sf-20w servo not enough

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NitroNation

NitroNation

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i recently installed this servo on my savage xs and even this has weak turning strength with only 2s. i have 3s packs ready to go looks like i need a stronger servo....any suggestions??
 
sf-20 servos are weak.......
Pretty much anything else with metal gears will be better. Hitec, futaba, savox, Get something with a lot of torque, but not too much (400oz in is NOT needed)
 
Upbasher said:
sf-20 servos are weak.......
Pretty much anything else with metal gears will be better. Hitec, futaba, savox, Get something with a lot of torque, but not too much (400oz in is NOT needed)
Click to expand...

Even a full size savage only really needs around 200 oz/in. for the steering. The Xs is alot smaller. As UP said though, the SF-20w is weak. Only 90.26 oz/in. Not sure if the Xs still has this, but make sure your servo saver is adjusted correctly. And replace the bushings in the servo saver with bearings.
 
NitroNation said:
i recently installed this servo on my savage xs and even this has weak turning strength with only 2s. i have 3s packs ready to go looks like i need a stronger servo....any suggestions??
Click to expand...


ya that servo aint gonna cut it. is for something like a 2wd buggy or truck.... you need a servo with at least 150 oz in or better.... don't go all crazy with it.... look at solar servos on HobbyPartz, they sell some that will work great and their prices cannot be beat......
 
WOW these guys are charging me close to $30 for shipping... price went up from 17 to $45 oh man....



Shopping Cart
Item Unit Price Qty. Cost
Solar Servo D772 High Voltage [email protected] 64g Digital Metal Gear $17.50 1 $17.50
Subtotal: $17.50
Shipping: $28.00
Tax: $0.00
Total: $45.50
 
international shipping and just so ya know shipping is free with a big enuff purchase(not sure on international shipping).... Thats what we try to do is pool our resources and order stuff all at once......
 
I'm gonna try it with eBay. I'll let you guys know what happens
 
Your wrong about the sf-20w servo not being strong enough, it's the stock sf-10w that's not strong enough. The one you ordered and the other one you posted a link to are way over kill for the xs. Your gonna tear up the servo saver with either one of those. Those 2 servos are more geared towards the full size savage. The problem with the steering has to do with the servo saver and it's design. And it's not adjustable like the full size savage either. Maybe adding some washers will put a little more tension on the spring, not quite sure, but it may work. The spring really isn't strong enough. I believe hot racing makes an alum replacement for the stock one and it comes with a couple different spring weights. Also, don't forget that you can adjust the voltage output to the servo via castle link. What voltage do you have it set on right now?
 
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I have no idea what voltage its set to nor do i know how to set it...
 
Small or big savage, either way the sf 20 is a weak servo, and more torque is always good, you just need to set the endpoints right so you don't tear stuff up.
 
NitroNation said:
I have no idea what voltage its set to nor do i know how to set it.../QUOTE]
If you don't know what it's set at, then it's set to the default voltage, which is 4.8v. The only way to change it is via castle link or the field programming card. The castle link software is free to download from castle's website, but you'll need the adapter to connect the esc to your comp. I can't remember how much it is, but you can probably find it for a good price on ebay. I got mine free when I origanlly bought my castle MMP for my blitz. I highly suggest you get the adapter and castle link software, the tuning possibilities are endless with it. Also, since you insist on going with 3s, you'll definitely have to add punch control and limit the torque on the motor with 3s. I did and even on 2s it's still a monster. That's why I gave up on using 3s,it's really wasn't that fun to drive. I haven't found a wide open enough space yet to run it on 3s at full throttle. And it also wasn't fun anymore having to walk 200-300 ft. every couple min to flip it back on it's wheels when the torque on 3s makes it flip on it's lid. But, you'll learn the hard way instead of taking veteran members advice.
Upbasher said:
Small or big savage, either way the sf 20 is a weak servo, and more torque is always good, you just need to set the endpoints right so you don't tear stuff up.
Click to expand...
Your are completely wrong. The sf-20w servo is plenty strong enough for the xs. Unless you actually have an xs, which I do and know what it's needs, more torque isn't always the answer. It has 100% to do with the servo saver. When I bought my xs used, the guy already upgraded the servo to a traxxas one that has about the same amount of torque as the sf-20w,which is plenty. The xs doesn't weigh as much as the full size savage so it doesn't need 150+ in-lbs of torque. 100-125 max in-lbs is all it needs. You've got to remember that the xs isn't actually a 10th scale rc car, it's actually smaller than 12th scale but bigger than 18th scale. He's also limited on torque values because he's only got 4.8v going to the servo. If he takes my advice, which time will tell, then he can program the esc settings and bump up the voltage to 6.0v, which will increase the torque output of the servo. He can also go to 7.4v as long as the servo is designed to handle that voltage.
Click to expand...
 
Well, yes, obviously, if he sets the voltage up to 6v then it will be a huge increase in performance.
Still, you can't go wrong with more torque. Is it needed? no. Is it better? yes Remember, the sf-20 is also pretty slow, so a high torque upgrade will most likely increase the speed also.
Another point, the sf-20 breaks easily due to weak plastic gears. A metal geared one will be far more reliable. I have owned 4 or 5 sf-20's, two of them blew up for no apparent reason, and one other one stripped the gears on a tiny little jump. The other two (the older ones that came in the savage x 4.1) are still going.
 
I'm getting ready to go to work right now and replying to the above post using my phone. All I have to say is that I will respond to it when I get home and on the comp.
 
Upbasher said:
Well, yes, obviously, if he sets the voltage up to 6v then it will be a huge increase in performance.
Still, you can't go wrong with more torque. Is it needed? no. Is it better? yes Remember, the sf-20 is also pretty slow, so a high torque upgrade will most likely increase the speed also.
Another point, the sf-20 breaks easily due to weak plastic gears. A metal geared one will be far more reliable. I have owned 4 or 5 sf-20's, two of them blew up for no apparent reason, and one other one stripped the gears on a tiny little jump. The other two (the older ones that came in the savage x 4.1) are still going.
Click to expand...
This is going to be my last comment on this matter, if it sinks in, it sinks in, if not, oh well... Sometimes "more" isn't always the answer, as with the xs. You still keep comparing it to the full size savage which weighs 3 times as much as the xs. So 150 in-lbs of torque is not needed, and only really need right around a 100 in-lbs of torque. The main problem with the steering is the servo saver. Just like the full size savage, the spring is rather weak and that's where most of your torque is being lost. That's also the reason why HPI came out with an HD spring for the servo saver on the full size savage when companies started coming out with stronger servos. As for speed, when you get a high torque servo you sacrifice speed, as with if you get a high speed sero you sacrifice torque. But with the xs and the high speeds (mph) it can go, a fast response servo is not what you want. If your goin full speed on 3s in the xs, which is a little over 50 mph, and you can't turn the wheel in small, smooth increments, your asking for a damaged truck. Imagine going 120 mph in a ford f150 and jerking the wheel left or right, what do you think will happen?
 
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