Kraton Servos - High Torque vs High Speed

[R/C_Fan!]

The steering servo in my new K8s is a piece of junk. I will be replacing this servo but after a bunch of research online, I still don't have a concrete answer.

I see that both high torque and high speed servos are available in true 1/5th scale sizes, but I do not know what would work better in our application. What I am reading on this forum, it would seem that everyone is opting to use high torque servos, but has anyone tried a high speed servo?

Can anyone clarify for me as to why one would work better over the other?

Thanks!

 

[SrC]

You don't need much speed in large scale rigs. But in general, if your torque is under spec for the size and weight of the rig, it will be too slow and then servo will struggle and just burn out. Torque is the priority.
This Primal RC Servo is probably the best servo for your 8S rig (both torque and speed) The price is right for these specs:

>>>62kg / 6.0volt. 73kg / 7.4 volt/ . 0.15sec/60 Degree at 6.0 volt. 0.13sec/60 Degree at 7.4 volt

Primal RC Raminator Monster Truck PM1373 Servo

Many 8S guys are using these servos.

Others may chime in with their favorite.

Good luck.

 

[R/C_Fan!]

You don't need much speed in large scale rigs. But in general, if your torque is under spec for the size and weight of the rig, it will be too slow and then servo will struggle and just burn out. Torque is the priority.
This Primal RC Servo is probably the best servo for your 8S rig (both torque and speed) The price is right for these specs:

>>>62kg / 6.0volt. 73kg / 7.4 volt/ . 0.15sec/60 Degree at 6.0 volt. 0.13sec/60 Degree at 7.4 volt

Primal RC Raminator Monster Truck PM1373 Servo

Many 8S guys are using these servos.

Others may chime in with their favorite.

Good luck.

Yeah, I was looking at that one and I like it. I did notice that it is not waterproof, and I was concerned that might pose a problem if I were to go through a puddle, or was in a very humid environment.

Do you think that moisture would be an issue or am I just over thinking things?

 

[Order66]

This waterproof 70kg unit definitely helped: Drfeify 1/5 RC Digital Servo Waterproof 70KG Steering Gear Spare Part Compatible with SPTZOHV180W RC Car Toy Accessories(Black) https://www.amazon.com/dp/B082KQZRYN/ref=cm_sw_r_cp_api_glc_fabc_cn2aGb74N59QV?_encoding=UTF8&psc=1

 

[SrC]

First, I generally avoid the super wet. Never snow or water for me. Have in the past, but RC electrics are not truly WP IMHO. Servos are fairly sealed well enough if they are NOT submerged or sit in water. Mud is not an issue.

But I always waterproof my servos, whether they state WP or not. It is easily done. If you are have never disassembled a servo it may be confusing at first.

The Primal servo doesn't state it is Not WP/water resistant. But I would say all servos are splash resistant for sure.

EDIT:

I take all my new servos apart and use Silicone Conformal coating on the electrical board and wire joints. I also use extra grease at the top gears. I reassemble the top and bottom covers at the edges with a waterproof dielectric grease or even liquid electrical tape. Then screw all back together, then wipe off the extra grease that oozes out the top and bottom covers. Just some ideas. Servos are real easy to work on and take apart. You have to do it a few times and is no harder than rebuilding a motor. All servos are built the same.
I run my brushed Crawler rigs in streams and water and my servos never fail.
But I never bash my big high power rigs in water in general however. The whole rig requires much more maintenance when they get wet, from BB's to all else. Crawlers are different because they don't have a true chassis that collects and holds water and they run so very slow . And I use SS bearings in my Crawlers. Bashing big rigs at high speeds through water craps out the whole rig fast IMHO. From experience.
Just my thoughts

I

 

[suchtragedy]

I take all my new servos apart and use Silicone Conformal coating on the electrical board and wire joints.

I highly endorse this recommendation. Ever since I discovered conformal coating (thx to this forum) I have used it on all my servos, receivers, and other odds and ends. It's super easy to use and 1 bottle will last forever.

 

[SrC]

^^^ I even took apart my cheap TTX300 I use for Crawling in snowstorms and the rain. I conformal coated the boards and used dielectric grease on the moving parts also. This radio has been completely soaked and keeps going. It's become a challenge to destroy this old RTR radio.
I've been through several bottles of ConF.
I even use Conformal coating on all solder joints, Lipos etc. They don't corrode over time. And you can rework solder joints through Conformal coating and reapply as needed.

 

[suchtragedy]

I have one crawler and I conformal coated just about everything including a RC sound box (coating on main board + spray on thompsons water seal on the speaker cones). It's been submerged a few times now and still works like new and I like how I can just hose the whole thing down now when I am done lol.

 

[SrC]

This waterproof 70kg unit definitely helped: Drfeify 1/5 RC Digital Servo Waterproof 70KG Steering Gear Spare Part Compatible with SPTZOHV180W RC Car Toy Accessories(Black) https://www.amazon.com/dp/B082KQZRYN/ref=cm_sw_r_cp_api_glc_fabc_cn2aGb74N59QV?_encoding=UTF8&psc=1

I noticed that this AMZ brand/ seller doesn't supply ANY Torque and speed specs with this servo.
Just that it is 70Kg.
But at what BEC voltages do you get spec'ed speed and torque?? I don't buy servos without these specs.
I would pass on this one.
Claimed to be waterproof or not.
The OP is is concerned with Torque and speed as stated. He wants spec's.
The Primal Servo is well known to be a brute, very durable and is less money than the above servo. Primal backs their products.
Just my thoughts.

 

[R/C_Fan!]

I have one crawler and I conformal coated just about everything including a RC sound box (coating on main board + spray on thompsons water seal on the speaker cones). It's been submerged a few times now and still works like new and I like how I can just hose the whole thing down now when I am done lol.

So, you can make non waterproof electronics waterproof? That sounds awesome! I'm ordering a bottle of that right now.

As far as servos are concerned, everywhere I am looking is showing a delivery date of the first week of February.

My local hobby shop has a Savox in stock, see this link for the exact one:

https://www.amazon.com/Savöx-SW0241...ild=1&keywords=SW0241MG&qid=1610793327&sr=8-1

This one is pricey, but I can pick it up tomorrow. Has anyone any experience with these servos? Is it a good one? or should I hold out for the Primal one and waterproof it myself?

 

[SrC]

(2) Kraton 8S w/ Primal RC PM1373 Servo - YouTube

 

[SrC]

So, you can make non waterproof electronics waterproof? That sounds awesome! I'm ordering a bottle of that right now.

As far as servos are concerned, everywhere I am looking is showing a delivery date of the first week of February.

My local hobby shop has a Savox in stock, see this link for the exact one:

https://www.amazon.com/Savöx-SW0241...ild=1&keywords=SW0241MG&qid=1610793327&sr=8-1

This one is pricey, but I can pick it up tomorrow. Has anyone any experience with these servos? Is it a good one? or should I hold out for the Primal one and waterproof it myself?

^^^ It is not strong enough IMHO.
You will be back at square one...
Not a fan of Savox in general and I avoid them now. After using several of them. And considering their price, Customer support is a ZERO. Been there with 2 out the box Savox's servos that were defective and purchased at the same time. They wanted them back and sent the same ones back and still no good. I checked them both on 2 different rigs and also on a servo tester. What are the odds that you get 2 defective servos together out the box?
It looked like poor Quality Control for expensive Savox servos.
Primal says "in stock". Just order the correct servo.

Primal RC Raminator Monster Truck PM1373 Servo

Why is your LHS offering that $Savox$ for your 8s??? Its not correct IMHO. Not any better if not worse than the Stock 8s servo.
Look at the specs of that Savox more closely. Not all LHS advice is good advice. They want to sell you a servo because you need one, I agree....
Just playing devils advocate.

 

[R/C_Fan!]

^^^ It is not strong enough IMHO.
You will be back at square one...
Not a fan of Savox in general and I avoid them now. After using several of them. And considering their price, Customer support is a ZERO. Been there with 2 out the box Savox's servos that were defective and purchased at the same time. They wanted them back and sent the same ones back and still no good. I checked them both on 2 different rigs and also on a servo tester. What are the odds that you get 2 defective servos together out the box?
It looked like poor Quality Control for expensive Savox servos.
Primal says "in stock". Just order the correct servo.

Primal RC Raminator Monster Truck PM1373 Servo

Why is your LHS offering that $Savox$ for your 8s??? Its not correct IMHO. Not any better if not worse than the Stock 8s servo.
Look at the specs of that Savox more closely. Not all LHS advice is good advice. They want to sell you a servo because you need one, I agree....
Just playing devils advocate.

Wow! I'm glad I posted this. I had no idea that Savox was such junk.

Is sealing up that Primal servo to be waterproof somewhat easy? I don't want to find myself learning on a new servo only to ruin it.


I am heavily leaning towards the Primal, but as long as I have your attention, what do you think about this option:

https://www.amazon.com/gp/product/B085W7Z8HB/ref=crt_ewc_img_huc_1?ie=UTF8&psc=1&smid=A1ZRSF6HVK2L2K

 

[SrC]

^^^ has less torque than the Primal running at 6v. BEC.
But, close enough as one option however.

For comparison and reference the Stock 8s S905 servo is slow (.20sec)and weak at 38kg/cm at 6volts BEC power. I would double that if it were me upgrading that servo. BTW, the S905 stocker is considered a 1/6 size servo in its dimensions, so any other true 1/5 scale servo will need the Arrma RX/servo mount kit below. Most upgrade servos wont mount to the stock RX box. 1/5 scale servo cases are larger.
Most guys need to buy this. This is common when getting rid of that stocker servo.
Food for thought.

So, you will probably also need this for any true 1/5 scale servo:


RECEIVER BOX (ARA320553) | ARRMA - Designed Fast, Designed Tough (arrma-rc.com)

Edit:

I emailed Primal RC regarding The PM 1373 servo and if it was Water Proof or Water Resistant. They responded very fast.

This is what they stated:

Steven Carlson,

This is an auto-generated email from an address that does not accept replies.

The case number 1378 has been updated.
You can check this case status by visiting this web page: https://www.primalrc.com/crm.asp?mk=cqohhfzfqi-1378

(Hotmail users may need to copy/paste this link into a browser manually.)

Important: If you have a "this is not spam" button in your email program, please click it to ensure you receive our next email when a representative responds to this case.

Ticket status: New

Department: Technical Help

Subject: Primal RC: Update Tracking #1378

Those servos are water resistant and not fully waterproof. They hold up well to water but if they get immersed in water then they could have issues. Thanks.

Sincerely,
Primal RC

 

[Reubydoobe]

I noticed that this AMZ brand/ seller doesn't supply ANY Torque and speed specs with this servo.
Just that it is 70Kg.
But at what BEC voltages do you get spec'ed speed and torque?? I don't buy servos without these specs.
I would pass on this one.
Claimed to be waterproof or not.
The OP is is concerned with Torque and speed as stated. He wants spec's.
The Primal Servo is well known to be a brute, very durable and is less money than the above servo. Primal backs their products.
Just my thoughts.

I know a few people who have run this for a while no problem, I've got one coming and I'll test in the wet and let you know how good it is. Or not

 

[dk3000]

My take is kinda personal. Why give a company like Amazon your $? They lost being a good honest company yrs ago. So to anyone recommending these overseas servo I'm not with it. Buy quality for your rigs. I have a new Promodeler servo that is outstanding, nothing will probably come close to what I'm seeing with this company. I'm not going to support junk just to save a few bucks especially from Amazon. IMO get off the Amazon servo band waggon and experience greatness! All in good nature but really guys? Amazon servos?

 

[SrC]

^^^ Without a doubt ProModeler servos are hands down the best. They command a high $ as a result. They are made from outsourced parts FWIW. Of course only the best parts. Largely Japanese Motors and Pots. Build and QC is top notch. There are Promodeler servos and then there are the rest. I agree.
But for bashing rigs, they can be overkill IMHO. Basher rigs can get expensive overall. To some of us, it makes no sense to put an F1 engine in a '72 Ford Pinto to drive around the block once a week. Get what I'm saying? And these Arrma rigs are far from precision RC machines out the box. Why need a precision servo realistically speaking. Just playing Devils advocate here.
There is a servo for everyone and their wallet out there. And it is not always the absolute best that money can buy. Because "some" of the other cheap servos are sometimes just "Good Enough". And yes some are even a complete waste, just outright garbage.
Yes, there is total garbage out there....Caveate Emptor. And some are fairly decent for the value they offer.
Fitting every one of my RC rigs with a ProModeler servo would be impractical for me and many others. Not everyone can afford a Ferrari or ever will. But I could see having a PM servo no doubt, down the road. They are clearly High End. Support doesn't get any better. They contract with the Gov't for Mil-Spec servos used in Drones. I don't need that level of quality though for my average quality Basher rigs.
The price point of "adequate" cheap servos are good enough for most. They are disposable at a pricepoint they have. Just have to know about servos better and how to choose. If a seller cant provide spec's just pass on it. Because any decent servo will Always offer that info. If not, they are probably just garbage anyway. Stay away.
The popular Savox's all suck IMHO. They are no better than the Cheap AMZ ones and others.
As far as AMZ, I buy from wherever gets me a decent price ands support. AMZ will step up with an issues if the seller drops the ball. From experience.
Everything comes from overseas, China and elsewhere these days. Had been for over 30 years. Will never change that Global concept of Consumer goods.
And here in the states, we are big Consumers. We are targeted as that type of market. Just how it is.
And if you want to boycott AMZ because they dropped the ball here and there, that's you prerogative. And where else will you go? You cant live in a bubble these days.


Edit: Promodeler Servos are known best for mission critical Air RC hobbyists.. That is Promodeler's typical retail market consumer.

 

[Greengaunja]

What he said^. Plus, with many shops offering curbside only, it gets hard to shop and compare. My LHS, I love them! Great advice and such. For me though, I can only benefit going in. If they don't have what I need, I can look around for an alternative and physically see what they have. What they don't have is an online inventory. Then there is the big box Boys, Great Hobbies. They have have almost everything in their online inventory. But for all the good it does them, 80% of it is either in another store, out of stock, or special order.
With Amazon, I can write the seller for details or ask questions that other people who bought that product can give feedback on. And if I don't like it or it was false advertising, Amazon steps in. Hell I got 4 FREE Proline Badlands solely because they didn't send the belted ones I paid for and didn't want a bad review.(they initially offered to refund the difference. I said no because I wanted belted Badlands)

EDIT: Should have said, it was an Amazon seller, not Amazon themselves.

 

[Greengaunja]

Lmao. Speak of the devil but I just took the dog for a walk and my second of 3 Amazon orders was at the door.

Probably far from the best, but its the same as the one I put in my 3s. Is it good? Dunno, I only ever bought 2 and they were the same. Personally, I don't like the speed, but my transmitter allows me to slow it down. Why didn't I try something new? Because I put the 3s through hell. The servo has been soaked, front end smacks have broken 1 knuckle, 2 hubs, the red stock servo saver, and more bumpers than I care to count. But the servo works as good as the day I installed it. It. L

 

[squidchief]

Hey, just my 2 cents worth...

If you don't want to go with the popular silicone conformal coating (FYI - MG Chemicals has retired the 422B formula and has replaced it with the 422C), you can use the GE Clear Silicone 2 caulk. I've used it for years on various automotive and outdoor electronic stuff.

** NOTE ** Do not confuse this product to the very similar Silicone 1. They are NOT the same. Silicone 2 is NEUTRAL curing which is what you want for electronics. Silicone 1 is ACID curing - you DON'T want that on electronics.

But just be aware it has a relatively short shelf life (not more than a year from manufacturing). Do NOT use it past the expiration date, seriously - It will not cure after that, just stays a sticky mess. My recommendation is to go all the way to the back of the shelf and pull out a later date one so you get more time to use it before it goes bad.

Just sharing for what it's worth...