Ok here we go. There are two key problems with this setup. First, the rear shock is several inches too short. Second, the front shock perch is too close to the control arm (thought the front shock may achieve the correct height setting...maybe). I'll explain with pictures.
Let's start with the stated spec. I asked for shocks that would allow me to set the car to the NSX-R specified height range of
165-175 mm Front and
203-213 mm Rear, as measured to the control bolts specified in the workshop manual. Here's a visual from the 1997 FSM:
Why that height? Well, I know that's about as low as I can go to clear the gutter curb to my driveway and the ramp to the parking garage at work. Those are hard limits. In my mind, this meant that, when set to the highest perch setting, the front shocks would sit at 175 mm and the rear shocks would sit at 213 mm. I asked for approximately 10 mm of "safe" adjustment down from that top setting, to account for corner balancing, load differences, etc.
After setting the MCS shocks to the highest perch, here is where I ended up. Note that the fronts are on 6" springs instead of the 7" that came with the setup.
You don't have to measure to see the the car is sagging badly in the rear- (reverse rake). As noted above, the rear shocks are 48 mm too short (213 - 165 = 48). Looking at the MCS rear dampers next to a genuine NSX-R damper, we can see why. Please ignore the brake line holder and 8 kg spring- we tried this setup on the front side to see if it helped by using the shorter shock body- it didn't.
Even without the helper spring fully compressed, the lower mount is drastically too short. Compressing the helper spring, like when the car is sitting on its own weight, only makes things worse (denoted by red arrows). The good news is that the adjuster perch does not seem to interfere with anything, so really all we need is to add 48 mm to the suspension height. I'm not a suspension design expert, but maybe that means either lengthening the shock body by 48 mm, or splitting the difference between more shock threads and a longer spring? You would have to be careful to not make it too long so as it cannot be installed. You can see that on the genuine R shocks, Honda used a really long spring, but it's not the only solution. These dampers will have to go back to MCS for revisions.
Next, attempting to adjust the front shocks to lower them to at least get a proper rake with this too-low rear height setting revealed the second problem: the adjusting perches are too low and hit the upper control arm. Let's take a look.
Here it's not so bad of a problem, but still, it won't work. You can see the difference on the perches. Honda set the perch far away from the control arms and used a very short spring. Even with the helper spring fully compressed (green dotted line) the perch is still too low. I didn't measure, but I think this setup might be better without the helper- the key is to get those adjusting perches far away from the control arm at ride height. However, even with the 7" spring, deleting the helper might make the suspension sit too low.
Looking at the R shock, you clearly don't need all of that droop. It may be better to go with a longer shock body (more threads) and a 4" or 5" spring to more closely match the Honda design, which as shown below, keeps the perch well clear of the control arm.
I was so furious on Saturday that I was ready to just throw the MCS in the bin and say f$@k it and just run the Type R (which is the perfect height and rides so nicely). But, they are a really, really good shock and I would like to try and make them work. I'll reach out to Martin at AR and see what they can do.
I'm going to do another post here explaining the issue with the MCS.
