RobFoard Posted October 2, 2020 Share Posted October 2, 2020 Hi all! First post here, hopefully I don't say anything to upset or offend! I recently purchased a 6x6 custom crawler off a chap, as a do up type project. It came initially with a cheapish Banggood brushless system which made it go like the clappers but it was pretty awful at low speed crawling, which, to be fair, may also be down to the fact that it has a slipper clutch. I bought an HPI 55t motor and HPI SC-3SWP3 crawler spec ESC, excitedly fitted it all to the truck, plugged in my 2S lipo, took it to my local crawling spot and........... instantly failed to get over a tree root that my TT02 would have no issues crawling over. I picked it up over the root, and as soon as it was on the flat, it seemed okay, until I noticed a horrendous smell, which I realised was the motor, which had also reached untouchable temperatures. Frustrated, I chose to return to the car and put the 6x6 away, and continue with my friends, and we picked our brains wondering why the truck had failed so much. I should mention that the truck weighs around 3.5kg, which is no means light, but it isn't too much heavier than my old Trailwalker crawler, and that was excellent (my friend now owns it). After we got back to the car park, my friend plugged his 3S lipo into the truck, and the truck seemed to perform a little bit better, but the motor was still very hot. The gearing on the truck is an 18t pinion gear and a 56t spur gear, powered by (as mentioned) a 55t motor, and a 2S, 5500 mAh lipo. I took the electronics out of the truck, and have been running them without any load for roughly 30 mins, and the motor has stayed cool and the shafts (apologies if this isn't the correct term) that would drive the wheels continue to turn, even when I try and stop the with my hands. What could the issues possibly be? Is the truck simply too big to be powered with a 2s lipo? Should I bother buying completely new electronics or rather buy a 4x4 kit and keep the truck as a shelf queen? TIA! Quote Link to comment Share on other sites More sharing options...
Andy-Roo Posted October 2, 2020 Share Posted October 2, 2020 Hi Rob, my first thoughts were the gearing and battery. A motor getting hot is usually down to it being over geared, so I’d drop down to a 11 or 12t pinion and see if that helps. As for the battery; I’d always run 3s minimum, especially in big rig like yours. In fact, the only 2s lipo I have is in my TX. I hope that helps. Quote Link to comment Share on other sites More sharing options...
RobFoard Posted October 2, 2020 Author Share Posted October 2, 2020 1 minute ago, Andy-Roo said: Hi Rob, my first thoughts were the gearing and battery. A motor getting hot is usually down to it being over geared, so I’d drop down to a 11 or 12t pinion and see if that helps. As for the battery; I’d always run 3s minimum, especially in big rig like yours. In fact, the only 2s lipo I have is in my TX. I hope that helps. Hi Andy, I hadn't though about gearing, I'll look into getting a smaller pinion! Would it be worth increasing the size of the spur gear too? I'll also look into getting a new 3s lipo thank you for your reply, hopefully this will remedy the issues I've been having. Quote Link to comment Share on other sites More sharing options...
Andy-Roo Posted October 2, 2020 Share Posted October 2, 2020 I’d just start with a smaller pinion and go from there tbh. Have you checked the drive line for any binding? Quote Link to comment Share on other sites More sharing options...
RobFoard Posted October 3, 2020 Author Share Posted October 3, 2020 20 hours ago, Andy-Roo said: I’d just start with a smaller pinion and go from there tbh. Have you checked the drive line for any binding? A 12t is on order! I've stripped the truck down and I can't find any resistance in the driveline - is there any part I should particularly look for? Quote Link to comment Share on other sites More sharing options...
Andy-Roo Posted October 4, 2020 Share Posted October 4, 2020 On 03/10/2020 at 20:10, RobFoard said: A 12t is on order! I've stripped the truck down and I can't find any resistance in the driveline - is there any part I should particularly look for? Sorry for the late reply, we’ve been away for the weekend. Nothing in particular, no. You’re just looking/feeling for anything that could be causing extra load on the motor and overheat it. But it sounds like it’s all okay so gearing is the likely problem. Quote Link to comment Share on other sites More sharing options...
RobFoard Posted October 6, 2020 Author Share Posted October 6, 2020 On 04/10/2020 at 22:28, Andy-Roo said: Sorry for the late reply, we’ve been away for the weekend. Nothing in particular, no. You’re just looking/feeling for anything that could be causing extra load on the motor and overheat it. But it sounds like it’s all okay so gearing is the likely problem. Not a problem - latest update on the truck is that the new pinion arrived as well as the 3s lipo. Fitted it all in, and it seemed to work okay, until i realised the motor itself was smoking, dodgy motor or is the truck just too heavy? I'm really close to simply pulling the trigger on a Carisma Brat crawler if I can't get anywhere with this 6x6 Quote Link to comment Share on other sites More sharing options...
Andy-Roo Posted October 7, 2020 Share Posted October 7, 2020 How heavy is the rig? What size wheels/tyres is it running? Both of these could cause the motor to over heat. What make is this 6x6? You say it’s a custom build but is it based off a known chassis; Traxxas or Axial for example? This is going to be process of elimination, so some pictures might help. Quote Link to comment Share on other sites More sharing options...
RobFoard Posted October 7, 2020 Author Share Posted October 7, 2020 41 minutes ago, Andy-Roo said: How heavy is the rig? What size wheels/tyres is it running? Both of these could cause the motor to over heat. What make is this 6x6? You say it’s a custom build but is it based off a known chassis; Traxxas or Axial for example? This is going to be process of elimination, so some pictures might help. With all the electronics, it's close to aroud 3.9kgs - not super lightweight I suppose. I should mention that I don't run it with the flatbed on the back, as it falls off quite easily and it weighs quite a lot. It's got some fairly chunky eBay wheels, 4.9" tall, and 2.2" wide! The axles are Axial, apparently, but the chassis is definately homemade (with the best will in the world, it's a better job than I could ever do) - as the pictures will show (the truck has been stripped down due to me needing to sort the shocks out and I have yet to rebuild it). 1 Quote Link to comment Share on other sites More sharing options...
Stormbringer Posted October 7, 2020 Share Posted October 7, 2020 Really nice truck and hope you get overheating issue sorted 🍻 Quote Link to comment Share on other sites More sharing options...
RobFoard Posted October 7, 2020 Author Share Posted October 7, 2020 2 minutes ago, Stormbringer said: Really nice truck and hope you get overheating issue sorted 🍻 Thanks mate, unfortunately the motor is totally kaput, spat flames even when it had no load! Back to the drawing board... Quote Link to comment Share on other sites More sharing options...
Andy-Roo Posted October 7, 2020 Share Posted October 7, 2020 A great looking truck but pretty heavy at around 8.5lbs. Maybe the motor just wasn’t up to the job but I’d have thought the ESC would have smoked itself before the motor. You said it went really well with the brushless setup, so maybe that’s what it needs but a crawler specific one, like the HW Axe for example. The trouble with BL setups is they ain’t cheap. Did you buy the HPI motor/ESC new? Quote Link to comment Share on other sites More sharing options...
RobFoard Posted October 7, 2020 Author Share Posted October 7, 2020 8 minutes ago, Andy-Roo said: A great looking truck but pretty heavy at around 8.5lbs. Maybe the motor just wasn’t up to the job but I’d have thought the ESC would have smoked itself before the motor. You said it went really well with the brushless setup, so maybe that’s what it needs but a crawler specific one, like the HW Axe for example. The trouble with BL setups is they ain’t cheap. Did you buy the HPI motor/ESC new? Funnily enough a couple of people were surprised that the motor gave up before the ESC. It seemed to work with the brushless system but it was simply too fast, I did think about the HW Axe but if I was to spend around £161 I'd rather put that into a crawler that I know will work - I'd be afraid of burning £161, literally! I did buy the ESC and motor new, although to be fair the motor was fairly cheap, so I'm not too bothered about it being destroyed. Quote Link to comment Share on other sites More sharing options...
Andy-Roo Posted October 7, 2020 Share Posted October 7, 2020 I have a 540 35t Austar motor that came out of a used rig I bought. Its of no use to me but you’re welcome to have it? It could help narrow down the problem - if it smokes then it must be the truck, or if it works it was a faulty HPI motor. If it’s of use just PM me your address and I’ll pop in the post tomorrow 👍 1 Quote Link to comment Share on other sites More sharing options...
RobFoard Posted October 7, 2020 Author Share Posted October 7, 2020 21 minutes ago, Andy-Roo said: I have a 540 35t Austar motor that came out of a used rig I bought. Its of no use to me but you’re welcome to have it? It could help narrow down the problem - if it smokes then it must be the truck, or if it works it was a faulty HPI motor. If it’s of use just PM me your address and I’ll pop in the post tomorrow 👍 That would be absolutely amazing, I'll send you a message now! Thank you so much! 1 Quote Link to comment Share on other sites More sharing options...
Andy-Roo Posted October 7, 2020 Share Posted October 7, 2020 No worries mate 👍 Quote Link to comment Share on other sites More sharing options...
stimpy Posted October 8, 2020 Share Posted October 8, 2020 Was going to say, it is possible that the motor got smoked with the original issue...If Andys 35T is too fast then I have a cheapo 45t here also.. 1 Quote Link to comment Share on other sites More sharing options...
RobFoard Posted October 9, 2020 Author Share Posted October 9, 2020 17 hours ago, stimpy said: Was going to say, it is possible that the motor got smoked with the original issue...If Andys 35T is too fast then I have a cheapo 45t here also.. Fantastic! I'll keep you all updated about the build - I've temporarily put the truck into a 4wd configuration as well to see if the additional two, humungous wheels are having a negative impact on how it rolls. Would getting my hands on some slightly smaller wheels be worth doing? Some of the guys I drive with have various spares so it might be worth a shot? Quote Link to comment Share on other sites More sharing options...
Andy-Roo Posted October 9, 2020 Share Posted October 9, 2020 1 hour ago, RobFoard said: Fantastic! I'll keep you all updated about the build - I've temporarily put the truck into a 4wd configuration as well to see if the additional two, humungous wheels are having a negative impact on how it rolls. Would getting my hands on some slightly smaller wheels be worth doing? Some of the guys I drive with have various spares so it might be worth a shot? Defiantly, yes! The wheels have a big impact on gearing. Quote Link to comment Share on other sites More sharing options...
RobFoard Posted October 9, 2020 Author Share Posted October 9, 2020 2 hours ago, Andy-Roo said: Defiantly, yes! The wheels have a big impact on gearing. I thought as much! I'll ask to borrow some 😆 I've also been casually doing some research and have noticed that some guy with 6x6 rigs are running a dual motor setup (one I have seen is running 2x55t motors) - worth looking into? http://www.rccrawler.com/forum/multi-axle-rigs/357391-axial-based-6x6-bullhead-cab.html Quote Link to comment Share on other sites More sharing options...
Andy-Roo Posted October 9, 2020 Share Posted October 9, 2020 It would be more powerful, but also more complicated. Traxxas and Axial both make 6x6’s that run a brushed setup. Traxxas uses a 21t motor and Axial a 35t (I believe), and both are extremely capable. So if it were me, I’d get the current issue figured out first and then move on from there. 2 Quote Link to comment Share on other sites More sharing options...
RobFoard Posted October 9, 2020 Author Share Posted October 9, 2020 4 hours ago, Andy-Roo said: It would be more powerful, but also more complicated. Traxxas and Axial both make 6x6’s that run a brushed setup. Traxxas uses a 21t motor and Axial a 35t (I believe), and both are extremely capable. So if it were me, I’d get the current issue figured out first and then move on from there. Fantastic - smaller wheels and the replacement motor, and fingers crossed! Quote Link to comment Share on other sites More sharing options...
stimpy Posted October 11, 2020 Share Posted October 11, 2020 On 09/10/2020 at 16:00, Andy-Roo said: It would be more powerful, but also more complicated. Traxxas and Axial both make 6x6’s that run a brushed setup. Traxxas uses a 21t motor and Axial a 35t (I believe), and both are extremely capable. So if it were me, I’d get the current issue figured out first and then move on from there. Bare in mind folks that Traxxas has a different final drive ratio, hence they can run that faster motor - I believe it is also a 550 which changes the torque aspect... @RobFoard - Yours should run fine with a new motor and more suitable pinion to spur. Unless there are issues elsewhere of course.... All the best! Quote Link to comment Share on other sites More sharing options...
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