View Full Version : Intermittent steering problem

2013.05.13, 07:02 AM
Racing Saturday and getting ready for a main and the steering would intermittently go in and out. Operating the steering and couldn't hear the servo buzzing or attempting to work. I would manually work the steering and then it would start working on its own until I put it on the track then it stop again. The gears seem smooth when I work the steering manually and when starts working it sounds smooth. But now the problem is consistent. I've seen the gear failure before and it doesn't seem like that(though I bought one just in case and will probably replace it regardless). I've had this MR03 for almost 3 years and this is the first problem I've had with it. Haven't had time yet to take it apart and inspect it yet. Any suggestions?

2013.05.13, 08:10 AM
Pinched/broken wire? Got a spare servo motor to swap in?

2013.05.13, 08:18 AM
Had the same problem with too much rubber in the gears.
Maybe not your problem, but you can clean it while you change servo gear and see if that fixes the issue.

2013.05.13, 11:46 AM
Cowboysir- no unfortunetly I don't unless I take parts out of my other MR03's.
Nobrainer-pretty much thinking the same thing. I hope that is what it is. It's just the way it acts that throws a red flag for me. When it stops working I try turning the wheels with the radio and you don't hear the servo motor trying to turn the wheels or feel it vibrate. And when I touch the wheels to make it turn while keeping the wheel on the transmitter to left or right it turns. Then it fine until I stop turning the wheel then it does it again. Mr02's you could see and feel if their is trash in the wheel. But I think the teeth on the servo gears are a finer pitch so maybe it will act different. Hopefully I'll have time this evening to tear into it.

2013.05.13, 01:29 PM
Loose connection at either the pot or the servo motor. I found this a while ago on one of my cars. Wire was making intermittent contact but would lose it when the steering was bumped. The sheating was intact on the wire but the wire was broken internally (towards the potentiometer).

Either that or a servo gear... the MR03s feel different from the MR02s when that primary strips out.

Check connections, check the gear. hopefully it's not a board issue!

2013.05.13, 07:52 PM
i had never seen this happen before so was stumped and guessed loose connection somewhere. the servo motor wires are absolutely tiny and always cringe when i have to put it back in.

bill also tested to make sure it wasn't his radio by binding to another radio and ye, same thing so ruled out the transmitter.

what made it really odd was the steering would drop under normal conditions and it wasn't until you bumped it into a wall or another car that it kicked in again, only to drop out going further down the track. so it wasn't bumps that caused it to fail but actually got it back going again. it failed under no steering load most of the time, from what i could see. i wasn't driving though.

2013.05.13, 09:00 PM
My next guess is that the potentiometer is shot.

2013.05.23, 12:21 PM
Well I finally got the time to take it apart last night. I checked the wires for the motor and pot and they were fine. Swapping out chassis since their a few stripped holes and decided while I had it apart to go ahead and put the metal gear in even though their is nothing wrong with it. Well a pile of parts, broken servo wire and a lot of choice language later it's all in a baggy to deal with later. :mad:

2013.05.23, 01:23 PM
changing out the 03 PCB is not as simple as the 02 was. the wires are smaller and tighter. i snapped off nearly every wire on my swap i did and still have not repaired the VE board i got with broken wires.

sorry to hear the efforts are stalled and did not go smoothly. even more odd that you found nothing wrong to explain the steering behavior.

2013.05.23, 04:52 PM
I see you verified the connections are good to the servo motor and potentiometer - Did you try replacing the pot? If the steering was intermittent and kicked-in when the car got bumped it sounded to me at first like a loose wire, but now I'm thinking the pot might be shot and the inside-pendulum moving piece of the pot may broke or worn-out.. A new pot may solve the issue entirely?

2013.05.23, 05:39 PM
I've found if the pot is bad the steering generally goes hard over to one side or the other. In this case I'd suspect the motor, the brushes in the coreless mr03 motors will eventually wear out.

My second MR03VE had a bad steering pot out of the box, the solder connections were 100% solid but if the pot was touched in the slightest the steering went hard left.

The small wires can be a pain to work with, a smaller tipped soldering iron with a clean tip will make the job easier.