Traxxas Sledge servo

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While selecting the best steering servo for Traxxas' fabulous Sledge seems simple, it's actually anything but as this beast demands more!

As is usually the case, one of these articles comes about after someone asks my opinion regarding one of our servos. This time regards using a DS630BLHV for steering a Traxxas Sledge. And not just one guy, but two this very morning (and maybe 15-20 over the last few weeks since its release). Then another guy wrote saying he'd not even ordered the Sledge yet, so he didn't even have it but wanted 'our' steering servo recommendation.

TL;DR . . . the short answer. To the first guys, no, we don't recommend the DS630 (a Series 1 servo) . . . get the DS635 (a Series 2 servo), instead. And for the third guy, the newbie still buying, same thing, get a DS635 for that rig. Why?

Simple, because a Sledge is pretty big and fast, so it especially needs a mechanically strong servo, and this requirement is exactly what led us to create the series 2 servos. As compared to a series 1, the series 2 has bigger gears and shafts plus a larger output spline! For the more nuanced answer, read on . . .

Q1. I've heavily modified my Traxxas Sledge and am wondering if the DS630BLHV is a good choice. Also, I've heard ProModeler servos won't work when plugged into the receiver, so I'm confused about this. Also, what's the warranty?

Q2. I am running a heavily modded Traxxas sledge and was wondering can I plug the DS505BLHV straight into receiver and use it? I've seen something about you recommending a separate battery so what's the real story? Also, I originally bought a servo off Amazon and couldn't get warranty help when I tore it up so is there any warranty for ProModeler products? Thank you.

Q3. I'm buying a Sledge but don't have it yet. Everybody says the stock servo won't last but when I look around for a replacement I hear so many things I'm a bit confused and overwhelmed with upgrades. What servo should I get and what other items would I need?

There are actually 4 questions within these three queries;

  1. Is a DS505 or DS630BLHV a good choice for a Sledge? Nope!
  2. Does it work when connected straight to receiver? Yes, but . . .
  3. What's the warranty? 1-year
  4. Which servo do you recommend for a Traxxas Sledge? Series 2 . . . DS635/845/1155

A. Is a DS505 or DS630 a good choice? Since the only difference is the motor (otherwise, they're the same servo), I'll answer for both with . . . nope, not a good choice. Not for such a fast and heavy rig as the 1/8th scale Traxxas Sledge (sorry if it's not what you want to gear, but you did ask).

Why not? Honestly? I wouldn't recommend any of our series 1 brushless servos for the job (DS505, DS630, and DS930). Maybe the DS930, but even then not really because all 3 share the conventional 25T output shaft (like the stock servo). And note; we're using the best steel there is and you can twist it upon impact (too easily in our opinion). So the rig just needs a more heavily built servo.

Eyeball this photo of a DS930 shaft damaged by a heavy rig. It's been twisted because of the external forces of hitting a stump or a curb (most likely). And we've even seen them snapped in two! And note; anything that happens to this servo, with the best steel money can buy, definitely will also happen to the output spline of any other servo on the planet.

- This is a steel output shaft of a DS930 twisted like a pretzel by an impact

Here's a photo of our original DS635 (with 25T spline shaft before we updated it to the 15T with the V2. Other than larger output shaft plus a larger bearing, they're basically the same. But take note the ginormous difference in the size of the spline! It's massive. In fact, it's what we use for our line of quarter scale servos, the ones outputting from 1500-2700oz-in. Anyway, once we updated them to the gnarly 15T spline, twisted shafts became a thing of the past.

- The larger shaft of the DS635 version 2 in the foreground

By the way, the spline isn't the only thing bigger about a series 2 versus series 1 servo, there are also larger gears inside. So let's frame this a bit better with another photo. This next one shows the relative size of DS505/630 output shaft on the left (remember they share the same gear train, just a different motor), then our DS930 output gear in the middle (also 25T), plus the 635 V1 output gear. While the 930 gears are larger than the 505/630, note how the 635 gears are a shade larger.

  • ProTip: the output gear is the biggest gear in the servo because it deals with the brunt.

- DS505/630 on left, DS930 middle, DS635 right

Background

So the output gear of the DS635 is thickest, next is the DS930 gear, then the DS505/630 which incidentally, has about the same size output gear as a Savox 2290SG. But don't mistake the DS505/630 gears for weak, just not our strongest. And don't misunderstand what we're saying; 505 and 630 are great servos, just not ideal for bashing.

Summarizing, it's my opinion, the right servo for the Sledge is going to see you stepping into a series 2 servo instead of one of our series 1. However, no matter what 'I' think, you're the customer - so you're always right - and if you want to use a DS505 or DS630 because you don't think you're going to stress it very hard, then KYO because you're a big boy and it's your money. But since I'm being asked formy opinion, then you're getting my unfiltered thoughts, capisci?

  • Yes, I'm telling you straight up; don't buy a DS505 or DS630 for a Sledge, get a series 2 servo like a DS635/845/1155, instead.

ProTip - while we offer three series 1 servos and three series 2 servos (DS505/630/930 versus DS635/845/1155), and while all six are about the same physical size (meaning a standard class 20x40mm footprint servo with conventional mounting beams), and while all 6 have all-steel gears, the series 1 servos are far more suited for crawling versus the series 2 are optimal for bashing. it's down to larger gears and shafts and because of the 15T output shaft. Everything is more beefy about a series 2 gear train (note; the 25T is the same as Futaba, Savox, et al).

So for bashing, you're going to be way ahead of the game by opting for the significantly more heavy duty drive train of our series 2 servos. Eyeball the next picture to see how they're built inside (photos of a type competing products never show you).

- Note the massive shafts and heavy reinforcements

What do you see? Not just big ass gears and larger diameter steel shafts, but look how the alloy case is heavily reinforced with bronze inserts. These are called hardpoints.

So basically, with ProModeler you're getting better parts from which to begin your adventure with your Sledge than if you bought an ordinary import servo. After all, better parts make for better servos, agreed? And we're trying to earn your business the old fashioned way . . . by giving you more bang for your buck!

DS635 or DS845 or DS1155?

OK, so we recommend a series 2 servo instead of any of our series 1, check. But which of the three is best? Short and sweet . . . it's our experience our DS635BLHV is well suited for the largely stock Sledge. But we don't know you. So if the servo is destined for a heavily modded rig, meaning heavier because of the addition of accessory alloy parts and bigger rubber, then we advise you opt for either our DS845BLHV, or DS1155BLHV (for the added grunt required when turning big heavy tires at high speeds).

The more nuanced reasons why . . . it's because more power is required as weight and speeds go up. Means it takes more torque from the servo to meet your expectations. And this is true even if you buy an import like a Savox 2290SG, an otherwise pretty decent servo.

Look, in offering up 22 volts of oomph, Traxxas put in your hands something which will hurtle into the 70s speed-wise! To put this into context, 70mph is about 100fps (feet per second). Since the average house is about 100 feet long, it means this thing is hustling along pretty quick at top speed . . . it's über fast (a technical term for lickity-split)

And your Sledge carries a lot of beef. Moreover, a modified version (with bits and bobs made of alloy and steel) plus larger tires? Well it weighs even more!

Why heavy and fast - together - matters!

Why? Simple, let's turn to Newton's law of Motion (there are three). The 2nd and 3rd are germane to the Sledge discussion. The 2nd states that the force on an object is equal to its mass times its acceleration. Written it looks like this; f=ma*a . . . if the mass is the same (same rig no matter how fast), as you're going faster and faster (definition of acceleration), then the faster you go the harder you hit the fence post, or plant it after a 100' jump. Means ultimately, something's gotta give! So that's 2nd law.

Meanwhile, the 3rd law states there's an equal and opposite reaction for every action. So if your rig just kisses a curb at 70mph then it's the same as if it were standing still and the curb came out of nowhere and hit your Sledge - at 70mph - it's the exact same exact thing, either way.

Put 2nd and 3rd together and it means the force being generated - maybe just cutting the wheels at a bit of speed - can be enough to overwhelm the gear train and spline of a conventional servo. Conventional being our Series 1 servos (as well as competing designs like Savox 2290SG, MKS HBL599, or Futaba CB700). Why? Just because a lot of mass at speed is harder to steer because it imposes higher forces!

This next photo shows the comparison of the Savox 2290SG gear train to that of the DS635 and take note of the relative size of the final drive, the output gear, the largest within the servo. This is an example of how bigger is better. Our series II servos are beefier inside and just more durable.

- 2290SG gears juxtaposed with DS635BLHV gears

Continuing with comparison to the Savox 2290SG (a good servo, we're not saying otherwise), but this time juxtaposed with the DS630 (instead of the DS635 we recommend), and which to remind you, differs in the motor only from the DS505, note the construction . . . one is reinforced, the other puts the steel gear shaft directly in the aluminum.

Steel, bronze, and aluminum - of course - are metals, but the bronze is second only to steel with regard to hardness within our servos (and both are FAR stronger and harder than aluminum). So putting a harder metal (steel or bronze) in place (an insert) to shield the soft aluminum is called metal reinforcing. So we use bronze (and sometimes, steel, or even bearings) when reinforcing our aluminum alloy servo cases where shafts fit in the highest impact location. In fact, we're unique in the industry in bronze reinforcing even our entry level $29.99 servos!

Which is best? Honestly, any of them are way better than the big fat nothing you find inside more cheaply manufactured products (to include the no-names on Amazon) plus a host of servos available by online hobby shops (ones who instead of handling quality brand name products seek a low cost manufacturer in Asia to produce their private label offerings). And note, since we buy competing servos and no-names to inspect for what we may learn, we weren't surprised to discover the hobby shop brands are actually made pretty much exactly like the el cheapo no-name products (and in one instance we know with certainty, by the very same Asian manufacturer).

Anyway, to the question of, is a servo better if it's made with reinforcements, or would you rather have a servo where the steel shafts are fitted directly into soft aluminum? We think the answer is a no-brainer but it's really up to you to decide, not us. Point being, when shopping, just because it's shiny and pretty on the outside doesn't mean jack!

Why the larger spline shaft and bearing?

Because all else being equal, when it comes to trucks, bigger is better . . . and yes, we have a Sledge horn available to suit. Part number PDRS16F-15T. Click the link and it'll open a separate browser tab so you don't loose your place.

- PDRS16F-15T Sledge servo arm uses the ball from Traxxas 2742

Recapping:

So we went bigger with the internal components expressly with the series II in order to handle the forces being imposed by faster and bigger rigs. Recall, Traxxas set about standing the 1/8th scale off-road world on its head with the Sledge. How? By redefining the entirety of the concept through their engineer's bag of tricks.

Tricks? Yes, because the Sledge is a monstrous rig operated at seriously fast speeds on high voltage. Honestly, just making it and bringing it to market (from 'this' product designer's perspective), has been quite an impressive trick in the first place! So trick is the right word in many regards. If nothing else, it's quite a trick rig all in and of itself, too.

Why doesn't Traxxas equip the Sledge with a better servo?

I alluded to it above. Successfully bringing it to market involves a host of compromises. Some will buy it for a 9 y/o who will dink around in the back yard until they break it before returning to their Nintendo Switch, the Sledge forgotten. So if Traxxas used the best of everything it would cost $2000 and nobody but aficionados would buy it - and certainly not the many Moms and Dads shopping for their little kid using a credit card!

So the major difference between you and Traxxas when selecting the steering servo is they have to factor cost above pretty much everything in order to broaden the market to include everybody. Nice thing is this means you can belly up to the counter and plunk down the MasterCard to bring together your vision of the perfect rig, while they have to contend with bringing the whole thing to market . . . at a price for which folks will step up to the plate and whip out the MasterCard!

Enter our Series II servos, which is what we unequivocally recommend for the Traxxas Sledge. But let's laser in on the answer to the actual question (unasked), what's enough torque and why?

  • Stock rig, light upgrades - DS635BLHV
  • Modded rig, quite a few upgrades and bigger tires - DS845BLHV
  • Heavily modded rig, best of the best, fast and heavy as they come -  DS1155BLHV

Let's close with regards to plugging it in to your receiver and will it work? Yes it'll work; here's proof!

  • But you're asking the wrong question.

Right question is, will it make rated power when connected to a receiver and powered by the typical hobby grade ESC with a BEC circuit? Nope, I don't think so, but you're free to do as you please because as we said earlier, you're the customer and thus, you're always right.

So if it were me, then instead of relying on a free BEC that came with the ESC,or even an aftermarket one because analog juice beats digital no matter what, then I'd run a dedicated pack like a B2S850 - or - pony up for a good quality stand alone BEC (if you insist on synthetic juice).

ProTip: while I recommend an 850mAh pack, our packs sizes range from 650-6000mAh, and the 850 is probably about right in my estimation (good for maybe 3 runs between charges), but if you can fit the 1500, then it'll run for about twice as long on a charge (call it every 6th time you charge the propulsion pack). Are we the only ones steering you away from using BECs with performance models? Nope, so does Futaba.

ProTip: our packs (and suggested BEC) come with 2 power leads to the receiver instead of 1. This is because otherwise, you can't comfortably get more than 5A into the receiver.

Eyeball the servo specs. Specifically, look at current draw while stalled (meaning when it's making rated power) and then you'll understand why single-lead 'solutions' are really anything but. One lead is a 5A connection to the receiver so a typical BEC backfeeding the the ESC into the receiver through the throttle channel lead limits you to 5A and begins overheating at the 3.5A the connector is rated for. So using two leads, one to the receiver at BAT and the orher connected to the receiver through an unused channel, maybe channel 4, gives 7A before beginning to overheat, a practical 10A in the real world.

A real world problem is the specs for a BEC don't mean what you think. I'm saying you can't take what marketing says as gospel because they lie. Especially companies selling inexpensive consumer grade goods imported from Asia (or even assembled in USA of imported components).

So like you read servo specs (and a Savox 2290SG, incidentally, makes rated torque at 8.3A), then you also have to read the specs of BECs, also. And if read the specs of products by the best companies, you learn 20A BECs aren't really 20A. More like 7-8 at the voltages we're concerned with. Yup, output current totally depends on voltage input. Also depends on temperature because they rate them at 77°F with a 10fps cooling breeze. Cooling breeze, under the plastic shell of a rig? Hah! Anyway, they rate them for lab conditions. You're not getting what you think and no matter what, they put out digital juice versus analog.

  • BEC versus battery is like the difference between Tang and real orange juice!

That said . . . and in fairness . . . while we believe you should use a separate battery to power it, you're the customer and may instead decide to wait and see. Wait for what? Until after you run it a while.

So how do you decide? Basically, if you want more power from the servo (you'll know), then you can order the battery and harness we offer for Traxxas owners (they're a 6V system so the harness splits power so only the servo gets 8V and thus, protects the radio from going poof).

Major point being, some folks are happy enough with the power they get from the servo using the built-in BEC, so if you're one of them, then you don't need a dedicated battery! By the way, I'd share the same advice with you regarding any servo making 500+ oz-in as this is a matter of physics, not opinion so if you decide a Savox 2290SG suits you better, I advise you treat it similarly.

Finally, the Sledge has a pair of motor clamp mounts which have a set of threaded holes in each. This makes for a great place to mount a bit of flat stock material for battery mounting. Use 1/8" plywood from the hobby shop. They sell 6"x12" sheets for a few bucks. Anyway, after you cut it out and drill the holes (obtain by transfer, e.g. rubbing a pencil on a piece of paper), then color it in with a black Sharpie and seal with thin CA glue. That, or a bit of 2mm carbon fiber sheet. Whatever!

- Gorgeous layout of the Sledge is simple yet sophisticated

Speaking of mounting the battery pack, I like using 3M brand Dual Lock Velcro TB4575, which I buy off Amazon. This will readily hold it in place.

Also, if you're curious, these articles touch on why we believe a dedicated pack's better. And like I've said, we'd say the same if you're running a Savox 2290SG, MKS HBL55, or Futaba CB700, or anything else making +500oz-in, then please believe me, a standalone battery is a better power supply for your control electronics than any BEC on the planet.

Warranty?

1-year parts and labor against manufacturing defects and workmanship.

Does this mean you can't break it? Hell no! Why not? Because we're not stupid, modelers can break anything! This includes even our Series 2 with the gnarly gears and massive 15T output shaft.

Anyway, good luck in whatever you decide but please trust my guiding you to a Series 2 steering servo versus one of our Series 1 or any competing servo using a 25T spline because as the designer, I know what our servos can take (and that Sledge is no joke, and definitely not a toy).

Summary
For a stock Sledge I'd use a DS635 and the factory BEC system (means just plug it in where the old servo was and it works). For a heavily modified one (lots of heavy aluminum aftermarket parts, big motor tires, etc.) then I'd use a DS635/845/1155 but with a battery. And I don't advise the series 1 servos because the more burly series 2 servos exist for good reason.

And review my thoughts for why opting on a $60 Amazon special isn't such a great deal. Ditto the hobby shop labeled imports because they're the same kind of thing (but with some hobby shop's whiz bang label engineering). Those compared to ProModeler, Futaba, MKS, Savox, et al. Trust me, I make these things and I know more than you - it's the same advice I'd give a nephew.

Of course, you're a big boy, so it's your decision. Anyway, whichever servo you decide is best for you, if it's ProModeler, you're going to like it. Ours are better built and more durable than the imports. There's a 1 year warranty, visit the page for the details.

Last thing; if you just plug it into the receiver and go drive the rig, it'll work. And yes you'll be happy - but - I predict one day you'll wish the steering were more crisp at higher speed. You'll want the rig to cut harder/better/sharper and that's when power decisions your make before installing the servo will affect the solution.

If you're using a dedicated battery, the solution will be a stronger servo. But if the servo is running on a BEC, then fixing problem of it not being crisp won't necessarily mean you need a new/stronger servo. Instead, it more likely means you'll need to upgrade how you power the servo (true for any 500+ oz-in servo regardless of brand). I say this because physics affect all servos equally. Nobody makes a magic 500-1000oz-in servo that uses half the amperage of someone else's, OK?

Fundamental reason will be the Traxxas servo-power supply (BEC circuit of an ESC is called a BEC for battery eliminator circuit). Anyway, it isn't really up to handling a high performance servo (which you'd expect since they're intent on building it as cheaply as possible so it sells better).

So the upgrade involves two power alternatives, an aftermarket BEC or a dedicated battery. Or you can spend a lot of money on a new motor and ESC which has a better BEC (and maybe it's good enough, maybe). Anyway, we have both, just click these links to learn about them before ordering your servo. Note; reason we don't recommend upgrading the stock Traxxas motor and ESC is they're actually pretty decent. So I wouldn't do that until they wear out, but it's your money.

Speaking of which, if you ask around on FaceBook, I predict 9 out of 10 say they use a BEC to power their system. But I also bet they've upgraded motors and maybe use an aftermarket ESC like Hobbywing, or similar. Lot of money, and remember, some of those aren't up to the job, either because hairy ass servos consume lots of power (amperage, not voltage).

Me? I'm an old engineer and thus, I know of no BEC that compares favorably to a battery. They're just not good enough. So for my models, I'll take the quality of a battery over a BEC any day of the week. And I advise, until you know more about this than me, you should also run a receiver battery, which incidentally is exactly what all the expensive gasser-powered rigs use.

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