Noob random questions

[PKMSM]

A few random questions that have come to mind while building my first two kits in recent weeks:

1. Is there a certain front/rear weight distribution that is ideal for jumping, or is this not something to focus on? One would think a neutral 50/50 would be the target?
2. To the above point, is there a "reasonably decent" cheap sacrificial RC truck ($100-150) to start practicing jumps before taking the more expensive trucks to the air? Or are you going to tell me to just take the expensive truck because breaking expensive things is part of the game?
3. The Castle ESC (as I am sure many/most other ESCs) has a percentage power setting option setting that limits max power. I know you can also achieve the same thing by setting the throttle EPA in the transmitter. Other than the convenience of having access directly from the transmitter, is there a difference in setting max power one way or the other?
4. The Castle ESC has an Aux wire that allows a chosen parameter to be changed in the transmitter. The instructions are not clear - to the noob - anyone has ever used this feature that can explain it to me?
5. And... why is it that RC cars don't have boots to protect CV joints and bearings? Weight? Overkill? Just wondering, the shocks have them...

I know there were a couple more, but these are all that come to mind for now. Thanks for the answers!

 

[Billl DeLong]

1. Is there a certain front/rear weight distribution that is ideal for jumping, or is this not something to focus on? One would think a neutral 50/50 would be the target?

This is more important for on-road racing... the weight transfers more aggressively with off-road such that spring tuning and chassis height are going to supersede any static weight measurements. Jump face angle, and approach to jump will effect your jump handling.

For example, the SCT410 is prone to having nose dive issues and this is addressed by installing larger EB48 springs on the rear to prevent the rear end of the chassis from slapping the the top of a jump which causes the nose to dive... other methods to address this issue is to make sure you're accelerating up the ramp of a jump which forces the weight of the buggy to the rear and keeps the nose up. If you are already at top speed before hitting the jump, then your car is decelerating as it goes up the jump which shifts the weight forward and then your nose dives because of the weight transfer.

Some people will run shorty packs and move them back to get more rear weight bias, but this is more for rear grip in the corners rather than jump handling.

2. To the above point, is there a "reasonably decent" cheap sacrificial RC truck ($100-150) to start practicing jumps before taking the more expensive trucks to the air? Or are you going to tell me to just take the expensive truck because breaking expensive things is part of the game?

I wouldn't recommend buying a less expensive car, they will be more likely to break and will be more expensive making repairs. Consider investing in Kydex bumpers from T Bone Racing to improve the durability of TEKNO cars.

3. The Castle ESC (as I am sure many/most other ESCs) has a percentage power setting option setting that limits max power. I know you can also achieve the same thing by setting the throttle EPA in the transmitter. Other than the convenience of having access directly from the transmitter, is there a difference in setting max power one way or the other?

Most racers in my area do not use many of the ESC programming features, they simply use the throttle speed and expo rates to improve traction, very seldom do I see someone actually reduce the throttle EPA... I only recommend reducing the EPA to a sportsman driver who is overshooting the largest jump at the track, it can be used as a "training wheel" to go WOT and land the largest jump perfectly every time, but then you lose top speed on the straights by reducing the EPA which is robbing Peter to pay Paul.

4. The Castle ESC has an Aux wire that allows a chosen parameter to be changed in the transmitter. The instructions are not clear - to the noob - anyone has ever used this feature that can explain it to me?

Not familiar with this feature as I run HobbyWing, seems gimicky to me, I simply use the radio to make all my adjustments.

5. And... why is it that RC cars don't have boots to protect CV joints and bearings? Weight? Overkill? Just wondering, the shocks have them...

I've since switched over to HB and no longer run TEKNO, there are boots on the center drive shafts for HB and while it's nice to protect these bearings a little, I don't think they're necessary, plus the boots wear and crack which add another replacement cost, which again really isn't necessary. The bearings already have rubber shields as it is.

The key is using an air compressor and blowing off your chassis after every run. Do a complete rebuild after 15-20 battery packs to ensure your bearings are clean and fluids are fresh. Apply fresh grease on all rubber seals in shocks and diffs. Replace any bearings that are starting to feel crunchy when you spin them. Remove the rubber shields and re-pack fresh grease in the bearings.

Lack of proper maintenance will cause more expensive repairs, a seized bearing may overheat and melt plastic which trickles down to other worn parts, possibly cooking your electronics which can be very expensive to replace. Definitely a lot cheaper to replace fluids and grease

 

[PKMSM]

1. Is there a certain front/rear weight distribution that is ideal for jumping, or is this not something to focus on? One would think a neutral 50/50 would be the target?

This is more important for on-road racing... the weight transfers more aggressively with off-road such that spring tuning and chassis height are going to supersede any static weight measurements. Jump face angle, and approach to jump will effect your jump handling.

For example, the SCT410 is prone to having nose dive issues and this is addressed by installing larger EB48 springs on the rear to prevent the rear end of the chassis from slapping the the top of a jump which causes the nose to dive... other methods to address this issue is to make sure you're accelerating up the ramp of a jump which forces the weight of the buggy to the rear and keeps the nose up. If you are already at top speed before hitting the jump, then your car is decelerating as it goes up the jump which shifts the weight forward and then your nose dives because of the weight transfer.

Some people will run shorty packs and move them back to get more rear weight bias, but this is more for rear grip in the corners rather than jump handling.

2. To the above point, is there a "reasonably decent" cheap sacrificial RC truck ($100-150) to start practicing jumps before taking the more expensive trucks to the air? Or are you going to tell me to just take the expensive truck because breaking expensive things is part of the game?

I wouldn't recommend buying a less expensive car, they will be more likely to break and will be more expensive making repairs. Consider investing in Kydex bumpers from T Bone Racing to improve the durability of TEKNO cars.

3. The Castle ESC (as I am sure many/most other ESCs) has a percentage power setting option setting that limits max power. I know you can also achieve the same thing by setting the throttle EPA in the transmitter. Other than the convenience of having access directly from the transmitter, is there a difference in setting max power one way or the other?

Most racers in my area do not use many of the ESC programming features, they simply use the throttle speed and expo rates to improve traction, very seldom do I see someone actually reduce the throttle EPA... I only recommend reducing the EPA to a sportsman driver who is overshooting the largest jump at the track, it can be used as a "training wheel" to go WOT and land the largest jump perfectly every time, but then you lose top speed on the straights by reducing the EPA which is robbing Peter to pay Paul.

4. The Castle ESC has an Aux wire that allows a chosen parameter to be changed in the transmitter. The instructions are not clear - to the noob - anyone has ever used this feature that can explain it to me?

Not familiar with this feature as I run HobbyWing, seems gimicky to me, I simply use the radio to make all my adjustments.

5. And... why is it that RC cars don't have boots to protect CV joints and bearings? Weight? Overkill? Just wondering, the shocks have them...

I've since switched over to HB and no longer run TEKNO, there are boots on the center drive shafts for HB and while it's nice to protect these bearings a little, I don't think they're necessary, plus the boots wear and crack which add another replacement cost, which again really isn't necessary. The bearings already have rubber shields as it is.

The key is using an air compressor and blowing off your chassis after every run. Do a complete rebuild after 15-20 battery packs to ensure your bearings are clean and fluids are fresh. Apply fresh grease on all rubber seals in shocks and diffs. Replace any bearings that are starting to feel crunchy when you spin them. Remove the rubber shields and re-pack fresh grease in the bearings.

Lack of proper maintenance will cause more expensive repairs, a seized bearing may overheat and melt plastic which trickles down to other worn parts, possibly cooking your electronics which can be very expensive to replace. Definitely a lot cheaper to replace fluids and grease

Thanks as always for the very detailed responses. Very helpful.

 

[Cheez]

1. Is there a certain front/rear weight distribution that is ideal for jumping, or is this not something to focus on? One would think a neutral 50/50 would be the target?

This is more important for on-road racing... the weight transfers more aggressively with off-road such that spring tuning and chassis height are going to supersede any static weight measurements. Jump face angle, and approach to jump will effect your jump handling.

For example, the SCT410 is prone to having nose dive issues and this is addressed by installing larger EB48 springs on the rear to prevent the rear end of the chassis from slapping the the top of a jump which causes the nose to dive... other methods to address this issue is to make sure you're accelerating up the ramp of a jump which forces the weight of the buggy to the rear and keeps the nose up. If you are already at top speed before hitting the jump, then your car is decelerating as it goes up the jump which shifts the weight forward and then your nose dives because of the weight transfer.

Some people will run shorty packs and move them back to get more rear weight bias, but this is more for rear grip in the corners rather than jump handling.

2. To the above point, is there a "reasonably decent" cheap sacrificial RC truck ($100-150) to start practicing jumps before taking the more expensive trucks to the air? Or are you going to tell me to just take the expensive truck because breaking expensive things is part of the game?

I wouldn't recommend buying a less expensive car, they will be more likely to break and will be more expensive making repairs. Consider investing in Kydex bumpers from T Bone Racing to improve the durability of TEKNO cars.

3. The Castle ESC (as I am sure many/most other ESCs) has a percentage power setting option setting that limits max power. I know you can also achieve the same thing by setting the throttle EPA in the transmitter. Other than the convenience of having access directly from the transmitter, is there a difference in setting max power one way or the other?

Most racers in my area do not use many of the ESC programming features, they simply use the throttle speed and expo rates to improve traction, very seldom do I see someone actually reduce the throttle EPA... I only recommend reducing the EPA to a sportsman driver who is overshooting the largest jump at the track, it can be used as a "training wheel" to go WOT and land the largest jump perfectly every time, but then you lose top speed on the straights by reducing the EPA which is robbing Peter to pay Paul.

4. The Castle ESC has an Aux wire that allows a chosen parameter to be changed in the transmitter. The instructions are not clear - to the noob - anyone has ever used this feature that can explain it to me?

Not familiar with this feature as I run HobbyWing, seems gimicky to me, I simply use the radio to make all my adjustments.

5. And... why is it that RC cars don't have boots to protect CV joints and bearings? Weight? Overkill? Just wondering, the shocks have them...

I've since switched over to HB and no longer run TEKNO, there are boots on the center drive shafts for HB and while it's nice to protect these bearings a little, I don't think they're necessary, plus the boots wear and crack which add another replacement cost, which again really isn't necessary. The bearings already have rubber shields as it is.

The key is using an air compressor and blowing off your chassis after every run. Do a complete rebuild after 15-20 battery packs to ensure your bearings are clean and fluids are fresh. Apply fresh grease on all rubber seals in shocks and diffs. Replace any bearings that are starting to feel crunchy when you spin them. Remove the rubber shields and re-pack fresh grease in the bearings.

Lack of proper maintenance will cause more expensive repairs, a seized bearing may overheat and melt plastic which trickles down to other worn parts, possibly cooking your electronics which can be very expensive to replace. Definitely a lot cheaper to replace fluids and grease

Thank you so much for sharing!