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Old 06-18-2012, 07:42 AM   #1
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Default EPA steering adjustment and influence on driving

Guys, I have never worked on my radio setting too much and never bother to understand it too.
But now I am trying to understand it better, and first question is how EPA on steering can change the driving style, some people say that car spins can be handled with this adjustment is that true?
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Old 06-18-2012, 07:53 AM   #2
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EPA is "End Point Adjustment". It means how far the servo moves.
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Old 06-18-2012, 10:52 AM   #3
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For OVAL Racing, I turn my EPA down to about 60%

That way when I dial Dual Rate down, to say 40%, it's really 40% of 60% and each click of steering is a smaller adjustment. (I also set my D/R wheels to 2 and 5, to have an even slower adjustment)

For "On-Road" I set my End Points so that the car will make an equal size circle in both directions (Usually about 4 to 5 feet at a very slow speed.) with the Dual Rate set to about 80%

That leaves me a little MORE steering I can put in, if needed but with the equal size circles (turning radius) it seems to make the car more stable turning both directions.

Using REALLY Fast/Good Servos, I also use the Servo Speed, and turn that down on Turn In speed to about 60% to start, and adjust from there. (I almost ALWAYS leave the return speed @ 100% so the car staightens up fast coming off a corner)

That seems to take a squirrley feel away from the car w/ fast servos.

...No Idea what GOOD Drivers do, but I know I drove a few PRO guys cars, and was shocked at how twitchy and out of control they felt going straight, and figured "WOW, these guys have hand control"
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Old 06-18-2012, 11:20 AM   #4
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Find somebody with setup stands. Use epa to adjust max steering lock at 100% d/r. You should have the same lock on both sides indicated by the number of degrees on he inside wheel. 25-30degrees is lots. Then you can adjust steering sensitivity with d/r or exp as prefered.
Your epa wont always be the same left/right. Depends how centered your servo arm is and now much mehanical exponential your steering system has. Straighter the steering link to the servo the better.
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Old 06-18-2012, 11:48 AM   #5
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I agree with Valk on using a setup system to get your steering throw equal. IMO it is bad practice to use EPA solely to get equal circles. If your steering throw is the same both sides and your car doesn't turn equal circles, there is something else out of whack on your car.If that happens, one really should find out what that is.
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Old 06-18-2012, 12:00 PM   #6
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you will find out that you don't need 100% steering on most conditions and that you are actually faster if you don't steer as much.
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Old 06-18-2012, 01:21 PM   #7
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To much steering input will cause the car to first push, as the slip angle on the tires is to much for traction. Once the speed is scrubbed off, the front tires will finally get bite, and the car will snap loose on corner entry. All to common when watching new racers that have to much steering.

A well setup car uses surprisingly small amounts of steering to turn the corner. A common sign of to much steering angle is front tires that wear out quickly (on pan), and removing the rubber off of the rim in TC.


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Old 06-18-2012, 01:56 PM   #8
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I always set my EPA to have the steering knuckles just off the C-hubs, so reduce them until the servo stops buzzing, then a couple of points more.

You can then use the dual rate to reduce it further if necessary and use expo to control the speed.

I try to have max dual rate and just use less steering.
I also have around -20 to -30% Expo so I can make small adjustments traveling along the straights etc without the risk of overdoing it.

The other piece of great advice above is the part about using as little steering as possible to turn a corner.
But you'll probably have to work up to this by steadily making the steering more sensitive over a period of time, to allow you to get used to it step by step.

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Old 06-18-2012, 02:39 PM   #9
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Quote:
Originally Posted by Skiddins View Post
I always set my EPA to have the steering knuckles just off the C-hubs, so reduce them until the servo stops buzzing, then a couple of points more.
+1 on this. No sense trying to force a knuckle through a c-hub.

If your servo is trying to move the knuckles past their physical limits and it has a big enough draw it can cause a type of "brownout" where the esc/receiver cuts out momentarily.
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Old 06-18-2012, 04:05 PM   #10
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Quote:
Originally Posted by FauxMako View Post
+1 on this. No sense trying to force a knuckle through a c-hub.

If your servo is trying to move the knuckles past their physical limits and it has a big enough draw it can cause a type of "brownout" where the esc/receiver cuts out momentarily.
If it starts to buzz it is also starting to cause tweek in the chassis.
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Old 06-19-2012, 08:09 AM   #11
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If my steering travel is unequal left to right, assuming the setup is 100% the same on both sides of the car and the chassis isn't tweaked, I turn the EPA down on the side with more steering and change the car setup to gain back overall steering.
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