plopes

I NEED TO BUY A BUNCH OF SERVOS FOR 60 SIZE AIRCRAFT.
HITEK 635HB AND JR DS821 ARE THE SAME PRICE.
WHICH DO I GET?

alan0899

G'day Mate,
I have had excellent results with JR servos for 26years, since I started flying in 1981.
I have no problem with Hitec, I've only had one & that was a 645MG, but was not powerfull enough, so I went to JR Digital.
But I still have the 645MG in a 60 size Diabolo, in fact I'm flying it tomorrow, with my new Spektrum DX7.
So I'm a bit biased I guess.

DaddySam

My Feedback: (9)

I'd go with the JR servos. These particualr Hitecs leave a bad taste in my wallet, since they were marketed as a replacement for the 605, which had no installation restrictions. After several gear or shaft failures Hitec now "restricts" these to 12lb planes, and don't recommend them for gas engine planes. While you're flying a .60 now, if some time in the future you go bigger, you won't need to buy new servos (within reason). There's a whole thread, if you search for it, on the subject.
Hope that helps,
Sam

Edwin

My Feedback: (2)

I like the JR over the karbonite hitec servos. In our area the JR's are a little cheaper.
Edwin

mtwister

The 821 is faster, and will hold the torque once the arm has stopped moving, as compared to the 635 will only create torque while it's moving. Makes a big difference as you go up in plane size.

Brian Smith

My Feedback: (117)

Don't they both have carbonite gears?? Brian

Edwin

My Feedback: (2)

As far as I know, Hitec is the only one using karbonite. Supposed to be their big deal.
Edwin

mtwister

The Jr servo's use a type of nylon that claims 4x more strength.

lrb75

My Feedback: (12)

Take a look at the output shaft on a 821. Same silver grey material as karbonite. Same 4x strength claims. Same output shaft failures when first released.

Edwin

My Feedback: (2)

Hmmmm! I did a search on "ds821 failures" and got two hits. But there was enough info in there to keep an eye on this. Mine are in 60 sized planes but was thinking about using them in a TF giant P-47. Maybe I'll just go with the JR sport 125 oz servos instead.
Edwin

Brian Smith

My Feedback: (117)

I had 4 HS475HB Hitec servos I installed new in a G38 powered "BIG" Stick.. On the 3rd flight the rudder servo stripped/broke.. I called Hitec and talked to Mike.. He exchanged them for 645s and said Hitec did not recomend carbonite servos in any gas models and nothing bigger than a 60 glo motors.. "If" they are the same material, I would be careful... The 821s I got in my DX7s do seem smooth, strong and tight. Brian Smith

Edwin

My Feedback: (2)

I've already sworn off hs635's. I bought 8 to put in the P-47. They never made it out of the box.
Edwin

Nickrc3

My Feedback: (6)

Does this similarity still exist with the 821 or were changes made? I hear a whole-bunch of problems with Hitec's "karbonite" gears, but very little with the JR 821.

lrb75

My Feedback: (12)

Once Hitec admitted there was a "problem" with their servos the number of people reporting failures seemed to go down alot. I don't know if I would even call it a problem, but the solution seemed to be reminding everyone not to use loctite and giving out free longer servo arm screws. Most folks who seemed to have trouble admitted to using loctite which apparently really messes up the new plastic. They also recommend using one servo per surface per 12lbs of plane. Probably overly conservative. The same rationale would probably be inorder for the DS821. I have 6 karbonite gear servos in service and haven't had any problems but the early failures did have me worried.

Edwin

My Feedback: (2)

Dont recall hitec admitting a problem. Just changing the specs. Hitecs web site states,

Applications: Sport to high performance aircraft to 12 lbs.

on their web site http://www.hitecrcd.com/homepage/product_fs.htm

I havent seen anything about 12lbs per flight surface.
Edwin

Brian Smith

My Feedback: (117)

** BIG BLUNDER ON ME*** Hey guys.. I had HS475HBs.. "NOT" 635HB.. But they did not say limited to 8 pound models when I bought and installed them. I do apologize to any one who read this thread and Hitec... Can I claim "old timers" ? Brian Smith

pilotpete2

Hi Plopes,
Wow what a difference in prices in your location, here in the States the Hitec 325s are less than half the price of the JR 821s. I have had very good luck with the Hitec 325s in applications that are meant to use a "standard" servo, but if you can get JR 821s (digital!) for the same price, no contest, though they are composite gears, just like Hitecs Karbonite.
It was unfortunate that Hitec oversold the Karbonite gears originaly, though the issue of some folks using Locktite on non metal servos output arms and shafts was not their responsibility, but then manufacturers do have to warn us not to use a hair drier in the tub
Pete

lrb75

My Feedback: (12)

I didn't and wouldn't say they admitted a real problem maybe an incompatibility but Hitec has a sticky in their forum that reminds people not to use loctite and numerous posts warning the 12lbs limit. They also replaced the short screws for free.