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Tamiya Vajra - #58497 (Radio Controlled Model)

1/10 Scale Electric Truck - AV Chassis:

  Released by Tamiya on September 14, 2011, the Vajra racing truck seems to be one of those models that divides opinion amongst Tamiya enthusiasts. Some love it, others say it is an expensive oddity that does not deliver anything like its perceived potential.

Tamiya Vajra - #58497 - 1:10 Electric RC Racing Truck

  The 4WD, shaft driven, double deck chassis for the Vajra, was based on the Avante 2011 Chassis (#58489), with a 15mm longer wheelbase, made from 2mm carbon fibre and provides a durable, rigid structure that employs two pressure plate ball differentials, four wheel double wishbone suspension and coil spring over oil filled shock absorbers. A full set of 26 steel shielded ball bearings, CVD drive shafts, GT-Tuned 25T brushed motor and V-pattern block tires with 5 spoke chromed wheels are also included in the kit. Radio equipment, battery, charger and paint for the body shell are required to complete.

  Constructing the Varja was not as easy as it might have been. Nimble fingers were needed for the small thrust bearings and although the supplied manual was simple to follow, with its diagrams and step by step instructions, care is required to put the right part in the right place.

  To get the best from the Vajra, it needs to be fine tuned to handle jumps under control and has enough grip to hug the corners at high speed, without slipping off the track. Small adjustments can make a Big difference and our simple to understand, step by step procedure, will guide you to the best Set-up for your driving style.


      Rating: 3.53.5 Stars out of 5 Reviewed by: RCScrapyard     Manual.





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Tamiya Vajra #58497 - Chassis
Tamiya Vajra #58497 Chassis
Tamiya Vajra #58497
Tamiya Vajra #58497 Body Shell

Buying a Used Tamiya Vajra
Truck (and What to look for)


   Buying a used Tamiya Vajra Electric Truck, or any used RC Model, has a number of advantages. It is generally cheaper than new, ready built and may come with a variety of expensive hop-ups already installed. Cheap, pre-loved bargains are always becoming available. However, depending on the age of your purchase, it may need a little tender loving care before you can take it out on the back yard.

   The one thing you will always need is an instruction manual. If not supplied with your purchase, they can often be downloaded from the Tamiya website, or purchased separately on eBay. With an instruction manual, any problems with your model Truck you may discover can easily be fixed.

Dampers
   When you receive your used Tamiya Truck, make a general visual inspection of the chassis, front and rear wishbones, suspension shock towers etc, for any broken parts that may need to be replaced. Then, take a screwdriver and box spanner and check each self tapping screw and nut for security, taking care not to over tighten.

   Next, for those Tamiya models with oil filled shock absorbers, remove them from the chassis and dismantle the coil springs. The damper shafts should push in and pull out with a smooth action. If you feel a jolt as you change direction, this means the oil has leaked out and must be topped up. At the same time, change the O-Ring seals to prevent more leakage. Also check the damper shafts for damage. If they are scratched, change them as soon as possible.

   If the body shell of your Tamiya Vajra is broken, ripped or damaged in any way, this can be easily repaired with rubber solution glue. Also, for added protection and if available for your Vajra model, fit an under guard to stop dirt and gravel entering the chassis.

Titanium Turnbuckles
   Examine the drive shafts for wear and replace as required. If possible, change them for titanium. The steel shafts wear and bend too easily.

   If you intend to race your Vajra Truck model at a competitive level, I would also recommend you obtain and fit titanium pivot shafts, turnbuckles, tie rods and steering rods.

   On Belt driven models, the Drive Belts need checking at regular intervals for wear, tension and damage. If deemed necessary, adjust the tensioning pulley until the belt can be depressed in the centre by no more than around 5mm. If the belt was slack, also examine the drive pulleys for wear. The teeth should provide a well seated fit for the belt teeth and not be rounded on the corners. If the belt teeth do not fit snugly, change the pulleys as soon as possible. For top level racing it may be prudent to replace all belts and pulleys after each race meeting.

   For Gear driven models, the gearbox of your used Truck should be opened up to check for gear wear and lubrication. A thin coat of grease is often used on internal gears and although this is fine for basic running around on the back yard, if you intend to race your Truck at a higher level, this should be removed and replaced with racing oil (ZX1 or Teflon Oil). Of course, this should be reapplied after each race meeting.

Spur Gears
   Gears are a weakness on all Truck RC models. Head on collisions can easily damage the gear teeth on nylon and plastic spur gears. Heavy impacts can also loosen the nuts or self tapping screws that hold the Electric Motor in Position, allowing the pinion gear to pull out of mesh slightly and rip the tops off the teeth on your spur gear. To minimise this possibility, fit bolts with locking nuts to the Electric Motor mount and remember to check them for security after every two or three runs.

   Ball joints always cause problems. For top level Electric Truck racing, the plastic ball connectors should be checked and if deemed necessary, changed after every meeting. A simple thing like a loose fitting connector popping off, could easily end your race, so better safe than sorry.

Servo Gears
   The Vajra steering servo is also prone to damage. In high speed crash situations, the fragile gear teeth of the servo can be broken off, rendering your expensive servo useless, so be sure to obtain a good quality "Servo Saver". Check out my Servo Information article.

   If body roll on your Tamiya Vajra is a problem, handling can be improved with the use of stabilizers, anti roll or sway bars, stiffer tuning springs and, or, thicker silicone oil in the dampers.

Ball Bearings
   If your used Tamiya Truck comes with plastic and sintered brass bushings (ring type bearings), check the shafts that run in them for wear. Dust and grit can get into these bearings and abrade the shafts. Therefore, you should replace them all with shielded ball bearings. If the model has been run with ring type bearings, you may have to change all the axles and driveshafts. For more information, take a look at my article, How to get the best from your Bearings.

   Finally, good luck with your Vajra model and good racing.


For More on how to Setup your Truck, check out my Hints and Tips page.














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Hints and Tips

Tires for RC Models

Rubber Tires:

   Rubber Tires ALWAYS should have either soft sponge or rubber inserts. They will not function as they should without them. And if you are totally serious about your racing they should be glued to the rims.

   You should also have at least three different compounds (Soft, Medium and Hard) for varying track temperatures in On Road tarmac racing Touring cars and varying pin sizes for carpet and Off Road racing Buggys and Trucks.


How to Mount Rubber Tires onto Wheels/Rims.

   Before mounting your Tires, I would recommend talking to the more experienced racers at your local club, as to what inserts they use. Even the top level racers rely on a bit of local knowledge on tracks they have never raced before.

1/   Once you have decided what inserts to use, position them inside the Tires ready to go onto the rims.

2/   You will need strong fingers to pull and maneuver the Tires over the rims, so you may need the help of an adult. I would recommend NOT using metal Tire levers or a spoon as they can not only damage the fragile plastic rims but can also put small tears in the rubber, that could cause problems later.
   The technique I recommend, is to first of all hook the Tire on one side of the rim, then using the thumb and forefinger, grip the Tire and pull it upwards and over into position around the middle of the wheel, then over to its final position on the far side so that the beading is seated in the spigot. then position the near side beading in the opposite spigot making sure the sponge (or rubber) insert is not trapped and positioned centrally.

3/   You have the option of either gluing or not gluing your tires in position. If the track you race at is not too grippy you can get away with it, but on high grip tracks there is the possibility the tire might pull away from the rim and ruin your race.
My recommendation is to glue them.
   Superglue is the thing to use. To do this, carefully pull the beading out of its seating, put on a spot of glue, then quickly push it back down. repeat this at least 6 times around each side of the wheel.
Superglue can be dangerous, so this is best done by an adult.

For More Setup Information check out my Hints and Tips page.



Hints and Tips


Electric Motors for RC Models

Brushless Motor Basics

   Choosing the right Brushless motor for your needs can be a daunting task for those new to Radio Controlled Models. If you have a local club perhaps you could ask some of the more experienced members for their advice, but a little basic knowledge about the subject, so you know what questions to ask is always useful.

   All Brushless motors are rated by Kilovolts (KV) and is an indication of the revs per minute (RPM) that particular Motor can attain running freely, under no load conditions, per Volt of input.

   For Example: To calculate the Maximum RPM of a Motor listed at 4000 KV, connected to a 7.4 Volt Battery, simply multiply the two: 4000 x 7.4 = 29600 RPM.

   The two main types of Brushless Motors used in RC are Sensored and a Sensorless Motors.
   Sensored Motors can be connected directly using s cable, to the Electronic Speed Controller (ESC). The ESC is then able to monitor the performance of the Motor and regulate Current output, to attain smooth, controlled acceleration. Advance and Retard timing is made automatically by the ERSC to change torque when exiting corners and give you more RPM for long straights.

   Sensorless Motors can only be set manually for Advance and Retard timing and once that setting is made you have to stick with it. For obvious reasons, Sensorless motors are cheaper to buy than the Sensored type: Ideal if you just want to bash around in the back yard, but not so much if you are serious about your racing.

   Brushless Motors, need a reasonable amount of maintenance if they are to remain competitive. For top level racing I recommend you strip, clean and re-oil the bearings every 2 or 3 meetings (Check out our "get the best from your bearings" section).
   Gearing your motor correctly for any given track is always important. (Check out my Gearing tips on the Pinions Section of this site) A cool motor is an efficient motor. As your motor heats up towards the end of a race, it will loose efficiency. Gearing correctly can avoid this problem to some degree and simply following my simple guidelines, described in the aforementioned article can help you not only keep your motor running efficiently, but help you stay in front of your opposition.

   One last tip .. When re-building your Brushless Motor, to safely replace the Rotor, use a rolled up piece of paper and place it into the Can. This will protect your rotor against damage. Then carefully remove the paper before replacing the endbell.

For More Setup Information check out my Hints and Tips page.









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