RCCrawler Forums

ROLANDROCKSHOP · 01-13-2011, 12:26 PM

a fellow crawler is having the same issue's
i think like 4-cc bec's in 2-4 weeks!!

HEY,..ROOTAR!!!

Robbob · 01-13-2011, 08:04 PM

chalk another one up

rebuilt the front end, cvds had a slight bur to them I cleaned up and became smooth. put everything together and rechecked epa's.

bec plugged into the rx ..... drove around flat ground and was fine, turned the wheel and tried climbing and the rx went dead - esc flashed and rearmed and rx came back.

plugged the bec into the servo, esc power back into the rx, drove around flat fine, again turned the wheel on a climb and that was it. servo stopped, green lights gone.

i put the servo back into the rx and left the esc power in. put a voltmeter on the battery plug and started wiggling the steering back and forth rapidly. the servo started getting slower after a couple seconds but the battery voltage only varied by .10-.30v while servo died out.

hoping it isnt the servo but gonna grab a different brand tomorrow night at my LHS and another bec to fry, i mean try. maybe Ill get lucky and get a few of these warrantied

JohnRobHolmes · 01-14-2011, 07:52 AM

When you turn the wheel hard, does the drivetrain change in rolling resistance? Are you hitting the stops of the knuckles?

Robbob · 01-14-2011, 09:34 AM

Quote:

Originally Posted by JohnRobHolmes

When you turn the wheel hard, does the drivetrain change in rolling resistance? Are you hitting the stops of the knuckles?

Nope. On the LCC I have about 1/8'' gap between the axle c and the knuckle where the steering rod attaches.

After I wired it to the servo last night I climbed a box, left front wheel articulated up - turned wheel left and that was it. Right wheel was free and clear of anything.

Charlie-III · 01-14-2011, 10:07 AM

Quote:

Originally Posted by JohnRobHolmes

When you turn the wheel hard, does the drivetrain change in rolling resistance?

OK, have you tried turning the front wheels to their stops and then try spinning the wheels (by hand) to see if the axles bind?
Have you looked to see if a wire is getting tight when the wheels are turned?

MikeinFresno · 01-14-2011, 12:02 PM

good ideas Charlie, good indeeed

Robbob · 01-14-2011, 12:48 PM

Quote:

Originally Posted by Charlie-III

OK, have you tried turning the front wheels to their stops and then try spinning the wheels (by hand) to see if the axles bind?
Have you looked to see if a wire is getting tight when the wheels are turned?

cant spin an LCC axle by hand ...... all my electronics are on the back tray, no wires stretched anywhere. completely rebuild the front axle last night, including tearing the cv's apart - cleaning bearings and checking housings.

ebomb · 01-14-2011, 01:00 PM

u better figure it out, comp is in 2 days

those dam worm gears, i take it u didnt get the lnc gears yet. hope u get it figured out so u can dnf, i mean crawl on sunday

davec · 01-14-2011, 01:03 PM

Robbob, from the sounds of it we are having the exact same problem. I spent about 2 hours last night going through everything. I disconnected the driveline from the front, then turned the worm by hand as I worked the steering back and forth. At full lock, I felt a little binding, so I tracked it back to a rough bearing. I replaced that, then went through everything again. There was still some binding, which I finally tracked down to the wheels being too tight and causing the hexes to bind on the knuckle. Loosened those up and everything was butter smooth by hand, steering both ways, articulating, etc. I thought I had it, everything solved, right..................nope. I hooked the driveline back up and did a few runs around the garage. Works good until I start up a little wall, then the steering starts twitching and the BEC flashes off.

So, I think maybe it is driveline binding. I go through all the trouble of taking out the motor so I can spin the tranny by hand as I work the steering, etc. Everything is butter smooth by hand, no binding at all with the wheels backed off a touch. I put everything back together and it does the same exact thing.

I have tried 3 different steering servos, so that does not appear to be the problem. The motor shouldn't be part of the problem because the BEC is isolated and only providing power to the steering. I will be getting a new BEC tonight to try, because that is all that I can think it is, unless it could be something in my receiver, but that just doesn't seem to be it. The dig servo and the ESC work fine when these little episodes happen. I am at almost a complete loss right now as to what it could be.

One other thing I noticed last night that was strange, and maybe this will help an expert figure it out, was that when I as on flat ground and turning the wheels and then gave the throttle a blip to full, the wheels would jump back to center real quick and then go back to turning. It was like for a split second the servo lost power.

Robbob · 01-14-2011, 01:23 PM

Quote:

Originally Posted by ebomb

u better figure it out, comp is in 2 days

those dam worm gears, i take it u didnt get the lnc gears yet. hope u get it figured out so u can dnf, i mean crawl on sunday

oh Ill be crawling sunday even if I have to do it with my sportsman rig and the secrets I got brewing with that one.

Quote:

Originally Posted by davec

Robbob, from the sounds of it we are having the exact same problem. I spent about 2 hours last night going through everything. I disconnected the driveline from the front, then turned the worm by hand as I worked the steering back and forth. At full lock, I felt a little binding, so I tracked it back to a rough bearing. I replaced that, then went through everything again. There was still some binding, which I finally tracked down to the wheels being too tight and causing the hexes to bind on the knuckle. Loosened those up and everything was butter smooth by hand, steering both ways, articulating, etc. I thought I had it, everything solved, right..................nope. I hooked the driveline back up and did a few runs around the garage. Works good until I start up a little wall, then the steering starts twitching and the BEC flashes off.

So, I think maybe it is driveline binding. I go through all the trouble of taking out the motor so I can spin the tranny by hand as I work the steering, etc. Everything is butter smooth by hand, no binding at all with the wheels backed off a touch. I put everything back together and it does the same exact thing.

I have tried 3 different steering servos, so that does not appear to be the problem. The motor shouldn't be part of the problem because the BEC is isolated and only providing power to the steering. I will be getting a new BEC tonight to try, because that is all that I can think it is, unless it could be something in my receiver, but that just doesn't seem to be it. The dig servo and the ESC work fine when these little episodes happen. I am at almost a complete loss right now as to what it could be.

One other thing I noticed last night that was strange, and maybe this will help an expert figure it out, was that when I as on flat ground and turning the wheels and then gave the throttle a blip to full, the wheels would jump back to center real quick and then go back to turning. It was like for a split second the servo lost power.

Same here, I tore the axles totally apart last night. I had a slight bur on one cvd end but filed and cleaned it up. CVDs rotated super smooth in my hand, bearings were fine and dont bind.

Gonna grab a different servo and big boy CC tonight and try some more.

scatterbrains · 01-14-2011, 02:34 PM

Got any other rx's? try that may have a wonky rx in the truck. What esc and motor are you running?

Robbob · 01-14-2011, 02:42 PM

Quote:

Originally Posted by scatterbrains

Got any other rx's? try that may have a wonky rx in the truck. What esc and motor are you running?

tried 3 different 603FF RX's ..... all the same.

Tekin RS /17.5 Redline

Anyone know if or how I could figure out the amp draw from the servo? Wondering if I could wire the servo up again and some how gauge the amp draw on the bec while im driving.

Charlie-III · 01-14-2011, 04:23 PM

Quote:

Originally Posted by Robbob

cant spin an LCC axle by hand ......

Hmmmm.....I believe you are correct, my bad. Maybe try disconnecting the motor and spin the driveshaft?

(I forgot about the worm drive on the axles.....sorry, I' still new to some of this)

WIDELOAD · 01-14-2011, 05:05 PM

Quote:

Originally Posted by Robbob

Anyone know if or how I could figure out the amp draw from the servo?

Try here man, if you can find your servo in the lists they list the amp draw at stall/lock

http://www.servocity.com/html/servos___accessories.html

Robbob · 01-15-2011, 05:51 AM

Quote:

Originally Posted by Charlie-III

Hmmmm.....I believe you are correct, my bad. Maybe try disconnecting the motor and spin the driveshaft?

(I forgot about the worm drive on the axles.....sorry, I' still new to some of this)

no prob, I appreciate the try.

Quote:

Originally Posted by WIDELOAD

Try here man, if you can find your servo in the lists they list the amp draw at stall/lock

http://www.servocity.com/html/servos___accessories.html

Thanks. Could be pushing the max 10amps on the little blue ones when full locked.

I got the bigger CC last night to try. My home pc powersupply crapped out last night so I couldnt set the voltage on it. Gonna fix that when I get home then set the castle and try it.

Fingers (and nuts) crossed

Rootar · 01-15-2011, 07:28 AM

guess ill chime in, i killed 2 back to back, i was running dual tekin rs with dual 17.5s had the servo wired direct on time and not direct the other time. Both on mine died while sitting still, no load. nothing was even remotely warm so definetly not over drawing the bec. I finally decided it was my servo and pulled the 7950 and swapped in a brand new 5955 i got from a buddy put a pair of caps together and plugged them into my rx to help the two little tekins internal becs keep up with the 5955 and thats how im running mine right now, no bec, pair of caps to rx, different servo. no troubles thus far.

Robbob · 01-15-2011, 07:40 AM

Quote:

Originally Posted by Rootar

guess ill chime in, i killed 2 back to back, i was running dual tekin rs with dual 17.5s had the servo wired direct on time and not direct the other time. Both on mine died while sitting still, no load. nothing was even remotely warm so definetly not over drawing the bec. I finally decided it was my servo and pulled the 7950 and swapped in a brand new 5955 i got from a buddy put a pair of caps together and plugged them into my rx to help the two little tekins internal becs keep up with the 5955 and thats how im running mine right now, no bec, pair of caps to rx, different servo. no troubles thus far.

What size caps you using? the normal silver ones from Tekin or something you got from like Radio Shack?

pics?

Appreciate the info .....

SuperRoo · 01-15-2011, 09:42 AM

Robbob, what radio you using?

If its the 4PK(S) try changing the SERVO RESPONSE to NORMAL and see if that helps.

It might also be worth getting your hands on the Hitec HPP21 servo programmer and turn down the current limit (OPL) on the servo to see if that help also. Might also extend the life of the servo too.

Robbob · 01-15-2011, 10:01 AM

Quote:

Originally Posted by SuperRoo

Robbob, what radio you using?

If its the 4PK(S) try changing the SERVO RESPONSE to NORMAL and see if that helps.

It might also be worth getting your hands on the Hitec HPP21 servo programmer and turn down the current limit (OPL) on the servo to see if that help also. Might also extend the life of the servo too.

3PMX ...... think its unchangeable in there.

Ill keep the OLP in mind, thanks.

Robbob · 01-15-2011, 07:46 PM

Ok update to what I been trying.

Got a Savox 7.4 servo, CC blue bec and a Castle big (size of a toaster oven) bec.

Put the Savox in using esc bec ..... was able to replicate the servo stall from wiggling the steering rapidly, tried crawling up something and stalled hard. No change.

Wired blue bec into RX, pulled esc red wire, set bec at 7.0v ........ no stall from wiggling on flat ground, went to crawl up something and servo still stalled but didnt pop bec.

Wired in 7950 servo directly to bec ......... test ended once I tried crawling. (not shocked)

Wired in big bec (20amp max) set @ 7.0 to Savox servo ........ no stall on the wiggle test, better on climbing and binding the steering up. servo still stalled out in bind but relating that to brand and less torque (servos only rated at 300oz @ 7.4)

Wired in 7950 to big bec at same voltage ...... again no stall on wiggle, climbed up with plenty of torque to move steering, bound the front end up and servo still had power to wiggle the rear end around ......

Servo seemed cool, bec fins felt cold still ......... May have fixed my problem atleast for now.

Think Killswitch has it right, the 7.4 servos are really pushing the envelope on the little bec's.

HS7950 servo @ 6volts is listed at almost 5amps so putting them at 7.4v may be peaking the blue bec's. Castles site has the blue ones listed as 7 amps max @ 12v's. The pro becs are 20 amps max.

Got a comp tomorrow so we'll see how that gos but so far so good.

I appreciate every ones help and ideas here.

01-13-2011, 12:26 PM	#21
ROLANDROCKSHOP I wanna be Dave Join Date: Mar 2007 Location: roland,ar Posts: 5,981	a fellow crawler is having the same issue's i think like 4-cc bec's in 2-4 weeks!! HEY,..ROOTAR!!!

01-13-2011, 08:04 PM	#22
Robbob Custom Carbon Fiber Join Date: Oct 2007 Location: Connecticut :( Posts: 4,501	chalk another one up rebuilt the front end, cvds had a slight bur to them I cleaned up and became smooth. put everything together and rechecked epa's. bec plugged into the rx ..... drove around flat ground and was fine, turned the wheel and tried climbing and the rx went dead - esc flashed and rearmed and rx came back. plugged the bec into the servo, esc power back into the rx, drove around flat fine, again turned the wheel on a climb and that was it. servo stopped, green lights gone. i put the servo back into the rx and left the esc power in. put a voltmeter on the battery plug and started wiggling the steering back and forth rapidly. the servo started getting slower after a couple seconds but the battery voltage only varied by .10-.30v while servo died out. hoping it isnt the servo but gonna grab a different brand tomorrow night at my LHS and another bec to fry, i mean try. maybe Ill get lucky and get a few of these warrantied

01-14-2011, 07:52 AM	#23
JohnRobHolmes owner, Holmes Hobbies LLC Join Date: Nov 2004 Location: Volt up! Gear down! Posts: 20,290	When you turn the wheel hard, does the drivetrain change in rolling resistance? Are you hitting the stops of the knuckles?

01-14-2011, 12:02 PM	#26
MikeinFresno Rock Stacker Join Date: Jan 2011 Location: Fresno Posts: 58	good ideas Charlie, good indeeed

01-14-2011, 01:00 PM	#28
ebomb Quarry Creeper Join Date: Aug 2008 Location: meriden Posts: 341	u better figure it out, comp is in 2 days those dam worm gears, i take it u didnt get the lnc gears yet. hope u get it figured out so u can dnf, i mean crawl on sunday

01-14-2011, 01:03 PM	#29
davec Rock Crawler Join Date: Oct 2008 Location: Sandy, OR Posts: 672	Robbob, from the sounds of it we are having the exact same problem. I spent about 2 hours last night going through everything. I disconnected the driveline from the front, then turned the worm by hand as I worked the steering back and forth. At full lock, I felt a little binding, so I tracked it back to a rough bearing. I replaced that, then went through everything again. There was still some binding, which I finally tracked down to the wheels being too tight and causing the hexes to bind on the knuckle. Loosened those up and everything was butter smooth by hand, steering both ways, articulating, etc. I thought I had it, everything solved, right..................nope. I hooked the driveline back up and did a few runs around the garage. Works good until I start up a little wall, then the steering starts twitching and the BEC flashes off. So, I think maybe it is driveline binding. I go through all the trouble of taking out the motor so I can spin the tranny by hand as I work the steering, etc. Everything is butter smooth by hand, no binding at all with the wheels backed off a touch. I put everything back together and it does the same exact thing. I have tried 3 different steering servos, so that does not appear to be the problem. The motor shouldn't be part of the problem because the BEC is isolated and only providing power to the steering. I will be getting a new BEC tonight to try, because that is all that I can think it is, unless it could be something in my receiver, but that just doesn't seem to be it. The dig servo and the ESC work fine when these little episodes happen. I am at almost a complete loss right now as to what it could be. One other thing I noticed last night that was strange, and maybe this will help an expert figure it out, was that when I as on flat ground and turning the wheels and then gave the throttle a blip to full, the wheels would jump back to center real quick and then go back to turning. It was like for a split second the servo lost power.

01-14-2011, 02:34 PM	#31
scatterbrains RCC Addict Join Date: Jun 2006 Location: hillsborough Posts: 1,031	Got any other rx's? try that may have a wonky rx in the truck. What esc and motor are you running?

01-15-2011, 07:28 AM	#36
Rootar Rock Crawler Join Date: Sep 2010 Location: Little Rock, AR Posts: 596	guess ill chime in, i killed 2 back to back, i was running dual tekin rs with dual 17.5s had the servo wired direct on time and not direct the other time. Both on mine died while sitting still, no load. nothing was even remotely warm so definetly not over drawing the bec. I finally decided it was my servo and pulled the 7950 and swapped in a brand new 5955 i got from a buddy put a pair of caps together and plugged them into my rx to help the two little tekins internal becs keep up with the 5955 and thats how im running mine right now, no bec, pair of caps to rx, different servo. no troubles thus far.

01-15-2011, 09:42 AM	#38
SuperRoo Quarry Creeper Join Date: Dec 2008 Location: Australia Posts: 269	Robbob, what radio you using? If its the 4PK(S) try changing the SERVO RESPONSE to NORMAL and see if that helps. It might also be worth getting your hands on the Hitec HPP21 servo programmer and turn down the current limit (OPL) on the servo to see if that help also. Might also extend the life of the servo too.

01-15-2011, 07:46 PM	#40
Robbob Custom Carbon Fiber Join Date: Oct 2007 Location: Connecticut :( Posts: 4,501	Ok update to what I been trying. Got a Savox 7.4 servo, CC blue bec and a Castle big (size of a toaster oven) bec. Put the Savox in using esc bec ..... was able to replicate the servo stall from wiggling the steering rapidly, tried crawling up something and stalled hard. No change. Wired blue bec into RX, pulled esc red wire, set bec at 7.0v ........ no stall from wiggling on flat ground, went to crawl up something and servo still stalled but didnt pop bec. Wired in 7950 servo directly to bec ......... test ended once I tried crawling. (not shocked) Wired in big bec (20amp max) set @ 7.0 to Savox servo ........ no stall on the wiggle test, better on climbing and binding the steering up. servo still stalled out in bind but relating that to brand and less torque (servos only rated at 300oz @ 7.4) Wired in 7950 to big bec at same voltage ...... again no stall on wiggle, climbed up with plenty of torque to move steering, bound the front end up and servo still had power to wiggle the rear end around ...... Servo seemed cool, bec fins felt cold still ......... May have fixed my problem atleast for now. Think Killswitch has it right, the 7.4 servos are really pushing the envelope on the little bec's. HS7950 servo @ 6volts is listed at almost 5amps so putting them at 7.4v may be peaking the blue bec's. Castles site has the blue ones listed as 7 amps max @ 12v's. The pro becs are 20 amps max. Got a comp tomorrow so we'll see how that gos but so far so good. I appreciate every ones help and ideas here.

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