Part one consists of replacing the balljoint with a bushing while retaining a common HICAS Eliminator bar and tie-rods. With a HICAS Eliminator, the range of motion offered by the balljoint is no longer needed and they can be replaced with the NA bushing. Note: This only makes practical sense if your balljoints need replaced (as an alternative to replacing the balljoints) or if you require additional clearance to fit wider wheels.The associated feature of the NA and TT knuckles are identical which means the NA bushing is a drop-in replacement for the TT balljoint. I had previously purchased an Energy Suspension bushing kit for the rear suspension links which includes the bushing for the NA toe rod. Normally this bushing is not used on a TT rear because the balljoint occupies that location. Alternatively you can source a replacement NA bushing (OEM or Nismo) if you're not changing the rest of the bushings. Here's a picture of the balljoint removed, next to the bushing which replaced it:
Here's a photo of the factory rod end next to the fabricated clevis rod end (note that this clevis rod end isn't finished, the two halves have not been welded together yet).
Here's a shot of the factory configuration (driver's side):
and here's a shot of the finished clevis rod-end / bushing conversion. A side point, note the difference in clearance between the rod end and the wheel:
Some additional notes:
- I had the car sitting with the tires on blocks so the suspension would be loaded at normal ride height while providing room to work under the car.
- The two clevis halves are installed under the car (again, at normal ride height) and tacked together in-place. I then removed the tacked clevis for final welding. I did this to minimize any misalignment. Upon installation the clevis bolt slid right in without any binding.
- The tie-rod threads are 12mm x 1.25. After failing to locate any tubing with that internal threadform, I made my own. Each clevis rod-end consists of two 12mmx1.25 nuts welded inside a piece of steel tubing. One nut would likely have been sufficient, but I added the second to increase the thread length of engagement. The nuts were positioned on a bolt, inserted into the tube, and welded. The bolt was then removed and the threads were "cleaned up" with a 12mmx1.25 tap.
Part Two is an alternative to the traditional HICAS Eliminator. In this section I swap adjustable NA toe rods onto the TT subframe. At the conclusion of Part One, my rear suspension looked like this:
* If starting with a stock TT rear, the HICAS actuator and tie rod ends would be present in place of the HICAS Eliminator and clevis rod ends shown.
The first step is removal of the HICAS Actuator / Eliminator and tie rods:
With the HICAS assembly removed, you'll notice the TT subframe already has the slots for the NA toe rods:
The stock toe rods used a cam bolt to adjust their length (just like the stock rear camber arms) hence the slot feature in the subframe. The rest of the NA toe-rod features are missing, but the presence of the slots makes locating the new toe rods MUCH easier. Aftermarket adjustable NA toe rods have built-in length adjustment so the stock cam-adjustment feature is not needed/used and, on the NA, serve only as a mounting point for the new arms.
With the NA mount hardware missing, the existing slot needs to be converted into a hole for the new arms. I did this by welding a 12mm washer to the subframe. First, prep the surface:
Using a 12mm nut and bolt, I bolted the washer to the subframe and slid it towards the outer end of the slot. The bolt provides alignment with the existing slot and tightening the nut holds the washer in place for welding. Nominally the washer should be centered in the slot, but I chose to align the washer to the outer end of the slot to minimize the length of exposed threads on the adjustable arms. I don't recommend doing it the way I did unless you're confident your arms have enough adjustment to accomodate the offset mounting hole. Here's a picture of the washer welded to the subframe:
Note: The welds were cleaned up and the area repainted prior to installing the toe rods, but I didn't get a picture.
Ideally I would have welded the washer to the inside of the subframe instead of the outside so the thickness of the washer would not affect alignment of the toe rods. The toe rods I purchased were able to easily accomodate the washer thickness so I welded them to the outside. If starting from scratch you're probably pulling the knuckles to replace the balljoint with a bushing (see Part One), so it would make sense to remove the axle shafts and weld the washers to the inside of the subframe.
With the washer welded in place and the TT balljoint replaced with the NA bushing it's time to test fit the adjustable NA toe rod:
You can see a couple mounting tabs in the above picture. At this point I had to decide how I wanted to fabricate an outer bracket for the arms. Initially I was going to fabricate a bracket for each side and weld them to the subframe, but in the end I decided to build a bolt-on bracket which uses the existing mounting points for the HICAS actuator. Here both arms are bolted in and the tabs are ready to be connected:
And the completed version:
Closeup of one of the finished arms:
