Chassis parts

  • How to fix the center bulk plate
  • Traction adjustment with center bulkhead plate and rear roll plate
  • Changing the flex using different material screws
  • Fix the servo mount with steel or high precision titanium screws
  • Thin Upper Deck to change chassis flex
  • Battery holder and chassis flex
  • Adjustment of car balance and flex with BD9 weight system
  • B9-00219H - BD9 Graphite Chassis (2.0mm/Hard)
  • Adjust balance & Low CG with Multi Weight Plate

  • Suspension
  • Adjusting the height when using a linear spring at the front
  • Incorrect Spring Cup for Ride Height
  • Careful work produces a smooth operation of the stabilizer
  • Perfect mounting of the suspension bushings
  • Optimize left/right balance through correct suspension mount alignment
  • Rear Toe Control (RTC) Suspension set up
  • Keep machine balance with New shock cap nut
  • Front & Rear Titanium 3mm Outer Suspension Arm Pins
  • B9-S5SHVF Shock Shaft
  • High precision titanium Φ4.8 Rod end ball

  • Drive Train
  • Fitting of joint protector and drive cup
  • Checking double joint universal drive shaft
  • Distinctive use of O-ring for gear differential
  • Aluminum Spool Cups
  • Low friction belt enhancing drive efficiency
  • B9-010BWS BD9 Double Joint Universal Dog Bone (38.5 mm)
  • BD9 Center Drive Pulley Notes

  • Note: some of the content below is a direct automated transaltion from Japanese without human correction.

    How to fix the center bulk plate

    Although it is a center bulk plate to be mounted on the front side of a motor mount or a center bulkhead, there was a case that the chassis warped due to a wrong mounting direction. The center bulk plate has a front and back side, the flat side is the upper side, the side with the step is the lower side. When actually assembling it, it is a procedure to attach the center bulk plate to the motor mount and the center bulkhead and then attach it to the main chassis, but if the reverse side is attached, a gap will be created between the center bulk plate and the main chassis If it tightens screws forcefully, the chassis will warp.

    Even when mounted in the correct orientation, there may be a slight gap between the center bulk plate and the main chassis due to manufacturing tolerances. In that case, please install with 3 mm stainless steel shim (ZC-S305, ZC-S310, ZC-S320, ZC-S330) etc. of about 0.05 ~ 0.2 mm thickness sandwiched according to the situation.

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    Traction adjustment with center bulkhead plate and rear roll plate

    Although it is possible to adjust the "traction" which pushes the machine forward by changing the pitching rigidity of the chassis, in addition to the center bulkhead which changes the rigidity of the center part in the BD9, it is made of graphite made of graphite for adjusting the rear roll stiffness In combination with the roll plate, it is possible to adapt to a wide range of situations.


    Bulk head plate (long) installation

    Regarding stock categories, center bulkhead is firmly fixed, and if rigidity is increased by using roll plate in combination, it is possible to increase traction and increase cornering speed while maintaining the front steering characteristics mild. If the road grip is high and you feel the weight on the cornering, I think that it is good to change the center bulkhead plate to an optional long. On the contrary, if you want to bring out the turning performance of the rear, removing the rear roll plate keeps the turning time to the minimum and leads to time-up.

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    Changing the flex using different material screws

    Included as standard with the BD9 kit are two types of screws – steel and aluminum. You can use these to change the rigidity or stiffness of the chassis, to adapt the car to your track conditions. In simple terms, when using steel screws, the flex of the chassis will be stiffer, whilst the aluminum screws will make the car softer. There are also optional titanium screws available, which will give a feeling in between the hard steel and soft aluminum.

    For the overall stiffness of the chassis (affected both by the screws used and the other tuning options available), a softer chassis setting will generally allow the tuning window to be wider, whilst a stiffer setting will sharpen the handling of the car. Therefore, if your track is low grip, or you don't have any setup information available, a good starting point is to set the chassis soft, and adjust the suspension settings from there, in turn also slowly increasing the chassis stiffness as well until you find the perfect balance level.

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    Fix the servo mount with steel or high precision titanium screws

    When securing the servo mount to the main chassis, we recommend a standard steel screw or high precision cutting titanium bis which can be tightly fastened. BD9 uses aluminum bis etc. to fix some parts in order to make use of chassis flex, but for servo mount it is easier to apply force than other parts and more secure fixing is required so strong We recommend steel screws that can be fixed to. In addition, the high precision cutting screw (RP-100B) of the racing performer is compatible with dish processing of the main chassis and it can be fixed with high precision Please try by all means.

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    Thin Upper Deck to change chassis flex

    We have now released the optional Thin Upper Deck (B9-00319T) for the BD-9 chassis. The part is made from 1.65mm carbon graphite material, and maintains the same shape and the standard upper deck. This is a good tuning option, as it allows an overall softer flex setting than the standard 2.0mm upper deck included in the kit.

    When using the Aluminum Main Chassis (B9-00219A), the overall chassis flex is stiffened. Using the Thin Upper Deck can give some more flex in the car, making it easier to drive and improving the overall balance feel.

    Alternatively, using the Thin Upper Desk with the standard carbon graphite chassis can provide more grip on low traction track. The flex setting and overall feeling can then be further tuned through the use of the rear roll plate (also included with the kit) giving more options to get the best balance and traction for your track.

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    Battery holder and chassis flex

    The battery holder used on the BD9 is a new type. Previously, most cars used glass tape to hold the battery in place, however this had some disadvantages – you could easily make the tape too tight and then affect the chassis flex, or have it too loose and not hold the battery in securely enough in the event of a crash. The new battery plate allows the perfect amount of play in the battery mounting, holding it firmly in place but also not affecting the chassis tweak or flex.

    There is also an optional carbon battery holder (B9-118G), which performs exactly the same function but has a neat carbon look. This works in the same way as the kit item, but is held in place by finger screws, still allowing the perfect amount of movement.

    If you use a super low-profile battery, the gap between the battery and the holder may be a little large. You can use the battery rubber sheet (B7-118RS) to secure the battery correctly.

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    Adjustment of car balance and flex with BD9 weight system

    For the BD9, a system of brass weights is available as a tuning option. There are four center weights( B9-BW20 ,B9-BW30, B9-BW40 ,B9-BW50 ) from 20g to 50g, as well as 10g front weights (B9-BWF10)

    The center weights can also be used to adjust the chassis stiffness. Like with the carbon pitch control plate included with the kit, it is possible to add screws along the center line. Adding all the screws will stiffen the overall chassis flex, whilst a softer flex setting can be obtained by using fewer screws. For the softest possible setting, you can use no screws in the center of the weight, or try having the weight 'floating' by not fixing it to either the motor mount or servo mount.

    The 10g front weights can make the car feel like it has more front grip under braking into a corner, but as the cornering force increases, the weights in this position will result in understeer. The advantage of this is best experienced on higher traction surfaces, as it can prevent the front wheels from lifting, help prevent grip roll, and reduce the chassis pitching under acceleration out of the corner. This can allow you to get on the throttle sooner after a corner and reduce lap times.

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    Adjusting the height when using a linear spring at the front

    In the standard specification of the kit, the progressive type is specified as the spring to be used for the front, but depending on the circumstances, the linear spring may match. Depending on the hardness of the spring, it is worth a try if you want to raise the sense of stability, because it is a little mild operability at the entrance of the corner compared to progressive.

    However, the linear spring has a spring length of about 0.5 mm longer than the progressive spring, and there seems to be a situation in which the vehicle height does not decrease as it is mounted. In that case, by replacing the spring cup (B7 - S3S - 680) for short shock used in BD 7 - 2014, you can lower the car height. Also, it is possible to lower the car height by cutting the shock end plastic part of the shock lower side by about 0.8 mm, but in that case please be careful to make the right and left lengths as uniform as possible. Interference with the suspension arm will also occur if it cuts too much, so please handle it carefully.

    Three linear spring types, jointly developed with AXON for BD9, will be released.

    • Linear front spring for B9-SLF260 BD9 (AXON made / 2.60)
    • Linear front spring for B9-SLF270 BD9 (made by AXON / 2.70)
    • Linear front spring for B9-SLF280 BD9 (AXON made / 2.80)
    The kit's standard spring requires a high level of stability and mild steering characteristics, and a progressive type in which the winding pitch changes from the middle is adopted. Aiming for stearin characteristics, it is designed to emphasize steering response improvement and cornering. Of course, there is also a balance with the setting balance before and after, but it is possible to have an aggressive run that suppresses the understeer and aggressively attacks the inn.

    In addition, since the overall length is shorter by 1.5 mm than the conventional linear spring, no shock-end processing is required when lowering the vehicle height. Depending on the type of tire, it may be difficult to lower the vehicle height due to its thickness, so depending on the situation, it can be used not only for the front but also for the rear.

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    Incorrect Spring Cup for Ride Height

    There was a mismatch of spring cups in part of the initial sales of BD9. There is no excuse. If you use the mixed spring cup as it is, you can not lower the car height, making it difficult to drive normally. We are very sorry for the customer concerned, but please contact our after-sales service (Tel: 03-5613-7553). I will exchange it for a genuine article in a hurry.

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    Careful work produces a smooth operation of the stabilizer

    Unlike the conventional stabilizer of the BD9, it is a ball bearing support system. The effect of the stabilizer increases by running smoothly, but if you attach the holder of the stabilizer diagonally to the stabilizer wire, the movement of the suspension will be hindered.

    Actual installation work is "carefully", but since the holder will become oblique especially if you tighten the mouse of the stabilizer holder in a complicated manner, so as to tighten little by little while checking the movement of the stabilizer holder Please. Also, at the time of attaching the holder, the condition with a margin to the left and right is ideal to some extent. When moving the stabilizer wire left and right, it is appropriate to move slightly rattling.

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    Perfect mounting of the suspension bushings

    The suspension on the BD-9 uses resin bushings in the aluminum suspension mount to set the toe in/out. It is important to make sure these bushings are always pushed fully into the mount, otherwise the movement of the suspension arm may bind up and harm performance.

    When you cut the bushing off of the plastic tree, firstly you should make sure there are no burrs left – these will prevent the bushing from sitting properly in the aluminum suspension mount. If there are any burrs left, cut them with a sharp knife or use some sandpaper to make sure the side of the bushing is completely smooth.

    The bushings are designed to be a very tight fit in the aluminum mount. You may have difficulty pressing it in just with your fingers – if so, place the bushing on a flat surface (such as your setup board), with the numbers on the bushing facing upwards as in the picture. You can now carefully push the aluminum mount down on top of the bushing from above, making sure to keep it straight as you do so.

    You can always check that the bushing is in place properly, as the surface with the numbers marked on will be flat against the outside surface.

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    Optimize left/right balance through correct suspension mount alignment

    In the screw holes on the chassis, there is a small manufacturing tolerance so the holes are slightly larger than the screws that fit through them.

    The figure below shows a simplified picture of installing the screws and suspension mount. Because the screw is slightly smaller than the hole, there is the possibility of the screw not mounting exactly in the center. The countersinking should help with the alignment, but as you tighten screw A, the other screw (B) may move slightly in the direction you are screwing.

    Even a small deviation of 0.2 or 0.3mm at the suspension arm can be increased by the end of the wishbone and create a difference in the toe angles of 1 degree or more between each side.

    To help minimize this, it is recommended to tighten the left and right screws a little at a time, alternating between them.

    The suspension mount may also move following a crash, so if you feel the balance of the car is not right, please check the mounts and carefully re-tighten them. This can easily help to improve the car.

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    Rear Toe Control (RTC) Suspension set up

    The rear toe control system (B9-RTC) is one of the key tuning options for the BD-9. It can be used to adjust the rear traction during cornering, to help your car fit the specific track conditions. The RTC system can have most benefit in providing more rear traction upon acceleration through a middle or high speed corner. It also has the benefit of allowing you to finely adjust the rear toe angle, again allowing you to tune your car to the exact track conditions.

    However, the RTC system does add weight to the rear suspension. The standard rear suspension is lighter and can also have some performance advantages. In particular, on a technical circuit, the standard rear suspension may be better as it will help with quick rotation in tight corners.

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    Keep machine balance with New shock cap nut

    The standard shock for BD9 adopted "High Big Bore Ultra Short Shock" that collaborated with AXON. Although it is a high-performance shock that enhances traction with smooth operation, we have released a new shock-cap nut with laser engraving.

    B9 - S4C1 Shock cap nut for BD9 (Laser engraved / 4 pieces in)

    Although the setting of the touring car is severe year by year, it is possible to perform more reliable setup by improving the reproducibility of the machine even during maintenance etc. Since this shock cap has been given a laser engraving that can check the front and back and the left and right, by using the shock always in the same position, while maintaining the individual difference of the spring and the assembled state of the shock, the situation before the maintenance It will be as close as possible.

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    Fitting of joint protector and drive cup

    The resin joint protector attached to the tip of the dog bone of the universal shaft is designed to be slightly tight against the drive cup to prevent play against the drive cup.

    Usually it will be familiar with running for a few minutes and will work smoothly, but if you are using a new item in a race etc, use waterproof paper about # 1000 on a flat plate (glass plate etc.) It is possible to get smooth operation from the beginning by placing it on the surface and rubbing the joint protector so that it rubs the surface. Of course, too much sharpness leads to backlash, so please make it slightly familiar to the end.

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    Checking double joint universal drive shaft

    The front of your BD9 is equipped with double joint universal drive shafts. These produce a smoother steering feeling in the car, and our team almost always will use these. However, when assembling your car, it is important to check that the set screws in the joint are fully tightened. From the factory, the screws may not be tightened up enough, which can cause a failure of the part when you are racing. So it's always best to check these set screws when using a new drive shaft, and regularly between driving too.

    When reassembling or performing maintenance, please also pay attention to the D-shaped cut out part of the joint, and make sure the set screw is visible at this point.

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    Distinctive use of O-ring for gear differential

    Although the rear of the BD9 is equipped with a gear differential, there are two kinds of O-rings to prevent oil leakage on the axle shaft. The standard black type is trying to reduce the friction as much as possible so that the operation of the gear differential becomes as smooth as possible, but as it is still a moving part, leakage of the oil may become matter of concern. In particular, if soft oil is used, the bleeding of oil will be more, so in that case the silicone red O-ring (BD-500GO BD7/BD5 ), you can prevent leakage.

    Also, when assembling the gear differential, when sealing grease (CS-SLG) is applied to the O-ring and gasket to a large extent, it is possible to prevent oil leakage and minimize the O-ring sucking oil and inflating It is possible to limit to the limit, please try.

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    Aluminum Spool Cups

    The weight of the drive train is a key part of your BD9's performance. A lighter drive train will improve the throttle response and provide more efficiency – keeping the battery voltage higher for longer. Yokomo has released an optional Aluminum Spool Cup (B9-501MCA) for the BD9, which reduces the weight of this important part by about 5.5g compared to the kit steel parts.

    The reduction in weight also helps to reduce the flywheel effect of a heavier drive train, which will make the front of the car more stable, increase the initial steering and give a faster response on-throttle out of the corner too. This is a great option part which can really help to reduce your lap times and make your BD9 even faster!

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    Low friction belt enhancing drive efficiency

    In the stock category where it is important to make full use of motor power, high drive efficiency is also a major factor to shorten the time. So we recommend low friction drive belts, using materials softer than the standard to reduce the efficiency reduction when the belt rotates, achieve acceleration power and top speed growth.

    BD-513LB Low friction front belt for BD9
    BD-189BL Low friction rear belt for BD series

    The design has been suppressed in strength to improve drive efficiency. Therefore, if you run with a high power modulated motor, tooth skipping etc. occurs due to insufficient strength, so we recommend to the category using stock motors such as 13.5T~21.5T.

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    B9-503GS BD9 10T bevel gear shim set

    B9-503 GS BD9 10T bevel gear shim set (4 pieces)

    This part is not a special optional part, it is a steel shim that is used as a standard for the gear differential of the kit. It is a sim that is also included in the gear kit 's maintenance kit, but why dared to release it separately, it appeared as a part to add to the standard gear differential.


    In the kit standard, this shim is included in the outside of the small bevel gear (10 T) inside the gear differential, but this is the proper value as a clearance for normal smooth operation. However, by daring this sim in two places and making the backlash tight, usage that increases the differential response response may lead to time-up. Especially effective is a tight turn of a technical circuit and a quick turn back chicane etc. It is possible to increase the acceleration response after clipping and lead to time-up.

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    B9-010BWS BD9 Double Joint Universal Dog Bone (38.5 mm)

    The other part is a dog bone for front double joint universal. It is a 38.5 mm dog bone 1 mm shorter than the standard (39.5 mm) and is used to make the clearance with the joint cup proper when narrowing the space between the inner suspensions with the suspension mount setting.

    Standard uses the suspension mount B at the front, but depending on the situation, using the suspension mount A, narrowing the front to narrow tread, or narrowing the space between the suspension pins, the wheel hub was changed to thick one to keep the tread width We may set up to enlarge the scrub radius. It is an effective setting on outdoor asphalt roads with a low grip, but the former narrow tread is getting better in the first half of the corner and the latter scrub radius change turns like firmly bending in the second half of the corner .

    In all cases, the entire suspension arm including the universal shaft becomes inward, and in some circumstances the tip of the dog bone may interfere with the back of the joint cup during suspension operation, so use this short dog bone to ensure clearance please do it.

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    B9-00219H - BD9 Graphite Chassis (2.0mm/Hard)

    A new hard main chassis for the BD9 is now available! The new chassis is 2.0mm thick – so thinner than the standard chassis, but offer stiffer flex characteristics through the use of a high-elastic material.

    This gives a third option for your chassis setting – in the past drivers would normally choose the standard carbon chassis for low-grip tracks, and the aluminum chassis for high-grip tracks, such as carpet surfaces. The new hard chassis fits between these options, so would be a good option for higher-grip asphalt surfaces.

    Additionally, the chassis features tighter tolerances in the production of the part. The screw holes are reduced in size, meaning there is less possible movement of the bulkhead and suspension parts when attached to the chassis. This will help keep the car tweak-free and give a consistent feeling and balance left to right.

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    Front & Rear Titanium 3mm Outer Suspension Arm Pins

    Titanium suspension arm pin, which is a new option part for BD 9, has been released.

    We realized 44% lighter weight than standard steel! Although it is a small part, the weight difference is slight, but with regard to exercise performance it is said that the reduction of the unsprung weight is more than 10 times more effective than on the spring, and although it is small it can be expected to achieve great performance improvement.

    It is a major objective to reduce the weight of the unsprung weight, although it is an improvement in exercise performance, please remember that the traction of the tire (the grip force to advance the machine forward) will go down. The weight loss of the suspension arm pin may become a negative direction on the road surface with low grip. On the contrary, if the road grip is high to a certain extent, it is possible to shorten the lap time, such as turning cornering quickly by improving the turning speed and stabilizing control at turning back.

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    B9-S5SHVF Shock Shaft (19.1mm/Heavy Fluorine Coat)

    A new shock shaft for the BD9 platform with a durable heavy fluorine coating on the surface to give the ultimate low friction performance.

    Developed in collaboration with AXON, the well-known RC accessories brand, the parts provide the ultimate shock performance for racing machines. Even small vibrations can now be absorbed by the shock absorber, giving more traction on all surfaces. The durability of the shock shafts has been tested by long-term running by Team Yokomo, and that has concluded these HVF shock shafts provide better performance than the previous versions. Come as a set of 4 shock shafts.

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    High precision titanium Φ4.8 Rod end ball

    Ultra-lightweight, high-precision titanium rod end balls for BD9 series platform!

    In addition to the S size (11.5 mm) and M size (13.0 mm) used for the upper arm and tie rod, a short neck type (11.5 mm) and a kingpin ball used on the top of the steering hub carrier are also available now. The ball part are Φ4.8 mm for all, and with the high precision surface finish provides super smooth operation. The weight reduction at the top of the chassis is also highly effective in improving driving performance, and is the ultimate item that contributes to lap time.
    • RP-101SH - High precision titanium Φ4.8 Rod end ball (S size/11.5mm)
    • RP-101MH - High precision titanium Φ4.8 Rod end ball (M size/13.0mm)
    • RP-101SHS - High precision titanium Φ4.8 Rod end ball (Short neck/11.5mm)
    • RP-102 BD9 - High precision titanium Φ4.8 King pin ball

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    Adjust balance & Low CG with Multi Weight Plate

    This is a weight plate for BD9 which is designed for optimization of the left-right balance and low center of gravity for the BD9 platform. The system is a set of shaped brass plate that can be used in various ways according to the situation. It comes as a set of three with a black coating and beveled edge design.


    When using a lightweight or super LCG battery, such as in Modified class racing, placing the weights under the battery will further lower the center of gravity. In the stock categories, which often uses regular standard Li-po batteries, the weights can be installed under the ESC or the Receiver to optimize the left/right balance. Each plate weighs 7g, and the size is 25 × 34 × 1 mm. A thin double-sided adhesive tape is also included.

    B9-MWP - Multi weight plate for BD9 (7grs x 3)

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