STX RX-8: Ramping Up For 2013

The 2013 Solo season is fast approaching, with the first event of the year being a Match Tour in Wilmington, OH on April 6th. That's a national level event at a new highly anticipated site, so it should be very popular and a potentially very demoralizing way to shake off the cobwebs.

In anticipation for things to get going again, I've been buying/making a lot of stuff so hopefully the car will be even better than it was last year. It's costing me a lot of money, so it had better be worth something!

#1: Dampers

I detailed a little bit of the build-out of my single adjustable Koni Sport dampers in an earlier post. That was pretty much the cheapest way that I could come up with to get a decent set of coilovers on the car, and those shocks have served me very well over the past 5 years. They definitely have some issues, like needing to be removed from the rear of the car to adjust rebound (so I pretty much never do it) and not having enough damping to control wheel hop on launch. They are also the same length as stock, though my car is nearly 2" lower than stock, so usable travel is pretty small, and it turns out that there's a reason why the stock spring is so huge in diameter, because the small-diameter race springs rub the shock bodies over bumps. I've dealt with these things for 3 years, so it's not like it's killing me, but my expectations for results have been raised significantly due to the car's performance last year so I was pretty set on a damper upgrade.

At Nationals, I had poked around the paddock a bit to see what kinds of dampers people were running so I could get an idea of what the fast guys did. I decided that I wanted something double adjustable (rebound and compression) and preferably a monotube so I could run the rears inverted and not have to deal with the springs rubbing. Those two requirements immediately put me up in the Moton/Ohlins territory that was greater than $5000 for a set of dampers.

Instead, I decided to take advantage of the modular construction of my existing dampers and I would have them revalved with higher damping rates and converted to double adjustable or at the very least, have the rear rebound adjustment be made external. This would run me about $1200 and wouldn't fix all of my problems, but it captures 90% of the improvement that I was looking for at about 20% of the cost.

This all changed when at the end of October 2012, I stumbled upon somebody on RX8club.com selling a set of Koni 2812's. These are Koni's top-of-the-line double adjustable aluminum bodied monotubes with some extra-fancy proprietary valving arrangement. They weren't cheap, but they also weren't $5000, so I waffled over it for a while like I always do about big purchases and then bought them.

 

Old vs New

 

So that's a big deal. I've done a little bit of stuff with these, and that'll be detailed later, but I'm pretty excited to see how this will affect performance.

#2: Limited Slip Differential

Another gigantic purchase that I had been seriously on the fence about is an upgraded differential. The RX-8 comes with a helical-gear Torsen-style differential which is theoretically great and it works pretty well, but it's totally untunable and I don't think that it's quite right for what I need the car to do. This is a tough decision similar to what I went through with the dampers because I know that the existing solution works, but there are better solutions out there. Unfortunately, it's nearly impossible to quantify the benefit of those better solutions, making the cost/benefit ratio indeterminate.

So...I decided to just bite the bullet and get the best/most expensive diff available for the RX-8; the OS Giken Super Lock LSD.

Picture from www.osgiken.net

It took me a while to figure out what was going on inside the OS Giken diff that was not happening in other clutch type diffs like Kaaz and Carbonetic, but when I finally got it, I deemed that it was enough difference to warrant the $500 cost difference. I hope that's true. And I'll never know if it is, so it doesn't matter.

In preparation for this, a good friend Rob and I pulled the car out of winter storage (wherein it is nearly touching the south wall of my garage to make room for the Starlet) and stood it up on stands to begin the brutal dismemberment of the rear end of my car (again) so that we can get the diff out.

The car is unbelievably dusty

Again, there will be more on that later.

#3: Wheels and Tires

I've been running on these cheap but heavy 5Zigen FN01-RC wheels in a 17x9 +43 wheels for a few years now. I got them because they are crazy cheap at around $800 for the set. They also look pretty cool, and I got them at the same time that I got wheels for our white Fit so both cars that we had at the time would match.

Somehow I don't have a picture of the two cars together

However, without exception, anyone who has been nice enough to help me change wheels at an autocross has commented on how obscenely heavy my wheel/tire package is. I've been tempted to buy some lighter wheels for a while but just like with the other upgrades, it was difficult to justify the cost when I already had a workable solution. I got lucky when fellow SE Michigan STX RX-8 driver Brandon decided to sell his Enkei RPF-1's at the end of last season so that he could fit a big brake kit. So now I finally have light wheels. Plus they're gold which is super sweet.

And they've been stored in the car since October

As for tires, there is currently a street tire arms race going on with Dunlop and BFGoodrich having already released their latest and greatest ST-legal tires and there have been talks of an entry from Bridgestone and possibly Kumho. I'm not sure what to do about that yet, so I'm going to wait and see if anybody gets some good testing in before I need to buy tires.

So that's a quick overview of what's happening with the RX-8. I'll get more in depth into some of this stuff when projects start getting completed. I really hope the car will be faster!