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Old 03-07-2010, 03:03 PM   #1
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Default How much dual rate do you use in TC ? expo ?

hello all;

I've been wondering for a long time how much dual rate to use on my TC. I've learned that in 1/12th using full steering throw is something that kills your cornerspeed, and ruins the balance of the car.

But in TC ? I see the latest xray has more steering throw. However in TC my experience has been close to my pan car experience: more grip front with less steering throw = better overall.

To be more specific : I used to have 100% steering throw with front tires sauced half the width for 20min while my rears were sauced 40min on the whole width.

Now I use maybe 70% dual rate( steering throw) with the fronts sauced on the inner 80% for 20 minutes. I even use a shorter wheel base and a LTCR, and the car is (I think) better.

That's on a tiny tech carpet track. So what's the point in having new c-hubs or whatever, to gain steering throw , when my car feels best with much less? Am I lost on a wrong setup path ?

I would like to have the experiences of very good TC drivers , to know what they do in which circumstances. How much dual rate do you use ? when? How many % ? how many degrees of the inner/outer wheels ?

On a related note, I read somewhere that Reinhard (for instance) uses insane expo values, like -70% on extreme cases. Is that something I should explore ? Like having a ton of steering throw AND a ton of expo, so that in wide corners I have little steering and a very short steering radius in the tight corners ? For now my expo is always between -15% and -25%.

We could also talk about ackermann, but the whole issue seems complicated enough already

I would like to have the input of good to excellent and eperienced drivers, please, so if you doubt that you're in that range, just read and learn- like me...

Thanks a lot ! and sorry about the approximate english.
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Old 03-08-2010, 02:27 AM   #2
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nobody? Is there something hard to understand inmy first message ? I can say it another way if you ask...
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Old 03-08-2010, 07:26 AM   #3
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I don't know who qualifies to answer that may be a reason for lack of posts, but I'll throw in my .02. I didn't think I was qualified to help but reading the Reinhard comment I felt the same. To me, there is a term I think of as usable steering. Think skid pad, whereas a turning radius a car can maintain before spinning. The radius is achieved through various tuning methods (shocks, castor blocks, tires etc.). Any steering over that radius to me only upsets the car to me and I dial out most of it with dual rate leaving a little room for play. Hence my dual rate on my sedan (with a one way) is @ 52 On straightaways @ speed I prefer for my smaller corrections not to be to large so I set my expo to -35 sometimes as high as -63 on my 1/12. Not saying I'm worlds material but I think it's a decent feel
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Old 03-08-2010, 08:03 AM   #4
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you're going to get answers all over the board for this, and that's okay, assuming it doesn't turn into a p*ssing match.

most of the guys i run with run around 5ft-5.5ft circles on the track. (the dual rate number is only a relative number). some of the guys i've run with over the years have run full lock (drew ellis to name one), while others prefer to run bigger circles (brad johnson lately). some use expo, while others don't like to monkey with it.

i liked the 5-5.5ft circles, and about 15% negative expo in my foam cars. on rubber, i'm still finding my way, but more expo does feel better if the car is agile enough. the rubber cars turn in, and quit, so the extra expo actually helps get back to a linear feel at the wheel.

i also won't run a ton of expo if the steering geometry/servo is slow. there's a general speed that has to be there, and if it isn't, adding expo will make it feel slower (because you have to turn the wheel further, not faster).

in short, keep things moderate, and go from there. like anything else, there's more than one way to skin a cat. if you want to run lock/lock, your setup will be different than someone who wants to run 8ft circles. each will have it's limitations, but if you drive both the way they need to be driven you'll get the same result.
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Old 03-08-2010, 08:17 AM   #5
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Lately I've been running more D/R with expo. Basically, to smooth out the initial steering, and then get it back mid-corner where the car wants to wash out somewhat. A little bit of expo goes a long way.

I like to set my steering to full lock, and then adjust the end points so it feels like it turns the same left to right on the track, rather than having my circles look them same in an open space. Then I adjust D/R and expo to get the feel and amount of steering I'm looking for.

I suspect you'll get as many different answers on this as you have people posting in the thread. It's one of those things that doesn't get talked about much, and I think makes it hard to really glean too much from someone else's car setup other than the basics. Find what works for you and make it fast.
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Old 03-08-2010, 08:52 AM   #6
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Thanks for the answers guys. I know that there are some very talented or at least experienced drivers here, so I have no problem choosing the quality of the answers at the expense of the quantity. You confirmed what I thought : different tastes, different habits, etc.

I get my butt kicked on a very regular basis by a friend who likes having a very wide turning radius, and he gets beaten badly by another guy who likes a small radius. So I suspected it was rather the driving abilities than anything else that made a difference.

I 'll try and explore these things when I get the occasion; one more line on my "to test at the track " list... ha-ha.

Keep the comments coming though, it's always an interesting read. Perhaps some Rc-semi-gods could tell us what they think ? M. Lemieux, M.Hohwart, etc, etc... or perhaps I'll just ask them in their respective threads ?
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Old 03-08-2010, 12:33 PM   #7
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Found this on Paul's old thread:

Originally Posted by tamiya_008:
"hey paul what sort of radio settings do you play with,like punch,curve,trim???also on a brushless do you set your radio so that throttle hits exactly at the end???"

"Hi, i Pm'd you also. I only use my Trims, sub trims, both Expos (curves) sometimes, and EPA's. my throttle is set so it is not full throttle untill the very end, or super close to it.
But i really dont play with anything except steering expo, car is twitchy and a bit hard to drive i will throw a little extra in, ill normally start with 10% and go from their, I only use throttle expo when im running 2cell lipo mod."

Thanks, Paul
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Old 03-16-2010, 01:32 PM   #8
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I always run no Expo and just adjust my D/R depending on how the car feels. I rarely run full lock but usually like 14-15 degrees of throw on the outer wheel.
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Old 03-16-2010, 01:50 PM   #9
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well, you guys are better wheel men than I. I have to use +57-65 expo on my radio. My hands get the shakes, and it seems the better I do, the wose it gets. So, I have to dial that out as best I can.
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Old 03-16-2010, 02:07 PM   #10
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Like Seaball said, I like to run enough d/r to be able to make a U-turn in the tighest part of the track, when required. Usually 5-6 feet works good. Then I'll adjust if required, but I usually just wheel it from there. As far as having more steering throw available, that could be a couple of things. As you approach the limits of any kind of travel, the car could start to do funny things. Increasing the limit could help prevent that. For example, we have a guy with a losi that locks his steering out when he hits the wall. The linkage goes past parallel and the servo can't return to center. We glued a small washer on the knuckle and it solved his problem. Better driver's, like Rheinard, may be able to control their cars better than the rest of us mortals and NOT turn the wheel too much. Instead of taking steering out of the car, he just doesn't turn the wheel that far, but has it available when required. I'll stick with D/R.
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Old 03-16-2010, 02:29 PM   #11
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The thing you have to be careful with on expo is that if you go much beyond a reasonable amount, say 15%, is that the car will feel dead off center and then the steering comes on when you don't expect it. I once tried a guy's car who had like 35% expo in it without him telling me. I was wondering why the car pushed and then POW it went into the board like something was broke. I did this like 3 times and then asked what was wrong with his car...he then told me he runs an ass load of expo

What I do find works better is to reduce the steering speed if that is available on your radio. It slows the servo down in a linear fashion, which is much more natural.
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Old 03-16-2010, 02:34 PM   #12
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I always set it on max. I check if the steering blocks not push to hard against the Castor blocks.
I always use max steering. I tried less but I play a lot with the steering.
Also do I use a lot of ST EXP.
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Just be careful with the steering els you will crash even on the straight.
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Old 03-16-2010, 03:07 PM   #13
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I believe it is true that on some radios + expo is the opposite as it is on others. Can anyone verify this? or do all manufacturers use the same +/- meaning?

With the Spektrum DX3R, + expo usually means less servo movement for more movement of the wheel or throttle. This effect progressively increases the movement of the servo/wheel or throttle, at a curve on a graph, that is determined by the % number, until full throw is achieved at the end of travel.

If some radios use - expo to mean the same thing, it would make things rather confusing, like Reinhard's use of -70.

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Old 03-16-2010, 03:12 PM   #14
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Interesting answers from you all...

I am tempted to test the "full lock + lots of expo" school just to see if it might be a good driving school, ie learning not to turn too much, instead of relying on the limits of my driving wheel 90% of the time but being forced to wait a bit because of the little understeer when my corner entrance is a little "optimistic"....Which happens easily if someones pressures me from behind, giving him( or her ) the opportunity to pass even more easily. That situation happens a lot, because I run 13.5 in our 10.5 class ... so I have to make tremendous efforts to keep the doors shut at all times!

I'll test it for a few packs with a grippy/agressive front end setup to see if I can get used to to it.

I hope my english is understandable.

Mikky what is "els" ? typo ?
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Old 03-16-2010, 03:15 PM   #15
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Depends on track you run.
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