The suspension is a work of art. Most of it, specifically the control arms and uprights. are CNC machined from aircraft-grade billet aluminum.


Heim Joint.png

The suspension uses 36 Heim joints (a.k.a., tie rod ends, spherical rod ends or rose joints). For 28 of those instances Superlite provides two aluminum cone washers and four grade 8 washers to mount each Heim joint (see the "Before" picture below). The cone washers allow the ball to rotate to a large angle without the case binding in the mounting bracket and the grade 8 washers take up the remaining space between the cone washer and the mounting bracket.

It's a simple but exasperating process to get everything lined up so that you can slide the bolt through, particularly if you're doing it by yourself. The bolt is a tight fit in the bracket and ball swivel holes (a good thing) and the diameters of the grade 8 and cone washers are different. 

I've taken these assemblies apart many times and I finally decided to improve things. I had Agile Automotive Performance make a set of custom cone washers. They have the following benefits:

  • They're a dream to install, no %@#! profanity required

  • They look great

  • They're a lot lighter

  • They allow the ball to rotate to a greater angle without binding; The Penske adjustment knobs on the front shocks were binding on the provided cone washers. However, I'm not sure if that would happen anywhere else

The weights in grams of the before and after assemblies are as follows:

  • 5/8" bolt: 80 vs. 10

  • 1/2" bolt: 46 vs. 12

So what does that amount to for the whole car? Approximately 2,096 grams (4.6 pounds) which is negligible. That said, the primary reason I made the change was to make assembly easy.

Hill perfectly aligned the suspension and then made a specific cone washer for every location. I decided to go with some standardized sizes and only make specific ones where warranted. The standardized sizes are:

  • S1: 1/2” x 0.438” (7x4=28)

  • S2: 5/8” x 0.373” (2x4=8)

  • S3: 1/2” x 0.312 (3x4=12)

  • Custom: 5/8” x 0.510” (1x4=4)

          Left SIDE Right SIDE
F/R Part Location Dia. No. Fore Aft Fore Aft
Front Lower Control Arm Front 5/8" 1  0.500" 0.510"  0.500" 0.441"
    Rear 5/8" 2 n/a n/a n/a n/a
  Upper Control Arm Front 1/2" 3 S1 S1 S1 S1
    Rear 1/2" 4 S1 S1 S1 S1
  Shock Top 1/2" 5 ??? ??? ??? ???
    Bottom 1/2" 6 ??? ??? ??? ???
Rear Lower Control Arm Front 5/8" 9 S2 S2 S2 S2
    Rear 5/8" 10 S2 S2 S2 S2
  Upper Control Arm Front 1/2" 11 S1 S1 S1 S1
    Rear 1/2" 12 S1 S1 S1 S1
  Shock Link Bottom 1/2" 13 ??? ??? ??? ???
    Top 1/2" 14 S3 S3 S3 S3
  Shock Bottom 1/2" 15 S3 S3 S3 S3
    Top 1/2" 16 S3 S3 S3 S3
  Toe Link Outside 1/2" 19 n/a n/a n/a n/a
    Inside 1/2" 20 S1 S1 S1 S1
  Cross Brace Top 1/2" 21 S1 S1 S1 S1
    Bottom 1/2" 22 S1 S1 S1 S1

Initial Control Arm Recommendations

Allan has built more SL-Cs than anyone and the following table provides his recommended starting point for suspension alignment. Wind the heim joints on the control arms all of the way in and then rotate them the indicated number of 360-degree turns.

Control ArmChassisUpright
Front Upper 5 Out 5 Out
Front Lower All In N/A
Rear Upper All In 2 Out
Rear Lower All In N/A


This picture has the upright pointed in the wrong direction! The one below has it correct.


Step down spacer, high misalignment spacer, safety washer, cone washer

3/8" x 0.125"

  • Left and Right Top