Thanks for purchasing MPP rear control arms for your Model S! Please read the instructions below carefully as these arms are not adjusted in the typical way.
NOTE: It is CRITICAL that your alignment shop be aware of these instructions and understand how to adjust your rear suspension. Don’t let them get it wrong!
THE FORWARD LOWER LINK (“TRACTION”) SHOULD NEVER BE LONGER THAN THE REAR LOWER LINK. IT ALSO SHOULD NOT BE MORE THAN 6MM SHORTER THAN THE REAR LINK.
Theory And Setup:
The rear toe arm is used as normal to adjust the toe. The adjuster can be easily accessed from both the top and bottom. Turning the adjuster in the EXTEND direction will extend the arm, toe-ing out the wheels.
Camber is more complicated. The Model S uses a semi-multi link design, where the two rear arms create what is effectively a traditional lower control arm. Thus by extending/retracting the two arms in unison, or with a certain offset, both the camber and the bump steer characteristics can be revised.
It is critical that the offset not be adjusted excessively, and this is the critical point that your alignment shop must understand. The bumpsteer with the factory link lengths will TOE OUT significantly under maximum compression, so if you are using lowering links at a low ride height, it is advisable to have the forward lower link (trailing arm) 3-5mm shorter than the rear lower link (rear lower control arm), this will reduce/remove the toe-out in compression at very low ride heights.
Bumpsteer in the rear of the car under compression is never advisable, as it creates an unstable platform when the vehicle is heavily loaded. Almost all production cars are designed to toe in during suspension compression, which adds traction and stability when accelerating or hitting large bumps. As the Model S is a very long vehicle, having zero bumpsteer, or even a slight toe-out in bump may be of benefit for advanced drivers. However, when running at a lower than OEM ride height, the toe-out in compression is in our opinion excessive and should be addressed.
Setup Guide (Traction Arm + Trailing Arm):
- Adjust both arms evenly
- Ensure the forward arm (what we at MPP call the trailing arm) is not any longer than the rear lower control arm (OEM bumpsteer characteristics, for OE ride height)
- Ensure that the rear lower control arm is not any more than 6mm longer than the forward lower (trailing) arm (For maximum reduction of toe-out in extreme compression)
Setup Guide (Adjustable Traction Arm Only):
If you want more camber than stock (for track use):
- Add the supplied 6mm spacers to the rear lower control arm (see instructions below).
- You can then adjust the front arm to balance the camber side to side while staying within the 6mm offset (keep a gap in the arm between 24-30mm)
- MPP recommends adding the 6mm spacer and a gap of 25-26mm in the front arm as a starting point for lowered track use vehicles.
If you want less camber than stock with a lowered vehicle:
- Install the supplied spacers at the upper camber arm, and fine-tune by simply shortening the traction link by up to 6mm (keep a gap in the arm between 18-24mm), this will remove up to 1 degree of camber.
Time Required: 1.5 hours for first pair of arms, 30 minutes for any arms beyond that. Plus alignment.
Tools Required: 10mm hex socket (for M12 cap screws), 14, 19, 21mm sockets and wrenches, and common metric socket/wrenches.
Difficulty Level: 4/10
Step 1 – Raise Car & Remove Trim
- Put the car into Jack Mode (Controls > Service > Jack mode)
- Turn the car off (Controls >Safety & Security > Power Off)
- Lift the rear of the vehicle either with two jacks or with a hoist
- Remove the rear wheels
Step 2 – Remove OEM Arms:
- Remove one arm at a time. Removing a number of arms at once will make it more difficult to re-install new arms.
- Start by removing the bolt through the knuckle (21mm), followed by the two bolts at the chassis (16mm).
- Use a few long extensions to make it easier to access the inboard bolts.
Step 3 – Prepare And Install The MPP Arm
- Ensure the pinch bolts are tight on the MPP arm
- Install the arm with the M6 pinch bolts facing downwards or upwards, as you prefer.
- Using the supplied cap screws, torque the inboard bolts to 58lb-ft (NOTE: Rear lower control arm uses the OEM bolts)
- Raise the rear suspension with a jack and torque the outboard bolts to 105lb-ft using the supplied MPP nut if required.
Step 4 – If Adding Camber Without The MPP Rear Lower Control Arm, Install Spacers
- If adding additional camber without the use of the MPP Rear Lower Control Arm, follow the steps below:
- Loosen the rear lower control arm outboard bolt (21mm)
- Remove the bolts on the chassis side (16mm)
- Use a breaker bar as pictured below to rotate the knuckle which will pull the arm away from the chassis
- Insert the supplied spacers while a helper holds the breaker bar
- Re-install the OEM bolts and torque to 58lb-ft
- Compress the rear suspension with a jack and torque the outboard bolt to 105lb-ft
Step 5 – Reassembly & Align
- Double-check the torque, paint mark your bolts
- Install the wheels and lower the car on the ground (torque the wheels!)
- Take the car for an alignment
- Extending the toe arm will cause it to toe out
- Extending either lower arm will cause it to add camber
- See the setup guide above for notes and requirements on setting up the lower trailing and rear lower control arm lengths.