how to adjust steering

[JeffKnob]

I was given an old electric car that was missing a speed control and a motor. Once I got a new speed control and motor installed and powered up, I noticed that the servo doesn't turn the wheels far at all. It has about a 20-30 foot turning radius. I thought maybe the servo was bad so I replaced it with a $13 futaba servo. This increased the steering very very little. I have adjusted the connecting rod to the steering so that it is on the furthest hole from the center of the servo. I hope that makes sense. It was only in the third hole from the center. I had to cut off the fourth hole because it would rub on the tub.

I am thinking that maybe the servo isn't getting the signal to go any further. Can this be adjusted? I don't know what kind of radio or receiver is on it. It was the original unit. I do know that the car is some sort of Kyosho. I hope a fix to this won't cost too much because I don't want to put anymore money into this. I would rather put money into my Savage or a new electric car.

[rocknbil]

First, with the servo disconnected from the linkage, is it nice and loose when you move it left to right? Resolve any mechanical binding.

Second, is there a servo saver built into the linkage? On many models there's an adjustable thumbwheel that tightens against a cam and is pressurized by a spring. On a hard hit, the cam separates and absorbs the impact rather than putting it to the servo. Make sure the 'saver is snug enough to not separate under normal driving but if hit hard it will separate.

Third, A $13 Futaba is not really a step up. :D It may be the same torque and throw as your original. for a car, it's probably fine. Remove the linkage and put the horn on with no linkage attached. Turn on the electronics and note how far the horn rotates in either direction. Now put the linkage on and do the same. If it doesn't push almost as far, the servo might not be strong enough for the task (but see below . . . )Also the below many give you more "throw."

Fourth, verify your batteries have a FULL CHARGE and the electronics are all working right.

Lastly, there **are** some adjustments on your radio (transmitter) that can do a couple things. A dual rate adjustment "narrows" the distance the servo moves to either side and is designed to dial out an oversteer condition. Make sure it's set to maximum. Also there is an End Point Adjustment that determines the farthest the servo will go; make sure it's out to max. Also check that the steering trims are not way off center, but that will usually only give you trouble on one side.

All in all if everything checks out, I'd say you need a stronger servo.

[JeffKnob]

First, with the servo disconnected from the linkage, is it nice and loose when you move it left to right? Resolve any mechanical binding.

Second, is there a servo saver built into the linkage? On many models there's an adjustable thumbwheel that tightens against a cam and is pressurized by a spring. On a hard hit, the cam separates and absorbs the impact rather than putting it to the servo. Make sure the 'saver is snug enough to not separate under normal driving but if hit hard it will separate.

Third, A $13 Futaba is not really a step up. :D It may be the same torque and throw as your original. for a car, it's probably fine. Remove the linkage and put the horn on with no linkage attached. Turn on the electronics and note how far the horn rotates in either direction. Now put the linkage on and do the same. If it doesn't push almost as far, the servo might not be strong enough for the task (but see below . . . )Also the below many give you more "throw."

Fourth, verify your batteries have a FULL CHARGE and the electronics are all working right.

Lastly, there **are** some adjustments on your radio (transmitter) that can do a couple things. A dual rate adjustment "narrows" the distance the servo moves to either side and is designed to dial out an oversteer condition. Make sure it's set to maximum. Also there is an End Point Adjustment that determines the farthest the servo will go; make sure it's out to max. Also check that the steering trims are not way off center, but that will usually only give you trouble on one side.

All in all if everything checks out, I'd say you need a stronger servo.

I got the cheap servo because it was cheap and would do the job on a car. I checked to see how far the servo would move and it moves about 180 degrees when moved without power. When not connected to the servo the steering moves about 3 times as far, with no obstructions. I am thinking the servo isn't getting a signal to move any further than about 20 degrees. Would this be something I would have to fix by throwing away the original old radio system and getting a new one with a dual rate adjustment?

Please let me know

[JeffKnob]

I am thinking about cutting my loses with this old car and getting a Traxxas Rustler as my second vehicle. I can then put the upgrade speed control and motor I bought in this vehicle. This would be a great vehicle for my wife to drive while I am out with my savage.

What do you think?

Where is a good place I can get it cheap?

[rocknbil]

.... it moves about 180 degrees when moved without power. When not connected to the servo the steering moves about 3 times as far, with no obstructions....

I really don't think it's a signal issue. The signal the servo receives is the same no matter what you do. It's either just not strong enough or you have something binding in the linkage, did you check that out? If it's smooth a stronger servo will fit the bill, anything 89 oz/in @ 4.8 v or better will work well.

Tower hobbies (http://www.towerhobbies.com) is a good place to start for buying something new, or you could browse through the list of online stores I've collected on my site (http://www.rc-resources.com/cgi/search.cgi?cat=1).

[JeffKnob]

I really don't think it's a signal issue. The signal the servo receives is the same no matter what you do. It's either just not strong enough or you have something binding in the linkage, did you check that out? If it's smooth a stronger servo will fit the bill, anything 89 oz/in @ 4.8 v or better will work well.

Tower hobbies (http://www.towerhobbies.com) is a good place to start for buying something new, or you could browse through the list of online stores I've collected on my site (http://www.rc-resources.com/cgi/search.cgi?cat=1).

So the radio receiver has nothing to do with how far the servo moves. If there is no adjustment on the radio then the servo will just move through its complete span as long as it is unobstructed? If this is the case then the car should be turning completely because there is no obstruction. It still won't turn much if I have the car off the ground and there is not even any friction from the ground. I have a feeling the receiver is telling the servo to move just so far. If that is the case then I will just scap this car and throw it away. It is not worth purchasing a new radio for.

[ITurnLeft]

Sounds like your end point adjustment is set to minimum throw. That's for customizing how far your steering goes when you turn the wheel all the way. What kind of radio is it? Any little knobs or dials that say EPA or TRAVEL? What about a thumbwheel, right above the trigger? If you have any of those, they should be set at 100%, then adjusted down to your driving style.

[JeffKnob]

Sounds like your end point adjustment is set to minimum throw. That's for customizing how far your steering goes when you turn the wheel all the way. What kind of radio is it? Any little knobs or dials that say EPA or TRAVEL? What about a thumbwheel, right above the trigger? If you have any of those, they should be set at 100%, then adjusted down to your driving style.

Nope, there is only steering and throttle trim. The radio appears to be the cheap one that came with the car. I am not even sure what model the car is. The body says it is a kyosho. It is probably very old. My friend gave it to me to mess with because he had it lying around. He doesn't even know what it is.

[rocknbil]

So the radio receiver has nothing to do with how far the servo moves.

Well it DOES, but in the conditions you mention - linkage on and linkage off- you've not made any adjustments to the radio, correct? The adjustments you make on the radio would not affect the strength of the servo. I say it's just not strong enough.

[Mike01]

There can be only two reasons why your servo doesn't move as far as it can: mechanical binding, and radio settings.

There might be a small knob somewhere on your radio called "dual rate" or "D/R". If you can find it, turn it and see what that does.

On the mechanical side, disconnect the link from the servo without removing the servo horn. Turn the wheel, and see how far it goes. If it goes all the way with the servo disconnected but not when its connected, then you have some sort of mechanical limit somehwere...find it and remove it. If it doesn't, it's a radio limit.

There is another possibility, that the steering link is built incorrectly. If the servo goes all the way but the wheels still turn a little, your problem could be there.

Lastly, what kind of car is this? Is it a hobby grade car or a toy? Toy cars rarely have tight turning radiuses.

If you've inspected your mechanical links, and you cannot find a dual rate knob anywhere on your radio (even cheapo radios usually have them) and you car is a hobby grade car, then you have a genuine mystery on your hands. I'd blame the receiver.