how are you powering your 7980?

[PipeDreams]

My xr isn't assembled yet but ya I hear ya that geometry plays a roll too... that's why the ax-10 guys running lots of steering use zero ackerman knuckles. What knuckles are you using? stock? If the horn still moves the tire then I can't see why the angles would be off. Power comes from the servo not from the tire. As long as the servo will still move the tire it doesn't matter if you can't move the tire by hand. The shorter the horn the more leverage! (think of a stick with weight hangin off one end... hold it at the other end and try to rotate you hand lifting the other end of the weight... pretty tough right? now move your hand to the middle of the stick and do the same... gets easier right? Now go as close to the weight as you can and it's really easy!) Look at my sporty build in my sig. you can see my servo horn is as short as I can get and still get almost max steering. Rule of thumb to get max leverage out of the steering you want the shortest servo horn with the longest kingpin to tie rod distance on the knuckle. Just remember the shorter your servo horn is the less throw you will have to get max angle of the steering ! Also the longer your links are the better the angles will be through the whole servo throw. Not to say other setups don't work but thats how to get the most out of your steering. It's a fine balancing act of short servo horn with long knuckle steering arm but still maintaining max angle!

[Krakker]

Taking a tip from 53Willy's, I used pins to connect the servo +/- strait to the BEC +/-, the signal (Yelow) wire is in a new plug that is sent to the rx. I currently have my BEC set to 7.4V. (running 3s lipo) I agree with 53, a bigger BEC or separate 2s lipo would only be more weight.
If the connectors are only rated for 5-7amp, why does the BEC got up to 10amp? IF there's a loss through the connector, what would be a good setting for the BEC to get 7.4V then? Or would you run it at 8.4 since it's 2s capable?

[rustyrooster]

Originally Posted by PipeDreams

Dx3e has epa's! When you'r crawling and it's bound up or not turning right where the wheel on the tx is not a big deal because it's normally not trying to stay there for a long period of time. As you crawl you are always moving your servo back and forth... More often then not though you are trying to max out the steering to get tight turns thus needing the epa's. The little bit of time it spends bound up or moving isn't enough to burn it out. They are designed to take some struggle but with out epa's you'r making it work much harder then you need to. Just look how often you hold the wheel on the tx at full turn one way or the other! The hard the time the servo is having moving to it's directed position the more amps the servo will draw. Place your crawler on a table and wit it on try turn your tires by hand.. it's tough because the servo is getting signal to stay centered but if you constantly make the servo work by holding it off from it's intended position it will burn out much faster then keeping the rig rolling and letting the servo catch up to where you are instructing it to go. Set your epa's and don't worry just drive! Do you know how to set them?

As I typed that last comment I was wondering how it would read. Now I know. I am good with my end points and how to set them and the intent.

Basically what I was wondering is if there is an rx out there that can be set to power off a single or all channels if that is the desired failsafe. I know I can program my dx3e with custom failsafe positions, but to my knowledge all failsafes on the dx3e are still providing power. If I could, I would set a failsafe so that when the rx does not receive a signal from tx, it stops supplying power to the channel my servo is plugged into. That way when I happen to be in a bound position that might cost me a $100+ I could turn off my tx and the servo goes ‘limp’ like it is when sitting on the bench with no power until I go rescue it.

[indiana mudcat]

Originally Posted by rustyrooster

As I typed that last comment I was wondering how it would read. Now I know. I am good with my end points and how to set them and the intent.

Basically what I was wondering is if there is an rx out there that can be set to power off a single or all channels if that is the desired failsafe. I know I can program my dx3e with custom failsafe positions, but to my knowledge all failsafes on the dx3e are still providing power. If I could, I would set a failsafe so that when the rx does not receive a signal from tx, it stops supplying power to the channel my servo is plugged into. That way when I happen to be in a bound position that might cost me a $100+ I could turn off my tx and the servo goes ‘limp’ like it is when sitting on the bench with no power until I go rescue it.

Your overthinking this, just do what I do in a bind, yank the throttle HARD. You'll eventually find all the weak spots, you can also get a Hitech servo programmer and set it to shut down.

[PipeDreams]

Krakker on hitec website it says the 7980 and 7950 are both designed for use with 2s lipo. which means both can run at 8.4v. It's up to you if you want to use the servo at 8.4 or 7.4 or 6 doesn't matter to me just letting you know you can. Just because the connector isn't rated that high doesn't mean it can't support more amps... that's why guys direct wire them and solder right to the board! That's what I did to get the most power on my jr servo and bec. I believe it says right on the package (or instructions) of the bec that the connector can't support more then 7 amps. If you're using the 7980 or 50 on 6v then you wouldn't need more then 7 amps anyway. But if you plan to start going higher I'd just solder it direct.

I agree you're way over thinking! When you're in a bind either throttle out or pick it up the choice is yours. It's not like you're leaving it in that bind for min before you get to the truck.

[Krakker]

Thanks for that clarification Pipe, perhaps you can answer another ?. "IF" I direct solder the servo wires to the board of the BEC, would the plug for the BEC still work for programing it even if the servo is still connected?? Would it send any funky programing to the servo?
My theory is that since it's only power wires from the servo that it would be fine, I could set it for 7.7 or even 8.0 "AND" I could shorten the BEC's pigtail. (since they are always too damn long anyway.)

"FYI": Thanks to EeePee, this tech thread is in the BEC install tips sticky that JohnRobHolmes has.
BEC to Servo connector

[PipeDreams]

I think you could ya. Like you said it's just power going to the servo and if you made a tiny short pig tail so you could still program it that should be sweet. Might be a bit tough to get both a power wire and pigtail on each solder tab but hey if your really good I'm sure you could!

[tigman250]

Originally Posted by rustyrooster

Sorry tigman if we are off topic a bit but i like what is being discussed.

After re-reading my post I could see how my off topic comment could be taken that way, I meant I was dragging it off topic by the question I asked ha ha!

Thanks for the great discussion guys, this thread has answered alot of my questions!

[PipeDreams]

No worries that's what this is all about! Amazing how much you can learn from a few guys on a forum and a bit of time reading.