The new Model S has an entirely redesigned rear suspension with some opportunities and challenges for the aftermarket. Part of the design process that we went through here at MPP was fully modeling the rear suspension and analyzing a number of characteristics of the rear suspension. Let us take you through the process and explain how we see the rear suspension of the Plaid:
One of the first items that popped up to us in the design phase was that when the Model S is significantly lowered, the bump steer becomes very extreme in compression. Normally the rear suspension of road cars is designed to toe in with compression to add stability. In the case of the Model S, the rear suspension will actually toe-out significantly when compressed in the range that a lowered Model S will run in. This is undesirable behavior! We suspect Tesla tuned it this way on purpose, as it actually works when at factory ride height and when running very little front camber. However, once the car is lowered and the front of the car is working (thanks to some big tires and camber!) having the rear suspension toe-out excessively when you’re asking for power coming out of a corner is the last thing you want!
Using the knowledge gained from modeling the suspension, and looking at the suspension from a practical standpoint, it made the most sense to adjust the lower arms. The lower arms are the easiest to access from the bottom of the car for an alignment technician. In addition, the factory “upper camber arm” already uses a sealed spherical bearing at both ends, so there was no performance benefit to changing this arm – not to mention it is a complex shape and thus very expensive to make an adjustable replacement for.
With the above in mind, we present to you our adjustable trailing arm (Tesla calls this the Lower Fore Link). This arm can be used along with included shims to provide bump steer correction, and additional or reduced camber for those who are looking either for less tire wear, or more performance on the track. We’ve also added a few aesthetic design features to make sure the arms are worthy of living on your world-class electric vehicle.
As you’d expect from MPP – the arms are easy and precise to adjust, and well indicated on which way to turn the adjuster to make the change you’re after. The arms replace the soft OEM bushing in the OEM “Lower Fore Link”, so you’ll also see a performance benefit from a reduction in rear compliance.
These lower control arms for Model S Plaid take everything we’ve learned from motorsport and road car performance for over 20 years and apply it to the Tesla Model S. We know how important it is for suspension arms to be easy to adjust, have great durability even in harsh climates, and have solid bearings rather than rubber bushings for the ultimate connection to the road.
We recommend adding our Front Upper Control Arms to also achieve more camber in the front of your Model S if you’re looking for additional grip (our FUCA kit can also lower your Model S – eliminating the need for lowering links). Our Rear Toe Arms are a worthy addition to help ease alignments, as to remove another rubber bushing in the suspension. We will have a matching rear lower control arm coming in the near future for those who want to easily be able to adjust both rear lower control arms, or for those who want to make large camber changes regularly.
Most aftermarket suspension arms are made using either urethane bushings, which are used because they are cheap – or spherical rod ends, which are ideal for performance but don’t last very long in sandy or salty environments. Our solution is to use an OEM production sealed bearing – delivering the performance of a spherical with the durability of an OE part. The sealed bearing is just like a ball joint, it is solid and has virtually no compliance while being lubricated and protected from corrosion. Since this part is from an OEM vehicle – and we use only the highest quality OEM bearings, you know this joint will endure the test of time.
Typical aftermarket arms use rod ends threaded into a suspension arm, which makes them very easy to adjust – whereas a pressed in bearing offers no adjustment. Our solution is to use a turnbuckle allowing for precise adjustment. Rather than use jam-nuts – which always affect the alignment when locking down the nuts – our clamping system allows the alignment technician to perfectly set the alignment, then tighten the clamp bolts without throwing off the setting. The turnbuckles are made from stainless steel – so they will never corrode or rust. The arms are CNC machined out of 6061-T6 aluminum, and anodized blue for durability and aesthetics. Arms come as a pair of two and are warrantied for 3 years.
Laser engraving indicates which way to adjust the turnbuckle to extend or retract the arm, saving any confusion for your local alignment technician, or for anyone trying to make some quick track-side changes. You can always easily set the arms back to the original starting point by simply using a paint marker and clamping the arms in the original position.
These billet aluminum arms come fully assembled and preset to the factory length. We always recommend using anti-seize lubricant to prevent any galvanic corrosion between the aluminum and stainless steel adjuster, and the arms are supplied with anti-seize applied.
As with all MPP products, documentation and support is our strength. Our instructions provide all of the data required to set up the suspension properly. It is critical that the shop doing the alignment reviews our notes to ensure they don’t incorrectly adjust your suspension! As always, feel free to ask any questions and we’re here to help.
Testing & Results:
As with all of our MPP parts, these arms are designed for and validated on the racetrack. We use our MPP adjustable trailing arms to fine-tune the bump steer on the rear of the MPP.R Plaid Model S. This has allowed us to balance out the massive increase of front grip thanks to our competition suspension and MPP Front Upper Control Arms (and 305s upfront!). As a result, we’ve been able to optimize the entry, middle and exit phases of the corner to maximize both the power potential of the car and manage the weight of this big car.
Along with the other upgrades we’ve done to the Plaid, the suspension links and 305 tires all around have allowed the Model S to corner with up to 1.4G’s at some circuits, on 300 treadwear Michelin PS4S tires! We’ve certainly started to tame the beast and we look forward to sharing more soon, but for now, we can say that the Plaid has consistently been the fastest car at each track day it’s attended by a wide margin.
Don’t be fooled by imitators who have routinely copied our innovations and ideas in the performance aftermarket. MPP was the first to use sealed spherical bearings and it’s become the staple of our aftermarket suspension offerings. We were also the first to preset our arms to OEM length to help make installation a breeze for you guys. We’ll continue to find new ways to make better performance aftermarket parts, and we appreciate your support and loyalty!
Aside from some self inflicted torture (I tried to use the factory flanged bolts instead of the provided bolts, duh), the install is straight-forward. The arms are precise and well made. It’s a tight fit and you have to work it into place. I haven’t taken it in for alignment yet. I am removing camber so I didn’t have to use the spacers but from the looks of it, not a difficult operation to add.