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1/10 Scale Electric Rally/Touring Car:

Yokomo YR-4 II (Radio Controlled Model Review)


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History, Info (and How To Set-up Tips) for the Yokomo YR-4 II:


  Introduced by Team Yokomo circa 1996, the 4WD YR4-2 Touring Car, was classed as an intermediate to entry level model.

  The YR4-2 is belt driven, on a GRP double deck chassis, with ball differentials, coil spring over oil filled dampers, universal joint drive-shafts and 14 ball bearings.

Yokomo YR-4 II - 1:10 Electric Touring Car
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  To race the Yokomo YR-4 II, 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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★ Yokomo YR4-2 ★
Yokomo YR4-2

★ Yokomo YR4-2 Chassis ★
Yokomo YR4-2 Chassis

★ Yokomo YR4-2 Chassis ★
Yokomo YR4-2 Chassis


Buying a Used Yokomo YR-4 II
Touring Car (and What to look for)


   Buying a used Yokomo YR-4 II Electric Touring Car, 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 road.

   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.

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.

   If the body shell of your Yokomo YR-4 II 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 YR-4 II 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 YR-4 II Touring Car 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 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.

   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.

Servo Gears
   The YR-4 II 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 YR-4 II 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 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 YR-4 II 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

Weight

   If you ever step up and enter a regional, national or international event in RC, you will find one specific rule concerning the weight of your car.

   At the time this article was written, the Minimum weight restrictions for 1:10 electric Touring Cars at different events, was between 1350g and 1500g. This includes your Motor, ESC, Receiver, Battery, Body Shell and the transponder.

   Out of the box you will find the majority of 1:10 Touring Cars, with everything onboard, are way over this Minimum weight and unless you are good enough to attract sponsors, getting your car down to anything approaching that minimum weight will be very expensive.

   There are things you can buy like micro ESC and Receivers. But Batteries and Motors are what they are and you have to work around them.

   To reduce the weight of your chassis, there are a number of things you can do. If the car you have is generally considered competitive enough, there are often carbon fibre main chassis, shock mounts and other alternative parts available, but they are expensive. And when the new version of your model comes out all the money you have spent is lost.

   The most cost effective weight reduction is the metal parts of your chassis. UJs, Drive and Pivot shafts and the like tend to vary from model to model, but turnbuckles can often be transferred and lengthened or shortened by using plastic ball connectors, so titanium is a consideration.

   Screw sets can also be transferred from car to car. Titanium screws and wheel nuts are always available, but there is a cheaper alternative Aluminium screws and nuts can reduce your cars weight cheaply, but be careful not to over-tighten them, aluminum is not as strong as titanium and can easily shear off if you are over zealous.

   Another weight reduction option is to drill holes along the base of the chassis. However, I do not recommend this. For one thing you are reducing the strength and making the chassis less rigid, but you are also raising the centre of gravity of your car, which can affect stability.

   If you do manage to get your car weight below the minimum allowed, this will give you an opportunity to add weight where you want it and lower the cars centre of gravity.

   One last tip: Knitting needles. When I first started in RC, money was tight and my dad came up with all kinds of ideas to reduce weight. He obtained a 3mm dye and found some of my mums old aluminum knitting needles that were just the right diameter. Having determined the length of the turnbuckles needed for my setup, he cut them to those lengths and threaded each end, so he could put plastic ball sockets on them. Adjusting them was a bit of a pain and they could be a bit fragile in crash situations, but they saved us lots of money over those early years.

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







Hints and Tips

Dampers

   Dampers, Shock Absorbers, Shocks call them what you will, they are one of the least understood, but most important tools you have for adjusting the handling characteristics of your RC model.

   In this article, I will endeavour to explain just what you can achieve by making simple tweaks to your shocks and how these tweaks can keep you ahead of your opposition on the track.

   In dictionary terms "Damper" is described as "A mechanical device to absorb the energy of sudden impulses." In plain language, they stop your car from bouncing all over the track.


So how do Dampers work?

   Basically what you have is a small amount of silicone oil contained in a sealed cylinder. Through the centre of that cylinder is a metal rod and on the end of that rod, a piston with a number of small holes in it. Pulling, or pushing the rod in and out of the cylinder, your will notice a certain amount of resistance as the oil is forced through the holes in the piston. To manipulate that resistance you have two options. You could use thicker or thinner oil, or change the size of the holes in the piston. So if you have thicker oil, or smaller holes, you have more resistance. Less viscous oil or larger holes, less resistance. This simple physical relationship, coupled with a good set of tuning springs, is all you need to set-up your car to beat the rest.

   Out on the race track, the main thing you want to avoid is your car bouncing around all over the place, sliding, or even rolling over when you negotiate a tight corner. To prevent this you need to make changes, but before you make those changes you need to consider what your problem is for that particular track. How your model reacts when cornering does it Under-steer? (Slide towards the outside of the corner) or Over-steer? (Turns towards the inside of the corner). Does it react differently when you exit the corner to how it did when you entered it?

   Once you have decided what your problem is, go to our "Set-Up" page linked below and follow the step by step instructions. But remember to only make ONE change at a time. If the first suggestion isn't enough to cure the problem, add the second and so on, until you find that perfect setting. Good luck and good racing.

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










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