The Revo Rocks Project II

Welcome to stage two of my Revo™ Rocks project. This is the follow-up article based on my Revo Rock Crawler project. I want to let everyone in on what I've been up to lately with my Revo crawler. Not long ago, I showed you an inexpensive way to get your Revo prepped for better climbing and improved rock handling. I also showed you how to make your Revo look more realistic while doing so. In this article, I'm going to show you a few newer items that I've found to enhance the realism of the truck, along with showing you how to super-size your Revo for better rock crawling performance.

Automotive rock crawling is an ever-growing sport that is also increasing in popularity in the R/C world. This means that choices for new tire designs, familiar off-road body replicas, and trick rock crawler wheels are increasing by the day. There are many different accessories available to set your crawler apart from the rest. With the addition of the Revo 3.3 to the Traxxas product line, there are more off-the-shelf Traxxas parts available to help with the conversion, including the extended wheelbase chassis. Check out what I've done to mine. Hopefully, it will inspire you to come up with your own creations. Remember, this hobby is all about fun and performance, and the Revo is the ultimate platform for both. Enjoy.

Super-size your Revo

Extending the Wheelbase

Extending the wheelbase is a major step in increasing the stability of your Revo. With a longer wheelbase, the truck will be able to negotiate larger rocks and steeper inclines without flipping over. It will also help keep the chassis from tipping when used with larger engines.

Here are two ways to extend the wheelbase of your Revo:

Extended chassis

For this project I contacted Ballistic Batteries for my extended Revo chassis. Ballistic Batteries offers extended Revo chassis with one full inch of extension over the stock Revo 2.5R chassis. This will extend the front of my chassis by an inch, which is pretty significant, and will most definitely be an improvement on the rocks. RD Racing Products anodized the chassis bright orange, which compliments the overall color scheme.

Traxxas now offers an extended chassis for the Revo (#5322X). This chassis is extended from the front end and is 30mm (1.25 inches) longer than the standard Revo 2.5R chassis. The best news about the new extended chassis from Traxxas is the price. It retails for $60.

Extended chassis installation tip

With the installation of an extended chassis, there are a couple of things that you'll need to do. First, the stock center driveshaft will not be long enough to connect the transmission to the front differential. Use the longer rear center driveshaft (#5415) instead. It assembles just like the short one, but the shaft is longer to accommodate the longer front end of the extended chassis plate.


Steering servo links

This is an easy fix. To get the output shafts of the servos closer to the steering arms, just flip the steering servos around 180-degrees, and reconnect them to the chassis. Then, adjust the steering links as needed to connect the servos to the steering bellcrank. See page 39 in your Revo manual for proper set-up.

Traxxas extended wheelbase rear suspension arms (#5333R)

Installing these new rear suspension arms by Traxxas is an inexpensive way to increase the wheelbase of your Revo. For under $20, you can add up to 19mm (approx. 3 D4-in) of wheelbase. This is also done at the rear, keeping the weight of the chassis toward the front of the truck, which is more desirable for most crawls.

There are two positions molded into the new rear arms, one that offers 10mm of extension, and one that offers 19mm. This is a perfect way for matching up your wheelbase with different body types and sizes. The extended wheelbase suspension arm set comes complete with bumper spacers that space the rear bumper out from the chassis an extra 6mm to help compensate for the new rear axle position.

Increasing track width

The second stage in making the truck bigger is to increase the track width. This is easily accomplished by using deeper offset wheels like these Maximizer composite offset wheels X-75 (#1301) with optional rock rings.

Keep in mind that increasing the width is not always the answer. Sometimes a narrower stance will work better on a particular surface or rock formation, like these Proline 40-series Cheyenne narrow bead-lock wheels (#2683-01), with Proline narrow Moab XL tires (#1119-00).

Make sure to check with you local hobby shop for the correct hub system required for your selected wheel style.

Experiment with different combinations for your particular conditions to see what works best.

Gearing options

In my first article I explained how important it was to gear the Revo as low as possible for best performance while crawling. With the optional gears available for the Revo, the lowest gear ratio available is the 14t clutch bell (#5214) coupled with the 40t spur gear (#3955). This combination makes a 2.86:1 ratio. This is good for most random terrain. However, there is a way to go even lower (without modification). Since the Revo and the Jato™ share the same slipper systems, the Jato spur gears can be used on the Revo, which opens the options up to lower gear ratio possibilities.

Remember, we are looking for the largest (usable) spur gear combined with the smallest possible clutch bell gear. The largest Jato spur gear that can be used on the Revo (without modification to the chassis) is the 56t spur gear (#3957). The smallest clutch bell available from Traxxas that is compatible with the Jato spur gear is the 16t clutch bell (#4116). Note that the #4116 clutch bell requires smaller 5x8mm bearings (#5114). These gears combined give a 3.5:1 ratio. This is significantly lower than the 14/40 combo, and the difference can really be felt during a crawl. Be aware, though, that Jato gears are not compatible with Revo gears, as they are approximately 32-pitch gears, and Revo gears are closer to 25-pitch.

Of course, the new larger and meaner Revo crawler wouldn't be complete without a larger body. The Pro-Line Hummer H2 body (#3165) is specifically made for large scale monster trucks. This is a perfect fit for the extended wheelbase of the new crawler, and simply looks sweet.


For the Hummer body, I wanted to go with chrome trim, so I chose these RPM chrome front and rear bumpers (front, #80453) (rear, #80483). I installed a pivot ball onto the rear bumper to act as a trailer hitch for some added realism. The bumper spacers from the Traxxas extended wheelbase suspension arms positioned the rear bumper in just the right spot for the Proline H2 body.

For those that want the extra grunt of a big block engine, there is the Traxxas big block conversion kit (#5360X). This kit includes everything that you need to turn your small block Revo into a big block monster machine. Keep in mind that smooth throttle response is crucial for a successful climb, so be careful with how much power you put into your Revo. This is a big reason why the TRX 2.5R Racing Engine works so well at crawling compared to most nitro engines. It has a very smooth power band. Engines with a harsh power delivery will make it difficult to control the truck during a climb and will break traction too easily.