Suspension

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 JOINTS / TIE ROD ENDS

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 at times exasperating process to get everything lined up so that you can slide the bolt through. The bolt is a tight fit in the bracket and mono ball swivels (the whole point of heim joint) and the diameters of the grade 8 bolts 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 lighter

• You can machine them to the perfect width

• They allow the ball to rotate to a greater angle without binding. For example, the Penske adjustment knobs on the front shocks were binding on the provided cone washers (I haven’t noticed this happening anywhere else).

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

• 5/8" bolt: 80g vs. 10g

• 1/2" bolt: 46g vs. 12g

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.

For the race cars, Agile perfectly aligned the suspension and then cut a custom-width cone washer for every location. I decided to go with some standardized sizes and only make specific ones where warranted. In the future, I will likely tweak every cone washer. For now, 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)

The following table lists all of the cone washers. “n/a” indicates that there isn’t a cone washer in that location. I plan to stamp all of the custom sizes with a two-character identifier using the “NO.” column and the 1-4 designations in the column header. For example, the Front Upper Control Arm Rear Aft cone washer is “D4”.

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.

Misc

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