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  1. #1
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    stampede 4x4 Sct 3800 2s acting sluggish.

    I'm trying to figure out a problem. My son and I each have a stampede 4x4 both upgraded to s sidewinder sct 3800kv. Running 2s 4000mh. The trucks get near the same use. I'm finding that my truck runs and acts as if it's set to no lipo cut off. Run around with it on gravel and grass for about 30 mins and it seems to slow down and drop in its abilities. I have tried switching the battiers to see if it's just a battery problem and my truck still does it. His truck will not no matter the battery.

    My lipo one of the balance wires came lose so I opened it up and repaired it. Was thinking this was the problem at first seeing as my truck was the one with the problem. But it would seem not. I have a EV-650 balance charger so I know the batteries are good. The truck just seems to run like I'm using a NiMh battery. I have checked settings on both using the link card. Both have same settings. I even redid them just to make sure. They are set to cut off at the default and both set to brushless.

    I know it's not bearings or anything as I keep up with these and check gears and grease as needed. We don't treat them as boats but they get some wet use. They are the waterproof versions tho. Just don't understand.

    The motors and ESC are only about 6 months old same with the batteries. And charger.

    I have not yet done a full takedown of the truck this year. But knowing the truck can bash just fine for the first 30 mins. I can't think why it would be any of the moving parts. We normal get about 45-60mins on these battles at our local BMX track.

  2. #2
    RC Qualifier JohnnyHildo's Avatar
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    check to see whether or not your esc is in "lipo mode" for starters.
    by your description it reads like you run the truck for 30 mins and it slows down which is in fact your low voltage cutoff kicking in.
    if you're getting 60 minutes out of a 4000mah pack you should contact the guiness world book of records because i can't get a 5000mah pack even close to that.
    also, burning a truck with a 3800kv on grass continuously for that amount of time is going to fry your motor if you aren't keeping tabs on temps so be careful.
    happy bashing!
    sl4sh 2200 / p4de 2400

  3. #3
    RC Qualifier cazrack's Avatar
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    Also check punch settings, with (wrong) settings electric power to engine will be delayed causing it to feel less responsive and aggressive when you press hard on throttle.

  4. #4
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    We live in BC Canada. Temps have always been good. And it's a mix of crawling and bashing. This is how we get the hour. It's not non stop full speed. Yes I checked settings. Cutoff Auto, cutoff 5v. Drag auto, break 20-30%, pukch control 0-10%"helps keep truck flat"

    Both settings on both trucks are the same. As for the slowing down part. I don't think you understood me. Before when it hits that low power mode. The truck will drop by say 50% speed. This drop is all of a sudden. Then shortly after the truck will just stop moving. Still has power to turn and all that. This is how it normally would act.

    Right now it's not. It's acting as if not in Lopo mode and after about 20-30 mins you can see and hear the truck slowing down as you drive passed your self. I tested again and can drive till it starts to jerk as it needs more power. Not the standard max speed then a massive drop. As I said it feels like it's running a Nimh well using a lipo. I know draining the battery is not good. But I'm still ok. If I let the truck sit for a few mins it has no problem then going full speed again. Although really fast it will repeat these.

    I would post some pictures but can't figure out how to with my iPhone on here.

    Ps we never bash hard in taller grass. Like a school field or back yard cut grass. I a side note I have not ran a Nimh bat in it since it started to do this. Was thinking changing the settings and running one thought it and then going back to lipo. Although I don't see how this would alter anything. As for my times. It's just how we drive. At the BMX track we get about an hour and 30 mins from our 4000 lipo and 3000 NimH. Five or take depending on all the factors. Timed this lots of times. Good amount of RPM in there lowered its weigh.
    Last edited by Deken187; 08-28-2016 at 12:19 PM.

  5. #5
    RC Turnbuckle Jr. Briber's Avatar
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    First heres my thought on drag brake. Set drag brake to 0%. All that does is apply brake for you when trigger is in neutral position. Unless you like the auto brake. I only use that on my speed runs in case it gets out out range it won't keep rolling for forever. If just bashing around no need for it and if anything will shorten run time. If your running and you let off throttle it will coast till it stops which uses no power from batt. If drag brake is on then when you let off throttle it uses power to slow truck down so it's always using power from batt.

    It could be motor or esc going bad too. Try swapping out sons motor for yours and see if it acts the same. Maybe motor bearing is going bad and as it heats up its binding. If I does then you know it's the motor. If not try the same with esc. Try his battery in yours. I did this with daughters truck many times to troubleshoot problems.

    One last thing to try is to tighten up your slipper. I don't think that's it either but worth a try if it's slipping to much. Have you done the aluminum bearing adapter upgrade? If the plastic one has melted over time it could be causing issues too. But I would think it would be happening all the time if it was the problem...

    Sent from Eastern Missouri
    Last edited by Briber; 08-28-2016 at 02:33 PM.
    Just need one more rc, then Ill be done...

  6. #6
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    Yup. Changed that out the first time the pads in slipper broke. I could not figure out why they bearing would not come off. So yes both have that upgrade both mesh are set with the paper trick and I have the slipper set so if we push down on the truck enough it will slip.

    I was thinking about the bearing binding that would cause it. I hear no signs of that. And both motors are only 6 months old so I would hope the bearings in there are good.

    We do like the 10% break as with a bad landing we like to just let the truck stop and roll with out having the tires spinning around effecting air travel. But also I guess worh more coast I t will help control the truck mid flight. So I may fiddle with that. But I don't think the 10% break would be effecting the trucks performance that much.

    As for swaping out parts. Sigh. The joys of that. I managed to get all the wires and crap all nice and neatly tucked away and does not fling around well driving. With some custom mesh tubing. As for the trucks side by side well driving. They act the same till the whole slow down part. His is just not doing the same thing. But I guess I will have to try this and swap parts to see if I can filter out the electronics.

  7. #7
    RC Turnbuckle Jr. Briber's Avatar
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    Quote Originally Posted by Deken187 View Post
    Yup. Changed that out the first time the pads in slipper broke. I could not figure out why they bearing would not come off. So yes both have that upgrade both mesh are set with the paper trick and I have the slipper set so if we push down on the truck enough it will slip.

    I was thinking about the bearing binding that would cause it. I hear no signs of that. And both motors are only 6 months old so I would hope the bearings in there are good.

    We do like the 10% break as with a bad landing we like to just let the truck stop and roll with out having the tires spinning around effecting air travel. But also I guess worh more coast I t will help control the truck mid flight. So I may fiddle with that. But I don't think the 10% break would be effecting the trucks performance that much.

    As for swaping out parts. Sigh. The joys of that. I managed to get all the wires and crap all nice and neatly tucked away and does not fling around well driving. With some custom mesh tubing. As for the trucks side by side well driving. They act the same till the whole slow down part. His is just not doing the same thing. But I guess I will have to try this and swap parts to see if I can filter out the electronics.
    Buddy started having problems with jerking and shuttering and stopping, come to find out his battery was going bad. One cell was way different than others.

    My sct combo 3800kv motor went bad within a few months, so 6months would be good compared to my experience. Lol. You don't have this problem but here's what mine did only a few months after getting it. https://youtu.be/Z5YtxqbOMtM So it's not out of the realm of possibilities for motor to be bad. Trust me I know that feeling of getting everything fitted and looking great only to have to tear it all out to repair or check something. It's part of the hobby! Uhhhg

    Sent from Eastern Missouri
    Last edited by Briber; 08-28-2016 at 05:23 PM.
    Just need one more rc, then Ill be done...

  8. #8
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    Quote Originally Posted by Briber View Post
    Buddy started having problems with jerking and shuttering and stopping, come to find out his battery was going bad. One cell was way different than others.

    My sct combo 3800kv motor went bad within a few months, so 6months would be good compared to my experience. Lol. You don't have this problem but here's what mine did only a few months after getting it. https://youtu.be/Z5YtxqbOMtM So it's not out of the realm of possibilities for motor to be bad. Trust me I know that feeling of getting everything fitted and looking great only to have to tear it all out to repair or check something. It's part of the hobby! Uhhhg

    Sent from Eastern Missouri
    The cogging thing our trucks have always done out of the box"combo". Just can't go that slow. But they will go slow enough to crawl. As for the battery's. I have run both our packs through each truck. They both run just fine for the first part of the bash. Then mine just seems to start to slow down. You can hear it as you rip around over time. Just don't make the same hum as the first say 15 mins or the other truck. And my charger info points to good cells.

    Something I have not touched on. The new combo is about 6 months old. On average they may get 2-3 hours a week at the park/BMX track.

    But time will tell. As summer is passing. the wet and cold is coming. They need a good cleaning and rebuild. And dust removed. This will allow me to check everything on each rig. I'm hoping it's just a bearing heating up and binding over something electric. What's a good ez to get motor cleaner. As if I'm going to check the bearings in there I may as well clean around also. Water and a little soap and let dry ok? They are water proof after all. The can does seem to be sealed tho where as or brushed motors"stock" could just drink water all day long like a boat. Lol

    Let it begin. I'll touch back on my findings. Any other thoughts info is still greatly appreciated and I'll keep tabs on this thread.
    Last edited by Deken187; 08-28-2016 at 07:35 PM.

  9. #9
    RC Turnbuckle Jr. Briber's Avatar
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    Quote Originally Posted by Deken187 View Post
    The cogging thing our trucks have always done out of the box"combo". Just can't go that slow. But they will go slow enough to crawl. As for the battery's. I have run both our packs through each truck. They both run just fine for the first part of the bash. Then mine just seems to start to slow down. You can hear it as you rip around over time. Just don't make the same hum as the first say 15 mins or the other truck. And my charger info points to good cells.

    Something I have not touched on. The new combo is about 6 months old. On average they may get 2-3 hours a week at the park/BMX track.

    But time will tell. As summer is passing. the wet and cold is coming. They need a good cleaning and rebuild. And dust removed. This will allow me to check everything on each rig. I'm hoping it's just a bearing heating up and binding over something electric. What's a good ez to get motor cleaner. As if I'm going to check the bearings in there I may as well clean around also. Water and a little soap and let dry ok? They are water proof after all. The can does seem to be sealed tho where as or brushed motors"stock" could just drink water all day long like a boat. Lol

    Let it begin. I'll touch back on my findings. Any other thoughts info is still greatly appreciated and I'll keep tabs on this thread.
    That wasn't slow, what you see in video was full throttle. That motor was getting less powerful then one day wouldn't move at all. Pulled it out and gave it full throttle. It would cog really bad like that then break free. I put back in truck and would move the truck. Pulled out again and shot video. All I'm trying to say is the motor going bad isn't out of the realm of possibilities. It can only be a certain few things.

    Bearings, some kind of drive train binding, battery, esc or motor.

    We can rule out battery and bearings according to what you've told us so far. The options left are what you'll have to work through one at a time to figure it out. I hate seeing fellow rc-ist having issues and just trying to help. Hope you/we can figure it out and help you get back to running 😎

    2-3 hrs a week isn't a whole lot of run time. I run that a day easy. But it's spread out now between 3 different trucks.

    Sent from Eastern Missouri
    Just need one more rc, then Ill be done...

  10. #10
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    Lol. To funny. That video. I watched and and its like ok give it some juice and then it seems you do. But it's just binding at full throttle. Lol.

    Yah nothing the same as mine. It's currently taken apart into the main chunks of it. I'll get into all the bearings and such tomorrow. To shed some light more onto how much we drive them. True not as much as other RC lovers. But I love the things. My RC days go back to the Ricochet. Love that thing so much. Just don't make them like that anymore lol. But my son now is getting into them. So we have started with these stampede 4x. Solid truck. But I digress. The stock motors Titan 12t I think they were. We used 2 of them over a year. So 4 in total and our 2nd one was removed and working for the brushless. When the first died in my kids truck and I asked the guy at our LHS. He LoLed at it lasting 5 months for us. Said his lasted 4 weeks lol.

    But I will update on my findings once I have finished rebuild and testing.

  11. #11
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    Alright. The outcome. So after taking apart both trucks to do a full cleaning. I have come across the problems.

    First after taking the lipo to the store to have it looked at. It seems 1 cell has less volts then the other. Not a big difference but one that can be seen.

    2nd and this problem is In both trucks altho mine way just a lot worse. Now I don't know the name but it's the gear cap"ring gear?" On the top of the diffs. Guess my seals had gone and was chewed up inside of the diff and had mud as Lub. The lack of seals made for apt of play inside and moving of parts. This wound up rounding out the inside of the cap with a lot of drag when turning. The guy figured on top of he battery problem that the truck was having to work a lot harder then normal to keep the diff turning and was in the end just draining the battery faster then normal. Why my truck was doing it. Both packs seem to act ok in my sons truck. My sons rear diff is about the same inside just not as worn.

    The fix. The guy at the LHS discharged the pack and at a really low rate and then balanced charged it back up again at a slow rate. This has fixed the pack and cells read normal now.

    As for the diffs well Ez fix just new parts. But after reading around I found something out. Now me and my son got the brushless ready stampede 4x4 versions. And you would think this means the truck is built stock ready for brushless. Far from it. Stock motor and Esc not brushless ready. That's a given. Center drive is plastic and not the aluminum where as I read the brushless version comes with it. The diffs. I see in the parts book the numbers for my parts are not the same as what's in there. I had the brushed version in there where as traxxas puts a different set into their brushed versions. This could explain the damage from our castle setup. Just odd that a box that says brushless ready has none of the parts from their brushless version.

    Stock rare gear https://m.traxxas.com/products/parts/6779 this is what I had.

    Upgrade part for brushless motors. https://m.traxxas.com/products/parts/6879 this is what we have now.

    Parts for the front are the same just a different pinion. At first I just replaced the rear but the truck was not happy well driving. The back wheels wanted to go faster then the fronts. So a lot of jumpy action from the back. Now that I have matched up the front with the same gearing as rear the truck is nice and happy. I gave up some torque for speed as a result. But with us running the SCT 3800kv combo we have more then needed.

    On top of this some of the bearing were well no good. So if you add all that up I guess it was the problem. With an adjusted pack some new bearings and new diff gearing the trucks flying happy again ready for its next fun fantastic epic break.

    Happy driving guys and thanks for all the input.

  12. #12
    RC Turnbuckle Jr. Briber's Avatar
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    Glad to hear you got it going. Brushed gearing in diffs is fine with brushless motor. Your final drive ratio is just different so one will be a little slower/faster than other. The only reason I switched to vxl diff gearing is because guy a hobby shop gave me wrong gearing and mine did same thing having different gearing in front and rear. I ran my other 2 Pedes with brushed gearing on a brushless motor until diffs gave out again. Then I put xo1 diffs in the pedes. I would reccomended that on next diff rebuild. Theres a bar inside the diff that keeps gears straight and tight inside the cup. Happy bashing friend!

    Sent from Eastern Missouri
    Just need one more rc, then Ill be done...

  13. #13
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    I know what bar you mean. The one the planet gears sit on. But with the lack of seals behind the 2 pinions inside the diff they were able to slid in and out about 8th on each side this damaged the inside of the ring gear on top and the bottom of the diff cup.

    But. Same thing happened. The replacement package for the ring gear"top of diff" had the right pinion and the wrong cap. So it didn't mesh at all. He didn't have a stock brushed one in. He said it should work just find not knowing the part was wrong. Package was already opened. Said it was an in house mistake or someone coming store. So he hooked me up with the correct pionion for thy ring gear. But after install thy truck was like. Ahh problem. And with the lack of stock I just picked up a 2nd to match. Now with my sons diff in more or less same condition. I have to decide.

    I have all together 4 stock ring gears. 1 warn bad. Do I just pick the best of the 3 and rebuild his 2 diffs or upgrade them both to match mine. Kinda like the trucks acting the same. Good for seeing/fixing problematic things. Mine does seem to have more punch now. And its turning and controlling better then before. I think it is worth is personally. With the new gearing being for s brushless setup. I would think it would cut down stress on the rest of the drive train.

    Oh btw. The stuff I picked up is. Factory team 5000cst silicone. Again it's a 3800kv. And we bath on gravel/cut lawn grass. Sometimes we hit the tall stuff. Never lasts long lol. Love the bmx track it's paved/gravel. And mud puddles. Streams. Put it this way. If I think we can we try it lol.

    Rest of drive train. Stock shaft stock axles. Mostly stock. Eating for things to break lol. They made these guys solid. Front arms rpm links replace to same as stock for stearing arms.

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