1/10 Scale Electric Rally/Touring Car:

Yokomo MR-4TC SD CGM Special
Radio Controlled Model

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History and Info:

   Introduced by Team Yokomo in 2004, the 4WD MR-4TC SD CGM Special Touring Car kit - MRTC-SD7 - replaced the old double deck design, with a new Carbon Graphite Molded chassis.

   An MR-4TC SD CGM Conversion kit - SD-CGM - was also available.

   The model is shaft driven, on a composite graphite molded chassis, with ball differentials, coil spring over oil filled dampers, universal joint drive-shafts, anti-roll bars and a full set of ball bearings.

Yokomo MR-4TC SD CGM - 1:10 Electric Touring Car

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To race the Yokomo MR-4TC SD CGM, 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.

MR-4TC SD CGM Special
Instruction Manual

MR-4TC SD CGM Special
Exploded View

MR-4TC SD
Parts Lists

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Radio Controlled Model Accessories:

★ Yokomo MR4TC SD CGM Chassis ★

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

There are essentially three reasons you might want to buy a used Yokomo SD CGM 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 SD CGM 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 SD CGM 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 SD CGM 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

The gearbox of your used Touring Car 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 road, if you intend to race your Touring Car 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.

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 SD CGM 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 SD CGM 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 SD CGM 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

Bumpsteer

   In plain language, Bumpsteer is exactly what it sounds like. If your car goes over a bump, it will affect the toe-in setting and can on some tracks make handling of the car in a straight line difficult.

   To check if your car might have any problems with bumpsteer, have it in race mode, with the motor and battery etc in position. Place the car on a flat surface and push down your car at the front. Looking down from above, keep a close eye on the wheels and watch for any angular movement to the side. If there is then you have bumpsteer.

   For off road cars, because of them having longer dampers in comparison to on road, a small amount of toe out is considered by many as acceptable in the lower position and can sometimes be used as a tuning option because of its aggressive effect on turning ability when entering corners. On road cars, because of the shorter damper movement and the greater need for precise steering and stability in a straight line, generally have less of a problem. However if bumpsteer is detected, drivers generally try to eliminate this as much as possible.

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Hints, Tips and Information

Battery Connectors

   Over the years I have been racing radio controlled model cars of all descriptions, I have tried a number of different connectors for my batteries.

   My first car was a Tamiya Boomerang, and of course the batteries I used all had the standard Tamiya connectors, which were fine with the kit supplied 27T silver can electric motor, but I soon discovered their problem when I installed my first Modified motor. The high current demands of the motor created so much heat, the plastic surround of the connectors melted and fused together. No matter how I tried they could not be disconnected. My only option was to cut the wires.

   From there I moved over to Corally connectors, commonly referred to by many now as Bullet connectors. Comprising of a short length of 4mm gold plated tube at one end, and what looks like what we used to call a Chinese lantern fitting that slotted inside the tube, also gold plated. Although they were highly efficient and reasonably easy to install and use, I never really took to this type of connector, I think it was the fact that there was always the possibility of the positive and negative being connected wrongly in poor light, and also that if positioned side by side, each connector could work loose and become exposed, leaving the possibility of a short circuit.

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