Muraco Steering Servo Problem, please help!?

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Chuzz

Chuzz

Well-known member
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Location
Staffordshire, UK
Corally RC's
  1. Muraco
Hey, I have a Muraco 6s. Took it out yesterday, walked it across a field whilst driving it. Put the control down, while taking my back off my back I heard the servo motor, looked at the car and the servo had gone fully to one side. Steering barely centred it. Switched it off and on, Reset the esc, re-bound the controller… The car doesn't really steer and took the whole width of a football field to turn around. Speed/brake is ok. Took the receiver out and the servo, the servo is juddering and only turning about 10º max.

I've swapped the leads in the receiver round so the steering operates the throttle and throttle operates the steering BUT the wheels don't turn/motor doesn't operate when I turn the steering wheel, although the servo tries to turn with the throttle trigger, but still judders and has limited turning.

I've attached a video to show the servo having problems, oh sorry, can't attach the video 👎🏼. So:-

Is this an issue with the servo? Or the Receiver? Or the Radio? Or all 3?

Only had this a month and I'm not very technical and not good with electronics (maybe I chose the wrong hobby!? 😫)
 
Chuzz said:
Hey, I have a Muraco 6s. Took it out yesterday, walked it across a field whilst driving it. Put the control down, while taking my back off my back I heard the servo motor, looked at the car and the servo had gone fully to one side. Steering barely centred it. Switched it off and on, Reset the esc, re-bound the controller… The car doesn't really steer and took the whole width of a football field to turn around. Speed/brake is ok. Took the receiver out and the servo, the servo is juddering and only turning about 10º max.

I've swapped the leads in the receiver round so the steering operates the throttle and throttle operates the steering BUT the wheels don't turn/motor doesn't operate when I turn the steering wheel, although the servo tries to turn with the throttle trigger, but still judders and has limited turning.

I've attached a video to show the servo having problems, oh sorry, can't attach the video 👎🏼. So:-

Is this an issue with the servo? Or the Receiver? Or the Radio? Or all 3?

Only had this a month and I'm not very technical and not good with electronics (maybe I chose the wrong hobby!? 😫)
Click to expand...
This is either a problem with that channel on the receiver or the servo is cooked. The servo may have cooked because the steering is not operating freely. Have you checked the steering by hand ie remove the servo horn from the steering servo and check for any binding in the hubs, steering and ackerman plate?

My guess (it's just a hunch) is that your servo is broken.
 
Horatio said:
This is either a problem with that channel on the receiver or the servo is cooked. The servo may have cooked because the steering is not operating freely. Have you checked the steering by hand ie remove the servo horn from the steering servo and check for any binding in the hubs, steering and ackerman plate?

My guess (it's just a hunch) is that your servo is broken.
Click to expand...
I checked the wheels turned freely, might start with a new servo and see if that works, oh to have many spares on hand.
Thank you for you help
 
Oder vielleicht Sevosaver-feder einstellen.
 
Chuzz said:
I don’t think it is the spring as I have disconnected it and it does the same. Ive ordered a couple of servos 🤞🏼
Click to expand...
Your stock servo is most likely to have had 'magic smoke'.

Are you happy to set endpoints on your steering and throttle? That's an essential thing to do. You need to make sure the servo isn't trying to push/pull past the limits of the steering/throttle during operation. These end points will not have been set up for you out of the box (or if they have, it's unlikely it'll be right).

On the stock steering servo saver, the spring is weak - I highly recommend that you check out the thread here and how to remedy it. Check out Dani's recommended spring and what numerous members (including myself) now run with.

Here's the steering servo I use. Extremely good value for money.
IMG_20211216_142838.jpg
 
Horatio said:
Your stock servo is most likely to have had 'magic smoke'.

Are you happy to set endpoints on your steering and throttle? That's an essential thing to do. You need to make sure the servo isn't trying to push/pull past the limits of the steering/throttle during operation. These end points will not have been set up for you out of the box (or if they have, it's unlikely it'll be right).

On the stock steering servo saver, the spring is weak - I highly recommend that you check out the thread here and how to remedy it. Check out Dani's recommended spring and what numerous members (including myself) now run with.

Here's the steering servo I use. Extremely good value for money.View attachment 3965
Click to expand...
I’ve ordered couple of waterproof servos, a 20 and a 25 kg one. Not the same as this one but hopefully
good/better than stock.

What is magic smoke? I’ve had some in my time but doubt it’s the same as what has happened to my servo 😊

I will check out the spring (although I don’t fully understand the servo saver springs job).

I’ve never set end points, I’ve seen about them, take it it’s not just turning down the dual rate?

Thanks for advice, hopefully it is just the servo and I don’t need a new transmitter and receiver!
 
Chuzz said:
I’ve ordered couple of waterproof servos, a 20 and a 25 kg one. Not the same as this one but hopefully
good/better than stock.

What is magic smoke? I’ve had some in my time but doubt it’s the same as what has happened to my servo 😊

I will check out the spring (although I don’t fully understand the servo saver springs job).

I’ve never set end points, I’ve seen about them, take it it’s not just turning down the dual rate?

Thanks for advice, hopefully it is just the servo and I don’t need a new transmitter and receiver!
Click to expand...
Magic smoke! 🤣 Erm, yeah not that kind of magic smoke!

Dual rates are handy for setting how responsive a model is. For example, you could set a rate on a child's buggy to only have 50% throttle, or on an RC plane you'd set rates for standard vs 3D flying.

End points are not that - end points set where the maximum movement the servo will make in each direction. This needs to be done regardless of whether you use dual rates.

For example, on a Nitro car with your throttle servo, you do not need any more servo movent once the carb is fully opened. So, you set the end point here - or risk repeatedly stalling the servo. Best scenario here is that it draws a lot of amps out of your battery. Worst case is 'poooff' - magic smoke - and a run away. Ditto for brakes. Ditto for steering.

Don't burn out your new servos - take a look at endpoints on your radio and I think that will solve your problem. 👍
 
Horatio said:
Magic smoke! 🤣 Erm, yeah not that kind of magic smoke!

Dual rates are handy for setting how responsive a model is. For example, you could set a rate on a child's buggy to only have 50% throttle, or on an RC plane you'd set rates for standard vs 3D flying.

End points are not that - end points set where the maximum movement the servo will make in each direction. This needs to be done regardless of whether you use dual rates.

For example, on a Nitro car with your throttle servo, you do not need any more servo movent once the carb is fully opened. So, you set the end point here - or risk repeatedly stalling the servo. Best scenario here is that it draws a lot of amps out of your battery. Worst case is 'poooff' - magic smoke - and a run away. Ditto for brakes. Ditto for steering.

Don't burn out your new servos - take a look at endpoints on your radio and I think that will solve your problem. 👍
Click to expand...
Ok thanks. Once new spring and servos have arrived and I’ve fitted them will set them up 👍🏻
I’ve ordered 10 springs so should easily have 5 to sell/swap.
Loving the Muraco but want a wt of decent (belted) hard surface/tarmac/road tyres and maybe badlands (for dirt and grass).
Quite fancy a 1/10 buggy to take to some tracks if I can find some, would rather keep brand consistency so I get used to working on them. Do TC do any decent 1/10 buggies?
 
Horatio said:
Magic smoke! 🤣 Erm, yeah not that kind of magic smoke!

Dual rates are handy for setting how responsive a model is. For example, you could set a rate on a child's buggy to only have 50% throttle, or on an RC plane you'd set rates for standard vs 3D flying.

End points are not that - end points set where the maximum movement the servo will make in each direction. This needs to be done regardless of whether you use dual rates.

For example, on a Nitro car with your throttle servo, you do not need any more servo movent once the carb is fully opened. So, you set the end point here - or risk repeatedly stalling the servo. Best scenario here is that it draws a lot of amps out of your battery. Worst case is 'poooff' - magic smoke - and a run away. Ditto for brakes. Ditto for steering.

Don't burn out your new servos - take a look at endpoints on your radio and I think that will solve your problem. 👍
Click to expand...
Hi Horatio,
I spoke to Modelsport. They have sent me a new servo under warranty! It arrived today, along with an aftermarket 20kg one, and I have a 25kg one should come tomorrow. Think I will fit the TC warranty one for now as it should keep me under warranty for a little while longer. Can't fault their service really! I plugged it in earlier and the servo worked normally, so looks like it was the servo. So will fit later and fit the new spring later/tomorrow too.
Then set up my endpoints! (Any links to youtube or web pages to do this would be most appreciated).
So, I have around 5 springs I can sell on. Is it best to put on ebay or start a new thread on this Forum do you think (or both)?.
Thanks to everyone for their help, can't wait to finally get back out with the Muraco. Just needs some decent off road/grass tyres now 😁
 
Chuzz said:
Hi Horatio,
I spoke to Modelsport. They have sent me a new servo under warranty! It arrived today, along with an aftermarket 20kg one, and I have a 25kg one should come tomorrow. Think I will fit the TC warranty one for now as it should keep me under warranty for a little while longer. Can't fault their service really! I plugged it in earlier and the servo worked normally, so looks like it was the servo. So will fit later and fit the new spring later/tomorrow too.
Then set up my endpoints! (Any links to youtube or web pages to do this would be most appreciated).
So, I have around 5 springs I can sell on. Is it best to put on ebay or start a new thread on this Forum do you think (or both)?.
Thanks to everyone for their help, can't wait to finally get back out with the Muraco. Just needs some decent off road/grass tyres now 😁
Click to expand...
That's great news! Loads of videos on YouTube on how to set endpoints, but I highly recommend you do this BEFORE running the truck again. 👌

As for selling the springs - ebay is probably the safest way to sell them, provided you factor in the fees into your costings.

Angrysection8 needed some - send him a PM he might buy them all. 👍
 
Horatio said:
That's great news! Loads of videos on YouTube on how to set endpoints, but I highly recommend you do this BEFORE running the truck again. 👌

As for selling the springs - ebay is probably the safest way to sell them, provided you factor in the fees into your costings.

Angrysection8 needed some - send him a PM he might buy them all. 👍
Click to expand...
Going to do it now, it’s all out back together. I do have some play in the servo saver, I don’t remember this before. Do I need to compress the spring more?
Horatio said:
That's great news! Loads of videos on YouTube on how to set endpoints, but I highly recommend you do this BEFORE running the truck again. 👌

As for selling the springs - ebay is probably the safest way to sell them, provided you factor in the fees into your costings.

Angrysection8 needed some - send him a PM he might buy them all. 👍
Click to expand...
doing it now 👍🏻 it’s all back together. But I do seem to have some play in the saver, don’t remember it being this loose before, is this normal?

image.jpg


image.jpg
 
Well @Horatio been out and put a 4s through the Muraco lunch time. Wow! Didn’t think I’d notice much difference but hell, it does seem to drive nice now!
Thanks for all the help and advice, I only found this TC forum by accident too…
I have a 25kg servo, would I notice much difference over the stock one do you think?
Might give it a 6s rip tomorrow 😁
 
Chuzz said:
Well @Horatio been out and put a 4s through the Muraco lunch time. Wow! Didn’t think I’d notice much difference but hell, it does seem to drive nice now!
Thanks for all the help and advice, I only found this TC forum by accident too…
I have a 25kg servo, would I notice much difference over the stock one do you think?
Might give it a 6s rip tomorrow 😁
Click to expand...
This is great to hear!! I hope it helped. 👌😎

You'll notice a big difference since the torque from your current servo can actually reach the wheels through a much stronger servo saver spring.

However, the Corally supplied steering servo is rated at 25kg, so should work well provided it's not been fried. 😜

Once upon a time, I ran digital Hitech servos on my Savage with a whopping 13kg and 0.12sec transit time @ 6v. It was fine.

Arguably, with these brushless rigs putting out >4hp, with belted tyres etc, it's fair to say they need more torque just to deal with the heavier wheels and greater gyroscopic forces.

My AGF is 45kg - which seems like massive overkill - but it's fast, accurate and centers beautully whilst being super smooth and quiet. I swear down it's just like my Protek 170 SBL/TBL servos, which are near enough double the price.

Enjoy the 6S joy ride. Just manage that throttle and don't land on power. 💪😁
 
Horatio said:
This is great to hear!! I hope it helped. 👌😎

You'll notice a big difference since the torque from your current servo can actually reach the wheels through a much stronger servo saver spring.

However, the Corally supplied steering servo is rated at 25kg, so should work well provided it's not been fried. 😜

Once upon a time, I ran digital Hitech servos on my Savage with a whopping 13kg and 0.12sec transit time @ 6v. It was fine.

Arguably, with these brushless rigs putting out >4hp, with belted tyres etc, it's fair to say they need more torque just to deal with the heavier wheels and greater gyroscopic forces.

My AGF is 45kg - which seems like massive overkill - but it's fast, accurate and centers beautully whilst being super smooth and quiet. I swear down it's just like my Protek 170 SBL/TBL servos, which are near enough double the price.

Enjoy the 6S joy ride. Just manage that throttle and don't land on power. 💪😁
Click to expand...
That’s all very technical to me I’m afraid. Is that why it doesn’t centre perfectly, needs a bit more power?
I thought the standard servo was 20Kg. May as well send that one back rather than keep for a spare then 😁
 
Chuzz said:
That’s all very technical to me I’m afraid. Is that why it doesn’t centre perfectly, needs a bit more power?
I thought the standard servo was 20Kg. May as well send that one back rather than keep for a spare then 😁
Click to expand...
Servos come in a variety of flavours. Size, material, digital, analogue, torque, speed, voltage handling, motor type, IP rating.

From an operational point of view, torque on servos is measured in kg/cm or ounce/inch. So from a set distance along a servo horn (1cm/1inch) the servo can hold however many kg's/ounces.

Transit time is measured in seconds over 60° of movement. This usually a fraction of a second, with fastest servos doing this in 0.06 sec. Anywhere between 0.06 - 0.10 would be fast. 0.10 - 0.13 is good and standard servos anywhere up to 0.24, which would be considered slow.

Some servos come in torque or speed versions. They are identical other than the gearing used. Trade off is less speed with torque versions and less torque with speed versions.

Quality high performance servos use hall effect sensors ('magnetic servos') to know where the output/horn is at. These are more accurate than standard potentiometers and less prone to wear.

Likewise, there are numerous advantages with brushless powered servos over brushed. There are also coreless servos which spool up quickly, but like brushed motors, can still wear out over time.

Your centering issues could be attributed to play in the steering, the size of the tyres, weak servo saver springs (not now you've changed yours!), under powered servo, or inaccurate/worn out servo potentiometer.

When you race and have to stay between the lanes, servo accuracy is just as important as torque and speed, which is why some people choose very expensive Futaba, Sanwa, KO, Hitec, Protek servos.

The market is flooded with a huge variety of cheap servos, with varying degrees of quality. For bashers, you just need it to work and take a beating really. Racers tend to stick with what they know works and pay the extra coin.

Your stock servo is this one, right?

Screenshot_20230519_105116.jpg



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Varioprop - Digital Servo - CRHV-7225-MG - High Voltage - Core Motor - Metal Gear - 25 Kg Torque
Varioprop - Digital Servo - CRHV-7225-MG - High Voltage - Core Motor - Metal Gear - 25 Kg Torque


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Varioprop - Digital Servo - CRHV-7225-MG - High Voltage - Core Motor - Metal Gear - 25 Kg Torque C-52022​

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25kg Digital Servo
Varioprop - Digital Servo - CRHV-7225-MG - High Voltage - Core Motor - Metal Gear - 25 Kg Torque

Specs:
  • Motor Type: DC Motor
  • Servo Technology: Digital Ultra High Voltage
  • Input Voltage (V): 6.0V - 8.4V
  • Weight (g): 63 g
  • Servo Type / Size: Standard
  • Length (mm): 40.5 mm
  • Gear Material: Metal Gears
  • Width (mm): 20.5 mm
  • Ball Beared: Ball Beared
  • Height (mm): 28.5 mm
  • Servo Case: Aluminium - Composite
  • Servo Power - Torque Kg/cm: 16 - 25 Kg/cm
  • Servo Speed 60?/sec: 0,14 sec / 60?
  • Speed 60?/Sec @ 6.0V: 0,14 sec / 60?
  • Speed 60?/Sec @ 7.4V: 0,13 sec / 60?
  • Torque kg/cm @ 7.4V: 25.0 Kg/cm
  • Connector type: JR
  • Spline size: 25T Spline
  • Water Protection: water-resistant
 
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