Revo 3.3 runaway?

[MooTheDog]

Hi there. So I’m new to nitro and have been lurking this forum as well as rc tech, rc universe and the traxxas forums just absorbing everything I can the last month. I’ve broken in my new Revo 3.3 and just started tank 6, tuning the carb for performance. This is not a tune question, so keep reading

I get the truck started and I intermittently loose “sensor” connection to the optidrive system. I’ve had a couple of runaways where when the sensor light shines solid red, the throttle stays where ever it looses connection and the truck takes off for 5-6 sec. Called traxxas support and they said it seems like I’m getting low voltage in the system and to check the voltage in the 5cell battery in the truck. I checked the voltage, 6.5volts so that’s good. They then said to send it in and I’m not throwing the towel in that easy.

I did figure out that when I push the reverse button on the transmitter, the truck intermittently goes in reverse, even when stationary. More troubleshooting found that if I push the servo arm after I push the button, it moves. It kind of needs a little bit of help to move.

Could this reverse servo be burning out and causing the voltage draw in the optidrive system causing it to loose sensor and the truck take off? Have a video but don’t know how to post it. I did unplug the reverse shift servo from the optidrive and run it in my garage in circles but am kind of gunshy cause I can only do so much cardio in one day Didn’t really have any crazy issues but only did it for a couple sec. thanks for reading if you got this far!!

 

[WickedFog]

Welcome to the forum. To share vids, you have to upload them to Youtube and post the link here.

 

[Losi215]

As far as I know, the optidrive causes nothing but issues and could very well be the cause of your intermittent runaways. I would get rid of the optidrive and reverse shift servo immediately and go forward only conversion inside the transmission. But, if you really want reverse, try a new optidrive system, servo, check you’re antenna wire from the receiver isn’t frayed or damaged, try a brand new reciever, etc.

 

[Chubaka]

As far as I know, the optidrive causes nothing but issues and could very well be the cause of your intermittent runaways. I wouldn’t get ride of the optidrive and reverse shift servo immediately and go forward only conversion inside the transmission. But, if you really want reverse, try a new optidrive system, servo, check you’re antenna wire from the receiver isn’t frayed or damaged, try a brand new reciever, etc.

You should be able to ditch optidrive and servo the reverse. You just can't hit the button with forward motion is all. Traxxas optidrive and servos ard problematic. Optidrive is hearsay, the servos I have a box of.

 

[MooTheDog]

Awesome! Thanks all for responding. I disconnected the servo from the optidrive and took it out in a fenced in soccer field and no runaways. I did try @Chubaka recommendation and just hooked the reverse sevrvo to the receiver and it still jammed up. Seems like that was the issue. Definitely going to look into the forward only conversion as a more perm fix. I’m going to upload it to you tube and link it here just in case anyone else has the same issue cause it definitely was wild haha. At most it will be another reason to ditch the optidrive

 

[MooTheDog]

Here’s the link. After watching it seems like the reverse servo is jammed in reverse with my transmitter button switched in forward.

 

[Doom!]

Welcome aboard, glad you've got it figured out.

 

[gandalfnz]

As far as I know, the optidrive causes nothing but issues and could very well be the cause of your intermittent runaways. I would get rid of the optidrive and reverse shift servo immediately and go forward only conversion inside the transmission. But, if you really want reverse, try a new optidrive system, servo, check you’re antenna wire from the receiver isn’t frayed or damaged, try a brand new reciever, etc.

Is there a "new" optidrive system? How does one recognise the new model?

I am having the same issues with my revo.

Cheers

 

[MooTheDog]

Is there a "new" optidrive system? How does one recognise the new model?

I am having the same issues with my revo.

Cheers

Hey gandalfnz. I think Losi was just saying go out and buy a new optidrive module off the shelf rather than a new version/model of the optidrive.

To bypass the system, unplug the grey and green plug out of channel 2 and 3 and plug the throttle (ch2)and reverse shift servo (ch3)directly in to the tqi receiver. (See pic) Be careful though because if you loose connection between your transmitter and receiver, you’ll definitely have a runaway because the optidrive will not default to break on, throttle off. I’d suggest doing this without the engine running so you can troubleshoot with the servos and optidrive.

 

[gandalfnz]

Hey gandalfnz. I think Losi was just saying go out and buy a new optidrive module off the shelf rather than a new version/model of the optidrive.

To bypass the system, unplug the grey and green plug out of channel 2 and 3 and plug the throttle (ch2)and reverse shift servo (ch3)directly in to the tqi receiver. (See pic) Be careful though because if you loose connection between your transmitter and receiver, you’ll definitely have a runaway because the optidrive will not default to break on, throttle off. I’d suggest doing this without the engine running so you can troubleshoot with the servos and optidrive.

Hi, thanks for your help.

I tried doing what you suggested with the car off, and always seems to be working as it should.
Issue is very intermittent, will need to give it a go with optidrive completely disconnected.
I do like the reverse though, and prefer to keep it.
Hi, thanks for your help.

I tried doing what you suggested with the car off, and always seems to be working as it should.
Issue is very intermittent, will need to give it a go with optidrive completely disconnected.
I do like the reverse though, and prefer to keep it.

 

[MooTheDog]

Did you check to see if each servo responds when subsequent button is pushed on transmitter? Could be same as I was having just a different servo.

 

[Unklrunk13]

Hi there. So I’m new to nitro and have been lurking this forum as well as rc tech, rc universe and the traxxas forums just absorbing everything I can the last month. I’ve broken in my new Revo 3.3 and just started tank 6, tuning the carb for performance. This is not a tune question, so keep reading

I get the truck started and I intermittently loose “sensor” connection to the optidrive system. I’ve had a couple of runaways where when the sensor light shines solid red, the throttle stays where ever it looses connection and the truck takes off for 5-6 sec. Called traxxas support and they said it seems like I’m getting low voltage in the system and to check the voltage in the 5cell battery in the truck. I checked the voltage, 6.5volts so that’s good. They then said to send it in and I’m not throwing the towel in that easy.

I did figure out that when I push the reverse button on the transmitter, the truck intermittently goes in reverse, even when stationary. More troubleshooting found that if I push the servo arm after I push the button, it moves. It kind of needs a little bit of help to move.

Could this reverse servo be burning out and causing the voltage draw in the optidrive system causing it to loose sensor and the truck take off? Have a video but don’t know how to post it. I did unplug the reverse shift servo from the optidrive and run it in my garage in circles but am kind of gunshy cause I can only do so much cardio in one day Didn’t really have any crazy issues but only did it for a couple sec. thanks for reading if you got this far!!

During my break in, tank 3, the throttle got stuck full open and ran away. I took the opti drive off and the truck seems to be completely better.

 

[gandalfnz]

Did you check to see if each servo responds when subsequent button is pushed on transmitter? Could be same as I was having just a different servo.

Hi

Whenever I tried, I could not reproduce the issue. Servos worked as they should. It was very intermittent. I tried different receiver and transmitter, problem was still there. Pretty sure its the optidrive.

 

[MooTheDog]

What about the voltage in the onboard 5 cell NiMH battery? Should be consistently delivering 6.5 volts. I'm actually seriously considering swapping it out for like a 2S Lipo or something like that and then upgrading the throttle and converting to single steering servo. If you think its the optidrive, then bypass and see if it still has the issue. Just make sure you test it without the optidrive on either a stand or in a fenced in area because if the truck looses connection to the transmitter and runsaway, without the optidrive failsafe it wont stop.

 

[gandalfnz]

What about the voltage in the onboard 5 cell NiMH battery? Should be consistently delivering 6.5 volts. I'm actually seriously considering swapping it out for like a 2S Lipo or something like that and then upgrading the throttle and converting to single steering servo. If you think its the optidrive, then bypass and see if it still has the issue. Just make sure you test it without the optidrive on either a stand or in a fenced in area because if the truck looses connection to the transmitter and runsaway, without the optidrive failsafe it wont stop.

Already there, I mounted two 18650 lithium cells for the receiver.
In saying all this, I am still to go out and give it another test, with optidrive disabled.
Just too busy loving my new Savage X at the moment, Revo will have to wait.

Oh, and I forgot to add, when it does go berserk, it will only do so for lets say 3 seconds, then it goes back to normal. Luckily this prevents it from slamming into something, as I test it in the park, with plenty of space around. I thought the actual fail safe was in the TQI transmitter, rather than optidrive?

 

[MooTheDog]

I'm not really familliar with the 18650 Lithium cells. Could be theyre not consistently providing ample voltage to power optdrive but not sure.

 

[gandalfnz]

I'm not really familliar with the 18650 Lithium cells. Could be theyre not consistently providing ample voltage to power optdrive but not sure.

No, thats not the problem. Two 18650 are slightly higher voltage than what stock AA will output.
Plus, truck did the same thing with stock batts.

 

[XeroMyHero]

I had all kinds of issues with the opti drive. I just took it out and don't use it. Others say just use forward only setup. But I didn't, and you don't have to either. You don't need the opti drive in it and you can still keep the reverse as well. Just remember you have to be in a complete stop to shift it from forward to reverse, and to shift it from reverse to forward. Like driving a real care, you are not going to shift from drive to reverse while driving down the road. If by chance you do shift gears while moving you will strip out one of two gears. the dog bone synchro slide into. You can buy the kit for both gears, and the dog bone synchro for about 10 bucks. I did it once not thinking. and I still don't know why I shifted it on the fly, but it is a cheap fix and easy to do. lots of videos on youtube to show you how to take it apart and put it back together.

I say take out the opti drive system and run it that way. Just come to a full stop before shifting in to other gear.

 

[gandalfnz]

I had all kinds of issues with the opti drive. I just took it out and don't use it. Others say just use forward only setup. But I didn't, and you don't have to either. You don't need the opti drive in it and you can still keep the reverse as well. Just remember you have to be in a complete stop to shift it from forward to reverse, and to shift it from reverse to forward. Like driving a real care, you are not going to shift from drive to reverse while driving down the road. If by chance you do shift gears while moving you will strip out one of two gears. the dog bone synchro slide into. You can buy the kit for both gears, and the dog bone synchro for about 10 bucks. I did it once not thinking. and I still don't know why I shifted it on the fly, but it is a cheap fix and easy to do. lots of videos on youtube to show you how to take it apart and put it back together.

I say take out the opti drive system and run it that way. Just come to a full stop before shifting in to other gear.

I am still to test my revo after bypassing the optidrive.
Will update once I have more info.

 

[MooTheDog]

So took it to the LHS and they said definitely the reverse servo went bad. Called Traxxas and got a replacement but bought the metal reverse servo at said LHS. Installed it plus the rpm tru track rear suspension arms and took it out yesterday and had no issues. Seems like reverse sitcks in the transmission so need to figure that out but all in all, no issues with upgraded reverse servo and optidrive system.

Broke a rear spring rod ball so now need to figure out what to replace that with.