nbTMM

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Everything posted by nbTMM

  1. nbTMM

    Utilising the 3rd channel?

    Yep, it should output a PWM signal for a servo/ESC. Usually, all the way one way is 1millisecond pulses and all the way the other way is 2millisecond pulses.
  2. nbTMM

    Bulk Screws vs. "RC" screws

    When the car does it's best cartwheel impression at 80kmh :). They usually bend a little before they snap. And yes, the heads getting ground off where there is a ground clearance issue - that's a problem for any type of screw though.
  3. So, the body. The body was sprayed with TS-38 Gun metal. The idea is that it is close enough to the black plastic that if it scrapes through it won't be overly noticeable. This was my first time painting a hard body so I made plenty of rookie mistakes. Minors runs, dust and dirt, that kind of thing. Also made the mistake of spraying the cab and tray separately from different angles so the metallic flake doesn't match up where they meet. No matter, the aim here is that if it looks cool from a metre away, mission accomplished. I think the bruiser's 'sleeper cab' looks ugly as sin so I built the body as a single cab ute instead. Of course, there is no back window supplied with the body so I laser cut one at work out of two pieces of 1.5mm acrylic. The interior was painted in TS-46 Light Sand, with some matte black and silver brushwork for the floor, dashboard and steering wheel. The dash decals were pre-applied to the interior tub and not easily removable, so I just painted around them. Aluminium tape inside these light buckets improves their realism Some choice decals from the sticker sheet were applied, I might get a white tailgate logo as I didn't think the included red logo would go well with the gun metal.
  4. Firstly, lets address the elephant in the room: this isn't a genuine Bruiser, but the chinese HG P407 clone. Tamiya diehards please don't grill me too much, hopefully the amount of other genuine Tamiya gear I own makes up for my sinful purchase . The main reason (other than the price) that I went for the P407 is for the almost completely metal drive train and because I plan on bashing it and as the thread title suggests, shifting gears on the fly (there will be an electronic gearbox controller, eventually!). If I rash up the shell or grenade the gearbox, I won't feel so bad as replacement parts are dirt cheap. I was also curious about the build quality of the clone. The aim of the build is to make something which drives as scale as possible, but not neccesarily look as scale as possible. It should accelerate and handle like a 1:1 version. Everyone is probably familiar with the way electric RC cars accelerate - unrealistically rapidly from a standstill and then the motor power falls off a cliff and the car cruises at top speed. I'll be designing an electronic controller to shift gears automatically and alter the motors power band so accelerates more like a real car. I purposely read as little information as possible about the Bruiser or P407 before buying this as I find one of the most enjoyable parts of the hobby finding mechanical design flaws and working out how to come up with a solution for them. Some of the problems below are probably common knowledge but new to me and maybe I've attacked them from an angle previously not attempted. So, on with the build! What's this then, it's already built?! Let me explain... This won't be a build in the traditional sense of logging every nut a bolt being put together as per the manual, but instead looking at some of the good and bad points of the kit and re-engineering of the parts that don't work so well. The P407 comes as both an RTR which is simply named "P407" and a kit that requires some assembly named "P407A". The RTR adds a transmitter, receiver, ESC, steering and shifting servos and a lipo battery. The RTR doesn't cost significantly more and seems like good value initially, however, I still went with the P407A for a couple of reasons. Firstly, all the extra gear included in the RTR kit would be surplus to my needs as I already had spare servos and an ESC to use, batteries/radio would be shared with my existing RC cars. I wasn't keen on having all that stuff sit around on my shelf, and probably eventually end up in landfill because I have better parts to use. The second reason becomes more apparent when you receive the kit. The 'kit' arrives partially assembled - most of the oily bits have already been assembled for you. The front and rear axles/diffs, motor/gearbox and most of the ladder frame chassis come as pre-assembled modules so the build consists of the suspension, installing propshafts, steering, wiring the electronics and attaching a few ancillary bits and bobs. The problem is that the pre-assembled modules aren't assembled with the care and attention that most members of this forum would be happy with. You will want to loctite almost every bolt too if you plan on bashing so tearing down was expected. Thankfully they include a full instruction manual for the pre-built modules in addition to a cut-down manual which just assembles the modules together, although the 2012 Bruiser manual will probably get you out of trouble too since this is almost an exact clone. I encountered bolts with the hex heads chewed out due to being over-torqued, bearings with rust on their casings and dust covers missing and bearings that were seized. These parts were tossed out and thankfully I had replacements on hand already. I figure the less parts pre-assembled the better as all the non-assembled parts were in good order. The first modules I tore down were the front and rear axles/diffs. There was a good amount of red grease applied in here, except that not much of it was on the gear teeth haha. I opened up a diff centre and there was ample grease in there too. The internal gears are brass - it was a prick of a job to line up all those gears and get the centre casing back together so I didn't bother disassembling the centre on the other diff - just removed the bolts and loctited them. I noticed that the input shaft of one diff bound up a little bit when I turned it by hand and the problem turned out to be the cast aluminium pinion gear. A bearing fits over the back part of the gear (coloured red below) and since the casting is not perfectly true this caused the pinion and pinion shaft not to run true. The outer part of the gear (coloured blue below) was contacting axle/diff housing. I mounted the gear in my drill press and gently ran a file against both surfaces. I stopped when the bearing started being a loose fit. This helped but it still does not run totally true. Thankfully it no longer binds on the casing and the wobble is mild enough for the universal joint of propshaft to deal with. Ideally you want to mount it in a lathe by the shaft hole and turn it perfectly true. Next I tore down the gearbox. There were several dud bearings installed in here, which were thankfully all common small sizes (5x10x4 mostly IIRC). The gearbox uses steel gears and anodised aluminium hexagonal drives and collars to shift. The motor spur gear and the planetary reduction gears are plastic, although that is not of concern since these gears are subject to the least amount of torque in the entire drivetrain. I believe the Tamiya gearbox has some material removed from the hexagonal parts so they are more 'star' shaped, although functionally they are the same. There was some light oil applied to the shaft and some grease on some of the gears but not nearly enough for my liking. I added more grease to the gears and reassembled. I ran the gearbox just with the motor attached and shifted it by hand and it didn't want to go into some gears easily so I ended up tearing the whole gearbox down again and taking some 400grit sandpaper to the sharp edges of all the hexagonal drives and collars (highlighted red below), cleaned/degreased all the grinding dust and regreased them. After reassembly the gearbox shifted much better, but still was hesitant to go into gears sometimes. Later I found this isn't really a problem - when the output shafts are under load gears shift much easier. Once I had the chassis fully assembled and tried shifting via the servo while in motion, I had a lot of problems with mis-shifting. The culprit turned out to be the servo saver. The included ones are not really strong enough to force the hex collar into the next gear when the hexes aren't synchronised initially. When this happens the gearbox can end up stuck in neutral. Sometimes playing with the throttle is enough to align the gears better so that the weak servo spring can get it into gear, other times you have to resort to hunting around for another gear that works. Since i'm going to have electronics shift for me, mis-shifts must be avoided at all costs. If you get stuck in neutral you'll have no brakes and since the controller could decide to shift at almost any time, randomly having no brakes and needing to intervene to get it back in gear is a deal breaker. I tossed the servo saver and put a straight plastic horn on. Shifting became 100% reliable after doing this. Of course, this will cause the servo to stall out until it can get it into the next gear so shifting must never be attempted when the car is stationary. Fortunately, this is easy enough to implement in the electronic controller. I also tossed the stock servo saver on the steering and put in a plastic one from a TT02 kit, which required the horn to be shortened slightly. Speaking of steering, many will know that this is the achilles heel of the Bruiser. This is due to the arrangement of the white plastic lever shown below which translates the fore and aft movement of the turnbuckle coming from the servo to side-to-side movement that turns the steering knuckle via a second turnbuckle. The problem is that the plastic part can rock side to side because the pivot hole is slightly larger than it needs to be. The side to side movement allows the wheels to turn when there is no fore and aft movement of the servo turnbuckle. There is an aluminium bushing inside the plastic part which was slightly longer than it - I shortened it by 0.5mm or so which allowed the steel part to be tightened down fully onto the white plastic lever. I tightened it just enough until I could feel some resistance when I rotated the plastic lever. This tightened the steering immensely however flex in the plastic part still results in a significant amount of steering slop when trying to turn the wheels against something e.g. when rock crawling. Additionally, the stamped steel part flexes. I plan to make an aluminium lever to replace the plastic one and add an aluminium brace from the head of the bolt to the other side of the chassis to stop flex in the stamped steel part. Next we'll look at the suspension. There is much discussion about removing leaves from the Bruiser suspension to make it less bouncy and have more 'flex' - i'll give my 2cents: no combination of the included leaves works perfectly. With just the main leaf, the rear suspension is a little bit too soft as it sags to about 50% of the travel under the cars own weight. This is probably acceptable for crawling but for the ultimate realism and handling over rough ground at speed, it should sag only about 30-40%, leaving 60-70% of the suspension travel to soak up bumps. At the front, due to the extra weight of the motor and gearbox, just one leaf is way too soft and suspension almost totally compresses under the weight of the car, causing the propshaft and front bash plate to hit the gearbox casing when the car drives over a modest bump. The problem with installing the additional leaves is that they do not increase the stiffness until the ends of the leaves 'engage' (touch) the leaf above them. So for the first ~50% of compression the suspension effectively has 1 leaf and is too soft, then the 2nd and 3rd leafs engage suddenly and the suspension becomes way too stiff. This is the cause of the Bruisers standard suspension configuration being comically bouncy. Even with all 3 leaves, the front suspension still compresses too much under the cars weight. The solution is helper coil springs in the front shock absorber assemblies which will increase stiffness through the entire range of suspension travel. I kept the small leaf as I like the 'scale' look of having multiple leaves, and the small leaf doesn't engage until the suspension is almost bottomed out anyway. Speaking of shocks, the ones included with the P407 are rubbish. Firstly they leaked everywhere. After sorting that out by replacing the o-rings with slightly fatter ones, they had way too much damping even with 350cst oil (thinnest I had), and felt really gritty as the shafts moved so I gave up on them. I purchased a set of Yeah Racing Desert Lizard shocks. These have internal springs and are advertised as 90mm but are actually longer than this (~100mm) because they have a 'droop spring' installed on the other side of the piston which prevents the shock drooping all the way. I'm going to leave this spring out - the leaf springs will limit droop anyway. There is a good selection of springs included so I should be able to find a combination which stiffen the front and rear suspension appropriately. The threaded end of the shaft is too short to fit the Bruisers rubber strut top but this is solved by installing 1 nut and then a brass standoff which the rubber bushing fits over, and then installing the second nut onto the thread of the standoff. Since the shock body is longer than standard, the standard shock mount on the axle won't work. I quickly cut an aluminium adaptor bracket and bolt spacer/sleeve to see if it would work. Turns out I don't have long enough bolts on hand, so I put some brass stand offs just to mock things up. Seems to be workable! Now I just need to get the correct length bolts, make enough for all 4 wheels and make them look presentable (round over the corners!) The next problem was that the rear trailing arms made jingling noises as the car drove over bumps. This was fixed by adding a 2nd rubber o-ring to the bottom side where it is attached to the chassis, and adding some adhesive backed closed cell foam around the axle end. A final simple and effective mod is to raise the front of the gearbox. I put 4mm of aluminium spacers at each mount. This gives more clearance for the front suspension to compress and tilts the gearbox at an angle, allowing the front axle to be tilted back at the same angle without causing vibrations of the propshaft due to different universal joint angles. Angling the axle backwards introduces caster to the front wheels which will make it more stable at speed. The angle of the rear axle should be adjusted too - there is no handling effect from changing it, it'll just allow the propshaft to run vibration-free again. Train spotters will notice the red motor. This is a trackstar 13.5t brushless instead of the included 540 brushed motor. There was nothing wrong with the included motor however the brushless is needed for the automatic shifting electronics I intend to build. It probably seems strange that I chose a 13.5t motor when even a 25t is probably overpowered for 'scale' driving. The reason for the motor choice is that I need the 3000kv to reach a realistic top speed without altering the standard gearing and the excessive power of the motor can always be dialled back by electronic control. In fact, having an excess of torque is desirable as torque-limiting can be used to shape the torque curve of the motor in a way that mimics an internal combustion engine and make it accelerate more realistically. We can take away torque at a given rpm but we can't add more, so starting with a powerful motor is more flexible. Also if I get bored with 'scale' driving can just turn torque limiting off and do mad launches Brushless allows motor speed sensing to be implemented with minimal complexity - I went with sensored since it further simplifies the speed-sensing electronics and the motor will run smoother when crawling. Also the spare ESC I had required a sensored motor. As far as the automatic gearbox controller goes I've got an Arduino reading 4 channels from the receiver and outputting 2 channels continuously. Still need to implement reading the motor rpm but that should be straight forward. The controller will sit between the receiver and the ESC / gearbox servo. It'll also tap off the motor sensor cable. By monitoring the motor rpm the controller will decide when it needs to shift gears and can intercept the throttle signal to either blip or cut the throttle to ensure a smooth gear change. Since I'm already intercepting the throttle signal and measuring motor rpm, implementing motor torque limiting/shaping is just a matter of software. Realistically the motor power should be turned down such that the acceleration is the same as the real car - if the 1:1 car does 0-100kmh in 12 seconds, then rc should do 0-11kmh in the same amount of time since the scale is roughly 1:9. With the correct amount of power and a realistic torque curve it should actually accelerate faster to it's top speed by working through the gears instead of just putting it in 3rd gear and planting it from a standstill. Another feature that should probably be implemented is to limit the braking force in 1st and 2nd gear so it matches 3rd gear, due to the braking force being multiplied by the gear ratios. I'll post more when there is something interesting to show! I think that's it for now
  5. nbTMM

    Bulk Screws vs. "RC" screws

    Stainless bolts are weak - don't use them anywhere they need to take a big load, especially a shear load, because they will snap. Get 10.9 or 12.9 alloy steel bolts ('grade 8' for imperial folk). They will rust if they get wet, but they won't break. I've filled my spare parts bins with most lengths of M3 button head hex 12.9 bolts, the cheapest from ebay, and never had an issue.
  6. This week it was time to replace the toy-like bumpers and side sliders/steps i got these generic steel side steps from ebay. The main square section extended past the step part and had mounting holes at either end. I cut these off and drilled two new holes underneath the step so I could utilise existing chassis bolt locations for mounting. Up front, I made an aluminium part which ties together the 6 bolts that the standard bruiser bar mounts to This allows a steel front bar to mount securely, and the chassis probably won't get bent if I accidentally bulldoze a small country. The front bar is the same as an RC4WD Trail Finder bar, but it's a cheap knockoff / factory second or some such that I found on ebay. The quality is not A1, some bars are off by a mm to two, but it's good enough for my purposes. I had to bend the steel plate section of the front bar a little as the bruiser chassis has a downward slope towards the front - I guess if I have a hard crash this is the part that is going to bend. There's a spot for mounting a winch on the plate section of the bar - I decided to put an LED light bar there instead. Down rear is another knockoff RC4WD bar. It turns out the bruiser body is about 1cm wider than the trailfinder body around the rear tail lights so the bar wouldn't fit. Fortunately, I was able to tilt over each corner/taillight section with the persuasion of a hammer so the top bar sits out 5mm wider than the bottom bar - as supplied top and bottom bars were equal width. I was worried the welds (or brazes?) would crack when I tried to do this, but they held up. Some paint cracked at the joints, but I just gave it a touch up with a brush and you'd never notice if I didn't point it out . The bottom bar sits underneath the body so it doesn't need to be wider. Another aluminium mounting solution mates it to the bruiser chassis. More black paint keeps things stealthy and factory looking Ready for a body - that's the next post!
  7. nbTMM

    Titanium coated aluminium pinions

    Might just be plain old gold coloured annodising which is still 1000x better than the tamiya gears which are not anodised. If it's meshing against a plastic gear, no need for anything more exotic than anodising, Annodising will last just about forever as long as dirt doesn't get between the gears.
  8. nbTMM

    TT02RR Upper arm ball is loose

    The metal balls upgrade should help a lot. The TT02RR upper arms are fairly fragile. If (when) they break, you can just screw a ball into the top of the upright, then get some aftermarket adjustable aluminium arms and put a regular ball joint end onto the turnbuckle instead of the huge TT02 style ball end. This works because the upper ball joint doesn't take the weight of the car so the upper ball needn't have such high retaining force. The bottom ball joint does, because that is where the shock is attached so you have to retain the big ball joint.
  9. nbTMM

    Flummoxed

    even if the bevel gears in the diff were totally locked up, it wouldn't cause any drivetrain loss when driving straight because those gears only rotate when one wheel is spinning faster than the other. Try removing the propshaft and turning the front prop joint by hand. If it spins easily then the front diff isn't the cause of the sluggishness in a straight line. If it is hard to turn then at least you know the problem is something in the front gearbox.
  10. I was tempted to do that initially but thought I'd see if the standard configuration could be made to work properly. The standard setup also has an advantage that the turnbuckle going to the steering knuckle is longer and less angled than when you do the front servo mod, which gives less bump steer. Ideally the servo should be mounted exactly where the standard lever pivot is, and that just isn't possible.
  11. The rear shocks were mounted exactly the same way as the fronts were. I had to cut away parts of the rear swing arms for the aluminium spacer to fit - this isn't an issue as the swing arms are just for show and don't bear any suspension loads. I could have reversed the mounts so the shocks were to the rear of the axle instead of the front as there are additional holes in the chassis to do this, however I think it looks better this way as my shock mount is tucked away and better hidden. I'm glad I didn't attempt to narrow the rear axle any further - the shocks are close to the tyres. If one rear wheel is fully drooped and the other is fully compressed the shock body does gently rub the tyre but not enough to be a problem. For springs I used the same configuration as the front with just the main leaf and the softest spring inside the shocks. This was a little too stiff since there is less weight over the rear axle than the front. The roll stiffness is higher at the rear because the springs and shocks are mounted further outwards from the centre of the car than on the front axle. This made a rear wheel lift off the ground first when flexing over uneven ground. Making the rear springs slightly softer than the front would match the roll stiffness between front and rear and give the most flex. Removing the internal shock spring made it too soft, so I kept the soft shock spring but moved the mounting position of the leaf shackle on the chassis. By moving the mounting point forward the shackle lays down slightly which results in a softer spring rate from the leaf. I also moved the shackle mount down slightly to regain some ride height. When the suspension is bottomed out the shackle is almost horizontal so this is as far forward as the shackle can be mounted without it trying to over-centre. The red circles show the original mounting holes on the chassis. I made an aluminium steering lever to replace the plastic one which flexed a lot. Also fashioned up an aluminium brace which ties the bottom of the lever pivot to the other side of the chassis. The steering is far stronger now. The weak point now actually seems to be the plastic rails that the servos are mounted on - it flexes under steering loads. The front bash plate also got a trim so the front suspension can now compress fully without the edge of the plate hitting the gearbox
  12. nbTMM

    4ws

    That circuit board is just an Arduino Pro Mini development board that they have loaded their custom 4WS software on - the holes are 0.1" / 2.54mm apart so not too difficult to solder. Shouldn't need a special tip on your soldering iron but having a vice or 'helping hands' to hold the circuit board and wires still while you solder will be invaluable. It looks like they get you to cut the two 3-pin cables in half, strip and solder the bare ends to the Arduino board. The hardest part will be stripping the 3 wire ends to the correct lengths without breaking off too many strands of copper which will cause the wire end to be weak. The insulation on those 3-pin cables usually is PVC instead of silicone like is used for RC power cables, so you have to work quickly with the solder iron to prevent melting the PVC insulation too much. Some glue (epoxy glue, hot glue) for strain relief is usually a good idea where you terminate bare wire to circuit boards too.
  13. nbTMM

    4ws

    Different model servos can rotate different directions. The choice of clockwise or anti-clockwise operation by the servo manufacturer seems completely arbitrary. If you have a few servos lying around you might be able to find two different servos that rotate opposite directions, then you can just use them with a Y cable. Reversing the external wiring of the servo will just cause it to stop working. It is possible to reverse the wiring of the internal potentiometer and motor which has the effect of reversing the direction of the servo:
  14. nbTMM

    Lble02s low volt cutt off

    Sounds like a logical solution to me
  15. nbTMM

    Lble02s low volt cutt off

    Actually the TBLE02S is configured to 2.45V/cell = 4.9V cutoff, way too low for regular LiPo chemistries but OK for NiMH and LiFePO4 which Tamiya recommend. Both the link in the previous post and my own testing confirm that it is 4.9V. The correct way to test the cutoff voltage after doing the resistor mod is to power the ESC with a variable DC powersupply instead of a battery. Hold the throttle down (doesn't have to be full throttle, just constantly running the motor), and slowly lower the voltage on the powersupply. When you reach the cutoff voltage the motor will stop running. You could also run down an NiMH battery until cutoff kicks in, but be aware that a NiMH battery's voltage will sag significantly under load, causing cutoff to trip, and then the battery will quickly recover in voltage possibly 1 volt or more. So you have to be measuring the voltage with a multimeter at the exact moment that the cutoff circuit trips. If you can run down the battery enough that you can get the cutoff to kick in while holding the car in the air and only being partly on the throttle, I'd recommend measuring the battery voltage under that condition.
  16. Important to note that "0 offset' RC touring car wheels are not actually 0 offset in the traditional sense. The surface on the wheel that mates to the hex adapter on a +0 wheel is actually about 6mm from the wheel centerline. I assume this is because the offset is measured with a hex adapter installed (6mm hex thickness perhaps?).
  17. If you replace +0 wheels with +6 wheels of the same width then the car becomes 12mm wider overall (6mm each side) measured from inner tyre edge to inner tyre edge, or outer tyre edge to outer tyre edge. Replacing the wheel hexes with different thickness ones has the same effect e.g. replacing a 6mm thick hex with a 12mm thick hex is the same effect as going from a +0 wheel to a +6 wheel. You'll need longer axles if you want to increase the hex thickness that much though. If you replace 24mm wide wheels with 30mm wide wheels, same wheel offset, then it becomes 6mm wider overall (3mm each side) measured from the outer edge to outer edge and 6mm narrower overall (3mm per side) measured from inner edge to inner edge.
  18. nbTMM

    Fastrax TT02B aluminium upgrades

    The threaded holes will be M3 just the same as the threaded ball joints from the factory arms. Re-use the ball joints instead of the supplied screws/spacers.
  19. These ones? https://www.fastrax-rc.com/index.php?_route_=fastrax-tamiya-tt02-aluminium-rear-hub-carriers-2&search=tt02&page=2 Looks like they are just the Jazrider ones: https://www.jazrider.com/tamiya-tt02-aluminum-rear-hub-carrier-light-blue-p-90061693.html I actually have a set of those, and mine fit fine... until I stopped using them - get hubs with 2-3deg toe, much better than these which have no toe. If they are too tight, just gently hand file/sand the hub or arm until it fits. You actually want a tight fit on these because slop in the pivot will make the wheel flop around and lead to unstable handling. More often than not I find myself actually throwing 3mm shims in that joint to tighten it up, especially after parts have worn.
  20. nbTMM

    TT02B high speed gear set (68T)

    The chart below shows you the possible gear ratios (aka final drive ratio or FDR) using the standard plastic motor mount and either the 68T (high speed), 64T (option) or 70T (standard) spur gears. You don't need the high speed gear set nor an aluminium mount to use a 22T pinion. It will fit with the standard 70T pinion gear just by moving the motor to a different set of holes in the plastic motor mount, see the chart below. The lower your final drive ratio, the less acceleration/torque you'll have but the higher your potential top speed will be. If you change to a 22T pinion from a 17T the car will certainly reach a higher top speed on smooth asphalt but it may go even slower on grass or gravel because it may no longer have enough torque low down to power through the rough ground. My advice would be to buy a 22T 0.6mod pinion since they are cheap, install it and see the effect for yourself. The main advantage of the high speed hopup is not to change the 70T spur gear for a 68T, since that is an almost unnoticeable change. The purpose is that you get the aluminium gear mount in the set so you need not restrict yourself to tamiya spur gears anymore. Any gear with 4 mounting holes that line up with the aluminium gear mount can now be used. Common aftermarket gears have a tooth pitch of 48P or 64P. 48P is a finer imperial tooth pitch than the metric '0.6mod' pitch that Tamiya normally use. 64P is an even finer tooth pitch again. As a rule of thumb, the finer the teeth the quieter and smoother the gears run but the more fragile they are. If you buy high quality 64P gears they will still be stronger and last longer than low quality 48P or 0.6mod gears however. When you start using 48P or 64P pitch gears instead of 0.6mod then you also need the Yeah Racing mount because the holes in the Tamiya mounts only give you adjustments which mesh 0.6mod gears properly. The Yeah Racing mount allows one motor screw to slide in a slot so that it is infinitely adjustable. That can be advantageous when you want to achieve a much lower final drive ratio than possible using 64T-70T spurs. Brushless motors typically have much higher torque than brushed and lower maximum rpm so they require a lower final drive ratio. Similarly, touring cars which race on smooth tracks will favour a lower final drive ratio since torque will be traded for higher top speed down the straights. It would not be unheard of for instance to run a final drive ratio of around 3.50 : 1 on a TT02 touring car with a 21.5turn brushless motor. There is honestly not much difference between the different tamiya 23-27turn brushed motors (silver can, sport tuned, torque tuned, super stock, etc). If you're after a significant jump in speed and power you'd be far better off going straight to a brushless motor and playing with gear ratios later. 13.5turn sensored brushless motor would be a good starting point and will work with the TBLE02S ESC if that's what you've got at the moment.
  21. Is the ramping current due to feathering in the throttle? 1:10/1:8 BLDC motors are typically about 40% efficient (at maximum mechanical power out), so 2.7kW electrical power in, ~1.08kW mechanical power out, 1.62kW heat! Seems about right for 7700kv on 3S to me
  22. 20Amps is the current rating. About 60-80A would be considered average for an 1/10 scale ESC these days. The higher the current, the more torque/power your motor will make when it is at stall (not turning, or turning very slowly) such as when climbing a rock or steep hill very slowly. Many ESCs like the Tamiya TBLE02S will go into a torque limiting mode when the maximum current is reached (such as when the motor can't turn the wheels because they are jammed by an obstacle), at which point you hear a buzzing or hammering sound coming from the motor, this is to protect the ESC from overload. Cheaper ESCs will simply just try to put out maximum current at all times and if pushed too far, blow up. If you get a beefy ESC you have to be mindful that the motor can't take a huge stall current indefinitely. Too much stall current for too long will make your motor overheat and fail. Looks like you're paying a premium for the Servonaut one for the integration with the Servonaut light and sound modules. They also make a claim about having more steps of speed control, which would give you finer throttle control, especially at low throttle which might be important for crawling. Without actually checking, I would hazard a guess that most half decent (>$80) escs would have fine enough throttle control for crawling anyway. The servonaut also switches at 16kHz so won't make an annoying squealing sound when at partial throttle. Other than those points, the servonaut one doesn't look like anything special to me, seems quite expensive for what it is.
  23. Less pinion teeth = more acceleration/torque, lower top speed More pinion teeth = less acceleration/torque, higher top speed The difference between 18t and 20t will be barely noticeable. For crawling you want lots of torque and a manageable speed so use as few pinion teeth as possible. For speedruns/bashing you probably want more teeth.
  24. nbTMM

    Can two Flysky Tx be bound to the same Rx?

    the telemetry capable receivers (e.g. GT5) cannot because they rebind the TX. I can't bind two GT5 RXs to the same model memory in my GT5 TX. I can however bind one GT5 RX to one model memory slot and another GT5 RX to another model memory slot. It's probably unlikely that you'd actually want to use two RXs simultaneously unless you want to double up on RX outputs in the same model, or drive two cars simultaneously using one TX. On my old GT2 TX I could bind as many GT2 RXs as I wanted to it and they'd all work simultaneously. I assume GT3 TX/RX work the same as GT2.