JC Auto Design - SCX10 Rear Upper Link Risers - Improved geometry

[monkeyracer]

Placed my order thanks "thumbsup"

Thanks!

Monday is a holiday. Doubt post office will be open.

:facepalm:

Well, they will be in the out-going bin anyway Monday for pick up Tuesday.


I've got some more information and installation instruction in the SCX10 section:

http://www.rccrawler.com/forum/axial-scx-10/479045-jcad-rulr-v3-install-instructions-tech-info.html

I got the camera working right and made a little portable photo studio to take some better pictures of these and other products coming in the future.

 

[monkeyracer]

All orders paid as of right now are packed up and ready to go. You should have received a notice from paypal saying it was shipped, but the tracking number shows "Stamp"... this is because I am sending these through a normal envelope.

As mentioned above, tomorrow is a holiday, so there is no mail being processed. I plan to drop these off in the overnight drop box so that they go out first thing Tuesday. International orders need to be dropped off in person, so those will go out at some point Tuesday.

Thanks for the orders! I've got plenty of these still in stock, so keep the orders coming!

 

[jh1985]

placed my order thanks man great stuff.

 

[mikro383]

Payment sent for two thanks

 

[skerb]

Using the 4 link calculator that was created on pirate4x4 that I used for my 1:1 jeep, I was under the impression that more separation at the frame increased squat. I filled in the calculator with the measurements from my scx rig and stock it has around 115%as but as I move the links back and up to match your brackets it brings the AS% down below 58%?

http://mysite.verizon.net/triaged/files/4BarLinkV3.1d.zip

 

[monkeyracer]

Using the 4 link calculator that was created on pirate4x4 that I used for my 1:1 jeep, I was under the impression that more separation at the frame increased squat. I filled in the calculator with the measurements from my scx rig and stock it has around 115%as but as I move the links back and up to match your brackets it brings the AS% down below 58%?

http://mysite.verizon.net/triaged/files/4BarLinkV3.1d.zip

I've never used the 4 link calculator because I would rather calculate all the geometries myself. I'm not sure how it calculates that, but there's got to be something wrong in the calculation saying vertical chassis separation decreases anti-squat.


From the Installation and Tech thread:

What is anti-squat?
There are many threads about Anti-squat, but sometimes the information can be hard to weed through, so here's a quick run-down.
Anti-squat or sometimes abbreviated to AS is the tendency of the rear of the chassis to raise up when forward power is applied. This fights the natural gravity/momentum induced squat where the rear of the chassis wants to 'squat' down on the suspension.

[Very technical engineering related explanation]
How this happens is that when power is applied through the transmission, it rotates the drive-shaft, which rotates the axle gears, and eventually the wheels. All this rotation experiences friction and that friction causes a reaction force (Newton's 3rd law - every action has an equal and opposite reaction...) in the axle housing (as well as reaction forces from the traction of the tires, the couple moment reaction from the normal force reaction of the left and right tires on the ground, and a reaction moment couple from the left and right shocks... all of these contribute to torque twist, squat/anti-squat, etc. regardless of what is causing the moment of inertia, it is there and affects the way these vehicles drive...)

This reaction creates a couple moment with the upper links and lower links. This rotational moment is transferred to the chassis, and depending on the geometry of the links will determine the direction of rotation of the chassis.
A squat geometry will rotate the chassis downward toward the axle, anti-squat geometry will go the other way.

Why is improving anti-squat important for the SCX10?
It's important to all vehicles, but especially for the SCX10. When climbing a steep ascent, the higher COG (due to more scale realistic features, heavy bodies, scale accessories, larger batteries, battery placement, etc) tends to allow the front end to lift, reducing traction to the front tires, causing the vehicle to eventually flip over backward.
Anti-squat helps to combat this tendency to reduce traction on the front tires by rotating the rear of the chassis up moving the weight of the vehicle more towards the front allowing better traction.

Think about how a door opens. If you push the door near the side on the opposite side of the hinges (where the knob is), less force is required to open it, or in other words, it's easier to open the door applying the same force. Move where you push on the door closer to the hinge and it's harder to open the door.
By creating the increased vertical separation at the chassis, the forces from the axles through the links are able to be more effective at rotating the chassis upward.


The physics of what is going in is, to me, more important than what an online calculator can tell you.

 

[skerb]

Your door analogy is not accurate because the stock scx suspension setup has the uppers and lowers at the chassis very close together which is like the hinge on the door you describe. When you move the mounts up it creates less lift because the pivot point are farther apart and not on a single hinge.

I know that the 4 link calculator works because I have moved my upper links on my jeep down to increase the anti squat. As before the move under hard acceleration the jeep would squat like a front wheel drive car.

 

[monkeyracer]

It breaks down to a simple force equation:

(M_z) = (F_x)(d_y) + (F_y)(d_x)

M_z is the moment (also known as torque in the right situations) on the axis perpendicular to the plane where forces are applied.

F_x is the force in the x direction

F_y is the force in the y direction

d_x is the horizontal distance from the point being evaluated

d_y is the vertical distance from the point being evaluated


So, to make M_z bigger, I would either need to increase the force, or increase the distance between the points. The math does not work out to say that increasing the distance decreases the force.

I know that the 4 link calculator works because I have moved my upper links on my jeep up to increase the anti squat. As before the move under hard acceleration the jeep would squat like a front wheel drive car.

That is exactly what I am saying; increased vertical separation at the chassis (by moving the upper links up) increases AS (generally). There has to be something wrong with either what you are entering into the calculator, or how it is calculating the values.

 

[skerb]

It breaks down to a simple force equation:



(M_z) = (F_x)(d_y) + (F_y)(d_x)



M_z is the moment (also known as torque in the right situations) on the axis perpendicular to the plane where forces are applied.



F_x is the force in the x direction



F_y is the force in the y direction



d_x is the horizontal distance from the point being evaluated



d_y is the vertical distance from the point being evaluated





So, to make M_z bigger, I would either need to increase the force, or increase the distance between the points. The math does not work out to say that increasing the distance decreases the force.











That is exactly what I am saying; increased vertical separation at the chassis (by moving the upper links up) increases AS (generally). There has to be something wrong with either what you are entering into the calculator, or how it is calculating the values.

Sorry moved them down. I mistyped on my phone. I don't know a lot about it, just relaying info I used from 1:1 jeeps. And it worked the exact opposite of what you claim with these brackets.

 

[skerb]

For more antisquat, the 4 link should have more angle, making the intersection shorter, for less anti-squat the links should have less angle. The height of the intersection is also important, the higher it is the more antisquat it has. Another pic, the red setup has more than 100% anti-squat, the blue has less. The drawing has a horizontal line through the CG, and a vertical line through the front wheel. Then a line is drawn from the rear tire contact patch through the 4 link intersection, till it crosses the front axle. In the drawing the CG happens to be 38" the red suspension crosses the front axle at 48" 48/38 = 1.26. Thats 126% anti-squat.
Alot of crawling buggies have more than 100% because everything is high above the axles. Making the frame mounts farther apart on the red example would give less than 100% while still maintaining clearance. This might not be good geometry for proper U-joint life and drive shaft extension, design becomes a juggling act of one requirement over another. High anti-squat causes the back end to jack up under power, which isn't such a good thing on a steep climb.

 

[skerb]

I think what I'm getting at is it's more than just raising the upper link, the lower link must move up as well.

 

[monkeyracer]

What you are saying is backwards from the way everyone has been building rc crawlers and scalers for the past 10 years.

There are certain geometries that have been tested and shown to work.

I'll bring this picture back up:

Squat vs. Anti-squat:

This simple $10 part increases performance. How it does it can be debated and argued, but it just does it. It helps the vehicle climb steeper climbs than without it. It does this by increasing the pivot point on the chassis to raise up the rear of the chassis to move the weight more towards the front tires to increase the traction on the front tires.

 

[hatefulboy]

Payment sent for two a few days ago, wondering if they have shipped?

 

[monkeyracer]

All paid orders are shipping either today or monday.

Speaking of shipping, if anyone receives an empty envelope, please PM with your information.
It seems the post office put these in the automatic sorter (rather than in the non-machinable bin.) and the sorter is ripping the envelopes to shreds.

I have received pieces of envelopes back but with no idea who they were for, so if you part of the first batch, and don't receive your envelope by monday, please let me know.

Thanks!

 

[kaneohecrawler]

Monkeyracer theres no need to defend your product. We all know it works. I did my own brackets last year.. worked but execution was bad(they wore and would rotate). But they worked. And i cant wait to get mine. Ill be doing real world testing on controlled surfaces controlled tires to figure out just how much increase there is by simply installing these. Im betting at a minimum 3°, which seems little but the diff betwween climbing 58° and 61° is very significant.

Ps has anyone started getting theres yet?

 

[monkeyracer]

Monkeyracer theres no need to defend your product. We all know it works. I did my own brackets last year.. worked but execution was bad(they wore and would rotate). But they worked. And i cant wait to get mine. Ill be doing real world testing on controlled surfaces controlled tires to figure out just how much increase there is by simply installing these. Im betting at a minimum 3°, which seems little but the diff betwween climbing 58° and 61° is very significant.

Ps has anyone started getting theres yet?

I've heard of people reporting results around that amount on an incline board (easy to control the angle) which should translate to the rocks and trails as well.

The first batch should have started showing up Thursday and yesterday, so hopefully someone will post up their results with the new steel version soon.

 

[ROLANDROCKSHOP]

best thing to happen for the scx chassis in awhile...

installed sets on my G6 honcho and G6 jk.

a noticeable difference in the front not lifting as easy going uphill.

"thumbsup"

 

[kaneohecrawler]

Recieved mine today. Envelope had tares in it as described. But both inside. Installed now. Gained 2° from stock. Awesome!

 

[Erbing]

Got mine few days ago, got it installed on mattzilla chassis and will be testing tomorow.....will post pics tomorow.

 

[badhoopty]

hevent recieved mine yet, and i think i was one the first mailing for the revised steel versions.

i work with alot of direct mail, and i know the mail-sort systems in the post office are brutal on launching things that are loose inside a standard envelope.