This post covers mounting the race tail diffuser to the chassis.
The SLC has the choice of two different tail treatments, the race tail and street tail. The street tail provides enough body coverage of the rear wheels to pass certain European regulations. The race tail has an aluminum diffuser which serves as an attach point for the massive rear wing and rear clam hinge.
Here is a video on the process…
Starting with cars ordered in 2018, RCR made a slight change to the diffuser so it clears the back of the Graziano transaxle without requiring modification. The 2018 change places the center panel flat at the diffuser bottom vs. positioning it at an angle as the lower outer panels. Here is a pic of the diffuser as supplied by RCR…
The Graziano sits offset to the right and the diffuser wants to sit slightly offset to the right of the chassis as well. You need every fraction of an inch to make room for the wing upright and keep the diffuser centered. Shaving a bit off the side of the Graz rear cap helps. The offending area on the Graz can easily be filed down by hand…
As delivered, the diffuser attaches to the chassis in 4 places. Two brackets are provided for the top corners and two brackets need to be fabricated for the two lower center attach points. The builder is also expected to further secure the diffuser to either the transaxle or the K-brace. Older versions of the diffuser with smaller transaxles connected to the K-brace. Most Graziano diffuser installs attach it to the transaxle.
Since I moved the engine back 1.5” the first step was to trim out the vertical inner plates to clear the transaxle mounting ears.
The diffuser top corner brackets attach behind the top rear control arm points. As supplied, the angle and spacing of the brackets are pretty far off so decided to make new ones. Pics of the trimmed diffuser and supplied bracket…
I found a nice technique to bend up new brackets without a metal brake. Used a hacksaw to cut 1/2 way through the 1/8” flat stock. In this case a 45 degree angle works well…
Put in vice and used a hammer to fold the metal over at the cut leaving the thinner area gap on the outside corner…
Welded up the outside corner to add back thickness and strength. Custom brackets that are strong and fit perfectly. I may box the top of the bracket in to add more strength…
Pic of the new brackets held in place with cleco fasteners. Just with the clecos in place it feels very sturdy…
For the lower attach points I simply used 1/8x2x2” aluminum angles and M6 cap screws and locknuts. I took special care to locate the holes midway in the pocketed area of the lower frame cross member. Pic of the lower attach points secured to the lower chassis cross member…
Followed in Allan and Cam T’s footsteps and fabricated a couple brackets to piggy back off the transaxle mounting ears. This adds a good amount of reinforcement to firm up both lateral and vertical loads on the diffuser. Used 3/16x2.5x2.5” aluminum angle, just some scrap I had lying around and it did the job…
Glamour shot of the rear showing the attached diffuser and rear of the SLC…