Winter: XIDAs, Tubular Arms, Front Sway

Ok time for some updates.

2017 was a big success, and I’m really happy to have some solid baselines and results in the bag. Now, it’s all about refinement and MORE in equal parts. In Decemeber with SLB fresh on my mind I did a fresh examination of the car and rulebook and identified anywhere I had room left on the table to maximize performance.

Big on my list is to really hone the chassis and suspension to the maximum possible, within the Limited class rules of course. This goal encompasses both the systems on the car as well as the track-side setup and tuning. A car with all the potential in the world won’t do much without putting in the testing and tuning hours to get everything working in unison.

Enter 949 Racing. They need no introduction, these guys are good at a lot of things, but perhaps what they’re the best at is setting up a car and extracting every bit out of it. That’s not a small talent. Breaking new ground in an underdog chassis, I think a key to success is going to be in getting more out of the car than the competition, and there’s a lot I can learn from these guys.

With 949 on board comes a change to the suspension to extract everything possible allowed by the rules; GTA Limited allows 3-way shock adjustment. Ergo, XIDA triples:

quite like the look of the coaxial top mounts in the engine bay:

Doing sub-1:50’s at Buttonwillow has me looking for more roll resistance, even on the street tires. With the downforce I’m seeing race tire cornering loads, and scraping the outer sides of the aero on the track. There’s no avoiding I need to go stiffer. The XIDAs come with another jump up in spring rate from my previous setup.

The front sway bar also gets an update. It was one of the last things that’s carried over in the build from pre-2017. At GWR we’ve been working with Karcepts, who make some really nice sway bars for the ND and a couple other chassis. I took some rough measurements and ran a few numbers and worked out that I just might be able to adapt some of the pieces of their ND sway bar to put together a 3 piece NASCAR style bar for this car. I ended up ordering a pair of their beautiful ND arms and their brackets/bushings for the S2000 because the measurements for those looked like they would work best, and a custom Speedway center tube:

Many times in and out figuring out dimensions, checking full range of motion, etc. Had to make a pair of adapter brackets for the sway bar brackets.. here everything is about 90% sorted but I needed to move the endlink bracket on the control arm forwards to shift the pivot slightly. No problem there because those lower arms need to go anyways…

In my factory lower arms I’ve been running an evaluation kit of press-in spherical bearings that replace all the bushings. Great concept, but unfortunately it turned out to not be the best execution in the product. Most people didn’t know that in the final week before SLB I discovered a critical problem in the bearings in the rear lower arms so I ran SLB (and Chuckwalla after that) on factory rear lower arms with 100k mile factory rubber bushings – because it’s what we had available at the last minute. Definitely not ideal. Time to get those arms out of the car and replace the front lowers as well to get the last of those bearings out and move on to something trouble-free.

V8R tubular pro series arms arrived. These arrived in bare steel so I could do the custom endlink mount on the fronts:

Then they went off to powdercoating to get finished up. Far more robust bearings in these, strong, awesome:

Just about everything is installed and sorted out at this point, and I’d love to show some pics of everything installed buuuut can’t really do that right now because this is the current state of affairs:


Yep, two weeks to go before first track testing of the year, still cranking away on things feverishly

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