XXX-NT RTR II w/XR2i & M15RE
TripleX-NT Tech Tips
"NT' Tips: although Team Losi’s XXX-NT Nitro Truck has only been released for a short time, you racers have gone wild buying them up as fast the dealers can get them in. With this popularity has come a few good questions as well as a few tips that you might like to take advantage of.
Gear Adjustment; to be able to accomplish a number of things critical to the design, Gil Jr. had to incorporate adjustable motor mounting. Don't worry though, setting the proper gear mesh is not difficult. The bottom of the NT chassis has machined slots where the motor mounting screws and countersunk washers go. These slots help tremendously in keeping the motor straight and the gear teeth aligned. With the mounting screws loose slide the motor back until the gears are tight to one another. Move the motor forward about 1/32". If you have trouble judging this, try placing a small strip of notebook paper between the gears where the pinion on the clutch bell contacts the spur before you slide the motor back. After securing the motor, the paper should roll out from between the gears with a fair amount of resistance. In either case, after the motor mount screws have been tightened there should be a slight bit of backlash as you rotate the spur gear. You want the gears to get about 80 to 90% engagement. To check this you can either rely on the "feel" as you hold the clutch bell and rotate the spur back and forth or look directly at the gears from the right side of the truck as you rotate the rear tires. There should only be a slight bit movement between the gears. The mesh is too tight if there is no movement between the gears or they make noise and the tires do not spin freely. Move the motor forward slightly to correct this. If there is additional movement or the wheels spin freely but the gears "slap" teeth as they rotate the mesh is probably too loose. Moving the motor back slightly will correct this. After you have tried several settings and techniques and observed the engagement from the side you should have no trouble getting a good mesh.
Monster Diff: The new "monster" differential designed for the NT will handle the extreme power of nitro motors. However, like all other differentials, it is not a slipper device. This new unit is designed to have not only greater power handling capabilities but also a broader range of adjustment. As with any differential, start by adjusting it per the instructions. The most reliable method of adjustment requires that you first lock up the slipper by tightening it until the spur gear won't move without ripping the flesh from your hand. Grab the spur gear tightly between your thumb and first finger while cradling and holding the right rear tire firmly between your forearm and chest. Now try to turn the left rear tire forward. If it turns at all tighten the diff 1/8 turn and test again. When the diff stops turning and starts jumping and locking again (often referred to as chirping or barking) requiring substantial twisting of the rear tire it's at the beginning of its useful adjustment range. Most of the pro’s run their diff on the right side but you should be able to find your "sweet spot" by gradually adjusting it tighter.
Throttle linkage; The NT includes linkage for both slide and rotary type carbs. More importantly, this linkage package allows for the use of radios without end point adjustment (EPA). More than a few throttle servos have failed due to the lack of this feature. Those of you with EPA would be wise to use this as well. Just as you don't want to stall the steering servo the same is true for the throttle. Install the small spring (uncompressed) between the pull side of the pivot on the servo arm and the set collar at the end of the linkage. This will absorb the extra servo movement and prevent stalling which will drain the receiver battery and eventually cause servo failure.
Find the Crystal; Want to change radio crystals without removing your receiver cover or cutting a big hole in it? Pick up a package of Team Losi #A-3244 4WD access plugs. Position the receiver with the crystal pointing out within the box created by the receiver cover. Cut a small rectangular opening 5/16" by 5/8" in the cover over the crystal and insert the rubber plug. Now when you need to change crystals all you need to do is remove the rubber plug. The receiver stays clean and dry.