Salut a tous
Voici un article de marcus sur les réglages rwd du train avant.
Je vous met un copier coller et vous laisse traduire
Une mise à jour sera faite à chaque nouvelle info
WHAT IS CAMBER?
Camber angle is the vertical alignment of the wheel relative to the driving surface. At the neutral steering position, the top of the tire should be leaning into the body, which is negative camber. The reference range of negative camber at the neutral steering position is around negative 4 to 8 degrees. I would recommend to set the default around negative 6 and adjust from there. You should have a camber gauge, that can measure from negative 10 to positive 10 degrees.
So what does camber actually do? When you roll a frisbee on the floor, the frisbee will roll in the direction it is leaning into. Negative camber will assist in stabilizing the chassis in the direction of the lean. For example if camber is zero at neutral, for the chassis to drive straight, it is mechanically less stable than having a negative camber. However, it is very important to have left and right exactly at the same camber, otherwise the chassis will be pulled to whichever that has less camber.
The other key element in RWD RC Drift is the front tire contact patch that is dictated by camber. Using the edge with less contact, or using the larger surface with more contact, on the leading and trailing tires. Typically, more negative camber will increase control, less negative camber will make the steering milder. However, this is relative to how the other alignment is set in combination with camber, and also the profile of your tire. Extreme camber 'oni-kyan' may look cool, but will not necessarily improve the drivability...so let's be practical!
HOW DO YOU ADJUST CAMBER?
Typical adjustment is using the turnbuckle or slide adjustment of the upper arm. I prefer adjusting the lower arms so the tire fitment to the body stays the same. Using the digital caliper to make sure the left and right is identical, is very critical. If you change camber, the steering linkage will also need to be adjusted for toe in and your ackerman.
WHAT IS CASTER?
Caster is the angle created by the steering pivot point or the king pin in the front to back direction of the chassis. This angle should be leaning towards the back of the chassis. Caster is like the steering fork of a bicycle, the more lean, the more stable it is, but also makes the steering sluggish, or unresponsive. The reference caster angle I would say is around positive 4 to 10 degrees, and would recommend to start from around positive 6 to 8 degrees. Caster can be measured by using a camber gauge to measure the side of the ball joints on upper and lower side of the front knuckle, however if you have different size ball joints or depending on the shape of the front knuckle, you may have to take an approximate reading.
Caster is closely related to camber. As you turn your steering, the camber throughout the steering will change relative to the caster setting.
Leading tire = Negative camber will be cancelled out by caster, eventually going zero camber, then positive camber depending on caster setup
Trailing tire = Camber will increase by caster, and can increase to extreme camber depending on caster setup
HOW DO YOU ADJUST CASTER?
Caster is adjusted by the front to back position of the front upper arm and/or the lower arm. The more you push the upper arm towards the back of the chassis will add positive caster, or bring the lower arm forward to add positive caster. You can use spacers or shims to do this, but note that adjusting the lower arm for caster will change the wheel base, so you may need to adjust the rear tire position to adjust for the wheel base when you make any significant caster adjustments. Once again, any caster adjustments will require the steering linkage to be checked and re-adjusted. It may change the full lock position if you have a knuckle stopper or possibly cause the linkage to rub against the wheels depending on how much adjustment you make.
TOE OUT?
You probably have seen many chassis with the front tires toed out. Front toe in RWD RC Drift has a different meaning than other RC categories. Toe is mainly used to set the ackerman, or change in ackerman throughout the steering. I will cover ackerman in the later bulletins, but for now, I would set the toe to either zero or slightly out, up to 2 deg or so. Extreme toe out may interfere with the ackerman. As you will have negative camber at neutral, a slight toe out will actually make the chassis more stable.
WHAT IS KPI (KING PIN INCLINATION)?
I'm sure you've heard people talk about KPI or seen it in the product name of a front knuckle. Caster is the steering pivot point or the king pin angle in the front to back direction of the chassis. KPI is the steering pivot point or the king pin angle in the left to right direction of the chassis, leaning in to the chassis at the top, but not to be confused with camber.
KPI will change the progression of the camber in combination with the caster throughout the steering stroke. This is a compound element of camber, caster and KPI, but in short, KPI prevents the front tire camber to become excessive in negative or positive.
Leading tire = KPI will add the amount of positive camber gain, so negative camber at neutral will progress to zero, then to positive camber
Trailing tire = KPI will cancel out the amount of negative camber gain to prevent reaching extreme negative camber
Below is a great link (in Japanese) using a test bench to explain KPI and how KPI affects camber progression.
http://blog.livedoor.jp/sin5deg/archives/51624000.html
*Courtesy of sin5deg
HOW DO YOU ADJUST KPI?
Adjusting KPI will require a specific front knuckle. Most brands have their version of front knuckles with KPI adjustment. Some provide very fine adjustability with spacers, some allows hole position of the top or bottom king pin or ball connection to be mounted.
Changing the KPI will require changing the length of the upper and/or lower arm, steering linkage, ackerman etc... so this is why KPI is a more advanced front alignment setup, and most likely it will be a trial and error until you find what you like.
WHY IS KPI IMPORTANT?
So why do you need KPI? KPI is to avoid the excessive amount of camber, both negative and positive when the tire as the steering progresses from neutral to a specific angle towards full lock position. As noted in the BASIC alignnment, it’s how you use the tire contact patch as RWD RC Drift tires are hard plastic. Using too much of the edge can pull the chassis in one direction having too much grip on either the leading or the trailing tire.
By controlling the progression of KPI, you can set the camber, say around negative 7 at neutral, and the negative camber on the trailing tire can actually be kept 'consistent' until reaching full lock. The leading tire can progress from negative camber to zero camber and allow full contact patch at the optimal angle, then transition to positive camber.
Final setting and preference is up to you and what surface you run. My default camber setting at neutral is negative 7deg, caster at positive 5 deg and KPI at 5 deg. This seems to give me a very neutral steering characteristic.
WHAT IS TRAIL?
This is another tricky one that not many people utilize. Trail is the offset of the tire axle or tire rotation center relative to the steering pivot point or king pin. Trail will add stability to maintain the direction the chassis is going, but too much trail will make the steering sluggish.
Trail has a similar effect as adding more caster, but adding extreme caster makes the tires lean too much at full lock, so adding trail and reducing the caster as a combination is another way to dial in your alignment for stability. Some front knuckles have additional holes in front or back of the hole on centerline of the front axle. Moving it forward to add trail will make the front tires stable. Moving it backward will make the steering quick, but will reduce stability. The picture shown below shows two rows of mounting pattern, forward/backward is adjusting trail, and inward/outward adjusts KPI.
WHAT IS SCRUB?
Scrub is the distance or radius of the steering pivot point or king pin to the center of the tire. What scrub does is it dictates how much the front tires move relative to the steering radius. More scrub you have, the more the tire will have to travel and not only will make the tire look funky at full lock, but too much scrub will drag the front tire as you steer and makes the chassis unstable.
Scrub is adjusted by the combination of knuckle, thickness of the hex hub and the wheel offset. Yokomo YD-2 comes with 8mm hex and wheel offset needs to be around 6-8mm to get a good full lock. This is 14 to 16mm scrub radius total, not taking into account the offset in the front knuckle for simplifying the discussion. YD-2 stock knuckles which believe has a small scrub radius in itself, but some knuckles have larger scrub radius, so you will have to determine the hex and wheel offset and try to find the minimum offset that gives you maximum lock angle. Less scrub is better, but I would not try to go too crazy in reducing the scrub as you will lose steering angle by reducing the scrub.
Additional element to keep in mind is that scrub will also change by adjusting camber and KPI. As the front tire leans more, adding negative camber, the scrub will increase, but very slightly. Addining KPI wull have more impact in reducing scrub. Scrub can also be adjusted with the holes on the knuckle if the knuckle has scrub option (hole option also shown on the picture above).
Voici un article de marcus sur les réglages rwd du train avant.
Je vous met un copier coller et vous laisse traduire
Une mise à jour sera faite à chaque nouvelle info
BASIC ALIGNMENT
WHAT IS CAMBER?
Camber angle is the vertical alignment of the wheel relative to the driving surface. At the neutral steering position, the top of the tire should be leaning into the body, which is negative camber. The reference range of negative camber at the neutral steering position is around negative 4 to 8 degrees. I would recommend to set the default around negative 6 and adjust from there. You should have a camber gauge, that can measure from negative 10 to positive 10 degrees.
So what does camber actually do? When you roll a frisbee on the floor, the frisbee will roll in the direction it is leaning into. Negative camber will assist in stabilizing the chassis in the direction of the lean. For example if camber is zero at neutral, for the chassis to drive straight, it is mechanically less stable than having a negative camber. However, it is very important to have left and right exactly at the same camber, otherwise the chassis will be pulled to whichever that has less camber.
The other key element in RWD RC Drift is the front tire contact patch that is dictated by camber. Using the edge with less contact, or using the larger surface with more contact, on the leading and trailing tires. Typically, more negative camber will increase control, less negative camber will make the steering milder. However, this is relative to how the other alignment is set in combination with camber, and also the profile of your tire. Extreme camber 'oni-kyan' may look cool, but will not necessarily improve the drivability...so let's be practical!
HOW DO YOU ADJUST CAMBER?
Typical adjustment is using the turnbuckle or slide adjustment of the upper arm. I prefer adjusting the lower arms so the tire fitment to the body stays the same. Using the digital caliper to make sure the left and right is identical, is very critical. If you change camber, the steering linkage will also need to be adjusted for toe in and your ackerman.
WHAT IS CASTER?
Caster is the angle created by the steering pivot point or the king pin in the front to back direction of the chassis. This angle should be leaning towards the back of the chassis. Caster is like the steering fork of a bicycle, the more lean, the more stable it is, but also makes the steering sluggish, or unresponsive. The reference caster angle I would say is around positive 4 to 10 degrees, and would recommend to start from around positive 6 to 8 degrees. Caster can be measured by using a camber gauge to measure the side of the ball joints on upper and lower side of the front knuckle, however if you have different size ball joints or depending on the shape of the front knuckle, you may have to take an approximate reading.
Caster is closely related to camber. As you turn your steering, the camber throughout the steering will change relative to the caster setting.
Leading tire = Negative camber will be cancelled out by caster, eventually going zero camber, then positive camber depending on caster setup
Trailing tire = Camber will increase by caster, and can increase to extreme camber depending on caster setup
HOW DO YOU ADJUST CASTER?
Caster is adjusted by the front to back position of the front upper arm and/or the lower arm. The more you push the upper arm towards the back of the chassis will add positive caster, or bring the lower arm forward to add positive caster. You can use spacers or shims to do this, but note that adjusting the lower arm for caster will change the wheel base, so you may need to adjust the rear tire position to adjust for the wheel base when you make any significant caster adjustments. Once again, any caster adjustments will require the steering linkage to be checked and re-adjusted. It may change the full lock position if you have a knuckle stopper or possibly cause the linkage to rub against the wheels depending on how much adjustment you make.
TOE OUT?
You probably have seen many chassis with the front tires toed out. Front toe in RWD RC Drift has a different meaning than other RC categories. Toe is mainly used to set the ackerman, or change in ackerman throughout the steering. I will cover ackerman in the later bulletins, but for now, I would set the toe to either zero or slightly out, up to 2 deg or so. Extreme toe out may interfere with the ackerman. As you will have negative camber at neutral, a slight toe out will actually make the chassis more stable.
ADVANCED ALIGNMENT
WHAT IS KPI (KING PIN INCLINATION)?
I'm sure you've heard people talk about KPI or seen it in the product name of a front knuckle. Caster is the steering pivot point or the king pin angle in the front to back direction of the chassis. KPI is the steering pivot point or the king pin angle in the left to right direction of the chassis, leaning in to the chassis at the top, but not to be confused with camber.
KPI will change the progression of the camber in combination with the caster throughout the steering stroke. This is a compound element of camber, caster and KPI, but in short, KPI prevents the front tire camber to become excessive in negative or positive.
Leading tire = KPI will add the amount of positive camber gain, so negative camber at neutral will progress to zero, then to positive camber
Trailing tire = KPI will cancel out the amount of negative camber gain to prevent reaching extreme negative camber
Below is a great link (in Japanese) using a test bench to explain KPI and how KPI affects camber progression.
http://blog.livedoor.jp/sin5deg/archives/51624000.html
*Courtesy of sin5deg
HOW DO YOU ADJUST KPI?
Adjusting KPI will require a specific front knuckle. Most brands have their version of front knuckles with KPI adjustment. Some provide very fine adjustability with spacers, some allows hole position of the top or bottom king pin or ball connection to be mounted.
Changing the KPI will require changing the length of the upper and/or lower arm, steering linkage, ackerman etc... so this is why KPI is a more advanced front alignment setup, and most likely it will be a trial and error until you find what you like.
WHY IS KPI IMPORTANT?
So why do you need KPI? KPI is to avoid the excessive amount of camber, both negative and positive when the tire as the steering progresses from neutral to a specific angle towards full lock position. As noted in the BASIC alignnment, it’s how you use the tire contact patch as RWD RC Drift tires are hard plastic. Using too much of the edge can pull the chassis in one direction having too much grip on either the leading or the trailing tire.
By controlling the progression of KPI, you can set the camber, say around negative 7 at neutral, and the negative camber on the trailing tire can actually be kept 'consistent' until reaching full lock. The leading tire can progress from negative camber to zero camber and allow full contact patch at the optimal angle, then transition to positive camber.
Final setting and preference is up to you and what surface you run. My default camber setting at neutral is negative 7deg, caster at positive 5 deg and KPI at 5 deg. This seems to give me a very neutral steering characteristic.
WHAT IS TRAIL?
This is another tricky one that not many people utilize. Trail is the offset of the tire axle or tire rotation center relative to the steering pivot point or king pin. Trail will add stability to maintain the direction the chassis is going, but too much trail will make the steering sluggish.
Trail has a similar effect as adding more caster, but adding extreme caster makes the tires lean too much at full lock, so adding trail and reducing the caster as a combination is another way to dial in your alignment for stability. Some front knuckles have additional holes in front or back of the hole on centerline of the front axle. Moving it forward to add trail will make the front tires stable. Moving it backward will make the steering quick, but will reduce stability. The picture shown below shows two rows of mounting pattern, forward/backward is adjusting trail, and inward/outward adjusts KPI.
WHAT IS SCRUB?
Scrub is the distance or radius of the steering pivot point or king pin to the center of the tire. What scrub does is it dictates how much the front tires move relative to the steering radius. More scrub you have, the more the tire will have to travel and not only will make the tire look funky at full lock, but too much scrub will drag the front tire as you steer and makes the chassis unstable.
Scrub is adjusted by the combination of knuckle, thickness of the hex hub and the wheel offset. Yokomo YD-2 comes with 8mm hex and wheel offset needs to be around 6-8mm to get a good full lock. This is 14 to 16mm scrub radius total, not taking into account the offset in the front knuckle for simplifying the discussion. YD-2 stock knuckles which believe has a small scrub radius in itself, but some knuckles have larger scrub radius, so you will have to determine the hex and wheel offset and try to find the minimum offset that gives you maximum lock angle. Less scrub is better, but I would not try to go too crazy in reducing the scrub as you will lose steering angle by reducing the scrub.
Additional element to keep in mind is that scrub will also change by adjusting camber and KPI. As the front tire leans more, adding negative camber, the scrub will increase, but very slightly. Addining KPI wull have more impact in reducing scrub. Scrub can also be adjusted with the holes on the knuckle if the knuckle has scrub option (hole option also shown on the picture above).