was not a happy add.

    Oh, I stripped an electrical mounting stud bolt on the 12v battery tray, and that cost me a minor stroke... then a few more hours for parts hunting and repairing that. I have posted into a separate thread on that accident.
     
  3. scottm

    scottm Active Member

    Joined:
    Jun 13, 2014
    Messages:
    1,990
    Location:
    Canada
    p.s. if someone knows or can determine the proper torque specs for these A-arm suspension bolts please chime in! If they're different enough from what I did, I may want to re-do mine.
     
  4. jelloslug

    jelloslug Active Member

    Joined:
    Jul 21, 2015
    Messages:
    2,512
    Location:
    Greenville, SC
    Upper ball joint to knuckle: 60Nm
    Upper control arm to chassis: 68Nm
     
  5. scottm

    scottm Active Member

    Joined:
    Jun 13, 2014
    Messages:
    1,990
    Location:
    Canada
    Thank you!! Hot damn!! Got lucky* on the difficult to reach bolts, very close guesses.

    My guess of 50 ft/lbs for front bolt = 67.8 Nm so bang on. And the rear bolt at 45 ft/lbs = 61 Nm I am going to leave alone, if a little light. I was sweating cold bullets torquing this one down to 45... Strip that and it's game over. Plus who says my torque wrench is accurate to within 5% any more... not me.

    My ball joint is a little light (35 ft/lbs = 47 Nm), but easy to redo, so I will beef that one up to 60 Nm.


    * In all fairness, I consulted my brother in law on "best guesses" as he's a suspension / alignment expert for GM cars and has seen them all. I told him the bolt dimensions, head size, materials, and bolting blind into frame... and took his suggestions. I'm glad he erred slightly on the side of conservative.
     

Share This Page