Preparing the XX-T 'CR'

1. Introduction
2. What race preparation is about
3. Routine maintenance after a run
4. Maintenance basics
5. Gearbox
6. Shocks
7. Suspension
8. Chassis
9. Tires

1. Introduction

This memo stays away from topics that are already dealt with in my R/C electric off-road racing FAQ (http://www.oocities.org/MotorCity/2314/rc-faq.html), and also avoids duplicating material that's in the XX-T 'CR' Owner's Manual. I don't cover the maintenance of motors and batteries, nor do I describe how to dial-in a truck to a particular track.

I describe only techniques that I actually use. I mention specific products and part numbers. Except where noted these are all products that I use. If a product isn't mentioned here, it is possible that I know about it but have chosen not to use it, or that I don't know about it at all.

Some of the tips here have been described by Team Losi in their "Tech Talk" advertisements. But I learned most of this stuff from other racers. There's no chance I can acknowledge every person who taught me something, but I learned the most from Ron Williams, who was a Team Losi sponsored driver at Hobby Haven Raceway in Livermore, California when I started racing back in 1989. Thanks for all the help, Ron.

2. What race preparation is about

The fun is not limited to the races themselves. Driving practice is fun, and it helps improve my driving, which makes the races more fun.

But if my truck breaks down, or my truck doesn't perform the way it should, that's not fun -- that's frustration. The way to minimize frustration, thereby having the most fun, is to prepare the truck before going racing. The goals of race preparation are:

• Make the truck more reliable -- more likely to finish.

• Make the truck perform as the manufacturer designed it to perform.

• Make the truck require less maintenance and/or be easier to work on.

How often you need to work on your truck depends upon many factors:

• How skillfully you've built and adjusted the truck.

• How faithfully you perform routine maintenance between runs.

• The type of dirt at your track.

• How hot a motor you run and how you gear it.

• How often and how hard you crash.

Preparation is an individual thing; you don't need to do everything described in this memo to be prepared. You may find that you can work on your truck less often and still have it work well enough to be fun to drive.

3. Routine maintenance after a run

• The longer the dirt builds up, the more likely that it works its way to someplace you don't want it to be, like inside a bearing or inside a shock.

• Sandy dirt under your battery pack will gradually sand away the shrink wrap on your pack; when the shrink wrap is gone, you'll have to rebuild the pack or risk a short-circuit.

• If a lot of dirt builds up, the dirt can hide problems that you are trying to find during the check-up.

• If you need to do some real work on the truck, say on the motor, shocks, or transmission, you don't want those parts getting dirty. By keeping your truck clean you help keep your workplace clean.

• Dirt is heavy; why carry it around with you when you race?

Here's the procedure:

1. Pull the truck off the track and stop it, then go pick it up. Don't stop at the edge of a straightaway, even if you think nobody else will drive there. They will.

2. When you pick up the truck, imediately check the motor's temperature by pressing your thumb on one of the motor endbell heat sinks. If you can't hold your thumb there for five seconds without pain you've got a motor overheating problem, and you'll need to drop a tooth or two from your pinion.

3. Back in the pits, remove the body and put it well out of the way.

   If your motor overheated, remove the pinion now to remind yourself that you need to install a smaller one.

   If you've recently adjusted the Hydra-Drive, remove the gear cover and check the Hydra-Drive temperature with your thumb. Same test as for the motor: If you can't hold your thumb on the Hydra-Drive case for five seconds without pain, your Hydra setting is too loose. Tighten it at least a quarter turn right now, before you forget. Replace the gear cover: Dirt will be flying around, and you don't want dirt getting on your gears.

4. If your tires are so muddy that you will need to wash them with water, remove them and set them aside; put the wheel nuts and front wheel bearings in a clean place. Otherwise just use your tire brush to clean the tires.

5. Remove the battery. This is easy to do if you are using connectors, which you should be. Place the hot battery in front of your pit fan.

6. Now remove the loose dirt from your truck. The ideal tool for this job is an old paint brush, about 2 inches wide. Just having this tool at your pit will help remind you what you need to do.

   First turn the chassis over and rap the bottom of the chassis with the brush handle. (It helps to pick a brush with a hefty handle, either wood or heavy plastic.) Any dirt that accumulated in the battery recess or around the servo should fall out.

   Then rap each suspension arm, rap each wheel; more dirt will fall. Holding the chassis vertcally, rear end up, brush off the remaining dirt, especially dirt in the battery recess.

   As you perform this cleaning, check the various suspension pivot pins in case you've lost an e-clip. As you rap an arm, check its inboard and outboard pivots. If a clip is missing, replace it right away, before you forget.

   If you've been running in muddy conditions then brushing won't be enough; you'll need to scrape the mud off, use a wet rag, etc. Ugh.

7. Take an old toothbrush and clean off the bottoms of your shocks. As you do so, notice how much dirt accumulated down there during the run. Normally you'll see the amount of dirt increase very gradually from run to run as the shock O-rings wear and more oil leaks from the shocks. The rear shocks get dirtier than the fronts because of all the dirt kicked up by the rear wheels.

   While you've got the toothbrush out, use it to clean any dirt from the motor's endbell bearing. Since you are running a gear cover, you shouldn't have much dirt on the motor's can bearing, so don't worry about that bearing.

8. Take a final look over the truck from front to back. Check for bent turnbuckles, loosened ball ends and shock mounts, loosened wheel nuts. Check the gear mesh -- the motor may have moved in a collision.

   If you are running a bushing motor you should oil both motor bushings.

   If everything checks out OK, you are ready to go as soon as the motor is cool and another pack is ready.

4. Basic techniques

Standard ball bearings should be cleaned using motor spray, then re-oiled using a drop of light oil.

Teflon-sealed ball bearings don't require routine maintenance. Just brush off loose dirt with a toothbrush. If a bearing feels gritty you can remove the shields and use motor spray. If this brings the bearing back to life then re-grease the bearing and replace the shields.

To remove the shields, it helps to know that the outer race of a sealed bearing is grooved on the inside to hold a retaining ring. This ring is what holds the bearing shield in place. To remove the ring you first locate the gap between the two ends of the ring. (If you've got one of those lamps with a magnifying glass that might help!) Then insert a sharp X-Acto knife into the groove at the gap, sharp side of the knife facing toward you. Use the point of the knife to pry one end of the retaining ring out of the groove. Believe me, this is much harder to describe than it is to do! With the ring gone you'll have no trouble getting the shield off.

Installing a shield is easier. The shield just drops in place and you retain it by snapping in the retaining ring. The ring goes in easily without tools if you start one end in the groove and just work the rest of the ring in.

Motor spray cleans ball bearings and other metal parts very well but depending upon the formulation it may attack plastics. So clean plastic parts, such as diff gears, spur gears, and transmission housings, using Simple Green cleaner, warm water, and a toothbrush.

5. Gearbox

Symptoms of wear

• The gears wear, increasing noise and decreasing power transmission efficiency. This goes for the gears inside the gearbox and for the motor pinion and spur.

• Dirt enters the bearings of the transmission, further decreasing efficiency. Fortunately, the most exposed bearings on the XX transmisson have Teflon shields that greatly reduce the penetration of dirt.

• The Hydra-Drive's seals wear, and Hydra fluid leaks out past the seals. Fortunately, the seals last a long time if you don't allow the Hydra to overheat.

• The slipper pad gets dirty and the slipper backplate accumulates a sticky glaze, increasing the starting friction ("stiction") of the slipper. The added stiction causes the truck to handle bumps and landings less predictably.

• The diff lube becomes contaminated from particles within the gearbox (bits of plastic worn from the gears, dirt that enters the gearbox.) The diff lube also migrates away from where it is needed, and the diff lube that's doing all the work breaks down from the pressure. Grooves wear in the diff rings, increasing drag. Eventually either the diff starts to feel gritty or the diff begins to slip and must be tightened to prevent damage (melted diff gears, square diff balls.) In either case the diff action becomes less free (rear wheels don't spin as long when you spin the diff.) The effect is that when entering a turn with power off, the rear end of the truck will be more reluctant to follow the front, inhibiting the turn; when exiting a turn with power on, the truck will lose traction at the rear, increasing the turn or causing a spin.

Teardown and inspection

1. A paper towel is a good place for doing transmission work, since you need a clean, flat surface for resting the sub-assemblies. A hand towel with some nap to it is useful for catching the diff balls -- you don't want to lose even one ball or you'll be buying a set!

2. A fat toothpick makes a good tool for popping the diff balls out of the diff gear. I don't know if a metal tool might harm the balls, but a wooden one surely won't.

3. A small vial is handy to hold the diff balls for cleaning. Spray the balls clean. Separately, spray off the caged thrust bearing. Wipe the diff rings clean; same for the grooved thrust rings.

4. Replace the diff gear and idler gear if the transmission was noisy, or if the gear teeth are no longer symmetrical (i.e. one side is now visibly flatter than the other.) If the gear teeth have worn to sharp points, you should have replaced the gears sooner! The idler gear is usually the first to go, but replace these gears in pairs.

5. If you remove the small top shaft bearing from the tranny case while the diff is apart, be careful not to mingle it with the two 8x5 mm diff bearings. The two types of bearing are nearly the same size, and the tranny won't work properly if you get the bearings mixed up.

6. If you've already used the diff rings on both sides, throw them away. If your diff was feeling notchy, and a new diff ring surface does not fix the problem, check the grooved thrust rings for damage; if they are damaged, replace the entire thrust bearing assembly and keep it greased better this time.

   The carbide diff balls are harder than the diff rings and, with care, should last for years. But if you've put in new diff rings and a new thrust bearing and the diff is still notchy, replace the diff balls.

7. If you are running dogbones, and the dogbone pins have worn grooves in both sides of the steel outdrives, replace the outdrives (and the dogbones if they are badly worn.) Worn outdrives reduce rear traction when the truck is accelerating through bumps or turns, because under those conditions the dogbone pins are partially locked in the outdrives, inhibiting rear suspension movement.

   If the outdrives are grooved on only one side, swap them left-to-right to get a fresh drive surface. You'll have to remove and reinstall the diff tube in order to swap the outdrives.

8. Remove the 4-40 mini locknut from its plastic carrier. (This is easy to do by turning the carrier nut-side down, then pushing a 4-40 screw into the exposed hole.) Either replace the nut, or slightly crimp the locking end of the nut to ensure that it really locks. If the nut has already been crimped once then replace it. Occasionally (say, once a year) buy the A-3078 kit and replace the nut carrier, diff screw, beveled washers, thrust bearing seal, etc.

   If any grease has gotten on the diff screw threads, wipe it off. You want as much friction as possible between the screw and the locknut.

9. Clean the side of the slipper pad that was rubbing the backplate by scraping it with an X-Acto knife. Just drag the blade lightly over the surface to expose a clean surface. If you cut or gouge the pad while cleaning it, flip the pad over or replace it.

   Remove the glaze on the slipper backplate by rubbing the backplate in a circular motion on a green 3M Scotch-Brite (tm) pad, ultra-fine sandpaper, or crocus cloth.

   If the spur gear teeth are damaged or noticeably worn, replace the gear. Examine the pinion for wear also, and replace it if necessary. If you run a hard steel pinion and a gear cover, the pinion should last for years.

Assembly

1. Place the diff balls onto their holes in the diff gear and pop them into place using the diff ring that you've assembled into the left diff half. Then grease the diff by placing a fairly heavy layer of grease on the outer portion of each diff ring, where the balls will ride. This procedure is much easier than greasing the balls individually and results in a fine diff.

   Always use the Team Losi thin diff lube, part number A-3065. By using this lube you'll get a freer diff action than with the older Jammin' Products diff lube.

2. When re-using the idler and diff gears you should assemble them in the same orientation as they had before; otherwise the tranny will make noise and run less efficiently. Losi marks the gears during manufacturing to make it easy for you to perform a consistent assembly. The idler gear has eight radial markings on one side and is smooth on the other. The diff gear has two markings on one side (closer to the center than the ball holes) and is smooth on the other. Pick an orientation for these markings and stick with it whenever you build a transmission. For instance, you might always arrange the gears so the gear markings face the right diff half. It doesn't matter what orientation you pick as long as you use it consistently.

3. When loading the thrust assembly into the left diff half, you can hold the assembly in place temporarily with a bit of wadded-up paper towel. The diff nut carrier usually stays in the right diff half by itself.

4. As you assemble the diff, tighten the diff screw slowly and stop as soon as the diff rings are forced into contact with the diff balls. At that point the outdrives don't wobble but the diff slips easily; you can hold an outdrive and the diff gear in one hand and easily turn the other outdrive with the other. You'll make the remaining diff adjustment with the tranny installed in the truck.

5. With the diff built, lubricate the gears before installing them in the transmission. Aero-Car Super Speed Gear Lube (part AC-1001) is excellent. This lube is solid at room temperature but liquefies once the tranny is put to use. Use only a small amount, or the excess will end up nestled in the corners of your tranny case. You can use Team Losi Hydra-Drive fluid or diff lube in place of Aero-Car Lube.

6. Unless you race on really sandy dirt, you can omit the blue foam outdrive bearing shields when assembling the transmission. By doing so you will reduce the drag in your transmission a little. If you install the shields, take care to center them properly, or you'll add unnecessary drag.

7. Seal up the gear case by running a small bead of diff lube all around the edge where the case halves mate. This seal will extend the time between rebuilds by keeping dirt out.

8. Three 4-40 screws attach the tranny to the motor plate. That's metal threading into metal, so use thread lock to keep the screws from backing out. Push the screws through the tranny and put a drop of blue Loctite 242 on each screw tip, then attach the motor plate. Don't over-tighten these screws; you don't want to distort the plastic tranny case.

9. When installing the Hydra-Drive you needn't install the slipper thrust bearing. This bearing has absolutely no function when used with the Hydra. Just install the long (gold) spring in place of the thrust bearing and the short (silver) spring. (The longer spring also makes the Hydra easier to adjust.) You can discard the short spring, but save the thrust bearing with the other parts needed to run the slipper without the Hydra.

Adjustment

1. Gear mesh. No gear is perfectly round. When you install a new spur gear, set an initial mesh and then check the mesh all the way around, looking for the place where the mesh is tightest. By adjusting the mesh you should be able to find one place on the spur where the mesh is tight, while everywhere else the mesh has some backlash. Mark the spur gear at this high point.

   Whenever you set the gear mesh, set it so there is a small amount of backlash at the marked high point.

2. Diff. With the transmission installed in the truck, and gear cover off, seat the diff parts by holding the Hydra-Drive and first spinning one of the rear tires forward, then spinning the other tire forward. (If you've installed a motor and meshed the pinion and spur you won't have to hold the Hydra-Drive, because the motor will hold it well enough.) Test the diff adjustment by holding the right tire and the Hydra-Drive with your right hand and turning the left tire with your left. Initially, the tire will turn easily. Tighten the diff a little, "work" the diff some more, and test the adjustment again. Repeat the tighten-work-test steps until the left tire becomes difficult to turn.

   Now if you want the diff to be consistent from the very first run you can break it in before you run it. (You'd do this if the first run on the new diff was going to be a race rather than a practice run.) Hold one tire and run the motor at low speed for two or three minutes. (A 4-cell pack is a good way to make the motor run at low speed.) Switch back and forth, holding the left tire, then the right. This break-in will start to wear a groove in the diff rings. Now test the diff one more time and tighten if necessary.

   You make the final diff adjustment at the track. Set the Hydra-Drive and current limiter the way you want them, and put the truck down on a high-bite section of the track. Point the truck toward you, roll it backwards, and punch the throttle. If the diff is slipping you will hear the slippage as a nasty groaning sound; tighten the diff and try again.

   When you get the diff adjusted to the track, feel how difficult it is to turn the left tire while holding the right tire and the Hydra. On a slippery track or with a mild motor you'll still be able to turn the tire with effort. On a high-bite track with a strong motor you won't be able to turn the tire at all. With experience you'll get a feel for this adjustment and will be able to adjust the diff nearly perfectly at the workbench.

   This adjustment procedure is designed to run your diff as loose as possible without slipping. Running the diff loose gives your diff a free-spinning action, which is usually what you want on a slippery track. When the track has more bite you may want to add some resistance to the diff by tightening it a little. You'll have to experiment with the diff adjustment in order to find what works best with the rest of your truck's setup and with your driving style.

Improvements

1. A simple maintenance-reducing upgrade you can perform on your transmission is to install Teflon shields (A-6918) on the exposed top shaft bearing. If you are working with an old bearing, be sure to re-grease it before installing the new shields.

2. The gear cover is prone to break at the mounting holes. Use RTV adhesive to glue on angled scraps of Lexan that reinforce those holes. At each hole, attach a Lexan washer to the outside of the cover using servo tape; this way as you tighten the mounting screw you can feel it get snug, so you stop before over-tightening.

3. A myriad of weight-saving parts are available from Team Losi and others.
   • The blue-anodized aluminum screw kit from Associated (part number 6911) includes screws that replace the three long steel tranny case screws. The tranny case screws are not highly stressed so aluminum screws work fine. Aluminum screws should not be used in mounting the transmission to the chassis.

   • Team Losi part A-9932 is a hard coated aluminum top shaft and gear. The shaft I bought was slightly larger than the standard steel shaft. My Hydra-Drive wouldn't fit the larger shaft without opening up the hole using a tiny file. Grumble.

   • Team Losi part A-9920 is a machined lightweight motor plate. The machined surfaces aren't exposed when the motor and gear cover are in place. But my lightweight motor plate has become dented in the thinned places where the rear end makes contact when landing off jumps. I'm concerned about the durability of the machined plate but it hasn't developed any holes yet.

6. Shocks

Symptoms of wear

• The shock oil becomes contaminated, mostly with dirt but also with particles that wear off of the shock piston and body. (Shock body wear contributed a lot to oil contamination in the days of anodized aluminum shock bodies, but is not much of an issue with modern hard-coated shocks.) The contamination makes the oil thicker.

• The amount of oil inside the shock decreases as oil leaks past the seals. The lost oil is replaced with air. As the shock works, the air inside the shock mixes with the oil, creating an emulsion containing tiny air bubbles. In effect the air thins out the oil.

• The shock seals get dirty. The dirt can increase friction and cause scratching of the shock shaft. The shock seals also wear, allowing more oil to leak past the seals.

• If not much oil leaks out and a lot of dirt gets in, or the seals get gritty, the damping rate of your shocks will increase. The extra damping can make the front of your truck lose traction on small bumps. Extra damping can also make your truck's handling more sensitive to steering inputs ("twitchy.")

• If a litle oil leaks out, the damping rate of your shocks will decrease. The decreased damping may cause your truck to square off rather than entering turns smoothly, and your truck may lose steering when exiting turns.

• If a lot of oil leaks out, your shocks' action becomes inconsistent. This is something you can feel by pumping the shocks several times. If they don't smooth out, then your truck's handling on the track is going to be inconsistent.

If your shocks are low on oil, don't just top them up. At least dump out the oil, clean the inside of the shock body with motor spray, and refill the shock. If that much oil has leaked out in a short amount of time, you need new shock seals.

Improvements

1. Shock seals make shock damping non-uniform: Damping is greater when the shock shaft is at rest than when the shock shaft is moving. Reducing the starting friction or "stiction" between the seals and shaft improves the handling of your truck. You can reduce stiction by lubricating the shock seals with a Teflon grease such as RC Performance Specialties Green Slime (RCPS part number 060.) The same grease is available in larger quantities from motorcycle supply shops.

2. If your shock cartridges are already assembled you have to take them apart in order to grease them properly. Use an X-Acto blade to get started, then use your fingernail to carefully pry the cap from the shock cartridge. If you damage the cap you'll have to glue it back on later, and you'll never be able to disassemble the cartridge again. Remove the o-rings and spacer with a blunt toothpick.

   Coat the o-rings completely with grease, and use the toothpick to put some grease in the hole in the spacer. Carefully insert one o-ring, the spacer, and the other o-ring back into the cartridge body. Clean any grease from the groove in the cartridge body and press the cap back on.

   Greasing your cartridges in this way makes them last longer, so the extra step saves effort in the long run while making your truck handle better.

3. You can significantly improve your shocks by installing hard-coated shock shafts (A-5061 front, A-5062 rear.) The hard coating of gold-colored titanium nitride results in a shaft that is very scratch-resistant. Scratched shafts wear out shock seals much more quickly than smooth shafts.

   Standard shock shafts need to be smoothed out periodically with emery cloth, and need to be replaced as they wear. Hard shafts rarely need to be smoothed and wear more slowly. They definitely save time and probably save money, too.

4. Team Losi recommends that when your shock seals wear out you replace the cartridges. That's $8 for four cartridges versus $2.50 to buy just the seals from MIP, so it is tempting to rebuild the cartridges a couple of times before throwing them out. I've been doing this for years and it works for me.

5. RPM sells ride-height adjusters for Losi shocks. With this setup you adjust ride height by adding or removing clip-on spacers rather than by moving the shock spring clamp.

   I really like the RPM ride-height adjusters. With them it is easy to try out an adjustment and then undo it if you don't like it. And you never have a problem getting equal preload on the left and right shocks.

   The thinnest RPM spacer is about 1/16 inch thick. For making finer adjustments I've made some thinner spacers from Lexan sheet. These are rarely needed.

   In using the RPM adjusters I like to epoxy the shock clamps to the shocks. That way they are less likely to move around.

6. The upper shock mount bushing (A-5008) has a tendency to loosen with use. A lot of bad things can happen when it loosens, like inconsistent handling, a bent upper shock mount screw, even a broken shock tower.

   This problem is easy to prevent. Attach the upper shock mount screw to the shock tower with a 4-40 locknut (A-6305.) This nut won't loosen. Then trim the shock tower end of the upper shock mount bushing by an amount equal to the thickness of the 4-40 locknut. Install the bushing and you're done.

7. I don't know about you, but my 1/4 inch nut driver doesn't work for installing the 4-40 nut that keeps the top of a front shock from falling off of the upper shock mount. The nut driver runs into the shock body.

   I fixed this by taking a 4-40 nylon nut (A-6301) and carving the top of it to match the dimensions of a 4-40 mini locknut (A-6306.) This is pretty easy to do by threading both nuts onto a 4-40 screw, so you can use the mini nut as a template. A sharp X-Acto blade makes short work of this little job.

   When you are done you can use a 3/16 inch nut driver, which should clear the shock easily.

8. If you buy an aluminum screw kit for your truck, don't try using aluminum screws for mounting the tops or bottoms of your shocks. The screws will bend. Aluminum screws are fine for the shock clamps.

9. Go to a good hardware store and buy yourself drill bits in sizes #55 and #56. You'll need them for making up odd-sized shock pistons.

7. Suspension

Symptoms of wear

The suspension usually deteriorates slowly, so there is little maintenance to perform. Sometimes a joint will get some dirt into it and start squeaking or tighten up; a cleaning of that joint is all that's needed. The pivot pins clean up well using a Scotch Brite pad; a pipe cleaner makes a handy tool for cleaning the holes in suspension parts.

Nothing is immune to wear. You might think that in a ball joint, only the plastic ball cup would wear, but the steel ball wears, too.

Improvements

1. The stock turnbuckles are, frankly, a joke. They bend quite easily. Lunsford's "Punisher" titanium turnbuckles are the standard replacements. You'll need these sizes:

       front camber link (with kingpin ball)    2 3/4"
                         (with stock ball stud) 2 5/8"
       rear camber link  2 5/8"
       tie rods          2 1/4"

   Even these turnbuckles will bend (the camber links are most vulnerable), but if that happens you mail the bent one to Lunsford and Lunsford mails you a new one. You might want to keep a spare.

2. The ball studs that screw into the rear bulkhead sometimes work-harden from the constant flexing they undergo in fast cornering. Then they snap off. To keep the stud from flexing, put a large flat number 4 washer over the stud before screwing it in place.

3. The kingpin ball (A-9708) changes the front suspension geometry, making the camber link longer. The truck's handling entering turns becomes more controllable. When installing this upgrade, remember to use threadlock on the set screw that secures the kingpin to the front axle.

4. Team Losi part A-9941 is a bearing spacer and rear axle washer set. The bearing spacers allow you to tighten the front and rear wheel axle nuts without the danger of damaging the wheel bearings by over-tightening. The axle washer presents a larger surface to the rear wheel than the stock spacer and, working with the rear bearing spacer, helps the rear wheels run with less wobble.

   A&L offered these spacers and washers long before Team Losi did. The A&L spacer and washer set (A&L part number 9612) goes Losi one better by including a pair of aluminum front wheel locknuts that are machined so they contact only the inner bearing race. So you can crank these nuts down without adding any friction to the front wheel rotation. For this reason I bought the A&L set, which has worked as advertised for me.

   When you run aluminum nuts on the aluminum front axles you must lubricate the threads to avoid seizing.

5. A simple maintenance-reducing upgrade is to install a set of Teflon shields (A-6918) on all eight of your wheel bearings. (A single A-6918 includes enough seals to upgrade eight bearings.) These shields save money in the long run because they make your bearings last longer.

6. There are a couple ways to improve some of your ball joints. These tricks apply only to ball joints where the ball stud remains more-or-less at right angles to the ball cup throughout the range of motion. Examples include the rear camber link, the inner end of the front camber link, the steering drag link, and the steering servo link.

   All of these joints can be greased and sealed. Put a small amount of grease into the ball cup before assembling the joint. If the joint ends up tight, you've put in too much grease; pop the joint open and try again. Use a "Foam Thing" (A-6003, or make your own) to keep dirt from entering the greased joint. Greasing the joints makes them last longer.

   You can take almost all the slop out of these joints by installing a rubber o-ring over the ball before installing the "Foam Thing" and assembling the joint. The o-ring keeps the ball cup pressed against the ball. A worn shock seal o-ring works perfectly. The joint should still work freely after you've added the o-ring; if not, remove the o-ring.

7. You can remove the end play that develops in pinned suspension joints by shimming these joints with motor shims. Don't go too far; the joint must still move freely after you've shimmed it.

8. You can drop some weight from your truck by installing titanium hinge pins in place of the stock steel pins. Titanium pins are available from Lunsford and RC Performance Specialties. Titanium pins are affected more by dirt than steel pins, so you may have to clean them more often.

8. Chassis

Symptoms of wear

Maintenance

1. Take apart the servo-saver and clean the surfaces that make contact when the servo-saver flexes. If the steering bushings have developed a lot of slop, replace them. You might as well replace all the plastic steering parts at the same time (A-1602.)

Improvements

1. Before mounting the ESC or receiver with double-sided tape, rough up the chassis with sandpaper at the mounting location. Do the same to the bottom of the part you are mounting. Clean off any sanding dust, then use the tape. The tape will hold much better this way.

2. A fast servo improves your ability to react quickly to driving situations. And a high-torque servo keeps the front wheels pointed where you want them, even under high cornering loads. An expensive servo is overkill when you are starting out, but as your skills improve a fast, high-torque servo will help you.

   I've been running the KO PS-1001 FET servo for several years now. Its performance has been excellent. It has plastic gears, and the gears have needed replacing once.

   The Airtronics 94157 servo seems to represent today's state of the art: aluminum gears, high speed, and high torque. I don't have any personal experience with this servo, but the earlier 94155 model had a good reputation.

3. I run a Tekin G12c speed control, which is very smooth driving and runs cool with no heat sinks.

   The power switch on a Tekin speed control has ears that allow screw mounting, which I really like. I mount the speed control in the usual location on the left side of the chassis, and screw the switch onto the vertical part of the chassis below the servo brace. The switch stays pretty clean here and is easy to reach.

   With the speed control mounted in the usual location, the wire harness to the receiver must pass beneath the battery. I put down a 1/4" wide strip of servo tape, press the wires onto the tape, then cover with duct tape. This works fine but trying out different battery locations is a pain. Nothing's perfect.

4. Team Losi part A-6912 is a set of tiny ball bearings for the steering. With ball bearings you can reduce the steering slop a little. An improvement, but at $20 this is a luxury item in my book.

5. Team Losi recommends against threading aluminum screws into the chassis proper. I see two places where it is OK to violate this recommendation: the screws that hold down the steering brace and the screws that hold down the rear end of the servo brace. These screws are very lightly stressed. Always install a steel screw first, then remove it, before installing an aluminum screw.

9. Tires

Symptoms of wear

As tires age the rubber loses some of its stickiness, so traction may go down while the tires sit on the shelf.

Improvements

1. Traction compounds for off-road tires are now popular. The effectiveness of these compounds depends upon the tire and the dirt. In some cases tire compound gives significant increases in traction, in others the compound reduces traction and makes tires wear out faster! You'll have to work this out for yourself.

2. Manage your rear tires. Don't wear one set bald, then buy a new set. Keep two or three sets in use. Use the oldest, most worn set for practice. Use a good set for most qualifiers. Use your best set for the main event, and for an occasional qualifier when it will do the most good (track is fast, you have a good starting position.) When the "good" set is no longer good, shift it down to practice, shift your good set down to qualifying, and buy a new set for the mains.