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1/10 Scale Electric Buggy:

Yokomo MR4-BX (Radio Controlled Model)


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History, Info (and How To Set-up Tips) for the Yokomo MR4-BX:


  Introduced by Team Yokomo circa 2006, the 4WD MR4BX Buggy - # MR4-BX - has the motor positioned more centrally, towards the front of the chassis and was described as being "designed to be the best in the world".

  The model was belt driven, on a double deck chassis, with ball differentials, coil spring over oil filled dampers, universal joint drive-shafts and ball bearings.

  An MR4BX Factory kit and later an MR4BX World Spec version were released soon after, with a revised layout for improved balance.

Yokomo MR4-BX
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  To race the Yokomo MR4-BX, it calls for fine tuning to attain better steering response and improve grip when cornering so you don't slide off the side of the track. Minute changes can make huge advancements. Our easy to understand list will show you how and lead you to the optimum Set-up to put you in front of the rest on the track.

  We give you all the basic information you need to guide you to the best Electric Motor for your MR4-BX and achieve the best Gearing, to get you in front on the track and keep you there.

  Find out how the worlds top professional RC racers get improved efficiency from their Bearings employing a number of sensible ideas. Find the way to avoid Radio interference, and basic instruction on how to Charge your Batteries, so they will last longer and provide improved power.









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★ Yokomo MR4BX ★
Yokomo MR4BX

★ Yokomo MR4BX Chassis ★
Yokomo MR4BX Chassis

★ Yokomo MR4BX Chassis ★
Yokomo MR4BX Chassis

★ Yokomo MR4BX Chassis ★
Yokomo MR4BX Chassis

★ Yokomo MR4BX World Spec Chassis ★
Yokomo MR4BX World Spec Chassis


Buying a Used Yokomo MR4-BX Buggy (and What to look for)


   Buying a used Yokomo MR4-BX 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 Yokomo 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 Yokomo 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 Yokomo 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 Yokomo MR4-BX 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 MR4-BX 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 MR4-BX 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 MR4-BX 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 Yokomo MR4-BX 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 Yokomo 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 MR4-BX model and good racing.


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


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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

Sway Bars

   On most forms of RC model cars, Sway Bars, also referred to as Stabilizers, Torsion Bars, or more commonly in some parts as Anti Roll Bars, are often nothing more than a short length of spring steel, clamped to the chassis or sometimes the gearbox of the car, extending out to the lower wishbones direct or connected to the wishbones using short adjustable or fixed length links and ball joints, depending on their position.

   The principal behind the Sway Bar is simple. As the car enters a corner, weight is transferred to the outside wheels, the chassis rolls due to inertia and the suspension dips and grip on the inside wheels is reduced. In an effort to counter this dipping effect and transfer some grip back to the inside wheels to improve traction as you exit the corner, the sway bars transfer the dip of the outside, to pull down the inside wishbones, improving grip on the outside wheels and improving overall stability.

   Sounds complicated I know, but for some tracks sway bars can be a useful tool when you have exhausted all other options to correct your handling problems.

   Tuning your Sway Bars is quite easy. Some manufacturers do offer colour coded tuning sets with varying thicknesses of spring steel wire, but the best way is to change the position the bar is attached to the wishbone, or on some variations you have the option of positioning the link on the Sway Bar itself. By simply moving a small collet clamped along the short length of the bar. Closer to the central pivot point reduces the leverage of the bar and effectively increasing its resistance, further away from the pivot point reducing resistance. More fine tuning can be achieved by adjusting the length of the turnbuckle link (if available) to pre load the bar.

   Personally, before I ever installed any sway bars I would always try changing damper tuning springs and oil viscosity settings, especially if the track was uneven and bumpy, in which case the effectiveness of the bars was minimal if at all.

   For those more into Drifting, Sway Bars can be an easy way to fine tune your car. A single turn on the turnbuckle links can be a way to simply increase or decrease wheel traction that minute amount you need to get the perfect balance.

   For more on how to use Sway Bars check out our Set-up tips page linked below.

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







Hints and Tips


Rechargeable Batteries
for RC Models


   At the time this article was written, there are four types of Rechargeable Batteries that are commonly in use for Radio Controlled Models.
Ni-Cad (Nickel Cadmium) Batteries have been around the longest. My first stick battery, purchased way back in 1987 was rated at 1200Mah (Mili Amp Hours) and with a silver can 27 Turn motor my Tamiya Boomerang would run around in the back yard for a good seven minutes before slowly coming to a stop. Ni-Cad development continued until around 1998 to a maximum rating of around 2000Mah and matchers pack builders and battery technicians were able to put together six cell packs with voltages approaching 7.4 Volts, to give those that could afford them, an edge over the rest.

   Ni-Mh (Nickel Metal Hydride) Batteries came along in the late 1990s and by the year 2000 were available at ratings up to 3000Mah. Again, matchers and pack builders worked hard to provide the ardent racer with packs to provide that little bit of extra power and ESC manufacturers also chipped in with improved controllers to take full advantage of this new technology.
   Now the problem wasn't gearing the car to get to the end of the race using the available battery power, but to find the brushed motor that could handle gear setting that provided the speed and acceleration without the motor overheating and wearing the commutator too much so it needed a skim after every 2 runs. My favourite at that time was the 9 Double.

   More recently, Li-Po (Lithium-Polymer) Batteries have appeared on the scene, providing are a huge step forward in performance when compared with Ni-Cad and Ni-Mh batteries. However, Li-Po Batteries are much more expensive than previous battery types, have a shorter effective life of between 200 and 400 charge cycles, compared to well over 1000 charge cycles for Ni-Cad and Ni-Mh and a high degree of care has to be taken when charging Li-Po batteries. They have been known to burst into flames or even explode, for this reason I do not recommend Li-Po batteries for RC beginners.
   Another problem with Li-Po packs is they are physically bigger in size, so for those with older "Vintage" models, they may not fit into the provided space for the battery on the chassis.

   The latest development in battery technology for RC are Li-Ion. Originally produced for Laptops, Ipods, Tablets and the like, they are now available for RC models. Much like Li-Po for price and charge cycle life, the power and capacity is a moderate improvement, but for me, at the moment, not worth the expense.

   One final word of warning. NEVER leave your charging Li-Po or Li-Ion battery unattended when being charged and NEVER above the recommended charge rate. After use, store each battery with about 60% charge remaining and always in a fireproof bag.


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









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