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King Mustard

Making steering less twitchy

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In the next few weeks, I am going to buy my first RC car.

It will likely be a TT-02, as I want 4WD. Specifically, I will probably get the Tamiya 58682 ('1991 Audi V8 Touring').

I know I will need to buy a radio, receiver, servo, battery and battery charger.

RC cars tend to be twitchy, from what I can tell, when you steer left and right. However, I want mine to be smoother - almost like a real car.

To do this, am I looking for anything specific when I choose the radio, receiver and/or servo, or do they all allow this option?

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There are two main things:

- Servo speed

- Precision in your fingers

I am afraid, that even slow servo will be MUCH faster than even professional racing driver in real car. Slow servo means around 0.2s from side to side movement. It is FAST, compared to real vehicle.

You will quite quickly find, that you need fast servo, because RC car reactions are much faster than real car. As an example, I can tell that I run my TT-02 on area with bit of dust and sand on the edges of asphalt. If I touch that part with rear wheel, car will rotate so fast, that it is even impossible to react. If cars starts to slide on asphalt, you need to react very fast, otherwise it will rotate.

I think that you need to think about RC car handling more like about F1 car than about passenger vehicle. Things happen real fast, even if you use weak, slow motor.

There is also Dual Rate option in most of good but still basic radios. It will limit angle of turned wheels, but you will have the same amount of steering on radio. Car will be less twitchy but turning radius will be bigger.

I know but have not tried, that on high end radios, there is a possibility to slow down servo.

Why you want to do this?

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I guess pretty much all radios have the dualrate (DR) adjustment. That will allow you to reduce maximum steering angle, which will make the car less twitchy.

Then mid range to high end radios have steering exponential (st exp or something similar) adjustment, which will allow you to make the steering response nonlinear. With negative expo, you will have less steering output near the middle position of the steering wheel, and more steering output near the ends. This may also help with too twitchy car.

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Regarding servo speed, in my opinion it is much easier to control a car with a fast servo. Otherwise it feels like the steering drags behind the control inputs, and it feels horrible.

 

edit: By fast servo I mean something in the ballpark of 0.1s/60deg or faster.

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A transmitter with EXP settings. 

kVyn3cn.jpeg

Also more toe in makes the car less twitchy. 

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These days both transmitters and servos can be programmed.  You can also purchase a gyro to help stabilize the car.  Some transmitter brands have receivers with gyros built into them.

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i guess a bigger steering wheel for the transmitter could be an option. but not that it would make a huge impact. a smaller steering wheel would turn sharper, but also be more sensitive. a bigger one could be better for precision steering as it need to rotate more to turn the same distance, thus reducing the twitchy feel.

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7 hours ago, King Mustard said:

RC cars tend to be twitchy, from what I can tell, when you steer left and right. However, I want mine to be smoother - almost like a real car.

Interesting that you get a barrage of tips before you even bought and built your TT-02. Fear not: there's really nothing twitchy about the TT-02. It's a mild understeerer designed to suit the greatest number of hobbyist and especially the newcomers. In fact if you build it per the instructions and using the kit supplied tires you will have to get your braking technique down to make it steer half decently (slight breaking before initiating the turn to load the front wheels and make then bite). I think it's actually very realistic and a joy to drive. 

Best of luck!

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16 minutes ago, Pylon80 said:

Interesting that you get a barrage of tips before you even bought and built your TT-02. Fear not: there's really nothing twitchy about the TT-02. It's a mild understeerer designed to suit the greatest number of hobbyist and especially the newcomers. In fact if you build it per the instructions and using the kit supplied tires you will have to get your braking technique down to make it steer half decently (slight breaking before initiating the turn to load the front wheels and make then bite). I think it's actually very realistic and a joy to drive. 

Best of luck!

I was thinking about saying something similar. 

In starting out in RC I think there's wisdom in starting with a standard (ish) build and experiencing how that drives and how you feel about that, in the hand as it were, before then heading down a track to make it different. 

I'm all about modifying stuff, and am sometimes guilty of modifying what I hardly even know, but that's because that's how I get my kicks. I'm not sure it's advisable really. Part of the fun is to start with something stock and then to make it your own. 

It could maybe be said that one person's "twitchy" is another's "responsive"? For me, a faster servo and faster radio just gets it to do what you want when you want it. I'm not sure that makes a car "twitchy" does it? 

I'm tempted to think that a more appropriate way to dampen how a car works might be found in stuff like tyres, setup (toe?) or the choice of the type of car, like something a bit slower and taller/softer for off road perhaps? 

Plus I think a considerable handling difference is inevitable when you're talking about the acceleration/speed/[choose your statistic] of an RC car which scaled up bares no resemblance to any road car anyway, unless you're in the world of scale off roaders, crawlers and the like. Scaled up, these things would probably take off! 

Also, as @Pylon80 says, the TT02 is understeery. It's also got quite restricted steering throw when built as stock. Many of us (me included) go looking for ways to fight these factors in the other direction. 

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You have many options to tune with. Expo and dual rate on the transmitter, toe on the car, servo speeds, tyres and more. 
 

As @Pylon80 and @BuggyDad say, start from a default build and find the direction you need to go in naturally, modifying at the start car be frustrating if it doesn’t suite your own style and can lead to rabbit holes.

Things on a transmitter you probably want are end points, exponential and dual rate. A Flysky GT5, gt3b or c or that DUMBORC one that came out short ago will do that without breaking the bank. 

As for a servo just have a look through some build threads on here and see what people are building with in terms of speed and strengths and what their experience was. Might help you find some tips n tricks for other parts of the car too. 

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1 hour ago, BuggyDad said:

I'm not sure that makes a car "twitchy" does it? 

Right on Mister @BuggyDad. I think it's a common misconception that a faster servo makes the car twitchy. Well, it could, it it were something like a poorly setup pan car on carpet; a slower servo would still not be the appropriate fix. Here, you could install the fastest servo on the market on a stock TT and then run it on your driveway and it wouldn't make it twitchy at all. There's just not enough front grip for that. 

There was once an interesting discussion here from a member who had built two rally chassis, an XV-01 and an XV-02 for good measure. Can't find it now. But anyway, he was complaining about the cars being close to uncontrollable. Turned out that he had maxed out ride height which left the cars with 0 droop, making them uncontrollable. In the meantime post after post were discussing which slower servo was urgently needed...

Let's put an S3003 in that TT and get it rollin' :D

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On most cars I would say you add or remove steering/responsiveness/twitchiness by changing toe. However, i'm not really sure what is mesnt by twitchiness in this case. 

The TT02 is the one car where i had all sorts of issues which was caused by the sloppy steering and it took ages to sort out, requiring a mix of hopups or ghetto mods. It also doesn't have toe adjustments as standard.

 

Given the OP hasn't bought a kit yet, I think the answer is to buy a TC01 or TA08 which won't have any issues out of the box. I've seen deals on the TC01 recently which would work out much cheaper than a TT02 with a few hopups

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3 hours ago, Jonathon Gillham said:

Given the OP hasn't bought a kit yet, I think the answer is to buy a TC01 or TA08

Just looked up the prices of these and am somewhat surprised they're £200ish against similar for TT-02 plus modest upgrades. I guess they need the caveat that they'll be a much more involved build so I don't know about them for a first kit but for sure if I was even vaguely considering a TC now I suspect I might be on one of them like a rash! 

 

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I just remember I had experienced one other possible reason for the car "twitching". Ages ago, I had a problem with the car suddenly turning right into a wall with no input from me. 

Although at that time, some "expert" said it is due to my "cheap" radio. I refused to believe it as it is actually a highly recommended radio here and used by many. So I  did further investigation. It turned out that it was the servo was overpowering the BEC. Everytime it tripled off and on the BEC, the receiver will "wiggle" the steering a bit as part of its startup. This gives the impression that the car was twitching. The trip and reset happens very quickly, and usually a distance from the driver, so it may not be noticed at all and put down to twitchyness. 

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The linked kit doesn’t have an esc included.  Choosing an esc with a decent BEC or avoiding an overpowered or power hungry servo would prevent a similar experience to what @alvinlwh had. 

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Thank you for all of your responses; it is appreciated it.

In the end, I decided not to go with a Tamiya RC car.

When my new car arrives, I will see how twitchy it is. I know there are many servo upgrades for it to make handling more responsive but as you can imagine from my original post, I may prefer stock if it's a little sluggish.

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19 minutes ago, King Mustard said:

Thank you for all of your responses; it is appreciated it.

In the end, I decided not to go with a Tamiya RC car.

When my new car arrives, I will see how twitchy it is. I know there are many servo upgrades for it to make handling more responsive but as you can imagine from my original post, I may prefer stock if it's a little sluggish.

What did you decide to get instead?

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1 minute ago, TurnipJF said:

What did you decide to get instead?

I have been told in many forum and Reddit replies to my posts, that Tamiya vehicles are mainly good for display purposes and not much else, too many times for me to ignore.

In the end, I got a Maverick Quantum RX Flux. It is RTR but there are enough upgrades I can do to keep me occupied for 6-12 months, so I went with that as my first RC car. After that, I will reevaluate.

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...And another potential Tamiya fan lost to the lies of Reddit... 🙁

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If newcomers are more interested in driving than building rc, then rtr is the way to go.  Trust your decision and it’s already the right one.

 

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Just now, ad456 said:

Hope the Maverick will hold up for ya🤞

The platform seems stable; as in, plenty of spares and opportunities to learn how to repair :)

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On 9/24/2024 at 10:18 AM, King Mustard said:

that Tamiya vehicles are mainly good for display purposes and not much else

What you heard is correct, at least for me. I build a Tamiya from nothing. Spend a lot of time and effort making it good, and lots of money as well! 

So I will want to baby it a bit. The RTRs I bought, gets trashed properly while most of my Tamiya sits safe on display, or driven gently. 

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