R/C Tech Forums

Go Back   R/C Tech Forums > General Forums > Electric Off-Road

Like Tree43Likes
Reply
 
Thread Tools Search this Thread
Old 01-19-2015, 08:59 AM   #15796
Tech Elite
 
Join Date: Mar 2011
Location: Houston
Posts: 2,557
Trader Rating: 1 (100%+)
Default

Quote:
Originally Posted by hacker View Post
why would you want less weight transfer?

weight transfer is good....isn't it?

weight transfer gets the job done of putting weight on the rear wheels during acceleration, and putting weight on the front when coasting/braking to assist cornering duties.
Why is weight transfer good? If it's good, when is there too much? When is there not enough? These are things I never see proponents of 4 gear and weight transfer answer and they are the first things that should be asked.

The proponents of 4 gear would say that you need weight transfer in MM in order to get rear traction. Fair enough. Why? Is it because of the location of the motor? If so, why? What does the rotational force of the motor in relation to it's location have to do with things? Isn't a motor rotating backwards always applying the same opposite rotational energy to the chassis? Yes, of course it is.

Let's look at conventional RM3 for a minute. The motor counter rotates to the wheels. That means that in RM3 mode, the motor is always trying to push the front of the car down under acceleration. The reverse is true in RM4 mode. However, people always want to add more weight to the front. They also run max antisquat which further prevents weight shift rearwards under acceleration. If someone can't get grip under acceleration, why do they always say to use more antisquat? I've always thought that was some of the worst advice that people think of as common knowledge. Anyways, the point being that in rear motor, people are trying to shift the weight forwards. They don't want all the rearward weight shift under acceleration. The amount of static weight they have is plenty for the job. Too much in fact.

Move that motor ahead of the rear axles and suddenly everyone is singing a different tune. People would tell you that the key to making mid motor work was by shifting to a 4 gear system and artificially transferring weight rearwards. Why did this work? Let's just look at the weight of the motor. I'm going to make up a generic number. Apply whatever unit of measure you want to it be it ounces, grams, whatever. The number is important.

Let's say we have a mid motor car with a 40% front /60% rear weight distribution. Now let's say that we have a motor with a weight of 10. Again, it's just a number and to further simplify things, let's assume that the motor is right on the center of gravity. That means that 4 of that motor is effectively on the front wheels and 6 is on the rear. Now let's take that motor and move it to the back behind the wheels. Let's move it to a distance that is 20% behind the rear wheels so if the wheelbase was considered 1 length, from the front wheels to the motor would be 1.2. Now that weight works differently. That motor now weighs -2 at the front and 12 and the rear. The motor is automatically taking weight off of the front wheels and adding it to the rear using leverage. The motor effectively weighs twice as much as it did in front of the wheels. Don't dissect the math too hard. It's an example so don't get caught up on technicalities. I'm trying to paint a mental picture of a concept.

We can see that by moving the motor forward, we removed a lot of weight from the rear wheels. Too much weight is bad but we can't develop any grip if there is no weight on the wheels at all. A weightless car is floating and would have no traction. We've added weight to the front wheels which is why MM cars can turn so well but the back end may wash out easier during off power corner entry due to a lack of rear traction. The car may also not accelerate as well for the same reason. If traction is high, it probably won't matter. This is why you see people say that MM is for high grip and RM is for low grip.

By using the rotation of the motor to help aid in weight transfer rearward during acceleration, 1 of the above 2 problems was solved. Let's go back to the numbers example. This time we are going to say the car weighs 10. If we transfer 100% of our weight onto the rear wheels during acceleration (a wheelie), that gives us 10 on the rear wheels for grip but 0 on the front. You can't steer with no traction. In MM, you don't drive full throttle/full brake as much but rather gently roll into it. This way you don't give full throttle to the rear all the time. That way you don't transfer all of the weight to the rear in all situations, like mid corner on power. The irony is that you are trying to get the weight shift to a balance around where it was with rear motor. Go figure. You still haven't solved the problem of weight on the rear wheels when not under power though. This is where off power corner entry will kill you. It doesn't matter if you are MM3 or MM4. Each lacks the static weight on the rear which is really the fundamental problem anyways. Keep in mind that none of this is theory. It's all known fact.

That probably raises the question, why wouldn't a person just run RM in lower grip conditions or in stock class where weight is the enemy? That's a good question. Why wouldn't you? I've stated that MM can work in any situation. That's true. It doesn't mean it's always the best option. I'd generally suggest to run MM3 if grip is high and RM3 if MM3 doesn't work. A neutral handling car would seem to be the best option when available.
__________________
Follow my rc products on Facebook at Raborn Racing Originals and the line of 3D printed parts at
http://www.shapeways.com/shops/rebellionrc

Last edited by fredswain; 01-19-2015 at 10:32 AM.
fredswain is offline   Reply With Quote
Old 01-19-2015, 09:14 AM   #15797
Tech Master
 
13Maschine's Avatar
 
Join Date: Jul 2012
Location: Los Angeles, CA
Posts: 1,554
Trader Rating: 1 (100%+)
Send a message via Skype™ to 13Maschine
Thumbs up

Quote:
Originally Posted by tc5 man View Post
Whats the offset of the new Exotek 12mm Rear hexs do you know ?
5.7mm is the offset of the new Exotek hexes. They are conveniently marked with 12mmx5.7mm on the face.

I'm using them on my DEX410 up front and I wish they were a bit narrower, perhaps also including spacers to adjust the front track.

I also use the Avid 12mm hexes in the rear (both 210 and 410) because they have a 4 piece set that has a narrow hex and a wider hex.
__________________
SoCal R/C Privateer, find me at either OCRC or SCVRC!
My JUNSI POWERED Rides: Xray XB2 CE, Hot Bodies D413, Kyosho RB6, HobbyWing Xerun 3.1, Futaba 4PX, Futaba and MKS Servos, Speed Passion Hirosaka and HW V10 Powerplants!
First car Kyosho Pegasus and RC10CE! More than 25 years Racing! Happy to lend a helping hand. Just ask! :)
13Maschine is offline   Reply With Quote
Old 01-19-2015, 09:27 AM   #15798
Tech Master
 
13Maschine's Avatar
 
Join Date: Jul 2012
Location: Los Angeles, CA
Posts: 1,554
Trader Rating: 1 (100%+)
Send a message via Skype™ to 13Maschine
Default

@fredswain: How do you determine front/rear and left/balance on your cars? are you using a set of scales? Or do you just balance the car on the centerline?

I think a simple way would be to use the balancing points like HUDY makes and measure the distance between the axles. Do you measure again when you change your wheelbase?

Have you done this with your 210 in mid motor with a shorty? Are you able to achieve 60/40 rear bias like you want? I assume to do this you'd need to add weights (based on your past posts). Or are you only able to get it close to 50/50?

Please elaborate if you can, always appreciated! Anyone else who has done this please jump in too Pictures are especially awesome!
__________________
SoCal R/C Privateer, find me at either OCRC or SCVRC!
My JUNSI POWERED Rides: Xray XB2 CE, Hot Bodies D413, Kyosho RB6, HobbyWing Xerun 3.1, Futaba 4PX, Futaba and MKS Servos, Speed Passion Hirosaka and HW V10 Powerplants!
First car Kyosho Pegasus and RC10CE! More than 25 years Racing! Happy to lend a helping hand. Just ask! :)
13Maschine is offline   Reply With Quote
Old 01-19-2015, 09:39 AM   #15799
Tech Initiate
 
Super08's Avatar
 
Join Date: Dec 2014
Location: Alberta, Ca.
Posts: 35
Default

I weigh mine in a while level attitude front and rear with a postal scale.
Super08 is offline   Reply With Quote
Old 01-19-2015, 09:42 AM   #15800
Tech Initiate
 
Super08's Avatar
 
Join Date: Dec 2014
Location: Alberta, Ca.
Posts: 35
Default

For example I am at 1700 with a full size battery and it weighs 1080 on the rear and 620 on the front. That gives me 63.5% on the rear axle.
Super08 is offline   Reply With Quote
Old 01-19-2015, 10:07 AM   #15801
Tech Prophet
 
tc5 man's Avatar
 
Join Date: Oct 2007
Location: levittown pa
Posts: 16,907
Default

Quote:
Originally Posted by fredswain View Post
Why is weight transfer good? If it's good, when is there too much? When is there not enough? These are things I never see proponents of 4 gear and weight transfer answer and they are the first things that should be asked.

The proponents of 4 gear would say that you need weight transfer in MM in order to get rear traction. Fair enough. Why? Is it because of the location of the motor? If so, why? What does the rotational force of the motor is relation to it's rotation have to do with things? Isn't a motor rotating backwards always applying the same opposite rotational energy to the chassis? Yes, of course it is.

Let's look at conventional RM3 for a minute. The motor counter rotates to the wheels. That means that in RM3 mode, the motor is always trying to push the front of the car down under acceleration. The reverse is true in RM4 mode. However, people always want to add more weight to the front. They also run max antisquat which further prevents weight shift rearwards under acceleration. If someone can't get grip under acceleration, why do they always say to use more antisquat? I've always thought that was some of the worst advice that people think of as common knowledge. Anyways, the point being that in rear motor, people are trying to shift the weight forwards. They don't want all the rearward weight shift under acceleration.

Move that motor ahead of the rear axles and suddenly everyone is singing a different tune. People would tell you that the key to making mid motor work was by shifting to a 4 gear system and artificially transferring weight rearwards. Why did this work? Let's just look at the weight of the motor. I'm going to make up a generic number. Apply whatever unit of measure you want to it be it ounces, grams, whatever. The number is important.

Let's say we have a mid motor car with a 40% front /60% rear weight distribution. Now let's say that we have a motor with a weight of 10. Again, it's just a number and to further simplify things, let's assume that the motor is right on the center of gravity. That means that 4 of that motor is effectively on the front wheels and 6 is on the rear. Now let's take that motor and move it to the back behind the wheels. Let's move it to a distance that is 20% behind the rear wheels so if the wheelbase was considered 1 length, from the front wheels to the motor would be 1.2. Now that weight works differently. That motor now weighs -2 at the front and 12 and the rear. The motor is automatically taking weight off of the front wheels and adding it to the rear using leverage. The motor effectively weighs twice as much as it did in front of the wheels. Don't dissect the math too hard. It's an example so don't get caught up on technicalities. I'm trying to paint a mental picture of a concept.

We can see that by moving the motor forward, we removed a lot of weight from the rear wheels. Too much weight is bad but we can't develop any grip if there is no weight on the wheels at all. A weightless car is floating and would have no traction. We've added weight to the front wheels which is why MM cars can turn so well but the back end may wash out easier during off power corner entry due to a lack of rear traction. The car may also not accelerate as well for the same reason. If traction is high, it probably won't matter. This is why you see people say that MM is for high grip and RM is for low grip.

By using the rotation of the motor to help aid in weight transfer rearward during acceleration, 1 of the above 2 problems was solved. Let's go back to the numbers example. This time we are going to say the car weighs 10. If we transfer 100% of our weight onto the rear wheels during acceleration (a wheelie), that gives us 10 on the rear wheels for grip but 0 on the front. You can't steer with no traction. In MM, you don't drive full throttle/full brake as much but rather gently roll into it. This way you don't give full throttle to the rear all the time. That way you don't transfer all of the weight to the rear in all situations, like mid corner on power. The irony is that you are trying to get the weight shift to a balance around where it was with rear motor. Go figure. You still haven't solved the problem of weight on the rear wheels when not under power though. This is where off power corner entry will kill you. It doesn't matter if you are MM3 or MM4. Each lacks the static weight on the rear which is really the fundamental problem anyways. Keep in mind that none of this is theory. It's all known fact.

That probably raises the question, why wouldn't a person just run RM in lower grip conditions or in stock class where weight is the enemy? That's a good question. Why wouldn't you? I've stated that MM can work in any situation. That's true. It doesn't mean it's always the best option. I'd generally suggest to run MM3 if grip is high and RM3 if MM3 doesn't work. A neutral handling car would seem to be the best option when available.



I know there was only one clay track i ran on that was actually tacky and the MM4 worked great. But the other two tracks one was slick with a mix clay and the other one pure clay but it was Med/Low grip but when wet higher traction.

And really dint care much running the MM4 it was just inconstant traction wise on the Rear end especially on the exit of the turns. Now they may be because im using 4000k in the Gear diff and not much lower.

I going to try the MM3 again and tune it a bit more to get more steering and turn in or do RM3 . Last time i tried the MM3 i like that it was easy to drive less steering and not nearly as twichy as the MM4 on lower grip .
__________________
Losi SCTE 4x4, Tekno SC410 4X4 SC, Associated T4.1, Hitec 7954sh, mamba monster 2200kv, airtronics MX-3 X. Losi SCTE 4x4, Tekno SC410 4X4 SC, Associated T4.1, Mugen MBX6 ECO .

Hobby Hut offroad, Mushroom bowl offroad, Fun Center raceway.
GS HOBBY , Stormer Hobbies, Amain Hobbies, RRP Hobby .
tc5 man is offline   Reply With Quote
Old 01-19-2015, 10:25 AM   #15802
Tech Elite
 
Join Date: Mar 2011
Location: Houston
Posts: 2,557
Trader Rating: 1 (100%+)
Default

Quote:
Originally Posted by 13Maschine View Post
@fredswain: How do you determine front/rear and left/balance on your cars? are you using a set of scales? Or do you just balance the car on the centerline?

I think a simple way would be to use the balancing points like HUDY makes and measure the distance between the axles. Do you measure again when you change your wheelbase?

Have you done this with your 210 in mid motor with a shorty? Are you able to achieve 60/40 rear bias like you want? I assume to do this you'd need to add weights (based on your past posts). Or are you only able to get it close to 50/50?

Please elaborate if you can, always appreciated! Anyone else who has done this please jump in too Pictures are especially awesome!
I use 4 scales. I remove the shocks and replace them with camber links that are set to achieve a ride height of arms level. This way I remove the inconsistency of spring load. I understand that I'm not weighing the shocks but the difference in result is so small that it's not an issue.

I generally like 65% on the rear but it's total weight on the rear wheels that is more important to me than just the ratio. If the ratio is correct but the car is super light, it still won't have enough grip. Fortunately that probably won't happen. This is why I'd prefer a side by side saddle arrangement in MM. The % distribution isn't as important as getting weight on the rear wheels. I just can't get it with a shorty. If I've got lots of weight on the front, it'll have a tendency to under steer during off power corner entry. I can generally tune that out with camber link adjustments. On power steering would be good though. You don't ever want 50/50 on a rear wheel drive car. Your front tires are skinnier than the rears. You'd overload the fronts in a corner and under load the rears everywhere else. You'd have a car that pushes like a snow plow on corner entry and just spins out on exit. It also would have terrible forward bite so acceleration would suffer.

I do have a high grip base setup worked out. It's a good starting point and then people can adjust camber links to fine tune from there. I could post it but it would need to be understood that you'd need the exact same components that I have in the exact same locations to get the same results. Basically a V2 car with V1 chassis and HRC rear block. Using a +8 chassis or an LRC block will not give the same results and it would be off. That's why I'm hesitant to post setups. They are an all or nothing thing. You can't use a setup but then have a car that is "close" and expect it to work the same. I don't want someone to take that setup and use it on a V1 car or a full V2 car or move components around and then complain it doesn't work well for them. For me, balance is critical and a tune is only setup around where everything is placed in a car. It is an MM3 setup using an inline shorty in the rearward position. The esc is on the right side and the receiver is on the left. F/R distribution is 40/60 so high grip is a must but the handling is very neutral. With our new indoor dirt track about to open, I'm strongly considering going back to RM3 because I'm pretty sure this setup won't work there. At least for a while until the track gets fully worn and packed in. Then I'll re-evaluate from there.
__________________
Follow my rc products on Facebook at Raborn Racing Originals and the line of 3D printed parts at
http://www.shapeways.com/shops/rebellionrc
fredswain is offline   Reply With Quote
Old 01-19-2015, 08:19 PM   #15803
Tech Prophet
 
tc5 man's Avatar
 
Join Date: Oct 2007
Location: levittown pa
Posts: 16,907
Default

Quote:
Originally Posted by 13Maschine View Post
5.7mm is the offset of the new Exotek hexes. They are conveniently marked with 12mmx5.7mm on the face.

I'm using them on my DEX410 up front and I wish they were a bit narrower, perhaps also including spacers to adjust the front track.

I also use the Avid 12mm hexes in the rear (both 210 and 410) because they have a 4 piece set that has a narrow hex and a wider hex.


Oh ok i see them numbers now .

Heres what im talking about with the offset on AKA EVO 12mm rims ones that fit Associated , Kyosho etc. Big difference with the Exotek and B4.1 Rear Proline Rear hex.

The right side its the Exotek 12mm hex and the Left side the Proline B4.1 hex . So it looks like i may be using the Proline B4.1 hexs.
Attached Thumbnails
Durango DEX210 Thread-win_20150119_220352.jpg   Durango DEX210 Thread-win_20150119_220406.jpg  
__________________
Losi SCTE 4x4, Tekno SC410 4X4 SC, Associated T4.1, Hitec 7954sh, mamba monster 2200kv, airtronics MX-3 X. Losi SCTE 4x4, Tekno SC410 4X4 SC, Associated T4.1, Mugen MBX6 ECO .

Hobby Hut offroad, Mushroom bowl offroad, Fun Center raceway.
GS HOBBY , Stormer Hobbies, Amain Hobbies, RRP Hobby .
tc5 man is offline   Reply With Quote
Old 01-20-2015, 07:52 AM   #15804
Tech Legend
 
Cain's Avatar
 
Join Date: May 2002
Location: West Fargo, North Dakota
Posts: 29,442
Trader Rating: 239 (100%+)
Default

well today is the maiden voyage of my dex210 on some carpet.

As I didn't want to really switch a bunch of stuff over the regular alloy chassis from the v1 just decided to mid motor my Dime chassis and see how it goes.

Thanks Dino for advise and setup info. I decided to keep your 1.5 x 2 X 1.1 x 2 pistons (I beleive that is right) in the rear and will see how it goes. Alot of other changes were relative to that setup you sent, and I am using a full size pack.

Didn't have the springs though in the setup for the rear, so should be interesting.
__________________
Member - Red River Radio/Control Car Club
< HB Racing D413 | Tekno EB48SL / SCT410.3 | Tekno EB410 | Yokomo YZ-2 DTM x 2 | LC Racing EMB-1 Buggies and Truggies >
Cain is offline   Reply With Quote
Old 01-20-2015, 07:57 AM   #15805
Tech Regular
R/C Tech Elite Subscriber
 
Join Date: Apr 2014
Posts: 276
Trader Rating: 12 (100%+)
Default

So Im just getting into 2wd buggy. Just got a good deal on a DEX210 v2. Actually from a sponsored racer. Anyway, Im starting to look at motors and ESC. Everything else I have has Tekin. Im not a brand loyal fanboy or anything I just want to use what works for the best price point. So naturally I started with Tekin and looks at the RS Esc with an 8.5T Proline. Is that a pretty good option to run or are there better options for the money? Thanks.
gablett is offline   Reply With Quote
Old 01-20-2015, 08:22 AM   #15806
Tech Legend
 
Cain's Avatar
 
Join Date: May 2002
Location: West Fargo, North Dakota
Posts: 29,442
Trader Rating: 239 (100%+)
Default

Quote:
Originally Posted by gablett View Post
So Im just getting into 2wd buggy. Just got a good deal on a DEX210 v2. Actually from a sponsored racer. Anyway, Im starting to look at motors and ESC. Everything else I have has Tekin. Im not a brand loyal fanboy or anything I just want to use what works for the best price point. So naturally I started with Tekin and looks at the RS Esc with an 8.5T Proline. Is that a pretty good option to run or are there better options for the money? Thanks.
Tekin makes great stuff, loved the reliability especially in the 1/10 size.

Probably the only thing I didn't like is that if I wanted to do customizations it was either through the lights, etc. on the ESC or via hotwire and you need a laptop. My color recognition is not that good.

They do have an app now for the android based phones, for the newer ESCs.

when running mod my opinion even if you find say motor "A" is more powerful than motor "B", you just go with a hotter motor.

In general like 8.5 - 10.5 for mod relative to the track.

For ESCs I have liked a variety from Speed Passion to Viper now, all worked really well.

I like Vipers for there long warranty and the profile feature for the programmer card.
__________________
Member - Red River Radio/Control Car Club
< HB Racing D413 | Tekno EB48SL / SCT410.3 | Tekno EB410 | Yokomo YZ-2 DTM x 2 | LC Racing EMB-1 Buggies and Truggies >
Cain is offline   Reply With Quote
Old 01-20-2015, 10:25 AM   #15807
Tech Elite
 
rcjunky1's Avatar
 
Join Date: May 2008
Location: Ottawa, Canada
Posts: 2,185
Trader Rating: 10 (100%+)
Default

The tekin hotwire works with Android phones now, even the original esc's. I recently played with my rs pro on my Oneplus One and it works great. Tekin stuff works well with great support. On a budget, my Toro ts120 works great, runs cool even in my dex410 with no fan
__________________
Official distributor of Dan-O-Mite Custom Parts- Durango 210 RF pivot blocks
Andrew Butters' Burghgraef
Team Durango Canada
Great Hobbies, Hobbico, Skyrc, Exotek
rcjunky1 is offline   Reply With Quote
Old 01-20-2015, 02:01 PM   #15808
Tech Master
 
13Maschine's Avatar
 
Join Date: Jul 2012
Location: Los Angeles, CA
Posts: 1,554
Trader Rating: 1 (100%+)
Send a message via Skype™ to 13Maschine
Default

speaking of the original HRC block (DEX210) does anyone need one? I have a V2 but still have my alum HRC block. This would only fit the original chassis unless you were to machine a space for the rear bumper. PM me and I"ll hook you up. Perfect condition. Can send pics.

http://www.team-durango.com/part-inf...artNo=TD330344

I've stocked up quite a bit of parts if anyone is looking for something. Please PM me.
__________________
SoCal R/C Privateer, find me at either OCRC or SCVRC!
My JUNSI POWERED Rides: Xray XB2 CE, Hot Bodies D413, Kyosho RB6, HobbyWing Xerun 3.1, Futaba 4PX, Futaba and MKS Servos, Speed Passion Hirosaka and HW V10 Powerplants!
First car Kyosho Pegasus and RC10CE! More than 25 years Racing! Happy to lend a helping hand. Just ask! :)
13Maschine is offline   Reply With Quote
Old 01-20-2015, 02:44 PM   #15809
Tech Master
 
13Maschine's Avatar
 
Join Date: Jul 2012
Location: Los Angeles, CA
Posts: 1,554
Trader Rating: 1 (100%+)
Send a message via Skype™ to 13Maschine
Default

Quote:
Originally Posted by Super08 View Post
For example I am at 1700 with a full size battery and it weighs 1080 on the rear and 620 on the front. That gives me 63.5% on the rear axle.
Can you elaborate a bit about where you place the chassis on the scale? Perhaps post a pic of your setup with the scales and all. Thank you!
__________________
SoCal R/C Privateer, find me at either OCRC or SCVRC!
My JUNSI POWERED Rides: Xray XB2 CE, Hot Bodies D413, Kyosho RB6, HobbyWing Xerun 3.1, Futaba 4PX, Futaba and MKS Servos, Speed Passion Hirosaka and HW V10 Powerplants!
First car Kyosho Pegasus and RC10CE! More than 25 years Racing! Happy to lend a helping hand. Just ask! :)
13Maschine is offline   Reply With Quote
Old 01-20-2015, 03:21 PM   #15810
Tech Regular
R/C Tech Elite Subscriber
 
Join Date: Apr 2014
Posts: 276
Trader Rating: 12 (100%+)
Default

Anyone have any experience with the Hobbywing X5A combo in 8.5t?
gablett is offline   Reply With Quote
Reply

Similar Threads
Thread Thread Starter Forum Replies Last Post
St Ives RC Club B4Bandit Australian Racing 16575 Yesterday 12:44 AM
EPMTs check in here. (a subsidiary of TNT) overtki11 Singapore R/C Racers 55470 05-08-2017 12:57 AM
Team Durango DEX410 ASH93A Australian Racing 925 04-08-2013 10:51 PM



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off



All times are GMT -7. It is currently 03:46 AM.


Powered By: vBulletin v3.9.2.1
Privacy Policy | Terms of Use | Advertise Content © 2001-2011 RCTech.net