스크랩 신제품 REVO?? Race Quad Project

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REVO?? Race Quad Project
Turn your Revo into an ATV racing machine!

Have you ever thought about what it would be like to race against a full field of R/C race quads elbowing for position and throwing whips over the tables? What about getting some of your riding buddies together for an R/C quad jump contest between riding sessions at your favorite off-road park? Yeah, I have too. Being a quad rider myself, I wanted a nitro R/C version that I could take to the trails when going riding with my family and friends.

ATV and MX racing brings some of the most intense racing experiences for riders as well as spectators. Straddling across a 50+ hp sub-400lb 4-wheeled machine with over 12” of buttery suspension just makes you want to rip the throttle over the next 70ft triple set. However, there are only a small handful of riders who actually get to experience that feat without breaking many fundamentally essential bones that provide the framework of our delicate bodies. The rest of us will have to live vicariously through them. A good solution would be to buy a plastic stunt double, and strap him to your nitro-powered Traxxas Revo, which is what I did.

But, I didn’t want to just slap a quad body on top of a monster truck and call it done. I wanted the look of a true race quad with the performance to match. I knew it could be done without having to own a machine shop. After mulling it over a bit, I thought, ‘What better nitro vehicle to create a killer quad machine than a Traxxas Revo?’ It has the speed and performance capabilities needed for the job, and most importantly, the Revo is extremely versatile to work with. I looked over the Revo to visualize what it would take to transform it into a trick looking and fully functional race quad. I realized that it wasn’t going to take that much to get the look I was after, and I would just have to wait and see how the Revo quad performed after completion.

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Critical Gear

I started with a bone-stock Revo 3.3, and as you can tell, you can actually get most of the look just by installing a quad body, adding a rider and narrowing the front tires. See, not too bad, huh? There are a handful of different quad bodies available for the Revo, but I chose the Pro-Line?? Razorback™ (#3199-00) quad body for my project. It’s the perfect looking body for the job.

The lines are very similar to the ever-popular Yamaha YFZ450™ factory race quad. The body comes with some cool ATV-style graphics and numbers. I painted mine with Pactra?? Blue Streak (#PACRC252) to keep with the Yamaha scheme, and then added sponsor stickers from an MX sticker sheet I picked up at the local Yamaha shop. This gives it that hardcore racer look.

I mounted the body using spare body mounts from my parts bin. The front of the body only needed one (in the center), so I removed the stock front body posts, and then cut off one of the posts to mount in the center of the body mount base by drilling two holes into the mount and securing the post with two 3.0mm button head screws. The holes in the post allow the post to be adjusted up and down for your desired body height.

Out back I used a similar set up from the Revo Rocks crawler project that I did a while back. I ground the tips of the stock posts off of the mount, and then attached another body mount upside down to get the extension that I needed for extra height. I used two 3.0mm screws with locking nuts to secure the mounts together. These screws are also used to secure the wheelie bar that I made (optional), which you can read more about below (see ‘Details…’).

When mounting a narrow body (like the Razorback from Pro-Line), something must be done with the stock roll bar. It could be removed for clearance, but it offers a couple of benefits that I didn’t want to give up – 1) It offers protection to the throttle linkage, carburetor, and air filter; 2) It neatly holds the fuel and pressure lines safely from danger. You can remove yours, and everything will work just fine. Just ensure that the engine mount brace is secured to the chassis with a 4.0mm nut and screw to keep the engine mount assembly rigid.

I decided to keep the roll bar, and remove the top center section to accept the body. This may reduce the effectiveness of the roll bar to protect the top of the chassis on its own, but the mod I performed utilizing the Traxxas Twist Lock?? (#1572) and mounting post (#1573) (see ‘Details…’) more than made up for the loss in protection. I left the outside portion of the roll bar exposed. I didn’t want to shorten this, because it still provides good coverage for the throttle linkage and air filter.

Now it’s time to choose your stunt double. (You didn’t think you were going to squat down on this thing did you?) There are lots of different toy riders for R/C quads and MX bikes on the market. You may already have something in the garage that can be used. I found two different riders for my Revo quad. One of them is from a toy R/C quad, and the other is available from Pro-Line. They actually named the fearless racer ‘Stunt Steve’ (#6116-00). Perfect! The two riders are actually very similar in design, but the toy model is a little larger and significantly heavier than the Pro-line rider.

After my first build of the chassis to get everything sized up for correct proportions, I put each rider on top of the bike. The toy rider looked to be almost a perfect fit in terms of being proportionally correct, but the extra weight would also give the bike awkward handling characteristics. On the other hand, Stunt Steve was much lighter and connected to the handlebars the best. Of course, he was made for the body. However, his slightly smaller size made the quad look a tad big, but not out of place. I figured using the larger rider, we’ll call him ‘Stunt Bill’ (as in the famous Yamaha pro rider, Bill Balance, 7-time GNCC national champion), for studio shots and light-duty riding, and I’ll let Stunt Steve handle the hardcore stuff.

Stunt Steve does not come pre-painted, so pick up some paint for flexible exterior duties. Check your local hobby shop for paint options.

Once the quad body and rider are ready for action, it’s time to finish it off with the right set of wheels and tires to give it an aggressive realistic look. Many of the popular monster truck racing tires can be used, and some even resemble an ATV racing tread, but most are made with small pins for the much smaller R/C tracks that they are raced on. Traxxas SportTraxx?? (3970R) monster truck tires for Maxx-sized wheels are designed with big lugs and happen to resemble many sport quad tires. The SportTraxx tire is very versatile and hooks up on all kinds of surfaces.

After choosing a tire, I needed a good wheel that would be durable and most of all resemble a wheel that should be on a race quad. Most every hardcore ATV racer uses bead locks on their rigs for maximum durability and performance. I chose the Maximizer?? bead lock wheel system (#1111 & #1301) for my quad. They are available with different reinforcement rings to suit different styles and color choices. I went with black wheels and red rings (#2223).

Mounting the rear tires was not a problem, as I chose to stick with the stock width for the best combination of traction and appearance. I used Lexan™ scissors to trim off the outer row of pins and to put a 45-degree angle on the pins in the second row. This shaped the profile of the tire the way I wanted, and will also help keep the tires from grabbing ruts.

The front tires need to be narrowed to look like sport quad front tires, so some modification was needed here. I started by figuring out what I could do with the wheels to allow a narrowed tire. I decided that I would not need to actually use the bead locking capabilities of the wheels up front, as I do not plan to make any tire changes to these wheels. I used tire glue to keep them secured to the wheels. This allowed me to eliminate the inner piece of the wheel, so only the two outer pieces are used.

I narrowed each front tire by eliminating the middle row of large block pins and one row of the smaller pins beside it. The best way to narrow R/C tires is to use sharp pair of straight Lexan scissors to cut out the section of the tire to be removed. Be sure to cut in a straight line and leave one side of the tire with a little bit of carcass beyond the last (inside) row of pins. This is for proper spacing between the two middle rows of pins when joining the two halves together. I then mounted the beads of the tire halves to the outer sleeve section of the wheel running the bottom of the beads along the outer edges of each side of the sleeve. I used thin tire glue to secure the beads to the sleeve. Important: Always wear proper eye protection when using tire glue to avoid injury.

Now that the tire is narrowed, you will need to narrow the foam insert for a proper fit. I removed a portion from the center of the insert and joined the two remaining halves with a small amount of contact cement. Remove about the same amount of material from the inserts as you did the tires to maintain consistency with stock performance. Now, stretch the narrowed insert around the sleeve and position it in between the two tire halves. Make sure the foam is seated properly and centered within the tire halves. Now, bring the two halves together to meet in the middle. Apply a small bead of thin tire glue to a joined area of the tire and allow it to hold. Repeat this step until the entire seam is complete.

The outer piece of the wheel is molded with the wheel dish and hex cup for the hub. Since both sides of the tire are glued to the outer sleeve, the wheel dish can be removed and replaced with one with a different style or offset. This is a sweet bonus. Now, you can exchange wheel designs easily by just removing the dish and replacing it with other style. I personally like the ability to change wheel offsets without having to dismount the tire and insert completely. Maximizer bead lock wheels are available in standard offset and a wide offset. The wide offset provides an additional 3/4” of track width to each side of the chassis for more stability. ATV riders generally run a narrow track width for woods and trail riding, and then switch to wide track for MX racing. Now you can do the same with your Revo quad.

Wheel Conversion Steps

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Front narrow set-up	Front wide set-up

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Power and Handling

Engine

The Revo 3.3 comes standard with a very potent nitro mill. The TRX 3.3 Racing Engine™ has a proven track record and happens to be the engine of choice for national champions in the R/C monster truck-racing scene. There’s no need to change anything here. However, I did decide to opt for the pull start on my quad. The EZ-Start™ will work just fine for the job. However, only a portion of the left rear fender will need to be trimmed for clearance. In an effort to keep weight down and the exterior appearance clean, I switched it out for the pull starter. Remember, when using a pull start, an external glow plug igniter will be needed to preheat the glow plug for starting. For Revo quads with a different nerf bar configuration, or none at all, a starter box can be used to remove the onboard starter system completely.

Exhaust

The stock Revo exhaust pipe will work just fine in this project, and will provide all of the power you’ll ever need. I’ve won many races with it, but I chose to try something a little different for this Revo project. I found that High-Velocity Technology offers a multi-piece tuned pipe for Traxxas engines that have a floating valve inside the chamber to react to the varying pressure patterns within the chamber to broaden the power band. This pipe also puts out a unique sound, so I thought it was fitting for a project like this. For formally sanctioned race, this pipe may not be legal due to the moving components inside. I would suggest using this pipe for recreational use only.

Transmission

I looked at the transmission for ways to improve performance to compensate for the additional weight (of the rider), and also for a wider range of control in the air during stunts. Normally, I would opt for a close-ratio (#5383) two speed for smooth shifts and strong second gear acceleration, but for this project, I wanted something with more RPM on top, but still have some low grunt to yank the bike out of the corners. Revo 3.3 comes stock with a wide-ratio (#5384) two-speed, which would work fine, but I wanted second gear to be able to tug the extra weight of the rider a little easier. This Revo quad is going to be blasting through a wide variety of terrain, so I went with the standard-ratio (#5385) gear set for the best of both worlds. To further improve acceleration and speed, I removed the reverse system and OptiDrive?? module, and installed the Revo forward-only kit (#5394X). This will reduce the rotational mass dramatically, but you will lose reverse capabilities.

For racing or track thrashing applications, I recommend using the Revo center differential kit (#5414) and rear brake kit (#5417) for the ultimate in control. I use the center diff and rear brake set up on 90% of the tracks I race on, and I know how much it improves traction and drivability. My Revo will be used primarily for jumping and general bashing though, so I stuck with the solid center output shaft. This equalizes power to the front and rear differentials to level the ‘front to rear’ gyro effect of the wheels when airborne for more dramatic tricks and improved control.

Traxxas offers a diff spool (#5381X) to lock the rear end for maximum traction on the sand.

Suspension

The stock suspension on the Revo 3.3 is more than up to the task. It just needed to be tweaked slightly for this particular job. A stock Revo weighs in at 9.5lbs, and most race-prepped Revos fall around a half-pound less than that. My Revo quad tips the scales at just about 10.5lbs with Stunt Steve. The extra weight saved by removing the EZ-Start and the reverse system helped bring it back down to just a pound over stock weight. This isn’t too bad considering you’ve got to have someone hanging onto the bars. The extra weight was going to require a firmer shock set up, and I also wanted to increase down travel of the suspensions arms to better absorb big jump landings. I swapped the stock white front springs out for tans (#5440), and the green rear springs for blacks (#5441). I filled the shocks with 60wt shock fluid to provide adequate damping for the firmer springs.

To increase suspension travel, I just repositioned the pushrods to the inner adjustment location on the suspension arms. I adjusted the spring preload collars to get the chassis to sit with the drive shafts just above level (diff output shaft higher than the axle). Tip: wheelies are easier to perform with higher ride heights. By raising the center of gravity, the chassis is more likely to tip back under acceleration.

With the quad body sitting on top of the stock Revo 3.3, I noticed that the wheelbase was just a bit under-sized. It actually looks pretty good, but to get the best result, I installed the extended wheelbase suspension arms (#5333R), and located the pivot balls into the 19mm position for maximum wheelbase. This was perfect.

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Details, Details, Details…

Of course, after all of this, the quad looks good enough to call it done and go have some fun, but I wanted to bump it up another level. So, I thought of a few ‘easy to do’ tricks and mods that would make this quad very unique. Check ‘em out.

 

Nerf bars/foot pegs

Nerf bars are the number one key-accessory in keeping your feet attached to your legs while ripping around the trails. A slip off of the pegs and serious damage can occur. Also, the protective bars between the front and rear wheels keep the bike from collecting trees and the tires of other quads from snagging your legs. Since I couldn’t find a nerf bar system made specifically for my project quad, I decided to build my own. Here’s another area where you can get creative.

I used Traxxas Monster Buggy roll cage halves to form the nerf bars, and I cut sections from the E-Maxx chassis to make the foot pegs. Check out the photos for all the details.

Right Side

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“I formed (curved) the front of the bars by preheating them with a heat gun. Caution: Use care when using heat guns, and always wear proper protection to avoid injury. I secured front section of the right side nerf bar to the chassis with a 4.0m screw and locknut just in front of the battery box. I attached the middle section to the right side steering servo guard. I used a 4.0mm Button Head Machine screw to secure the rear section to the rear of battery box. I used a section from each battery tray from an E-Maxx chassis to act as foot pegs and to secure the rider’s boots to the bike.”

Left Side

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4	5	6	7

“I mounted the front section of the left side nerf bar to the chassis just in front of the left side steering servo and secured with a 4.0mm screw and locknut. I attached the middle section to the left side steering servo guard, just like the right side. The back section required replacing one of the engine mount screws with a longer one. I attached the foot peg to the middle bar stemming from the servo guard, just like the right side. The rear of the foot peg is secured to the back section of the nerf bar. Be sure to left some room between the foot peg and the chassis for an easy fit of the rider’s boot.”

Securing Rider's Boots

I removed a small amount of material from the rear slot area of the foot pegs to fit the boot mounts into. I secured the rider's boots with larg body clips.

Traxxas Twist Lock??

The Twist Lock is a handy feature found on the Villain?? series of Traxxas boats. A simple twist of the wrist quickly secures the upper deck to the hull of the Villain boat. It consists of round plastic thumbscrew that twist-locks into place onto a mounting post.

I secured the mounting post to the interior section of the roll bar. I measured the height of where I wanted the body to sit, and then bolted the post to the roll bar with 3.0mm screws and lock nuts. Next, I trimmed the excess plastic from the roll bar that protruded past the mounting post.

The body will need a hole just large enough for the thumbscrew to slide through. Finally, the thumbscrew is secured by a retaining ring, and is free to pivot.

This was an inexpensive and easy way to provide extra reinforcement for body and rider in addition to the front and rear body mounts.

 

Wheelie bar

This is purely optional, and not very realistic, but it is very cool for doing controlled wheelie stunts, and it does a great job of protecting the exhaust canister. I trimmed a Jato 3.3 plastic wheelie bar (#5584) to the desired length, and then secured it to the rear body mount with two 3.0mm screws and lock nuts. You can experiment with different lengths to get different wheelie angles. I added the optional red anodized wheels and rubber-capped tires (#5186) for visual appeal.

 

 

Canister pipe

To add realism to the quad, I wanted to install an exhaust canister on the pipe just like a real bike. A large enough tube should not affect performance and will add a slight hollow tone to the exhaust note, fitting the bike’s personality.

I use the interior section of a stock Revo drive shaft for the body of the canister. I connected the canister to the stinger of the exhaust pipe with a stock T-Maxx exhaust coupler (#5246). I used another T-Maxx exhaust coupler to cap off the canister forming an exhaust tip. I used zip-ties to secure the couplers.

 

Lights/covers

I picked these up at the local MX shop. They’re valve stem caps made for typical MX inner tube valve stems. They make them in various shapes and schemes. For mounting the caps, I bolted plastic spacers onto the front of the body mount (where the body post screw pins used to go) with 3.0mm screws and lock nuts, and then threaded the caps onto the spacers.

Handlebar dampers/savers

You could consider this the R/C equivalent to an ATV steering stabilizer; only in this case, it is to save the handlebars from damage. Quad riders like to use steering stabilizers to smooth out the impacts and jolts from the handlebars when blasting through deep ruts and over large rocks. That’s obviously not the reason for this project, but the rider does put a considerable load on the small plastic handlebars. Out of fear of snapping the bars, I decided to fabricate a suspension system for the handlebars to allow a certain amount of give when the rider is pushed into the bars from impact rollovers and hard landings. This was accomplished with shock springs, spring retainers, and long 3.0mm shoulder screws.

Series of handlebar photos

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“I used a red T-Maxx shock spring for my damper system, but any medium rate shock spring should do the trick. You can experiment with different length to get the desired flex from the bar mount. Grind away the outer edges of the molded reinforcement ribbing located around the mounting holes of the handle bar mount to keep the spring centered (see photos). Place a lower shock spring retainer on top of the spring, and then use a long 3.0mm shoulder screw to secure the assembly. The handlebars should be able to pull away from the body, but not too easily.”

Rear grab bar

Most every ATV has a rear grab bar. The grab bar is there to aid in pushing or pulling the bike when moving it from place to place while in neutral. They’re also used for mounting flags when riding in the dunes. They fly high signaling that there is another rider over the hill to prevent blind collisions. The stock Revo rear bumper mount serves this purpose just fine, and I positioned it between the wheelie bar and the upper body mount cross piece using the same 3.0mm screws and lock nuts used for the wheelie bar. 

 

Iron cross bumper

You can use most any bumper made for the Revo, or you can make your own like I did. Iron cross bumpers are popular with a lot of sport ATV riders, and are also used by top pros like John Natalie. I carved this one out of a block of composite plastic stock. I used a rotary cutoff wheel and grinding bit to shape and finish the bumper. I secured the bumper to the stock front bumper mount with two 4.0mm screws, and finished it off with red number plate backing, just like in pro ATV off-road racing. 

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Performance

My first run was with the larger heavier rider to see how it would react with a higher CG. It acted as I expected, a little top-heavy. It wasn’t too bad until I picked up the pace a little. I think for most applications and hard running, I will stick with Stunt Steve. Once I strapped Stunt Steve to the bike, it came alive. The extra weight on top is definitely noticeable compared to a typical truck set up, but not so much that you can’t throw the Revo quad around in the turns and drive hard. The TRX 3.3 had plenty of power to get the quad up to a fast speed in a hurry, and would lift the front end from the ground when traction allowed.

Blasting into corners and roosting out of the berms looks just like the real thing. I found that the spool made it a little difficult to control high speed loads on most surfaces, and the rear end would want to walk around a bit, but it feels right at home in the sand. I recommend sticking with the standard differential for most conditions, and leaving the sand duties for the spool.

My favorite part is jumping the Revo quad. Using the higher rpm capabilities of the standard or wide ratio two-speed gear sets allow crazy jump tricks and more control over the attitude of the bike in the air. Back flips are easier with the increased (unloaded) axle speed, and correcting the bike while in mid-air is easier with the solid output shaft in the transmission. For controlled four-wheel drifts, just yank the trigger and crank the wheel. Driving the Revo quad is a blast.

I highly recommend trying this project if you’re looking for something different, yet highly entertaining, to do with your Revo. You never know, there may be many others with the same passion for four-wheeling as you, and you could find yourself having a blast racing and bashing your Revo quad at your local track or at your next off-road camping trip.  See ya!!!

Action Video clip

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Check out my Pit Pass section for more articles
on setting up the Revo for more performance.

Photo Gallery

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