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TITANIUM94010

XV01 steering is weak.

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So after driving around my XV01, I noticed that I could just move the front wheels with my hands a bit, and the steering points would be messed up, and I would have to bend it back. I thought the servo horn was stripped, but it was intact. 

Is this because of my servo?, or did I do something wrong? I'm using a Savox 1257TG super speed servo, which really shouldn't strip because of the metal titanium gears inside. 

Can someone help?

Thanks!

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Are you using a solid servo horn, or a servo saver?  If you're using the Tamiya servo saver with the Savox then it might be binding.  I have found with Tamiya servo savers in metal servo outputs that the screw and washer can clamp down on the servo saver and stop it from springing back into place.  This doesn't happen with plastic gear servos because the self-taping screw is held tight enough by the plastic that it doesn't need to screw down hard onto the servo saver.  The solution is to slacken off the screw a little and use threadlock to keep it from unwinding, although it's not perfect either way.  You can also put a ziptie around the servo saver spring to increase its tension.

A better option is an aftermarket servo saver.

If you have an aftermarket servo saver then check it for play.  It shouldn't have any.  If your servo saver is OK or you're using a solid horn and it's not stripped or loose on the servo, then you'll have to check each part of the steering to see where the play is.  Your Savox servo should be more than up to the job but it's worth checking that the play isn't inside.  Savox servos can usually be rebuilt if it has stripped.  Check the servo is secured properly to the servo posts and the posts are secured properly to the chassis.  Check the steering cranks are securely bolted down and the bushes/bearings haven't failed.  Check the ball-ends haven't worn.  Even in a high-end kit like the XV01 there will be a little bit of play in the ball-ends, there's not much you can do about that, but it shouldn't cause the steering to stick one way or the other hand require constant re-trimming.

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I have this car and a decent servo and I do not get much play in the steering when pushed with the hand. You say the servo is not stripped but you might have the wrong servo spline adapter on? These can spin on the spline and show no signs of it AND seem pretty tight when tested. These adapters can be annoying to get the right one for the brand of servo. HiTEC for instance is not even covered!  In my case with a High torq Chinese servo, one was a nice push on fit BUT sliiped  the other took great force to get on the spline BUT was the correct fitment.Have a check.

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2 hours ago, Mad Ax said:

Are you using a solid servo horn, or a servo saver?  If you're using the Tamiya servo saver with the Savox then it might be binding.  I have found with Tamiya servo savers in metal servo outputs that the screw and washer can clamp down on the servo saver and stop it from springing back into place.  This doesn't happen with plastic gear servos because the self-taping screw is held tight enough by the plastic that it doesn't need to screw down hard onto the servo saver.  The solution is to slacken off the screw a little and use threadlock to keep it from unwinding, although it's not perfect either way.  You can also put a ziptie around the servo saver spring to increase its tension.

A better option is an aftermarket servo saver.

If you have an aftermarket servo saver then check it for play.  It shouldn't have any.  If your servo saver is OK or you're using a solid horn and it's not stripped or loose on the servo, then you'll have to check each part of the steering to see where the play is.  Your Savox servo should be more than up to the job but it's worth checking that the play isn't inside.  Savox servos can usually be rebuilt if it has stripped.  Check the servo is secured properly to the servo posts and the posts are secured properly to the chassis.  Check the steering cranks are securely bolted down and the bushes/bearings haven't failed.  Check the ball-ends haven't worn.  Even in a high-end kit like the XV01 there will be a little bit of play in the ball-ends, there's not much you can do about that, but it shouldn't cause the steering to stick one way or the other hand require constant re-trimming.

 

I've got new Altus servo which is died only after a few runs. I've been using the Tamiya Hi-Torque servo saver, and one of their aluminium hop-up horns. I wonder if the strong spring (the x3 rings you have to build) for the servo saver has killed the servo.. :/

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16 minutes ago, dc-arena said:

I've got new Altus servo which is died only after a few runs. I've been using the Tamiya Hi-Torque servo saver, and one of their aluminium hop-up horns. I wonder if the strong spring (the x3 rings you have to build) for the servo saver has killed the servo.. :/

The rings themselves shouldn't have killed the servo, but the Hi-Torque servo saver transmits more impact into the servo than the stock one does.  Unfortunately the stronger you make the servo saver, the more impact will be transmitted into the servo.  If the servo has plastic gears it might have stripped.

Did you mean Altus or Alturn?  I have been using Alturn hi-speed and hi-torque metal gear servos for years and found them to be good, but last year I had a couple of very slow ones.  Although oddly I hooked one up two weeks ago and it seemed to be fast again, maybe my radio config had got corrupted (I've had that before on my DX3C where for some reason a setting goes way out of whack and the servo is miles off centre or ridunculously slow and can only be fixed by doing a reset on that model number).

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2 minutes ago, Mad Ax said:

The rings themselves shouldn't have killed the servo, but the Hi-Torque servo saver transmits more impact into the servo than the stock one does.  Unfortunately the stronger you make the servo saver, the more impact will be transmitted into the servo.  If the servo has plastic gears it might have stripped.

Did you mean Altus or Alturn?  I have been using Alturn hi-speed and hi-torque metal gear servos for years and found them to be good, but last year I had a couple of very slow ones.  Although oddly I hooked one up two weeks ago and it seemed to be fast again, maybe my radio config had got corrupted (I've had that before on my DX3C where for some reason a setting goes way out of whack and the servo is miles off centre or ridunculously slow and can only be fixed by doing a reset on that model number).

I meant Alturn (video game hobby merging into RC for brief period then :) ). The servo in question is actually a metal geared one, so not sure what it could be. The servo just goes to one side as soon as it receives power.

https://www.modelsport.co.uk/alturn-usa-high-performance-race-servo-high-speed-/rc-car-products/359785

It seems to OK for a bit, then will suddenly pull to one side, and wont go back.

 

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@dc-arena that sounds more like an electrical fault than a mechanical one, although it *could* be a damaged positioning potentiometer.  Have a look at this post - I opened up a micro servo this weekend to remove the potentiometer.  The Alturn probably has something similar and there might be damage or a bad connection.

Have you tried a different servo and does that also do it?  Does that servo do the same if you plug it into a different radio?  Does it do it / stop doing it if you wiggle the wires?

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1 hour ago, Mad Ax said:

@dc-arena that sounds more like an electrical fault than a mechanical one, although it *could* be a damaged positioning potentiometer.  Have a look at this post - I opened up a micro servo this weekend to remove the potentiometer.  The Alturn probably has something similar and there might be damage or a bad connection.

Have you tried a different servo and does that also do it?  Does that servo do the same if you plug it into a different radio?  Does it do it / stop doing it if you wiggle the wires?

 

If I plug another servo in its absolutely fine. I've not tried wiggling wires, I'll give it another go. Thanks!

It's a weird issue. Maybe it is a bad connection because at one point, I took the saver, horn, steering rods etc off and tested it, and it was fine, then I rebuilt it all, tried the car and it immediately pulls to one side, permanently. Maybe it was when I turned the car over (access is from underneath; MF01X)

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Update:

- So I take off servo saver again and try it. It works fine.
- Put servo saver on, it works fine
- Turn off, turn on, it works fine
- Turn off, turn on, servo rams to the right, and you can ear the servo motor pulling against it.

Its so weird.

 

OK so now it’s not doing the crazy to pull one side, but after steering one way, it won’t recenter properly. You have to steer the opposite direction, then it will recenter. It does the same when turning the car on.

 

Could the servo be knackered? I don’t think I’ve set the high torque servo saver up wrong, you just fit together the three rings, right? There’s no adjustment to be made. I’ve got the hop up Tamiya horn too.

 

 

 

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12 hours ago, TITANIUM94010 said:

Do I need a servo saver to run my xv01? I have a very similar servo in my slash without a servo saver.

The servo saver serves the purpose of "saving" the servo in the event of impacts, depending on the strength of your servo, you may get away without one, just know that an impact could break the servo. I know 1/8 racers who basically run no saver on their 1/8 buggies, we're talking $200 (AUD) servos that are very strong and last no problem. I'd imagine that on an XV01, if you are using a quality servo, you could easily get away without a saver, and I will probably consider this when I build mine very soon

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I never knew you could use a servo horn without a saver. I am not even sure how it'd screw it in place without the saver being there (as in, the screws would be way long, and then the horn would be right next to the servo casing).

I am confused! :)

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On 6/3/2020 at 8:25 AM, dc-arena said:

I never knew you could use a servo horn without a saver. I am not even sure how it'd screw it in place without the saver being there (as in, the screws would be way long, and then the horn would be right next to the servo casing).

I am confused! :)

Your servo probably came with some servo horns, right?  They are plastic (or sometimes aluminium) pieces that have the correct splines in the back to fit over your servo outdrive.  Then you screw them on just as you would a servo saver.

In order to maintain the correct steering geometry you would have to find one that is similar in length and depth to the Tamiya servo saver.  You might also have to drill out the hole to accept the Tamiya ball screw, as IME servo-supplied horns have very small holes (I guess they're intended for aircraft pushrods).

Sometimes you can find a servo horn on a Tamiya part tree.  Originally they would have been supplied to operate the mechanical speed controller.

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59 minutes ago, Mad Ax said:

Your servo probably came with some servo horns, right?  They are plastic (or sometimes aluminium) pieces that have the correct splines in the back to fit over your servo outdrive.  Then you screw them on just as you would a servo saver.

In order to maintain the correct steering geometry you would have to find one that is similar in length and depth to the Tamiya servo saver.  You might also have to drill out the hole to accept the Tamiya ball screw, as IME servo-supplied horns have very small holes (I guess they're intended for aircraft pushrods).

Sometimes you can find a servo horn on a Tamiya part tree.  Originally they would have been supplied to operate the mechanical speed controller.

 

Thanks for info, I will look into this. I am kinda hoping it was just an unlucky failiure of the servo and not as a result of using the high-torque tamiya saver :/

 

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