Originally Posted by
MikeR
If it has 160oz of torque as those specs show then it should easily return to center unless it has a bad servo motor pot and cannot properly sense its center point.
What you want to do is;
1. Charge battery and turn all power on including the radio.
2. Disconnect the servo turnbuckle and try and move the servo horn by hand.
3. Watch and determine if the horn moves/slips without the servo turning. If so then servo saver is at fault.
4. Or determine if the servo horn is not slipping on the servo but instead the servo output gear is able to turn/move by hand each direction. If so then faulty servo centering pot.
Another thing to do is try swapping servos between your 2 cars to see if it works better with different servo and servo horns.
Lastly check your radio steering wheel- is it turning freely or is it 'sticking' when you turn it?
Thanks for the thorough reply and suggestions.
With the battery peaked and the servo saver tightened as much as possible, I can force the servo saver to move a little, but it requires a LOT of force and I think something in the suspension would break before it could exert that level of force on the servo. Nonetheless I tried replacing the servo saver with a fixed servo horn and the steering behaved the same.
The horn cannot be moved by hand with any reasonable degree of force.
This is the second servo in the car; the SF-50 was bought to replace the stock SF-10 on the assumption the steering issues were a result of the stock servo being too weak.
Without the steering linkage attached, the servo seems to have no issue centering consistently. Once the linkage is attached though it struggles to do so. It will get about 90% of the way back to center immediately, then you can hear the servo motor continuing to run for perhaps another 1/2 second, possibly pushing the wheels slightly further, before eventually stopping roughly 95% of the way back to what should be center.
The best way I can describe it is that the centering force of the servo doesn't seem strong enough to center the wheels, which seems crazy given the specs. And this is the second servo, so while I could write off the stock servo as being kinda weak I have trouble accepting that HPI's strongest servo has the same problem. It seems more likely the linkage is just terrible and doesn't give the servo enough leverage to move things properly.
Right now I'm struggling with a reason to spend $50 on yet another servo to hopefully fix things when for another $100 on top of that I can get a TC4 chassis that should work a lot better. I dunno...I want to like this car but the steering is terrible.
EDIT: I should add I'm just running this thing casually in the street. I'm not looking for out and out performance but given that I'm on a somewhat narrow street, having a car that doesn't wander is the difference between having enough room to play and frequently hitting the curbs.
Endaar