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Old 08-30-2012, 11:21 AM   #1
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Default On-Road Steering Setup

This topic is not necessarily about the technical minutiae regarding mechanical settings related to the front end of your car, but more so what everyone's approach is to how much steering travel they actually use on their cars and how it affects their overall setup.

Premise:

I also participate in full-scale motorsports--track days (auto and motorcycle), autocross, and even managed to take home podium spots at the local and regional SCCA levels.

One observation I find quite interesting is that on full-size cars, we are no-where near using 100% of the total steering travel. On a track day, maybe we are using 360 degrees out of a total 900 degrees of steering lock, which amounts to 40% of total steering travel. On an autocross, we are using 540 degrees out of a total 900 degrees of steering lock, which amounts to 60% of total steering travel.

Now on r/c cars, just about everyone is using 100% of their available steering travel (i.e. people are right on the mechanical stops) to clear at least 25% of the corners on the track (I'm guilty of this myself). This is more prevalent with cars running front spools.

This, to me, shows that while we all maybe getting around the track quickly and consistently enough, that there is massive amounts of tire scrub happening on the front end of our r/c vehicles--leaving room for a better, more balanced setup. On my 1:1 cars, if I had it set up the way I have my current r/c setups, I would be very, very slow and shredding front tires every single weekend.

I've already started testing to see what reducing steering throw will do to my times and setup. I've reduced dual rate such that my car can just make an 4' turning diameter at slow speeds(minimum ROAR track lane width is 8'). So far, at least on my touring car, I've been able to not run any expo on the steering (I'm liking the more linear feel), replaced the front spool for a gear diff, and overall have been setting up the car to get more oversteer, which in turn has given me a setup where the front springs/dampers are very close to each other in terms of spring rates, oil, and pistons. I've also adjusted to a more flowing driving style, with less drag brake, and higher corner speeds.

I'd like to get thoughts and comments if anyone else is running their cars similarly. Let's keep it constructive as this is meant more as a discussion of the different philosphies of car setup and not a discussion of what is the "right" or "wrong" way to setup a car.

Last edited by TwoWheel; 08-30-2012 at 12:56 PM.
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Old 08-30-2012, 11:38 AM   #2
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I typically run my dual rate at 80-85%, and still do not hit full steering lock unless I've made a driving error (entering too fast, etc). And this is on a small carpet track with lots of hairpins. 8' turning circle seems a bit extreme, depending on your track. It's nice to have the extra throw when you need it, you just need to learn to modulate your steering input.

I see a lot of less experienced racers steering lock-to-lock and tuning their chassis with a lot of understeer to compensate. Obviously this is not the fastest way through the corner. See if you can test drive one of the fast guys' car at your club, I bet it will be a lot more twitchy than you're used to. It sounds like you're on the right track
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Old 08-30-2012, 12:45 PM   #3
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I have thought about doing this a few times, but never put the time into it. I believe that the relative grip we have compared to 1:1 is so much different that we cannot simply go by "what works there". We also have easy access to ackerman adjustments, which can vary your slip angle greatly between the highest and lowest settings in most cars.
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Old 08-30-2012, 12:48 PM   #4
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I set up my car for 100% mechanical steering throw and run 100% D/R. that does not mean I will use it but it is there when you need it. Especially when you need to turn out of trouble.
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Old 08-30-2012, 01:16 PM   #5
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Edit: Main post edited to show that the turning radius for my car is 4' instead of 8' (I was typing furiously away and my brain was falling behind )

I wanted to set this "artificial" limit to see what it would do to my setup--and I I'm still able to do a u-turn in half the minimum lane width.

@Rick, thanks for posting and your input is greatly appreciated. My baseline setup is for 100% mechanical steering and 100% D/R. With that setup, I have to run some negative steering expo in order to have a car that was stable enough for me to drive quickly, at least for my skill level. What I don't like about it is the non-linear steering feel--although I have been dialing back the expo as I've upgraded to a nicer radio system.

I think what I really would like is a transmitter that had more steering wheel throw than the 90-120 degrees that we are getting now. So in that respect, that's what I'm attempting to do with my setup--lots of steering wheel throw but I want it to be linear--which means no expo. I sacrifice total mechanical travel to get that though.

Thanks for the replies so far, keep them coming.
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Old 08-30-2012, 01:36 PM   #6
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As you've said, to be able to get the ultimate fastest laps, you want a car that will turn with the bare minimum of steering lock being used.
This is easier said than done, as by the time you have a car setup that will achieve this, it will be very twitchy and far more difficult to drive.

However, once you can drive a car that is more on edge you will be faster.

Your idea of having more lock available on the transmitter is not ideal as you will be wasting time turning the wheel.
Try and get used to only using small amounts of lock.

Skiddins.

P.S. I always forget to reduce my D/R on carpet, so I have 100% lock, I just try to use whatever is needed in any corner.
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Old 08-30-2012, 01:41 PM   #7
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Quote:
Originally Posted by Rick Hohwart View Post
I set up my car for 100% mechanical steering throw and run 100% D/R. that does not mean I will use it but it is there when you need it. Especially when you need to turn out of trouble.
+1 or in my case try and keep my car under control when I make mistakes or bounce off a barrier.

I'm sure if I could run a great line lap after lap it may be different?
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Old 08-30-2012, 01:46 PM   #8
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While I'm a complete noob here to onroad RC, I do have a few 1:1 track days under my belt. I just don't think you can compare the two directly. First thing I've notice is the lines. In RC, it seems that the fastest lines are an early apex, which is NOT the fastest line IRL. But, IRL, we don't have cars that can go 0-600 mph in 2 seconds, so diving into corners cutting off those on a "proper" line is rewarded with a place advancement.
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Old 08-30-2012, 01:52 PM   #9
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Quote:
Originally Posted by Rick Hohwart View Post
I set up my car for 100% mechanical steering throw and run 100% D/R. that does not mean I will use it but it is there when you need it. Especially when you need to turn out of trouble.
I need to learn how to steer like this with 100% DR. I currently set my dual rate low and have a 100% DR panic button I can punch when I get in trouble, but it's somewhat difficult to reach and sometimes gets me into even more trouble when the car is suddenly turning at 100% with the same input that steered 65% just a second ago. <-- is that a run on? Also, having to click in/out DR on the straight can be nerve racking and result in epic crashes.
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Old 08-30-2012, 02:09 PM   #10
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Quote:
I think what I really would like is a transmitter that had more steering wheel throw than the 90-120 degrees that we are getting now.
You could try getting a bigger wheel, or wrapping the wheel with something, this would effectively give you a more granular feel, slowing down the steering response.

Another option, is many radios have "steering speed" settings. I turn my down a bit to make the servo a little slower.
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Old 08-30-2012, 02:25 PM   #11
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Another option, is many radios have "steering speed" settings. I turn my down a bit to make the servo a little slower.
That is a bad crutch to rely on in my opinion.
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Old 08-30-2012, 02:38 PM   #12
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What ive tried lately is setting my
Max epa to 25 deg. I dont run any dual rate but possitive expo. This has helped me learn to corner with the throttle better and find the RIGHT corner speed to not scrub. Car is very sensitive but im finding myself feathering the throttle
More to get around corners than cranking the wheel a lot.
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Old 08-30-2012, 02:40 PM   #13
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When I first started racing I had HORRID steering habits. If I wasn't dead center or full lock, but nonetheless always let the wheel "pop" back to center under it's own device. I didn't even realize I was doing it until a local fast guy pointed it out. In an effort to rid this habit I started practicing on VRC a bit.. but I did something a bit extreme. I actually removed the steering return spring from my 3PK. Yeah, now that's difficult let me tell you. It forced me to keep control of the wheel otherwise the steering simply wouldn't do anything at all. I don't have that habit anymore.

Steering setup probably has quite a bit to do with driving style I imagine. I've improved greatly in the 1.5 years I've been racing and find that I tend to steer fairly smooth now. My car never really looks fast even when I'm putting down respectable laptimes. As noted I use a 3PK and I've been driving a JRXS-R since day one. My EPAs are set for 16* of full lock steering at 100%, but I typically drive at 93% (15.5*). I always run 20% expo. As far as how often I use all 93% I'm not really sure. Would be nice to put a GoPro on my Tx and watch the steering/throttle throw (from the display) in replay. Hmmm... that's actually a really good idea...
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Old 08-30-2012, 02:46 PM   #14
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Quote:
Originally Posted by erchn View Post
You could try getting a bigger wheel, or wrapping the wheel with something, this would effectively give you a more granular feel, slowing down the steering response.

Another option, is many radios have "steering speed" settings. I turn my down a bit to make the servo a little slower.
Quote:
Originally Posted by Steve S View Post
That is a bad crutch to rely on in my opinion.
I actually used this at first to help curb my steering problems. I didn't use it for very long though. I really think the return spring training was the single biggest factor in helping me kick the bad steering habit.
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Old 08-30-2012, 03:30 PM   #15
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We are thinking about this all wrong, 1:1 or 1:10, cornering force is still Velocity Squared / Radius. If an R/C car were to take a corner the size of a real race track, like a nice big oval would have, it only needs a tiny fraction of its steering throw. Oval cars do this, set to where max lock on the transmitter is only how much they need to clear the corner.
Real car racetracks have the advantage of never having a super-tight hairpin where the car has to change direction 180 degrees in three car lengths, if they did, like on an autocross course, you would be either at full lock or swinging the back around just like R/C racing. Real cars also have the advantage of driver feedback, if you had to watch your 1:1 car start to go loose and then react through a control, it takes many times longer than it does if you're actually in the car, as a result r/c car have to have a super forgiving back-planted setup.
One other reason for lock-to-lock racing is the massively increased number of steering inputs per second an r/c car has as opposed to a real car. My home track has a layout which a 1/12 scale car can go around in ten seconds flat with good traction, and in that ten seconds you may make 20 distinct steering inputs, more if you count pauses at center. It is beyond human ability to figure out how far they have to turn the wheel for each one if the punishment for turning the wheel too far is to spin out. That doesn't even count throttle inputs.
I think if we had a superhuman reflex acumen an r/c car could keep more energy through corners if the wheel was only turned the exact amount it needed to be, but its infeasible for real humans. Lock to Lock Forever!
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