In 2009, as the rock crawling segment was off and running (albeit slowly–get it?), Traxxas released the Summit which it dubbed an “extreme terrain monster truck.” Based on the Revo platform, built to take a beating and equipped with features such as remotely locking differentials and a 2-speed transmission that is also controlled from the transmitter, the Summit was–and still is–a basher’s dream come true. There is a lot to like about the Summit, but as soon as I saw one I couldn’t help but think–probably because I had crawling and scalers on the brain–that a more realistic stance would take the truck from cool to killer? After happening upon some Summit builds from other enthusiasts and then talking to a few behind-the-scenes folks at Traxxas, I came up with my Summit LT conversion–a more scale take on Traxxas’ multipurpose off-roader.
SUMMIT LT CONVERSION STEP BY STEP
- Replace suspension arms (upper and lowers) with Slayer Pro arms
- Replace steering and suspension links (eight total) with Slayer Pro links
- Modify suspension arms as needed for clearance
- Replace cantilevers with Progressive-2 cantilevers
- Shorten plastic drive shafts
- Replace 17mm hexes with 14mm hexes
- Swap monster truck tires and wheels for 2.2/3.0 wheels and 2.2 crawler tires
The stock Summit is a monster truck, or as we often say in RC, a MT. While the Summit has a semi-scale body (kinda a cross between a later model Chevy Blazer and a 2-door Jeep Cherokee), it certainly isn’t a model of anything you’d see rolling down the street. My goal with this project was to transform the MT into a vehicle you might just see on the street and the trail. While there is nothing light duty about the Summit, LT–or light truck–seemed to be the most fitting designation for a more realistically proportioned adaptation.
WIDER ISN’T ALWAYS BETTER
In my opinion, at a little over 18.5 inches at its widest point, the Summit is just too big. Again, its way wide stance is great for bashing, but I knew narrowing the track would provide two very valuable benefits. First, the truck would instantly look more scale. Second, it would be able to go where scalers go–well, at least with a little finesse. Instead of bashing its way down trails, a narrower truck could be maneuvered.
The key to the narrow transformation is the use of Slayer Pro arms and links. That part is pretty simple and a bolt-on affair–well, almost a bolt-on affair. The arms are sold in pairs–an upper and lower arm in each parts bag. There is a parts bag for each corner (see parts list below).
I found that once I had the arms bolted on and started cycling the suspension by hand that the arms needed to have some material removed for clearance. This is because of link placement and because the Summit, with its locking differentials, has gear cases that bulge on one side. I used a rotary tool with a cutoff wheel and a sanding drum to clearance the arms as needed. The arms that need the most attention are the upper and lower arms on the right rear corner and the left front corner, but check the entire suspension setup for equal amounts of up and down travel. The cutting and sanding process is best done slowly (wear eye protection), testing as you go. Doing this modification will ensure the links don’t interfere with the arms and the differential housings don’t rub against the arms, and ultimately allows you to have equal amounts of up and down travel on each side of the suspension and a smooth, consistent suspension.
The switch to the narrower Slayer Pro setup requires the use of the Progressive-2 (90-T) rocker set for the cantilever suspension system, and it’s also important to note that the stock Summit springs will not work. The stock springs will be far too stiff when the leverage of the long arms is lost. I experimented and found the springs listed below to be ideal for my Summit LT, but what is ideal for you is personal preference and dependent on items used for electronics, tires, wheels, etc. The end result, depending on wheel selection, is about six inches narrower than stock!
TRAXXAS SUSPENSION PARTS USED
- Aluminum Red Push Rod Slayer >> 5918X >> $13 (2X)
- Rocker arm set, Progressive-2 (90-T) >> 5358 >> $11
- Spring (tan) >> 5440 >> $6
- Spring (yellow) >> 5435 >> $6
- Suspension arm upper and lower (left front) >> 5932X >> $8
- Suspension arm upper and lower (left rear) >> 5934X >> $8
- Suspension arm upper and lower (right front) >>5931X >> $8
- Suspension arm upper and lower (right rear) >> 5933X >> $8
- Tubes toe links 7075-T6 >> 5939R >> $22 (2X)
The long Summit driveshafts are an easy fix. I recommend using a rotary tool and a cutoff wheel (remember to use eye protection) to cut down both the male and female pieces. Make sure don’t remove too much material, making the drive shafts too short, or they could pop apart.
Once you get the suspension and driveshafts narrowed up, you have the bulk of the work done, but new none-monster truck tires are definitely needed. I used Pro-Line Interco TSL SX Super Swamper 2.2 tires with the included memory foam. These tires have worked out perfectly. I selected Traxxas’ Slayer Black Beadlock Split-Spoke wheels because they looked good and because you need wheels with a 3″ inner diameter to clear the pivot ball suspension. So, with short course being so popular, you have a number of options as the short course industry standard wheel is 2.2″ outer diameter with a 3″ inner diameter. I removed the Summit 17mm hex hardware and used 14mm aluminum hex adapters to be able to bolt on the Slayer wheels.
DID YOU KNOW?
Usually we save the “Did You Know?” fun facts for reviews, but this one is too good not to share. It’s a little known–or realized, I guess–fact that the original Slayer is the reason we use 2.2/3.0 wheels as the short course industry standard. The original Slash came with 2.2 wheels–outer and inner diameter. The foam was the same thickness all the way across the tire and the outer and inner sidewalls were the same height. The Slayer with its pivot ball suspension needed a unique wheel and the 2.2/3.0 was born. Even aftermarket companies were already offering 2.2 short course tires and wheels, Traxxas and aftermarket companies essentially ran with the wheel that would fit all trucks instead of having to manufacture two different size short course tires and wheels. So, in the end, a truck that almost never sees the track and is significantly outsold compared to all the electrics, set the industry standard.
To fit the 2.2 Super Swamper tires, I test fit them (“measure twice, cut once”) and found the tire coincidently had a molded-in line that served as a perfect guide. If you go with these tires, you’ll see what I mean. I then cut away at the memory foam until it worked with the 2.2/3.0 wheel. Once everything was glued up, the end result looked as factory as the rest of the Summit LT.
TIRE AND WHEEL PARTS USED
- Pro-Line Pro-Line Interco TSL SX Super Swamper 2.2″ >> 1166-14 >> $31 (2X)
- Traxxas Black Beadlock Split-Spoke Wheel >> 5974 >> $8 (2X)
- Traxxas Wheel Hubs Hex E-Maxx >> 4954R >> $3 (2X)
To really bring the dual purpose nature of the Summit LT to life, I wanted to up the power. I installed a Tekin RX8 1/8-scale brushless system with a matching Tekin T8 2000Kv motor. Because this system is sensored, low speed crawling isn’t compromised, and since it’s built for 1/8-scale use, it’s more than stout enough for the heavy Revo platform. The T8 motor I selected is spec’ed for truggy use which gave me even more confidence putting the system into the heavy Summit LT. The motor and speed control are listed separately below, but you can save some money and buy them as a combo pack. I paired the Tekin system with two 2S 9000mAh LiPo XL packs from MaxAmps.com. These packs, wired in series, provide 4S or 14.8 volts of power.
TEKIN PARTS USED
- RX8 Speed Control >> TT2300 >> $200
- T8 2000 Kv motor >> TT2361 >> $180
I also modified the steering system using a GH Racing (Golden Horizons) Aluminum Steering Arm Pin Mount which features no steering throw stops and Pro-Line’s now discontinued Single Servo Arm for the Revo. While the Pro-Line part may prove hard to find, if you do want a single steering servo, STRC offers an aluminum single arm servo mount that is well made and inexpensive (item no. STP6037B). For every little bit of steering throw, I also carefully sanded the main steering arm where it contacts the steering arm mount. For optimized steering power, I added an Axial aluminum servo horn, Traxxas’ heavy-duty servo saver spring and literally stuffed in a Hitec HS-7980TH Monster Torque servo. This servo is a tight fit (be prepared to bust out a file and some elbow grease), but it dishes out 500 oz./in. of torque when matched with the Tekin RX8 6V BEC. Even more torque (600 oz./in.) is possible if you use an external BEC. All of this modifications were done to beef up the steering and to get as much steering throw out of the truck as possible.
STEERING PARTS USED
- Axial racing Aluminum Servo Horn >> AX30835 >> $16
- GH Racing Aluminum Steering Arm Pin Mount >> 2283 >> $15
- Hitec HS-7980TH >> 37980S >> $175
- Pro-Line Single Servo Arm >> Discontinued
- Traxxas Heavy-duty Servo Saver Spring >> 5344X >> $3
I’ve seen enough RC builds–from bolt-on bonanzas to custom creations–to know that just because a project seems like a good idea on paper doesn’t mean it will meet expectations or, heck, even work all that well. I had no idea how the Summit LT concept would handle and I knew that other than looking more scale than the original, it could actually perform poorly. Well, I’ll spare you anymore dramatic lead up–the Summit LT is amazing. It’s tremendous fun.
With the 2000Kv Tekin brushless system, it’s fast, but better than just being fast, the Summit LT can completely handle the speed. The Summit LT doesn’t get sketchy at full speed like you might expect since it’s narrower than stock but essentially just as heavy. Overall, it’s easy to control–even with the trigger buried. I’ve driven the truck on grass, dirt, gravel and at the race track and it always exceeds my expectations. That Revo-style suspension just works when it comes to soaking up bumps and jumps.
Speaking of jumps. The Summit LT can also get airborne. In fact, it goes through the air just as well as the average basher and lands without issue. Some trucks fly well but upon meeting the ground take awkward bounces careening to the left, right or back up with a donkey kick. In contrast, the Summit LT is a great jumper. It might not be the first truck I would grab for a trip to a skatepark or BMX track, but I’ve launched it off my bigger wooden test ramp and even ripped laps around an RC track. The Summit LT receives fairly high marks for this kind of jumping. It can’t jump with the finesse of a short course truck, but it will out jump any dedicated crawler that I have ever seen.
With high speed handling and jumping covered, it’s time to shift gears figuratively and literally. When you lock the diffs and shift into low gear, the Summit LT can crawl. I don’t care what any jaded purists say, the Summit LT can actually crawl. Is it a comp crawler? No, but it isn’t designed for that kind of use–that specific and singular use–at all. My answer to that is a close-minded argument is in the “Summit LT in Action — Can Your Crawler Do This?” video. So, the Summit LT crawls, but how well does it crawl? It has plenty of power and torque thanks to the big motor and the 70:1 final drive ratio. When you combine that with capable tires such as the G8 compound Pro-Line tires, the Summit LT can climb rocks. Now that it’s much narrower than stock, you can actually maneuver the truck and not just bash your way over rocks relying more on speed than crawling ability. The Summit LT drives and behaves like a proper scale crawler and not a monster truck. On the rocks, it’s a whole different beast than the original Summit. Better put, in a good way, it’s less of a beast. It’s two biggest handicaps on the rocks are its fairly high center of gravity and its long wheelbase. Like a lot of other scale crawlers, it can tip over backwards when the going gets too steep. The long wheelbase simply and expectedly hampers maneuverability. While the high CG is what it is and probably not all that worse than many other scalers and smart use of the locking and unlocking differentials greatly improves the Summit LT’s turning radius.
In addition to all of the companies below that supplied parts, I would be completely remiss if I didn’t thank Traxxas not only for providing many parts, but also for their technical support. I would also like to thank Bill Zegers of Zegers RC Graffixx for the paint work.