The OPTIMA Batteries OneLapCamaro - Final Preparations

[James OLC]

With the 2010 Tire Rack One Lap of America coming up in less than two months, David and I thought we would start a post on the final preparations of the OPTIMA Batteries OneLapCamaro. We’ll run down some of the work that we’ve done over the last year to dial in the front suspension - all the way to the work we did last weekend (updating the car with new Speed Tech upper and lower control arms) - through the next six and a half weeks of last minute preparation.

Looking back almost a year ago today, the car was just about a mess; I wish I could be kinder about that but it had a lot of issues. Don’t get me wrong, it was far and away the best First Gen that I had ever driven and was more than capable of holding it’s own but it had a ton of issues… first and foremost was a clearance problem between the outer tie rod ends and the inner hoop of the wheel. Admittedly at 5.9” of backspacing we were pushing the envelope but despite having nearly 3/8” of static clearance, there was contact due to deflection under load:



If you notice in the picture (looking past the disturbing trail of aluminum) you’ll see that we were not running any bump stop spacers (mostly for space) at this point. The car felt good on the road 9 times out of 10 but hit a big bump and that 1 out of 10 times was ‘alarming’. HRE helped us out by rehooping the inner wheels so that we could gain some clearance and properly space the rod end for bumpsteer but that left us running a narrow tire (255/35) on a narrow rim (8”) which was less than ideal. We also had no rear sway bar (so the car was rolling pretty badly) and a very conservative alignment.

This was the starting point for David.

The first thing that we addressed at Pozzi Racing was the rear sway bar. We went through (seemingly) countless renditions to get us to where we are now. We started with an off the shelf Second Gen Camaro rear bar that David modified to work with the Lateral Dynamics 3-link:



He cut the ends off and welded on an extension which allowed for adjustability. This setup was really good on the road and pretty decent (a huge improvement) on the track but we were fighting an understeer at autocrosses and the car was simply not rotating the way that we wanted it to. David modified this bar three times - progressively getting shorter and shorter - until it was working fairly well but unfortunately, the packaging was no longer working out.

Taking a step back, David then designed a completely new rear bar starting with a piece of old rebar that was kicking around the shop. One he had the geometry that he was looking for and got it to fit in the car, he called up David Wheeler and the guys at Hellwig Products who built us new rear bar that worked great!



…it was a long (but fun) process of ‘trial and error’ to get it dialed in. We would go to an autocross and run the car, try an adjustment on the rear bar, and run again. We did that for probably three events until we had the rear bar exactly where we wanted it.





At which point we determined that we had just slightly too much front bar. Hellwig Products had built us a great hollow front bar that was working really well with the untuned rear but as we got the car to start turning in better, we wanted to soften the front a touch. Hellwig again came to our rescue and built us a new front bar with a slightly thinner tubing that reduced the rate about 10%. It took nearly 11 months and seven or eight different renditions but we finally have a car that turns.

[James OLC]

While all of the sway bar tuning is going on, David is working on his own Skunk Works style project – reengineering the steering on the car to provide clearance for wider front wheels and tires as well as near ideal bumpsteer and alignment.

We were starting with this:



And hoping for something like this:



To do that he created a new center link, repositioning the inner tie rod end pickup points:



Rebuilt the steering arms – moving the outer tie rod end pickup point up:



And found a new inner tie rod end that worked with a custom fabricated adjustor sleeve and a rod end for the outer…



The result was near ideal bumpsteer characteristics, no shims (but the ability to add them if need be) and more than enough clearance for the wheels:

[James OLC]

And while all of this is going on, we are closing in on springs and shocks and looking at how we were going to shove another inch of tire on the front (and, ok, the back too). We went through a couple of different spring rates and added some progressive (but modified) shock mounted bump stops bet were still looking for increased travel on the front. We were borderline on the compression height and wanted to add an inch of travel just to be on the safe side; it wasn’t bad but we wanted a little bit more travel to allow the car to set and go rather than worry about bottoming on a hard corner.

The solution came from Blake Foster and the guys at Speed Tech Performance. We decided to change out our old Global West control arms in favor of a new set from Speed Tech for a couple of reasons…

First - Speed Tech’s high clearance upper control arms allow for more backspacing and still give lots of wheel clearance:





And second - Speed Tech’s lower control arms have a generous spring pocket which, when combined with ATS Chicane coil over lower mounts, place the lower shock mount about ¾” lower than the GW’s. David and I had toyed with cutting the GW’s up to lower the mount but this was a much easier solution.

Lower shock mounts welded, waiting for paint…

[James OLC]

One thing that we found with the high clearance upper arms was that we needed a bit more clearance on the frame while at full droop. Mary was quick to come to the rescue…



Shaping the frame mount just a bit


Giving us a perfect fit


Keeping in mind that we needed that clearance at full droop on the hoist, a condition that we acknowledge we’ll only encounter if we’re sailing through the air. But, we thought, better safe than sorry.

[James OLC]

At the end of the day, the Speed Tech upper and lower control arms went in with minimal fuss and took (significantly) fewer shims to align than we had used previously. Ultimately we decided on a conservative alignment for the car – settling in at just over 5.5° of caster (slightly more than that on the right side) and slightly more than 1.5° of negative camber; toe in is set at 1/16”.

The finished product:







I can’t say enough about the great product and outstanding customer service that Blake and everybody at Speed Tech provided! It’s really nice to have people like them supporting the hobby with great products and advice!

[James OLC]

We were hoping to get our new ZR1 stlye front hubs installed over the weekend as well, but UPS did not share our sense of urgency. Instead we tweaked the exhaust a bit to make sure that we had all the clearance we wanted and then tacked everything to hold it in place. Once again, Mary was quick to come to the rescue:

Same line, different context… it stuck.


We also took the opportunity to raise the ride height a half inch on the front and ¾ or so on the back – just for bit more road clearance. We rescaled the car (3,582 pounds with a 49.8% cross weight) and tightened the rolls bars up and are one step closer to the One Lap of America starting line on April 30th.

David is working on the pinion angle now – trying to eliminate the slight driveline harmonic that has been annoying us since day 1. The ‘funny’ thing is that the pinion angle is technically correct but the driveshaft angle is a bit steep. We’ll get it figured out…

Coming next (hopefully) will be the ZR1 hub install and a quick check of pinion angle at the new ride height. Then we wait for new wheels and tires and we should be good to go at the Run To The Coast in three weeks! Oh… and I guess the trailer hitch and trailer setup have to be squeezed in here too…

We’ll keep you posted.