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RCScrapyard Radio Controlled Models
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1/10 Scale Electric Buggy:

Academy Mercury Xi-4 (Radio Controlled Model Review)


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History + Information (and How To Set-up Tips):


  Introduced circa 1986, the 4WD Mercury Xi-4 Buggy was originally produced by "World Engines" and subsequently distributed by Academy, Graupner, Ryuz and Mugen and came with a Mabuchi 540 motor.

  The model is belt driven, on a four piece molded plastic chassis, with gear type differentials, coil spring over oil filled dampers, plastic telescopic universal joint drive-shafts, bushings and some ball bearings.

Academy Mercury Xi-4
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  To race the Academy Mercury Xi-4, it requires a high level of tuning for improved stability when cornering, to keep it on the track and give you more grip under acceleration. Even the smallest change in your cars settings can make a Big difference. Our simple to follow instruction chart will show how to attain the best Set-up for your personal requirements.

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★ Academy Mercury Xi-4 Chassis ★
Academy Mercury Xi-4 Chassis

★ Academy Mercury Xi-4 Chassis ★
Academy Mercury Xi-4 Chassis

★ Academy Mercury Xi-4 Chassis ★
Academy Mercury Xi-4 Chassis

★ Ryuz Mercury Xi-4 Chassis ★
Ryuz Mercury Xi-4 Chassis


Buying a Used Academy Mercury Xi-4
Buggy (and What to look for)


   Buying a used Academy Mercury Xi-4 Electric Buggy, 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 Academy website, or purchased separately on eBay. With an instruction manual, any problems with your model Buggy you may discover, can easily be fixed.

Dampers
   When you receive your used Academy Buggy, 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 Academy 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 Academy Mercury Xi-4 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 Mercury Xi-4 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 Mercury Xi-4 Buggy model at a competitive level, I would also recommend you obtain and fit titanium pivot shafts, turnbuckles, tie rods and steering rods.

   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.

Spur Gears
   Gears are a weakness on all Buggy 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 Buggy 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 Mercury Xi-4 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 Academy Mercury Xi-4 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 Academy Buggy 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 Mercury Xi-4 model and good racing.


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Or, check out our RC Model Car Setup Guide


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Manufacturers and Brands Catalogued and Listed by RC-Scrapyard.


   At present, the RC Model Manufacturers, Brands and Distributors covered by us are: ABC Hobby, Academy, Acme Racing, Agama Racing, Amewi, Ansmann Racing, ARRMA, Team Associated, Atomic RC, Axial, AYK, Bolink, BSD Racing, Capricorn, Carisma, Carson, Caster Racing, Cen, Corally, Custom Works, Durango, Duratrax, ECX - Electrix, Exceed RC, FG Modellsport, FS-Racing, FTX, Fujimi, Gmade, GS-Racing, Harm, HBX, Helion, Heng Long, Himoto Racing, Hirobo, Hitari, Hobao, Hong-Nor, Hot Bodies, HPI, HSP, Intech, Integy, Jamara, JQ Products, Kawada, Kyosho, Losi, LRP, Maisto, Mardave, Marui, Maverick, MCD Racing, Megatech, Mugen, New Bright, Nichimo, Nikko, Nkok, Ofna, Pro-Pulse, Protech, PTI, RC4WD, Redcat Racing, RJ-Speed, Robitronic, Schumacher, Seben, Serpent, Smartech, Sportwerks, Step-Up, Tamiya, Team-C Racing, Team Magic, Thunder Tiger, Tomy, Top Racing, Traxxas, Trinity, Tyco, Vaterra RC, Venom, VRX Racing, WLToys, X-Factory, Xmods, Xpress, Xray, XTM, Yankee RC, Yokomo, ZD Racing and Zipzaps.

   This is an ongoing project, with new and "lost in time" RC Model Brands being added as they are found and although most of those listed above have been covered in relative detail, some are still being researched and will be completed in the near future.


















Hints and Tips


How to Charge Rechargeable Batteries
for Radio Controlled Models

Ni-Cad (Nickel Cadmium) Batteries


1/  All Ni-Cad Batteries have to be Discharged soon after use. This is to avoid the dreaded "Memory" effect that on subsequent re-charges can cause a momentary drop in performance during a race. A simple discharger can be made from a car 12v bulb.

2/  Try to time your charge to complete just before a race. This will ensure maximum punch and duration. If a Ni-Cad is left to cool after a charge this advantage dissipates.

3/  The higher the charge current the more Punch the Ni-Cad battery will have (up to around 8 amps), however, the downside to this is a reduction in duration and effective battery life.

4/  Ni-Cad Batteries should be left to cool for about an hour after use before recharging. This will increase the effective life of the battery.


Ni-Mh (Nickel Metal Hydride) Batteries


1/  Never charge Ni-Mh batteries at a current higher than 4.5 amps. Although these batteries can give a higher voltage than Ni-Cad Batteries, they are much more sensitive and easy to damage if charged too quickly.

2/  Charging methods for Ni-Mh batteries can also be detrimental. The best I found was the "Slope" method. Avoid "Pulse" charging as this tends to effect crystal formation detrimentally and (it seems to kill them off) thus reduces duration over time.

3/  If using a temperature cut off charger on Ni-Mh batteries set to no more than 40 Degrees Centigrade. Any higher than this can damage the crystals.

4/  It is not necessary to discharge Ni-Mh Batteries. Unlike Ni-Cad batteries they do not develop a memory. Also, if they are totally discharged they sometimes will not charge straight after and need to be coaxed with a 10 minute trickle charge.

5/  Ni Mh Batteries can be recharged shortly after use without any discernable detrimental effects.


Li-Po (Lithium-Polymer) Batteries


1/  Li-Po batteries are a huge step forward in performance compared with Ni-Cad and Ni-Mh batteries. However, care has to be taken when charging. If certain procedures are not followed they could burst into flames or even explode, therefore I do not recommend Li-Po batteries for RC beginners.

2/  Li-Po batteries are more expensive and have a shorter effective life. Generally considered to be between 200 to 400 charge cycles compared to 1000+ for Ni-Cad and Ni-Mh.

3/  Consider a Battery pack listed as "2S 5000Mah 40c 2C".
"2S" is the number of cells in the pack, in this case 2 cells. Each cell provides around 3.7 Volts, so a 2S pack is around 7.4 Volts.
"5000Mah" (Mili-Amp-Hours) is the capacity. The amount of charge the pack can hold.
"40c" is the maximum Discharge rate. Which in our example would be calculated as 5000 (Mah) x 40 = 200000Ma (200 Amps).
"2C" is the maximum Charge rate. 1C being 5 Amps, so in our example 2 x 5 = 10 Amps.

4/  To safely charge your Li-Po Battery I would recommend a good Computerised charger, preferably one that can handle a Charge current of around 25A and always place the charging battery on a fireproof surface.

5/  Finally. NEVER leave your charging Li-Po battery unattended and NEVER EVER charge it above the recommended rate. When not in use, store with around 60% charge remaining in a fireproof box.


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







Hints and Tips

Ride Height

   To allow the suspension on any RC model to do its work properly, it needs to ride in a position where it is able to react to any bumps and holes it may encounter on the track. Therefore, it needs to be adjusted to somewhere in-between those limits. That position is commonly termed "ground clearance" or "ride height" and is generally measured as the distance between the underside of the chassis and the ground, with the motor and battery etc installed.

   Simply speaking, determining the optimum ride height is dependent on the specific track conditions and "droop" setting (see my previous article). For Off Road models the rule is simple, the bigger the bumps and the deeper the holes, the higher the ride height. And for On Road, the lower the ride height, the better.

   For 1:10 Buggys I generally recommend a starting point for ride height at around 3/4 of an inch or 20mm. 1:10 Trucks and Truggys,1 1/4 inches or 30mm upwards, depending on the wheel diameter. For On Road models, somewhere around a 3/8 of an inch, or 5mm.

   Ride height doesn't just affect the way the car handles uneven track conditions, it also influences the way the car handles when cornering. For a stable car, body roll must be kept to a minimum and keeping the ride height low, is by far the best and easiest way to control it.

   Before you begin to set the ride height, it is best to make sure that each pair of shocks are exactly the same length, have the same spring type and same silicone oil weight. Also, if you don't have a ride height gauge of any kind, decide what height you want set your car to and prepare some kind of slip gauge to that dimension, a book, a pen, or anything that measures to what you want. I used an old square plastic servo mount, which was exactly 5mm for my touring car. It may be low tech, but it is just as accurate as any gauge you can buy.

   To set the ride height, the race ready car must be placed on a flat surface. Slide your slip gauge under the chassis and adjust the height by adding or removing tension to the damper springs. This is done on most models by using small C shaped clips, placed over the damper, above the springs, or via clamp type collars. On a number of top of the range models, this adjustment can be made by screwing a knurled nut on each threaded damper body. As a rule if the springs are compressed by more than 25% they should be replaced by stiffer springs. The gauge should just slide under the chassis on all four corners of the chassis.

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










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