When we created the Rock Bug, designing a high performance rear steer axle was a must for driver Tracy Jordan.  We understood Tracy’s position on this one as anyone who can master the art of rear steer is virtually unstoppable in the rocks and Tracy Jordan is without question one of those masters.  Unfortunately, with nearly twice as many W.E.Rock competitors in the more restrictive 2009 Pro-Mod class, which doesn’t allow rear steer, Tracy decided to run a solid rear axle in the Rock Bug in an effort to compete against as many drivers as possible. Although the 2009 competition was a complete success for both Tracy and the Rock Bug, you could tell Tracy was missing his rear steer axle.

Now we’ll fast forward to March 27th, 2010 as W.E.Rock kicked off a brand new rock crawling competition season in Oroville, CA.  Although Tracy would run the Rock Bug’s rear steer axle any chance he could get, word was the number of competitors in each class was inline with last year (around 12 Unlimited and 24 Pro-Mod rigs). So, like last year, the decision was made to run the Rock Bug as a Pro-Mod rig.  Then, literally 1 hour before the start of the competition in Oroville, everything got turned upside down.

As it happened, we discovered the morning of the event both Unlimited & Pro-Mod classes had nearly the same number of competitors (about 12 in each class).  Although the Rock Bug was set up as a Pro-Mod, there was no question that for the rest of the W.E.Rock season Tracy would be running the Unlimited class with the Rock Bug’s rear steer axle.  The question of the day though was what to do about this first event.  Do we run the Rock Bug in Pro-Mod and then Unlimited for the rest of the year eliminating any chance of capturing the season title? Do we attempt to run the Rock Bug as set for Pro-Mod (37” tires and no rear steer) in the Unlimited class, something that has to date never been done before, so that the season title could possibly be captured?  With no easy answer in site and now less then 1 hour before show time, Tracy calls for a coin toss.  Heads we run Pro-Mod, tails we run Unlimited.  I flipped the coin and tails it was.

Now making a very long story short, for the next two days Tracy Jordan battled it out with his Pro-Mod rig in the Unlimited class. This meant he would compete against rigs with larger tires and rear steer axles.  In the end, Tracy would prove once again why he is rained as one of the best rock crawlers in the world as he pulled off what seemed nearly impossible.  In a Pro-Mod rig, Tracy Jordan won Unlimited!

Tracy & the Rock Bug will be back competing in the Unlimited class  May 1-2 in Tucson, AZ and this time with 40” tires and a rear steer axle.  In the meantime, check out the video above of Tracy Jordan running the final obstacle of the competition, The Shootout, a course where only 1 other driver out of 12 was able to complete.  We also have a great collection of photos below from ace photographer Chad Jock showing off some of the many  teams running Spidertrax Spider 9 axles & components.

Tracy Jordan & The Rock Bug soaking in some Moab beauty. (Photo: Tim Magee)

It’s always nice to see recognition for one of the funnest projects we ever had the pleasure to work on. Tim Magee wrote a great piece coupled with some of the most amazing photography to date on the Rock Bug in this month’s issue of Crawl Magazine (Issue #21).  If you haven’t got your issue yet go ahead and steal your friends now. It is packed not only with this great article but in-depth coverage of this year’s King of the Hammers competition.

Once again a big thanks to John Herrick, Owner/Publisher of Crawl Magazine, for letting us post a digital copy of The Rock Bug article right here on our blog for free.  In addition, we called up Tim Magee and got a hold of rest of the photos from The Rock Bug photo shoot that didn’t make it into the magazine.  Hope you enjoy the article and photos as much as we did!

Download the full print article “The Rock Bug”, courtesy of Crawl Magazine.

                                    
Photos from The Rock Bug photo shoot that didn’t make it into the magazine.

Monster Jam | XORRA: Round 1

Monster Jam | XORRA: Semi-Final

Monster Jam | XORRA: Final

First, I have to confess.  The last time I went to a monster truck show was way back in the mid 1980s.  If memory serves me right, Bigfoot was the truck to beat back in those days.  Now fast forward 25 years and you will find that monster trucks take part in one of the biggest live motorsports events of all time.  Feld Entertainment’s Monster Jam is said to pull in more than 2.5 million people each year.  Vehicles like “Grave Digger” & “Monster Mutt” have literally become household names.  Come to think of it, my 4 year old son has a Monster Jam Xbox 360 game. Yes, they’re everywhere.

Now let’s jump to our end of the market.  The Weaver’s, who manage the XRRA rock racing circuit under the umbrella company XORRA, have talked about running a separate stadium type series for years now.  Nearly overnight, this concept of “arena rock racing” just got one step closer to reality. XORRA, with the help of XRRA driver Dan McDonald, struck a deal with Monster Jam to run one small arena rock racing competition during a live Monster Jam show.  The idea was to treat this first show as an exhibition or pilot in hopes the audience would like what they saw.  If they did, maybe arena rock racing had a future with Monster Jam.

With literally no prize money at stake (aside from any contingencies) and only two weeks before King of the Hammers, six XRRA drivers hauled out to Angles Stadium in Anaheim, CA to put it all on the line in front of nearly 50,000 spectators.  In the end, I think they put on one heck of a show!  Yes the courses were short and yes the XORRA portion went very fast.  However, all the XRRA drivers showed the highest level of professionalism anyone could ask for.  Just as important, the audience really seemed to enjoy the show.  Only time will tell if something comes out of all of this, but hats off to everyone involved for making it a true success.

It’s hard to imagine that this time last year we were still wiring up the Rock Bug (see “Rock Bug Weekend Update for January 24, 2009”).  Despite all of our best efforts to have the Rock Bug ready to race 2009 King of the Hammers (KOH), its highly custom Scat V4 motor decided otherwise.  Literally one day before the race, severe lack of engine performance forced driver Tracy Jordan and the Rock Bug to bow out of the 2009 KOH competition.

It was a tough blow, especially given the amount of time and energy devoted to the Rock Bug project.  There was little time to feel bad about it though as the 2009 W.E.Rock rock crawling season was about to begin.  So we were all back at it trying to make the Scat V4 motor happy.  It took us the first two W.E.Rock competitions before we were able to get the Scat V4 motor under control.  Once we did though, the fate of the Rock Bug had permanently changed. 

With a perfectly running Scat V4 engine, Tracy Jordan and the Rock Bug seemed unstoppable, taking home 1st place spots in the final two W.E.Rock competitions.  Shortly after, the 2009 W.E.Rock season ended on the highest note we could ask for. Tracy Jordan and the Rock Bug won the 2009 W.E.Rock Grand Nationals (see  “W.E.Rock 2009 Grand Nationals – Tracy Jordan & The Rock Bug on the Shootout (Part 2 of 2)”) which is one of the highest rock crawling awards of the year.  Life was good.

With a full year of rock crawling competition (and three victories) under its belt, we’re more ready then ever for this years 2010 KOH competition. Instead of rushing to put together a brand new concept vehicle, we are now able to take our time and focus on many of the smaller items we ran out of time for last year.  We spent most of this year’s  preparation on cooling (larger transmission cooler, radiator cooling fins, oil sump scoop), modifications to comply with new rules (rear light bar, bladder style fuel cell with firewall, window net changes), and small go-fast improvements (higher performance alternator, on-board tools, fresh air system).  All in all, the Rock Bug is now looking ready to race.

The Rock Bug will be back on the road tomorrow heading over to Gerald’s place for final wiring on the new electrical goodies.  After which, Tracy and the Rock Bug will be heading out to the KOH lake bed for some final tuning.  Set your calendars for February 12th, 2010 which marks this years KOH race day.  Hope to see you out on there!

A picture of the Rock Bug sway bar mounted in front of the rear axle.

A few months back, a client came into our shop and asked a very thought provoking question. Does it matter if the rear sway bar is mounted in front of the rear axle or behind the rear axle? The understanding by the client was that placing the rear sway bar closer to the front suspension (in front of the rear axle) would have a greater negative effect on the front suspension then mounting it further away (behind the rear axle).  Is this really the case?

I have always struggled with this as I couldn’t see how placing the sway bar in front or behind the axle mattered in terms of effecting of the opposing suspension.  So, I figured I would break out the old engineering paper and geek out a bit with a few static diagrams to help better understand what’s going on.  Disclaimer – The purpose of this blog post is only to draw attention to the problem and create a good platform for debate. I am in no way taking a position of authority on this problem and am only looking to better understand the question myself.

The static diagram below starts with a force (Fi) on the passenger sway bar and follows the effect of Fi through the passenger sway bar, the bar itself, and the driver sway bar with Wd and Wp representing the weight of the axle.  In the end, the static diagram shows the net effect on the chassis as a resulting Moment (Mv1y) with vertical forces Fd2z and Fp1z and moments Md2x and Mp1x being equal and opposite.

Therefore, according to this static diagram above, mounting the rear sway bar in front of the rear axle should have the same effects on the front suspension as mounting the rear sway bar behind the rear axle as the Moment (Mv1y) would be the same with all other vertical forces (Fd2z & Fp1z) and moments (Md2x & Mp1x) cancelling each other out.

Your thoughts are encouraged here so please leave your comments for all to see, read, and digest.  As always, I am happy to be both challenged and corrected on any issue and look forward to updating this blog entry with more details as they are presented.

UPDATE [17-Dec-2009] – How About the Sway Bar’s Position in the Vertical Plane?
The above analysis focuses on a sway bar’s effect in the horizontal plane (front & back) and takes the position that in this plane, the effectiveness of moment Mv1y is equal along the entire x-axis.  Thanks to an awesome thread on Pirate4x4, another great question came up, one that I have never considered prior to hearing it.  Does it matter where the sway bar is mounted along the vertical axis (up & down).  After studying this question myself, I have to take the side of yes it absolutely matters.  Grabbing the same old engineering paper once again, here is a static diagram looking at the forces on the bar in relation to the vehicle’s roll center (detailed toward the bottom of the paper).

In terms of effectiveness, the position of the sway bar in relation to the vehicles roll center along this vertical plane does matter.  What is so interesting about this case is it would be easy to assume that whatever ineffectiveness the sway bar has can be overcome by simply installing a heaver sway bar.  Although this is true, larger diameter sway bars result in a smaller allowable angles of deflection (how much twist the bar has before it yields).  Therefore, if you are building a multi-purpose rock crawler / rock racer, it very well may be best to position the sway bar as close to in-line with the vehicle’s roll center as possible in this vertical plane.  Thoughts?