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Throttle/Brake cutting out...

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Runaway Jim

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Hey Everyone,

Breaking in a new 3.3 last week and noticed that my throttle/brake servo was cutting in and out every so often. It would stop working for a 3-5 seconds then kick back in. I thought I had a low battery so I replaced them in the transmitter and charged the receiver pack. Same thing happened again after the charging. Any ideas as to what may be causing this problem? I was thinking of replacing the servo but wanted to get some opinions here before I did that. Thanks everyone.
 
I think I'd replace it too RJ, if the steering is working fine. Do you still have the Opti-drive in your Revo? It's mainly to keep you from shifting between forward/reverse without the rig being completely stopped, but you never know if it might be interfering. Do you have an electronic fail-safe?
 
Sounds like RF interference. Radio frequencies, especially in the AM band, are easily corrupted. You need a failsafe if you don't already have one. It won't solve glitching but it will keep your truck from running away from you if you loose contact with your receiver. It is hard to determine what is causing the glitching. Could be RF from the servos themselves or anything in the area that is on or near the frequency you are using. The easiest solution is to buy a few different sets of crystals--the best and most expensive solution is go to a 2.5Ghz FM system. I am an Amature Radio operator and I can attest that RF can be the bane of anyones existance.

Another thought--you might want to look for a loose connection at the receiver or a bad solder joint at the servo end of the lead before you get carried away with RF.

If I can think of anything else I will post it here--I can bet others will have ideas as well. It is all about trial and error--eliminating one "could be" at a time...
 
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Thanks guys, I'll try going through all of your suggestions to see if it helps. One thing I forgot to mention in my original post was when I did drive it last I felt that it happened more right after applying the break. I did a few high speed runs and let it slow enough on it's own, no brake, then turned. Then I did a few and used the brake to slow it down and the cut out seemed to happen more than. In fact I think that's the only time it happened. I looked at the servo action when the motor was off and it doesn't seem like anything with the brake linkage is binding. Could the servo be going bad in one direction? Is that possible?
 
I've recently been having the same problem and thought that it was just the reciver battery also. I noticed that whenever the throttle wouldn't work that there would be a red light on insted of the normal blue and green lights for the opti drive.
 
Have you come up with a fix for the issue yet GusMax86 or are we both still working through it...?
 
Runaway Jim said:
Thanks guys, I'll try going through all of your suggestions to see if it helps. One thing I forgot to mention in my original post was when I did drive it last I felt that it happened more right after applying the break. I did a few high speed runs and let it slow enough on it's own, no brake, then turned. Then I did a few and used the brake to slow it down and the cut out seemed to happen more than. In fact I think that's the only time it happened. I looked at the servo action when the motor was off and it doesn't seem like anything with the brake linkage is binding. Could the servo be going bad in one direction? Is that possible?
Click to expand...

This new info kinda changes things a bit. I would look for binding in the linkage. Baring that check the teeth on the servo and horn/saver for broken teeth. Could be that the servo gear is sticking as well. Disconnect the horn and run it in reverse then again in forward and see if it sticks.

Good luck and keep us posted!
 
I'll get back to you tommarow. It started to rain then the sun went down. I hate it when that happens.
 
You can try resetting the Opti-crap...... I mean drive. The instructions are in the manual on how to do it. If it's still doing the same, you can by-pass it by hooking the throttle/brake servo lead into the receiver and disconnecting the Opti-drive. I believe you will lose the ability to shift into reverse, can't remember, it's been so long since I used it.
 
I had a problem like that once. My brake wouldn't work for about 3-5 seconds (which can be plenty of time to crash) I tried out my other transmitter and had no problems. So my conclusion was the transmitter was bad. I called Traxxas and they said to mail it to them with a money order for about $12.
 
Not to hi-jack RJ's thread, but are you going to do the center diff or just the FOC? Either way I think you'll like it. Wait till you see all the crap that comes out of the tranny, I was like 'this is all that goes back in?'.......LOL. I think there is 4 gears left when you're all done.
 
if your planning on some serious power the centerdiff is the way to go, keeps the truck off its roof. throw the opti junk in the trash and do the foc with or without the centerdiff its a great upgrade. while your at it i would consider ditching the ezystart (if you still have it) and go for a pullstart or roto. puts the truck on a good diet and it shows when you drive it!
 
This thready sure mushroomed into a big weight watchers session for a Revo 3.3 pretty fast! HA! Thanks for all of the advice. I just got a new 3.3 engine and have completed the break in. It's running like a dream. I kept the ez start on through the break in just in case it gave me problems but now, I think that I'm gonna ditch it and go pull start. I haven't put much thought into the center diff, FOC mods as of yet. I just tool around with the revo and will never race with it so it's hard to justify the expense. If I can get this servo issue resolved and get the pull start on it this week, I'll be very very happy. I'll take all of your advice as to what to check on and update this thread with what will hopefully be a successful fix thanks to you guys.:D
 
I don't race either and I still got rid of the reverse. The FOC costs about $40, that is with the center diff which requires a rear brake kit. If you do just an FOC I think it only runs around $25.

I think ditching the Opti-drive will also extend your run time, less draw on the receiver battery. Keep us posted about what you find with the servo.
 
Yep FOC is going to be the plan. I reset the Opti #$%^&&^%$ Ahem... Drive today and it did no good what so ever. The throttle/brake not working is consistant with a red light comming from the opti drive so I am almost positive that it is the cause of the problem. Still working on that OS 21 Vid work is seriously cutting into play time this week.
 
sorry for the long delay on posting the resolution to the original problem in this. I finally got back to working on the truck again today. After reading the posts in this thread about the opti drive and how crappy everyone thought it was I decided the first thing to do was to take it out. For some reason, luck was on my side this time. The electronics problem is gone. No cutting out at all for 2 full tanks so far. While I was at it I took off the ez start motor, gears and wiring and put on a pull start. I can't believe how much of a difference it made with the truck. Much quicker for sure. I've got to adjust the shift point now to compensate the RPMS are getting to high too quickly. Thanks for all of your advice. Have a good one...
 

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