Polystrand GT-Lite CRX: Part 4 - Bringing the Design Concept to Life!

by Jonathan Spiegel

As we left off in the previous installment, we’d completed our prototype suspension design, done some analysis on the springs and arms, and sent the dissected chassis off to the body shop to get some much needed love. Now comes the part that is almost as much fun as driving – bringing the design concept to life!


A trip to the bodyshop to check on the progress. We wanted something bright, and, of course, with PPG providing such great support, we chose from the PPG palette. Yellow is always a good racecar color, and we narrowed it down to about 5 choices. This particular color is a GM color, called “Velocity Yellow.” Appropriate name for a racecar paint, we figured.

If you’d like to catch up from the beginning, click here for part 1 and here for part 2. A lot has happened since we last updated the story, and we’re looking forward to digging into the driveline as well in future installments. We’re also very excited to welcome some new companies to the team to help us in our quest for more speed – AEM Electronics, Brian Crower, Inc., Action Clutch, and Oneiric Systems, Inc. Along with PPG and Rassini, we’re building what we hope will be a formidable team.


You can see some of the subassembly starting to take shape. We’re building more than one – gotta have a spare, right? Plus, the extra IRS assembly will make a nice stand-alone display for the trade shows we need to prepare for. On the lower left, you can see the “tab and slot” methodology we used to replace the forming operations our vendors didn’t have time for. Tony referred to this method as “castle cutting,” since it resembles the crenellations often seen on the top of old castles.

Our future plans for B-series power should make for an interesting build – since the GT-Lite class allows a wide range of powerplants across a variety of manufacturers, engines are intake restricted based on things like displacement and number of valves. We’re planning on a B18B, which means that we’ll have to feed all of the intake air through a restrictor with a diameter of only 22.5mm – less than the size of a quarter! Right now, though, we need to get this thing rolling.


Here’s a little better picture. You can see here how the spring mounting pockets can slide in and out in their adjustment slots.

In order to get this done in the next five weeks, it would take a few different vendors, a lot of elbow grease, and a fair dose of scrambling around shipping things around the country. In order to stick to our timeframe, Tony did a lot of legwork lining up the right vendors – and we determined that the flat pieces would be done by one shop, the formed parts at another, and we’d do the tubular parts and machined parts ourselves. Hopefully, everything would arrive on time and fit together properly so that Chris and Tony could assemble, weld, and install the IRS module before the deadline.

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Thursday, May 28, 2015 5:18 AM
Congrats on getting your design built! Looks like you'll need to take it to a chassis shop and get it tweaked a bit. It's looking really cool, can't wait to see it with an engine inside and on the track!
Thursday, May 28, 2015 10:51 AM
Did not realize you were an hour north of me (at least Polystrand is). Awesome.
Friday, May 29, 2015 3:17 AM
Wait...wait....Solidworks on OSX???
Jonathan Spiegel
Jonathan Spiegellink
Friday, May 29, 2015 9:51 AM
We'll either try and pull it, or we'll re-center the IRS under the body. Hopefully get it on track at HPR or Pueblo in July.

Solidworks.....under Parallels Desktop!
Friday, May 29, 2015 2:14 PM
I don't see any shock absorber ? what will you use ?
Friday, May 29, 2015 4:43 PM
Ha! Polystrand is just on the other side of the airport from my office! Maybe I'll see you out at High Plains in the next couple of months.
Friday, May 29, 2015 6:16 PM
I'm already signed up for Pueblo (NASA) in July. It'd be awesome to see this there. Won't run High Plains again until Sept or Oct. I assume your HPR will just be test and tune. Will you TT or W2W this in either NASA or SCCA?
Jonathan Spiegel
Jonathan Spiegellink
Saturday, May 30, 2015 7:15 AM
We'll be using some shocks built by Oneiric Systems. They have a really unique design where all flow through the shock runs in one direction, so lag/hysteresis at the transition between rebound and compression is essentially non-existent, and the shocks run at very consistent temps.

I'll be running SCCA Majors events. If I make the early July event, it will be with the existing EW motor. Hope to have the B18 done for Pueblo.

Nice to see some local guys following the story!
Tuesday, August 25, 2015 6:04 AM
any updates?
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