am i damaging my servo, possibly esc?

[inebriatedmarmoset]

Hi all,

i've got an hpi crawler king with a tekin fxr and a hi-tech 7955tg

the other day while crawling, the screw on the servo that attaches the steering link onto the horn broke, so i had to repair it out in the field. I didnt have a screw as thin as the one that was on there, so i had to use a body reamer to open the hole on the horn big enough to screw in a wider (m3x8mm i think) screw to continue...i don't know what measurement the original screw was...

but now im wondering if that had anything to do with why my servo is now omitting a constant "thinking" buzz where as before it did that only under duress or just during normal steering and I know that buzz is normal but just sort of goes in and out when neutral, but now it's a constant buzz even when "letting go" of the steering and returning to neutral. sometimes when i adjust the steering trim a little or steer slightly left and right it goes back to the normal on/off buz...but if i turn the steering trim all the way left of right i get the constant buzz / it did not do this before / ..i can get the normal buzz if i play around with it like im trying to settle it back in a neutral spot by turning left/right, just btw, the trim is never in the center spot, wheels are always to the left side if the dial is in the center..

I ALSO when i tested it the next day, same thing, but i noticed that my fxr was pretty hot, not to the touch, but it was almoooossst having a faint smell, not like burning but shouldn't have had a smell only after running it for about 15 minutes in my house and just testing the steering

so, my question is, is this maybe something with the digital servo not holding center or is something off that's causing the esc to heat up? am i damaging my servo gears bec it's under stress even when at a neutral point? im still kind of new to the game and am not sure if this can be solved by something i can program digitally with the 7955tg or something. or is it time to even consider replacing the stock tx ?

any advice is most appreciated! thanks again in advance!

[shannow]

Hello ,

I can only guess but have you only reamed the horn hole ? If so that means the link before was already 3mm diameter . Admiting the screw was 2.5mm before it then had a some play movement so it could easily find a neutral point for the servo .
But even so it shoudn't give much stress there , can you easily move the servo horn with you fingers ? (with batteries disconnected)

The trim should only be used for fine adjustements only .
When you put the horn on the servo the servo should be switched on and without any trim whatsoever so that it's in neutral position . Then you mount the horn so that the wheels looks as straight as posible (servo still on power holding it's neutral position) .

The 7955tg gobbles 4.2amps @6.0v when lock/stall so I would think it's too much for the 3amps bec of the fx-r .

[tigman250]

My HiTec 7954 hums and buzzes all the time from the day it was new, I read somewhere that the HiTecs are noiser servos.

I would agree that you are possibly now stalling out the servo, creating more heat in your ESC. I was stalling out my 7954 (didn't know it at the time) and it was overheating my Rooster Crawler ESC to the point it would shut itself off, without stalling my ESC would barely get room temp.

[inebriatedmarmoset]

Originally Posted by shannow

Hello ,

I can only guess but have you only reamed the horn hole ? If so that means the link before was already 3mm diameter . Admiting the screw was 2.5mm before it then had a some play movement so it could easily find a neutral point for the servo .
But even so it shoudn't give much stress there , can you easily move the servo horn with you fingers ? (with batteries disconnected)

The trim should only be used for fine adjustements only .
When you put the horn on the servo the servo should be switched on and without any trim whatsoever so that it's in neutral position . Then you mount the horn so that the wheels looks as straight as posible (servo still on power holding it's neutral position) .

The 7955tg gobbles 4.2amps @6.0v when lock/stall so I would think it's too much for the 3amps bec of the fx-r .

Originally Posted by tigman250

My HiTec 7954 hums and buzzes all the time from the day it was new, I read somewhere that the HiTecs are noiser servos.

I would agree that you are possibly now stalling out the servo, creating more heat in your ESC. I was stalling out my 7954 (didn't know it at the time) and it was overheating my Rooster Crawler ESC to the point it would shut itself off, without stalling my ESC would barely get room temp.

Thanks for your replies, guys! Yes! I am able to move the servo horn with my fingers, batteries disconnected...and i think when I was out on the rocks i mustve repositioned the horn so that it wasn't in neutral position. Originally when i did the servo over axle mod for the CK, it was hard to get an ultimate neutral point, had to really mess around with the lengths of the links and different horns/screws....but tonight played around with it more and made sure when i turned it on with the horn OFF and the trim centered, then attached the horn and adjusted the lengths of the links so that it wouldn't pull/push as much from the neutral point, and also! which im not sure how it stiffened, but c hubs were really tight which maybe was causing the servo to stall and get pulled when steering and letting go for it to return to neutral....which was weird though bec it was fine when i started crawling before the screw broke, i didn't notice ANY heat up, but yeah, when i disconnected the link from the horn, the wheels were hard to turn with my hands, so i loosened the top and bottom screws on the c-hubs, though now they protrude quite a bit which kind of bothers me, but the resistance is far less when letting go of the steer and it returns to neutral without getting too much of that constant buzzz...maybe i just need some lube on those hubs?

I'll still have to play around with it more to get an optimal neutral point, plus i did end up upgrading the stock tx to at least a spektrum dx3e, (on a budget for now) so hopefully that'll help me get more accurate adjustments for the end points n such

[Rig Rocker]

Your knuckles should move freely on the c-hubs when screw is tight. Did you accidentally lose the bushing that goes in between them? Its called a flange pipe and part# is ax30450

And your steering should move freely when disconected from servo. If not, find out where it's binding. Sounds like you have isolated it to the flange pipe listed above. Is it there? Or did you get loctite on the flange or knuckle that is freezing it up?

Originally Posted by inebriatedmarmoset

Thanks for your replies, guys! Yes! I am able to move the servo horn with my fingers, batteries disconnected...and i think when I was out on the rocks i mustve repositioned the horn so that it wasn't in neutral position. Originally when i did the servo over axle mod for the CK, it was hard to get an ultimate neutral point, had to really mess around with the lengths of the links and different horns/screws....but tonight played around with it more and made sure when i turned it on with the horn OFF and the trim centered, then attached the horn and adjusted the lengths of the links so that it wouldn't pull/push as much from the neutral point, and also! which im not sure how it stiffened, but c hubs were really tight which maybe was causing the servo to stall and get pulled when steering and letting go for it to return to neutral....which was weird though bec it was fine when i started crawling before the screw broke, i didn't notice ANY heat up, but yeah, when i disconnected the link from the horn, the wheels were hard to turn with my hands, so i loosened the top and bottom screws on the c-hubs, though now they protrude quite a bit which kind of bothers me, but the resistance is far less when letting go of the steer and it returns to neutral without getting too much of that constant buzzz...maybe i just need some lube on those hubs?

I'll still have to play around with it more to get an optimal neutral point, plus i did end up upgrading the stock tx to at least a spektrum dx3e, (on a budget for now) so hopefully that'll help me get more accurate adjustments for the end points n such

[inebriatedmarmoset]

Originally Posted by Rig Rocker

Your knuckles should move freely on the c-hubs when screw is tight. Did you accidentally lose the bushing that goes in between them? Its called a flange pipe and part# is ax30450

And your steering should move freely when disconected from servo. If not, find out where it's binding. Sounds like you have isolated it to the flange pipe listed above. Is it there? Or did you get loctite on the flange or knuckle that is freezing it up?

hmm no, i believe the flange pipe is there, it looks like a top hat, right? i made sure when i replaced the stock knuckles and hubs with rcp's clockable c's and high clearance knuckles I made sure i didn't lose any parts.....and I think I may have loctite it when i installed those, so i will try and take it apart and see if that's the case, thanks big rocker!

[Rig Rocker]

Originally Posted by inebriatedmarmoset

hmm no, i believe the flange pipe is there, it looks like a top hat, right? i made sure when i replaced the stock knuckles and hubs with rcp's clockable c's and high clearance knuckles I made sure i didn't lose any parts.....and I think I may have loctite it when i installed those, so i will try and take it apart and see if that's the case, thanks big rocker!

No problem