1/10 Scale Electric Rally/Touring Car:

Yokomo MR-4TC Pro - Radio Controlled Model

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History and Info:

   Introduced by Team Yokomo circa 1998, the 4WD MR-4TC Pro Touring Car - MR4TCPRO - was originally developed for the US market with a number of team spec parts as standard.

   The Pro model is belt driven, on a molded plastic chassis, with new top deck, ball differentials, coil spring over oil filled dampers, universal joint drive-shafts and a full set of ball bearings.

   A replica version MR-4TC Worlds Edition - MR4TCW - that was based on the MR-4TC Pro, was released in 2000 to celebrate their World Championship win, driven by Atsushi Hara, at the Yatabe Arena in Japan.

Yokomo MR4TC Pro

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To race the Yokomo MR4TC Pro, 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.

Yokomo MR-4TC
Instruction Manual

Yokomo MR-4TC
Parts Lists

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Radio Controlled Model Accessories:

★ Yokomo MR4TC Pro Worlds Edition ★

★ Yokomo MR4TC Pro Chassis ★

Buying a Used Yokomo MR4TC
Touring Car (and What to look for)

There are essentially three reasons you might want to buy a used Yokomo MR4TC Electric Touring Car; you may be a collector, looking to restore and display it; restore and sell for a profit; or simply restore and race an iconic vintage model. Personally, I used to get a buzz out of restoring an old clapped-out model, installing modern day electrics and maybe a few hop-ups, then showing the gang at our local club, just how competitive those old models could still be.

Cheap, pre-loved bargain models, parts and spares are always coming up for sale, but once you have made your purchase, 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 Touring Car you may discover, can easily be fixed.

Make a General Visual Inspection

Dampers
When you receive your used Yokomo Touring Car, 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.

Check the Body-Shell

If the body shell of your Yokomo MR4TC 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 MR4TC model, fit an under guard to stop dirt and gravel entering the chassis.

Drive Shafts and Turnbuckles

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 MR4TC Touring Car model at a competitive level, I would also recommend you obtain and fit titanium pivot shafts, turnbuckles, tie rods and steering rods.

Examine the Drive System

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.

Pinions and Spur Gears

Gears are a weakness on all Touring Car 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.

Don't Neglect the Ball-Joints

Ball joints always cause problems. For top level Electric Touring Car 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.

Steering Servo and Servo-Saver

Servo Gears
The MR4TC 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.

Stabilizers

If body roll on your Yokomo MR4TC 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.

Don't Forget those Bearings

If your used Yokomo Touring Car 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 MR4TC model and good racing.

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Manufacturers and Brands Catalogued, Listed and Reviewed 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 Models and 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.

RC Information and Advice:

Hints, Tips and Information

Driving On Road

   The basic driving style most commonly used for all forms of on road, tarmac and carpet racing, involves using the full width of the road available, and cutting each apex as tight as possible, whilst keeping complete control of the car on the track. The style, often referred to as "Rounding" looks quite simple to those watching, but to get it right needs good hand eye coordination and lots of practice.

   Consider a 180 degree turn. As you enter the corner, start with the car positioned close to the outside of the track, then as you approach the corner brake hard, but not too hard, just enough to slow the car so you maintain control and smoothly guide the car across the point of the apex, gently sweeping round until you are approximately 75% around the corner. At this point, gradually increase the throttle out of the corner, under full control and guiding the car to the opposite outside line. By the time the car is pointing straight on the track, you should be at almost full throttle, before you brake hard again for the next corner.

   Developing this driving style comes in stages.

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Hints, Tips and Information

Roll Center

   One of the least understood settings on RC model cars is concept of roll center. The simple definition of roll center is a point in space that the chassis rolls from side to side as the car maneuvers around a corner.

   To calculate roll center you have to consider things like the height of the axles, the inside and outside camber link positioning, the length of the suspension arms and the location of their inside pivot point. Sounds complicated doesn't it - and in truth - it is.

   On all RC model cars, most of the cars weight is above the chassis and the center of gravity of the car is not only from front to rear, but also from top to bottom. This point is called the "true" center of gravity and is the point around which the weight of the car will want to roll from side to side, but it is the roll center of the chassis that the chassis will actually roll around, not the center of gravity.

   Once you have determined the positions of roll center and center of gravity, you can calculate the "roll moment". It is this that determines how easily the chassis will roll from side to side.

The Effect of Roll Center on your Car

But what does all this mean? I hear you ask. Well, it gives you some insight to what changing the position of your camber links can do to the way your car handles.

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