Anti-Squat on RC Crawlers - Part II: The Demo
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- čas přidán 2. 07. 2024
- In this follow-up video we demonstrate the concepts originally presented in The Definitive Guide to Anti-Squat on RC Crawlers.
00:00 Intro
00:33 Theory Recap
02:43 Driving Examples
03:26 What is the Myth?
03:54 Rear Torque
04:47 Double Blind Testing
05:36 Demo 1 - Torque
09:07 Demo 2 - Climbing
11:33 Conclusion
About The Author
www.linkedin.com/in/jason-chamberlain-96970a19 - Auta a dopravní prostředky
I can appreciate when someone was smarter than me explains it in a way that I understand. Because better tuning is important. Getting fed a bunch of wrong information and believing into it is dangerous. Thank you for taking the time to bring this forward. I found it most interesting.
Thank you!
Glad I haven’t bought into the hype don’t have “link riser” yet ,
Great work👍 as always
In rc rock crawling there are times where you “bump” or “give the beans” to quickly jump up an incline. In this case, anti-squat dynamics would be at play and would make a difference in performance.
I completely agree.
Great topic for a future video.
This is my driving style. Lots of anti squat, lots of throttle. In the right circumstances it will jump squarely up an obstacle. But I also run a very light sway bar
yes but still most crawlers have good anti-squat out of the box
@@BoomslangSusscan you do videos explaining pros and cons on using wheel spacers/hubs
These are the kinds of videos I’ve been searching for! Actual engineering discussion with examples! I’ve been in the crawling community for 20 years now and there has always been something that everyone takes at face value because that’s what everyone online is saying to do, but no one can produce actual evidence for whether it helps or not. Thanks and keep them coming!
Yes, this is why I started the channel. The crawler community has been largely underserved and ignored when it comes to tech data, which is why so many thing have gone off the rails from otherwise well intentioned anecdotal experience and word of mouth. I hope to add some science here and that at least some people will embrace it.
Saw the first video you did on this and it made total sense. Great explanation 👌
Thanks for diving in deep for us. This is great information.
Glad it was helpful!
I’ve been watching your RC tech videos. Thank you for providing clear and concise explanations. When I started RC crawling I bought a link riser because it was recommended to improve performance but in all my testing I couldn’t really tell a difference. I’m glad it wasn’t just me! haha At least I know now what types of driving a link riser/high anti-squat are actually beneficial for (throttle bumps/quick acceleration)
AS certainly has it's purpose and place. It just doesn't hold your front end down at slow speeds. Thanks for watching and I have a quite a few more topics I hope to release. Stay tuned.
still would love to see this compared with a straight axle vs portal axle.
also, in the climbing test, there was a noticeable difference. minor, but there was a difference. low antisquat setting you couldnt even apply any throttle without the front tipping back, but you were able to apply power with the high antisquat setting. some more testing is needed there to quantify your results
I see what you are saying. If you look closely, you will see that the rear wheel is slipping first on the high setting. When the wheel slips, the front will stay down, obviously. At the moment when the wheel has grip, the front lifts about the same in both settings. There is a guy on FB rn showing 74 deg climb and his wheels are slipping the entire time. That is a different test altogether than what I am trying to demonstrate.
The difference in AS between the two is about 35% so IF there was a difference I would think it would be more obvious. I attribute any discrepancies in this test to wheel slip AND outside of wheel slip I think it's all within experimental error - certainly not a 35% difference.
What are you hoping to discover with portal v. straight so I can address it from a relevant perspective?
czcams.com/video/SBM-YNwr2qU/video.html
I look forward to these videos! Completely making me rethink stuff. As a matter of fact, I’m making a hardware order for my small scale crawlers, and they’re Torx fasteners!
I love that! You won't regret the effort and investment in Torx - high quality and won't strip.
Maybe that's the way to go, I've lost count on how many hex screws I've stripped or straight up just broke on 1/24 scale.
Great video and nice follow up
Thanks 👍
Well done, thanks!
Thank you too!
Less feeling's more facts😂 how relatable in today's world.
😅👍
Very nice clip...thats the reason I drive portals in the rear 😉
MUCH better! Previous videos were light on narration and a bit overwhelming with the volume of material covered and the high number of graphics utilized. This video seemed less rushed, better presented and any graphics helped demonstrate and reinforce theories. Nice! I have a feeling though, that you're going to piss off a lot of people, lol! Subscribed 👍
Thank you. Yes. Already agitating people for sure.
Those jerseys in the background! So jealous!
Thanks! I hoped someone would enjoy them.
A couple of things I'd like to see if youre interested in expanding on this.
1. Does a link riser affect articulation? Looks like you get more twist out of the higher setting. Dunno if the articulation increased or your torque twist increased.
2. Does the link riser do more on a car with the upper and lower link mounts closer together on the chassis side? I notice with the length of your rear links the links barely move away from being parallel. More chassis side pinch would be interesting to see.
3. Can you get the back end to sag before the front end lifts. I think that would help on a straight climb just by the fact it'd lower CG
I agree with your assessment. I also noticed a slight difference in torque twist watching the tests
@@mikerainey3847 I think the visible difference comes from the fact that the wheel is slipping slightly and momentarily in some of the trials. At the moments when the wheel is perfectly hooked up I am not seeing a difference.
1) Yes, the trajectory of the articulation changes a little, but I have not wrapped my head around the effect precisely just yet.
2) The short answer is no. You have to look at the full picture of link angles and position. The I.C. is a result of those links and you can have a fairly large variety of link geos that produce the same IC location. I've done it hundreds of times on mountain bike 4-bar suspension designs - the IC location, and IC migration are key, and just looking at 2 pivot locations doesn't capture the whole story.
3) Agreed, lower is better and preferred. I kept the spring rate in this test such that we didn't reach full droop so that any AS effect had room to extend or compress the rear shocks if it so desired. In the real world I'd run it mostly slammed as you point out.
Is there a negative effect to raising the rear links? I have found link risers helpful to avoid binding issues and making space for bent or high clearance links.
No, there is not really a downside. Raising for clearance purposes is a terrific reason. You will also have the side benefit of increased anti-squat which helps in quick, punchy accelerations, like when you have to throttle bump over an obstacle. Typical link risers add 20-30% more AS, which is helpful but not enough to be harmful, generally speaking. Again, it ONLY matters in dynamic situations.
One thing i will mention... because i noticed very little difference with link risers....... Too much articulation hurts performance, i had better results with a light sway bar to combat the torque twist.
Many people question this method, but it's real simple. Do you have 3 tires touching the ground? Or all 4?
If your truck constantly pulls the front tire off the ground during a climb, a sway bar might not be a bad idea. Helped in side hill situations as well.
I like it. It adds a little bit of spring rate to the articulation too to help returns to level.
Your amazing my friend! IDE just like know more about tuning shocks and location of them! And how weight gains traction or not enough ect! Idk but your awesome! ❤
I plan on doing a video that explains all the shock mounting holes. As far a tuning the shock, that's a very touchy subject, but I may tackle it at some time. Some people like 15wt oil and some like 100wt so it's a pretty broad topic with little chance of bringing people together, but I can publish the basics.
I'm thinking of building a mud race rig with an old c-channel frame I robbed parts off of. Would a link riser be more beneficial in a rc like this since I'd be giving it the beans hopefully the whole race in the mud lanes?
So at slow speeds a riser does nothing. I wouldn’t say that a riser would automatically be an improvement under acceleration, but it would certainly cause an effect, good or bad. You’d want to know what the stick AS number is before arbitrarily adding a riser. Might make it worse.
Its not about just adding/moving a part AS and TT are effects of each other. Id be curious to see the effects of the drive shaft angle along with the geometry.
Same here, keeping in mind the sleeve/piston action to make up for suspension. I’ve been pitching my rear axle slightly back to make a clean line to the transmission which then pitches forward as suspension activates and puts the top link mounts at a 12 o’clock position, some argue it’s best to have the axle at a straight 12 o’clock position. I argue at slow crawl and trailing it’s best to have a clean shaft line. But wtf do I know, I’d love to hear it from our guy.
@@independentmind1977 This would make a great topic for a future video. The torque in the sliding portion of the driveshaft causes friction and resistance to sliding, which reduces suspension freedom because your drive shaft has to slide in order for suspension to move. It's always best to minimize the amount of sliding if possible and have a smooth, direct angle on driveshafts.
Yes, I would love to see a video on it sometime@@BoomslangSuss - if anything these are great studies in movement Engineering....I'm also jealous of the signed jerseys and found myself pausing and zooming in LOL - Miranda Miller is an absolute monster on two wheels!!! Did you have any say on the design of the Specialized Demo?
@@independentmind1977 I love that you appreciated the jerseys! I hoped at least one person would notice. I was the lead designer & engineer on all Demo platforms up until this last season. There are a few videos of Demo development on this channel.
@@BoomslangSuss I ride the Chisel these days, best HT I’ve ever owned and I’d pick it over my wife’s CF frame! The Demo is an amazing frame, great engineering, lovely work sir, chapeau.
When force applied to rear axle links apply pressure to chassis, for most part slow crawling doesn’t matter that much but if you punch it to get over a steep obstacle I believe it helps still.
I mean when you get to risers and link geometry on a custom build you are getting extreme and then it may help as well on supper steeps to get from 55 degrees to 60+?????
Sorry but the rear wheel weighted down wasn’t going to show anything.
I will say the long long links on this chasis also must reduce the force,
Neither made the climb, sooo decrease the angle till one fails.
Fine tuning is fine tuning.
And can go to far always.
Love your videos!!!!
So we will be seeing you at supershafty or any national comp and see how your setups do vs the best drivers and chassis manufacturers in the industry?
Probably not. I just drive cheater rigs for fun.
Competing on a National level will prove nothing if he's not a National level driver (no matter how good his setup). What I'd like to see, though, is these 'theories' tested in a real world environment. I'm all for putting a rig in the hands of a recognized driver and then running back to back comparisons to measure how performance is truly affected. That will be a true measure! 👍
@@jerryvolpini7987 I’m not trying to prove the theories. This isn't new. Anti-Squat is a thoroughly established and proven concept accepted worldwide by suspension engineers from Toyota to Tesla, from Specialized Bicycles to Yamaha, from Ferrari to F1. I am nearly trying to demonstrate them.
@@BoomslangSuss I wasn't questioning what you were saying, I was actually supporting your position. I do feel that we need to see these principles tested in the real world - what works, what doesn't, when, when not. Hard to question long held beliefs without backing it up with more thorough testing.
@@jerryvolpini7987 Thank you my friend! I totally agree, more demos and tests at all levels are good, pro and amateur.
It depends on your build. I have had vehicles that wouldn’t make certain climbs and I tuned and tuned and at my wits end against my better judgment added a riser and the went right up the line then there are rigs like I just posted and it doesn’t have a riser and it climbs extremely well. I think Capra axle with the absolute worst geometry are one that will need a riser 99% of the time.
It look like it did a little better on the traction board with the riser
I couldn't detect a significant difference either way. With such a big difference in AS%, if it were different it should have been really pronounced and obvious. I also tried to film the transmitter to show the amount of throttle input but it was drowned out by glare.
Hey awesome video would be cool to see a video on caster and link geometry ! Or a simplified video for cavemen like me on the ideal crawler setup. I've done some reading online but I'm still unsure.
Caster would be a great topic. Short answer - as much as possible in the front, zero in the rear if you have rear steer. I talk briefly about it here around 1:50:
czcams.com/video/TBqS80_JkSw/video.htmlsi=5ZMPCSOagepuPOU4
I talk a lot about linkage in this video (don't worry, I am working on a version that you don't have to read! ). The short answer is linkage geo is less important when you are moving slowly, but that's a great idea and I should make a simplified video.
czcams.com/video/-ad04wUd8PQ/video.htmlsi=grs4v9EH6AJZEwbQ
@@BoomslangSuss Hey I really appreciate you replying and sharing that information with me I will definitely put it to use when I go to tuning. Also I apologize, I'll need to re-watch with my undivided attention I often work on my crawlers while watching youtube 😅 Thanks and have a good one!
@@isaiah9313 No need to apologize! I was just trying to point you in the right direction, and I will certainly have more videos coming to help you out. Thanks for the ideas.
Does this also mean anti-squat has no effect on side hill driving when slow crawling?
Correct. Side hilling would be more a function of roll center geometry, but that is also a dynamic response to high speed cornering, not creeping. The best thing for side hilling is simply low CG and wide stance. And sway bars but those have other drawbacks.
Kinda off topic but I’m in the market for some deluxe fab straight axles like what you have. Just trying to figure out all the parts necessary to order them 🤝🏻
I actually have portal C hubs so it starts as a straight axle but converted to portal. They are really nice axles. In the front I use Vanquish for different reasons.
I would love to hear your insights on overdrive at the axle vs overdrive in the transmission
What aspect are you curious about? In general it doesn't matter where the gearing reduction is. The effect of torque twist is between your contact patch and your pinion. The motor housing reacts to the resistive torque in the pinion, starting from your tire through the drivetrain to the pinion. Total torque is the same regardless of where the gearing reduction is in between. Does that help?
@@BoomslangSuss there were some discussion a while before, that it makes a difference,
1. That the "plowing" effect is different.
2. Overdrive in the axle causes a larger gaps in gearing between that two ends of the driveshaft causing more torque twist.
@@AnanFakheraldin 1) I'm not sure what's meant by plowing. If you have front overdrive and forward weight bias, you front wheels will have more traction and drag the rear wheels.
2) If the available gear ratios are different between driveshaft, portal, axle and/or transmission then yes, the resultant torque will be different. If you are assuming an identical gear ratio from wheel to motor then there will not be any difference in torque twist. Think about what causes torque twist - picture your motor spindle/pinion being locked. The motor housing, which is connected to the chassis, rotates around the pinon, causing the chassis to rotate relative to the axles. The magnitude of this torque is the total gear ratio from your tire (assuming equal sized wheels) to the pinions. It doesn't matter where the gearing change is in between - only the total net torque is what matters.
Some people will say that portals have less torque twist, which is true if you are simply adding the 2:1 portal reduction on top of your other gearing. But you wouldn't just add portals without adjusting your other gear ratios accordingly. You can't just add a 2:1 gear reduction and say the result is different. You've also halved your speed so it's no longer apples to apples. A portal makes no difference in torque twist if your total gear ratio from wheel to pinion is equal. If you are adding a portal with no other changes, yes your result will be different.
@@BoomslangSuss it make sense, your explanation about torque twist is different from what i understand, as i always though its the due to the difference gearing on the chassis than on the axle rather than the transmission case that wants twist.
@@AnanFakheraldin Your entire drivetrain sits on bearings, so there is no way that any part of that drivetrain could rotate it's housing (except for a negligible amount of bearing friction) until there is resistance. The only resistance is at the tire and at the motor and that's where the reaction forces act.
So if you also go watch a video from cleetus with live video of the rear suspension, it lifts under acceleration, which I'm turn puts more weight on the front, also with separation at the chassis it creates more leverage on the chassis it's self actually trying to stuff the front end into the ground. Same goes for anti dive, this stuff is all apart of almost every live axle vehicle.
Who is this cleetus?
Was the vehicle front or rear drive or 4 wheel? I’d be interested to watch that also
@BoomslangSuss yea I agree links and anti squat play a huge part in rc tuning. We're not like the 1:1 gas powered rigs he showed as examples
@@lowslowcrawlers1304 At slow speeds the linkage geometry does not matter. There is simply no math that supports that. If you find some, please share.
@@independentmind1977 The vehicle in this video is 4WD.
If torque twist is caused by the motors rotation, could the motor be turned 90 degrees to change the movement front to back, rather than left to right? Do MOAs have torque twist?
MOAs do not have torque twist - that is the beauty of them. I like where your mind is going. As long as there are perpendicular driveshafts I believe torque twist is still going to be there. A belt drive front to rear where the torque is never redirected 90 deg might have to be the design. This deserves more research. I want to design a MOA that still looks like a shafty - same axles but with a motor attached to the rear axle and driveshaft to the front - could possibly eliminate MOST of the twist since it comes primarily from the rear.
@@BoomslangSuss both of those sound like a good idea!
@@BoomslangSuss this may not apply, but rc planes have the motor angled to offset the torque of the motor and fly straight. Could a combination of offset differentials, and angling the transmission the right way, make the driveline no longer perpendicular to the axles to offset some of the torque twist? The driveline u joints would be stressed at the axle side from the high angle, but it would be worth it for reduced torque twist.
@@ShoddyRC I like how you are thinking. You would need to have the pinon coming off the pumpkin skewed to one side for it to work.
@@BoomslangSuss that’s probably why it hasn’t been done. I think your moa rear axle idea is the most realistic.
The only difference ive seen with a link raisers was side hilling.didnt make sense to me but my rig was more planted on sidehill
It changes the way the rear axle swings side to side, so I could see this being the case. Great topic to research more.
I think it's a topic less explored do to lack of knowledge.squat and dive I use more in racing off road..but like I said I played around with a link raiser to see if it helped with my up hill climbs it made no difference.but I left it installed because I noticed it did help on my side hilling.i haven't put much thought into the why it helped part
Your not changing the AS enough for the design of the rig.
What is the actual AS numbers of your High and Low AS?
I should definitely make one that is more exaggerated.
@@BoomslangSuss so are you not doing the math to find the actual AS numbers?
@@phuzzit Yes, I know the AS numbers and you are highlighting a great point. Many people probably don't know where their AS is to begin with and how much/little it changes with a link riser. Also, the primary point of this demo is to show that changing your AS doens't push down the front end. Even if you started with 50% Anti-Squat and switched to 200% Pro-Squat you would not see a difference in this slow test. Finally, I selected this link riser height because it's pretty typical of the height that most after-market risers offer, but you make a great point that a more exaggerated difference might be more compelling, though the results would not change.
On this test vehicle, the low setting is 105% and the high setting is 135%. Typically, a 10% difference is any human factor experiment is detectable by feel or by eye.
@@BoomslangSuss that's not typical rear AS numbers for people that comp (and thats without taking into account what your front AS is), so your findings aren't quite reliable. Your crawler also is not setup in typical fashion, you have it setup to to give your the results you want.
So the comparison of your rig to others won't be the same.
@@phuzzit I think you are missing the point - AS is irrelevant at slow speeds. The underlying physics apply regardless. I would like to see the contrary if you can demonstrate it. Also, no such thing as front AS.
Gonna stop at 2 minutes and say anti squat is part of the acceleration but it's not, i would say it's more based on the torque being I've messed with rc suspension alot and seen first hand how link separation(mostly chassis side) makes a huge difference while under load.
Firstly, there is no suspension engineer in the world that would agree with that - every anti-squat tratise talks about acceleration. Secondly, find a first year engineering student in Statics 101 and ask them to draw a free body diagram and you will see that link separation is not a factor in any way. But if you found a set up that works for you, run it! Don't let me dissuade you.
Me looking at the comments and trying to understand all this scientific stuff on suspension setups and gearing and such when I only just got started in crawling and building on a Redcat Everest 10 looking at it thinking like wtf have I gotten myself into here😂
Yes I know my grammar and punctuation sucks but I don't care
This is a great hobby for tuners and tweakers, but don't let that overwhelm you. Just get out there, drive and have fun.
Just curious, have u ever built an MOA rc crawler? Do a test on real rock. With link riser and without.. not on a stock trx4.. a super class full custom crawler.. every single competitor in the past 10 years has used a link riser lol
That doesn't mean it's right. F1 cars don't look anything like they did 10 years ago. Duplicate this test with any Super and you will see the same results.
Sorry i won't be taking my link risers off or telling people at the comp next week that link risers don't work. U didn't even mention overdrive vs antisquat and a lot 0f people run overdrive.. how many 1:1 run overdrive? 0
@@lowslowcrawlers1304 Funny that you mention that because I did an entire video on overdrive.
czcams.com/video/Eb5xjllzd4E/video.htmlsi=kxzclsrXGWhLtI--
I still fail to see how putting the rear tires in a complete bind proves anything. Any type of suspension setup would react the same way.
High anti-squat looked better on the ramp.
When you are climbing up an incline, your wheels are turning clockwise and there is resistive force at the tire contact patch, that wants to turn your axle and everything attached to it counter-clockwise. The steeper you get, the greater that counter rotating torque on the chassis. Eventually, your chassis will flip over backwards. Holding the rear wheel simply jumps you ahead to that tip over point. Force directions, actions and reactions are the same at any force and torque levels. Binding the rear wheel is just greater force than creeping up an incline.
Your words exemplify my point exactly. "Any type of suspension would react the same way." This is exactly what I am trying to point out. Your wheels turn CW. Your chassis turns CCW. There is no linkage design that will change that. It's impossible to push the front end down - it can only lift.
czcams.com/video/SBM-YNwr2qU/video.html
While slow crawling it make no difference. But when I need to "attack" the rock full speed or break during downhill, imo, Anti Squat & Dive helps. The myth, if I understand correctly, is that AS improves slow inclines, right? If so, I agree! Here's my *1/24 MOA* "racing" up the rock... czcams.com/video/ZO3l_SIyc2A/video.htmlsi=BFPqVJTBfenx4E5C&t=83
One could argue that having MOA (front/back like your setups) can change the dynamics though, regardless risers are really nice to move links out of the way! I wish I knew the math, but I would also be intrigued to look at how vehicle weight/distribution vs torque affects things...You're on a light vehicle with some nice torque, but with the ability to really do a speed jump, it's very unique (I've seen it jump from one rock to another.) PS..I ordered a crawler ESC from that German company you recommend, taking a long time to Canada.
@@independentmind1977 Yes, overdrive (20%), weight distribution, low sprung-mass plus the AS should help doing the rock jumping it does. Once planted I like to see the overdrive to suck down the front shocks first, followed the rear. Another big advantage is, that with MOAs there's no need to worry about torque twist.
@@independentmind1977 Hey, that's great. Did you order their new ASX24 ESC? You wouldn't be disappointed.
How much was the shipping cost to Canada?
That little rig is SICK! Dual MOA and your link geometry is even less important. No torque twist and super light sprung weight. I don't think you have enough sprung weight to overcome damping force at any acceleration level. I want to build something like that - super cool.
@@rcrockcrawler I got the next gen model which is for crawlers, so I think that is the one you mention. Shipping wasn’t bad at all to Canada. It was cheaper than buying a mini ESC from the USA and getting it shipped. Also my exchange is better against Euro vs USD. I decided on this one because it is quiet and made by people who are making something unique with real engineering instead of just flashing an am32 chip and overcharging for it. Now to find a small enough battery! It is a long term project for me, not Moa, using a chassis from Prophet Designs (the echo v2) battery on front axle.