why are JR servos so glitchy @ center???

[airdreams1]

Ive heard so many people raving about them being so great on here. But localy, Ive met several people that say they all have centering issues!

Anyway I have 2 JR z9100t & both have a glitch when centered. Both are used, but 1 is supose to be rebuilt/replacement from JR racing.
I dont have the issue with my Hitec's or any other brand servo hooked up to the exact same electronics combo. So, Whats the deal? Just a crappy design? bad part that I need to replace? Or just a bunch of people with flawed opinions?

[ohh EPiC FAiL]

i had a z9100t in my e buggy and it had the same problem. i didn't wanna deal with it so i sold it.

[binaryterror]

This almost always means the plastic upper case where the shafts fit is worn.

I have installed the HV aluminum upper cover on my 8711 and its run now for over a year without this issue. Also my 8711HV has not ever had this issue, but it came with the aluminum cover.

What's odd it before I did the upper case swap, I could over time see the JR wiggle, but in racing use I have servos much older run more than the crawler ones and they don't do this at all. Must be the force we apply that causes the stock upper case plastic to distort/wear.

I've run every brand of major servos (though not recently the newer Futabas) in racing and crawling...you'll never see me use a Hitec, Airtronics...not even if they were free.

[airdreams1]

any ideas if the alum upper case is available for the z9100t or where Id be able to get one?

[binaryterror]

Originally Posted by airdreams1

any ideas if the alum upper case is available for the z9100t or where Id be able to get one?

It's available, but you need special hardware. I'll take a peak on here, I know XJ Farmer or jcboof posted about the needed screws for the conversion.

[binaryterror]

Here is the front case you need: http://www.horizonhobby.com/Products...D=JRPSC8711HVT
Here are the screws you need: http://www.horizonhobby.com/Products...ID=JRPSH8711HV

The hardware link looks like the wrong picture, but thats the number I used.

[airdreams1]

both links errored. But I found them by the part number.
I only need the top, as I have dozens of the screw sets with the rubber mounts from way back when every servo came with them. lol

[jcboof]

Originally Posted by airdreams1

both links errored. But I found them by the part number.
I only need the top, as I have dozens of the screw sets with the rubber mounts from way back when every servo came with them. lol

The aluminum case takes a Machined screw. Not the coarse thread screw like the plastic cases. If you have machine screws, i'm sure you'll find something that works.

The top case on the JR's have a brass bushing in them. For some reason the bushing kind of seizes to the gear shaft and causes the bushing to spin/rotate in the case top. Over time, the case wears to create a little slop. This slop is what causes the servo to "hunt" back and forth for center. It is a digital servo and is constantly looking for center.
Replacing just the case works good, but eventually it will start to wiggle again. Replacing the gear set and the case will basically make it a new servo again, but it will probably start to wiggle again over time, but it will last longer than just replacing the case.
Replacing the upper case with an aluminum case is the ONLY way I've found to permanently cure the problem.

[MR.VERTICAL]

Originally Posted by binaryterror

This almost always means the plastic upper case where the shafts fit is worn.

I have installed the HV aluminum upper cover on my 8711 and its run now for over a year without this issue. Also my 8711HV has not ever had this issue, but it came with the aluminum cover.

What's odd it before I did the upper case swap, I could over time see the JR wiggle, but in racing use I have servos much older run more than the crawler ones and they don't do this at all. Must be the force we apply that causes the stock upper case plastic to distort/wear.

I've run every brand of major servos (though not recently the newer Futabas) in racing and crawling...you'll never see me use a Hitec, Airtronics...not even if they were free.

Itook your advice and got the hv case wow that made all the differnce in the world thanx.

[BigSki]

Great info in this thread. I have the Z9100T and it does what you guys are talking about, I just figured that 2 years of comp crawler duty and then 1 year of service in the large scale Willys just took its toll, now at least I know that I can squeeze some more life out of it.

[airdreams1]

havent bought the top yet, but have 1 more question about it...
the screws your talking about are the 4 that go all the way through the servo correct? (& they are fine thread for the alum top / corse for the stock plastic top.)


Also, would this set work & or be overkill? Servo Case: 8711HV, 8717HV, Z9100HVT, Z9100HVS | Horizon Hobby I know its spendy, but I was thinking it would make it bullit proof. I realy dont want to have to mess with it again if posible.

& Im wanting to water proof it wile its apart too.

[xiteamxi]

i have the 9100hvt and it does the same thing sometimes so i don't believe its just the case tho i'm sure the case would help

[binaryterror]

Originally Posted by airdreams1

Also, would this set work & or be overkill? Servo Case: 8711HV, 8717HV, Z9100HVT, Z9100HVS | Horizon Hobby I know its spendy, but I was thinking it would make it bullit proof. I realy dont want to have to mess with it again if posible.

You only need the top and the 4 long screws.

Replacing the center, center top and bottom are a pain, and do not help especially not for that price.