Here are the instructions on installing our Mountain Pass Performance Corkscrew Front Upper Control Arms. These arms are extremely simple to install, but there are a few details that require careful attention as they can save you a lot of time and effort. Please read this fully!
NOTE: For safety, only licensed mechanics should be allowed to work on braking and suspension systems
UPDATE: In November 2020 this product was updated with the inner arms no longer being symetrical. Make sure you use the correct arm for each side of the vehicle. The holes for the wheel speed sensor wires should be forward facing!
Difficulty Level: 2/5, Time Required: 1.25 Hours

Tools & Equipment Required:

  • Impact Gun or Breaker Bar to remove wheels
  • 1/2″ Torque Wrench
  • 3/8″ Torque Wrench
  • Socket + Wrench Set
  • Metric Allen Keys
  • Torx T50 Socket
  • 3/8″ 12 Point Socket
  • Prybar
  • Floor Jack or Transmission Jack
  • Jack Stands
  • Grinding Tools

Kit Contents:

Inspect your kit to ensure you have everything well before taking your car apart. The kit includes:
  • (2) Front Upper Control Arms (inner part, one left and one right)
  • (2) Balljoint Housings (outer part)
  • (2) 2mm Shims
  • (2) 4mm Shims
  • (2) 8mm Shims
  • (4) Ziptie brackets
  • (4) M4 Screws
  • (4) 3/8-16 x 1.25″ Bolts
  • (4) 3/8-16 x 1.75″ 12point Bolts
  • (2) M6 bolts, nuts and (4) washers

Functional Overview:

Our front upper control arms are designed to be very easy to adjust – in fact, adjustment to the camber can be made even without removing the wheel. Adjustments typically take as little as 1 minute. However, it is CRUCIAL to ensure the correct length of bolt is used with the shim stack used. There must be a minimum of 8 TURNS of the bolts between the outer balljoint housings and the inner arm.  For up to 8mm worth of shims, use the 1.25″ long bolts. Above that, use the 1.75″ long bolts. The 1.75″ long bolts are acceptable for up to 16mm of total shim thickness. When camber changes are made to the front upper control arm, this results in huge changes in front toe as the tie rods do not shorten or lengthen along with the upper arm, something you can observe by moving the knuckle inwards and outwards by hand. We have a guide at the bottom of the recommended tie rod adjustment relative to the OEM (14mm) shim thickness. This allows you to make quick adjustments at the track and keep the total toe almost exactly the same even with a change in shims. It also allows you to revert back to the original “street” settings at the end of the day! We chose the settings with an easy to execute number of turns for the tie rods, if you are looking for something in between you will have to do some measuring.

Installation Instructions:

OEM Front Upper Arm Removal:

Rubber shroud removed on the right
  • Remove clip securing front of cowl tray and loosen the four bolts securing the damper and front upper control arm carrier.
  • Remove the wheel speed sensor harness from the upper control arm clips and from the knuckle clip.
  • Remove the pinch bolt to free the balljoint from the knuckle.
  • Remove the anti-roll bar endlink from the damper.
  • Loosen the bolts securing the front upper control arm to the front upper control arm carrier
  • Remove the lower 21mm damper bolt (not pictured)
Loosen / Remove all items circled as described above.
  • Slide the damper outwards and swivel the upper damper/front upper control arm carrier to pull it away from the chassis. This is required to gain access to the front upper control arm bolts.
  • Remove front upper control arm

MPP Arm Setup

NOTE: Ensure the correct arm is used for the correct side. In November 2020 all FUCAs are no longer symmetrical. The holes for the wheel speed sensors are facing forwards.  The speed sensor clamps bolt on to the FRONT of the arm (towards the front of the car when installed).
  • The kit comes with 2mm, 4mm and 8mm shims. This allows for a range of 0 – 14mm in 2mm steps. Additional shims can be purchased if you desire less than OEM camber.
  • Install the desired shims, select the correct bolt below, and torque to 20ft-lb
  • Install the supplied ziptie clamp blocks for the wheel speed sensors.
PASSENGER side arm shown (Balljoint to the rear). Note as of Nov 2020 all supplied FUCAs are no longer symmetrical. The wheel speed sensor holes are pointing towards the FRONT.
Shim Stack ThicknessApprox CamberShims RequiredBolt Length
14mm-1.2 (OEM)2 + 4 + 8LONG
12mm-1.54 + 8LONG
10mm-1.92 + 8LONG
8mm-2.28SHORT*
6mm-2.52 + 4SHORT
4mm-2.84SHORT
2mm-3.22SHORT
0mm-3.5NONESHORT
*Confirm adequate thread with this shim thickness. Use no washer if required, or the long bolt. If using the long bolt, ensure the bolt is not bottoming out in the arm. Due to manufacturing tolerances we don’t want to say the long bolt is always OK. If using the long bolt ensure it is not bottoming out before appropriate clamping is established! Installation of the MPP front upper control arm is the reverse of OE removal. It is not mandatory to torque the arm at ride height as the arm uses sealed spherical bearings – so they are free to move even when tight! Due to slight variations in the casting of the upper suspension assembly, you may need to flex the arm slightly to install it in the upper suspension assembly.
  • Remove the OEM zipties from the wheel speed sensor harnesses and ziptie the wheel speed sensors to the ziptie blocks.
  • Ensure there is adequate slack at both the inboard and outboard ends. Steer the wheel fully left and right to ensure the wheel speed sensor is not being strained.
  • The speed sensor wire can be moved within the rubber mounting sleeves to gain clearance to the tire at full lock
NOTE: The right side knuckle seems to have a higher chance of rubbing the wheel speed sensor than the left (driver) side. This can occur with very large wheels/tires that are close to the knuckle. We suggest bending the bracket up on the knuckle as pictured below and checking for clearance at FULL STEERING LOCK with the suspension at ride height.
  • The inboard end should not be strained even with the arm fully pressed up against the chassis. The outboard end should not be strained even with the wheel turned fully outwards.
Pay close attention to the wheel speed sensor mounting. It may help to use a pry-bar to press the upper control arm balljoint into the knuckle.

Fender Liner Securing

When using a large shim stack, it is possible that the arm can touch the plastic fender liner. To ensure this cannot happen it is recommended to pull the plastic fender liner out of the way and drill a 1/4″ hole and secure it with the supplied M6 hardware to the existing open hole in the chassis.
While holding the fender liner rearwards and outwards, drill a hole lining up with the bracket shown (same on the driver side) to ensure the fender liner cannot touch the arm.

Alignment Changes

Changing the shims is extremely quick and easy. All that is required is to jack the car up, and without removing the wheel, loosening the bolts a few turns to allow the shims to pop out. The shims have been designed so they can be installed and removed without fully un-bolting the outer balljoint carrier. Simply remove the shims and install the thickness desired. Pay attention to the orientation of the dowels. Note the bolt lengths required above. If the shim change requires a change of bolt length, remove and swap one bolt at a time. Never remove both bolts at the same time as if you do the knuckle will become loose and this will put the full weight of the wheel, tire and knuckle on the wheel speed sensor wire. Not good.
Loosen the bolts a few turns, pop the shims out, insert new shims and tighten. That’s it!
As mentioned earlier, we have established a guide for the common shim thicknesses recommended. This guide will be updated in the future with more precision, but for now, it is still an accurate tool that allows you to change the shim thickness and adjust your tie-rod to keep the toe within ~1mm of the original setting. First, using a paint marker mark the current position of the tie rod once you get an alignment with the Front Upper Control Arm set to 14mm (recommended street setting)
Note the paint marks to accurately line up the tie rod after a full turn of change.
Next, use the table below to determine how many full turns of the tie rod is required to keep the toe approximately the same as the starting point:
Shim ThicknessTie Rod TurnsToe Change
14mm (Starting Point)
8mm1 Turn SHORTER-1mm TOE OUT Per Side
0mm2 Turns SHORTER+0.5mm TOE IN Per Side
As shown above, a 14mm shim change closely matches with 2 full turns of each tie rod. An 8mm shim change closely matches 1 full turn of each tie rod. The same general rule of thumb can be applied for other shim thicknesses. For example, if the shim stack is changed from 12mm to 6mm, you can expect 1 full turn shorter of the tie rod to result in a total toe change of approximately 2mm (1mm per side) That’s it! Enjoy using our “Corkscrew” Front Upper Control Arms – we put a ton of work into the design of these so that they offered the ultimate in performance with zero compromises on the street, all while offering extremely easy and repeatable adjustments.
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