fq06

iTrader: (12)

So I was racing tonight and the top cover to my trusty old airtronics 94359 servo broke.

Replaced with a savox 1258TG fresh from the track shop to finish the last heat and main but my sc10 4x was undriveable.
Power would cut out, it would go sraight when I wanted to turn and turn when I wanted it to go straight.

Been racing there for a while and never any radio interference, no other issues before the servo swap.
Esc: rx8 with Novak glitch buster cap, never had a problem. Motor: tenshock 411 4600. Radio: old Jr xs synthesized Fm radio... never any issues, no one runs Fm any more.

I thought the rx8's bec would be able to handle that servo without any issues, guess not.
Can I run an external bec? Guy at track shop said can't use external bec or you'll damage the internal bec.

If I can't run that servo without a ext bec and I cant run a ext bec, that servo is a $80 orange paper weight.

Any ideas?

Pulse_

I have the same servo and use a 10A castle bec with success since the beginning. There is no risk to damage the bec of the rx8

electricRCrocks

iTrader: (7)

You can run the Castle Creations External BEC with the RX8 if you disconnect the center wire of the plug that goes into the receiver. We buy a servo extension and take that center wire out to leave the one on the RX8 intact. It's the best and provide nice strong voltage rail to your servo. The RX8 BEC is 5A @ 6V whereas the external CC BEC is 10A @ 6V!

fq06

iTrader: (12)

Thanx, I already use an extension so I'll pull the wire from there and go ect bec.

only8ight

iTrader: (29)

I have same exact issue at West coast too, I was there last tuesday and my car was undriveable too! i checked everything and founf out it was my reciever and ESC bec is dead. I am now using 10amp bec .problem solve, i guess rx8 bec is not tough enough to handle high voltage sesrvo.

Vegatron75

iTrader: (4)

Idk, I run the 1258, rx8, mrt transponder, airtronics rx and haven't had any glitching problems. I've missed a few laps over the loop though.

Lately I've been missing laps at the very end of a 5-8min qualifier or main. This is in my SC10 4x4. I think a cap will solve that problem.

Like I said,no glitching problems w/ the savox and rx8 bec. I think the mrt hogs a little more juice than the mylaps, ran the mylaps and didn't miss any laps. Spektrum rx's are also major power hogs....

Been running this setup indoors and outdoors for about a year.

fq06

iTrader: (12)

I have another top for my airtronics servo so I'll probably just put that back in and the savox becomes a paper weight.

Just don't want the rats nest of wires from adding a external bec.

motorhead68

hi, what would the effects of adding timing on the esc be?? like maybe 10 degres would it make a 1700 any faster?? does it get much hotter?would
the 1700 be closer to a 1900??? thanks

Burgrc8b

a quick question in relation to the origional topic. tekins rx8. what happens if i run the motor just hard wired, and no data cable from the esc to the motor? does that make it a brushed motor? cause it works either way.
thanks

Krio

iTrader: (159)

It's better to gear up for more speed than to add timing with these larger 4-pole motors.

Not brushed, but instead of relying on the sensor cable to tell where the rotor is it runs it in sensorless mode. It does this automatically so you don't have to worry about it.

Pulse_

Yes...and yes.

Like Krio said you should use a bigger pinion first and check the temps. I have a 1400kv 5S setup that reaches about the same rpm compared to a 1700kv in 4S but provides more torque and less heat and I couldn't be happier than this setup.

I tried 2200, 2050kv in 4S 1350 and 1400kv in 6S and came back to 5S with great results. I use 7 degrees of timing because I drive on high bite tracks. The only downside of a lower kv system is that you'll need a bigger pinion to reach the same speed which results in higher temps so it depends on the weather where you live. If you live in a very hot area I would switch for a 1900kv. This said I live in Belgium and don't even use a fan with my RX8. On a very hot day and high grip track I reach 3 leds on the controller which is reasonable

Does anybody know at what temp does the fan start on the RX8?

Waflet

iTrader: (35)

Hideeho
Something I've been thinking about for a while is running a 2650kv on 3s. I currently run a 2050kv on 4s geared 15/44 w/ rx8 in an agama ebug conversion on a small (105'x55') indoor track. Usually we have a full length straight (full 105') & at least 1 large jump w/ a short run up. Typical lap times are sub 20 seconds (16sec+/-currently). How can I expect the 2650kv on 3s to perform compared to the 2050kv on 4s? Bottom end torque, top end rpm, temp, & run time.

fq06

iTrader: (12)

Could not find my spare top case so I picked up a CC bec.

Question, can I solder the bec to the + & - posts on the rx8? Or further upstream on the wires? I wouldn't think it would matter but I don't want to fry my rx8 for the sake of this stupid savox servo

I will probably go back to the airtronics servo once I get a replacement part for it... but want to hit the track in the next day or two.

Krio

iTrader: (159)

At the posts is fine.

Bortzilla

iTrader: (26)

Ughhhh...The 'C' solder post pulled out of my 2 month old RX8 at the racetrack today. Guess I won't be racing for a while...Not a happy camper.