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nbTMM

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Everything posted by nbTMM

  1. Sounds like you need to calibrate your ESC to the transmitter. Check the setup steps in the manual https://www.mtroniks.net/download.asp?ResourceID=1947
  2. Finished the mostly-sealed tub TT-02 with some custom FRP side trays and some closed cell foam to fill the gaps and make a tight fit to the body. Oh and some stupidly overpowered weatherproof electronics of course (7.5t running sensorless + Hobbywing 8BL150 + 3S). Now i'm waiting for some rain so I can test if it actually works or if it's still just a fast bathtub
  3. The 6amp figure is based on absolutely no load (pinion removed or motor out of car), and while it is not the most accurate way to tune the timing it will at least get you in the ballpark (+/- 5 degrees). The most accurate way to set timing is with a dyno to measure peak power. A less accurate way is to measure lap times but this introduces a problem as you're always testing with the same gear ratio so you will arrive at the most optimal timing setting for your current gear ratio, but a different gear ratio and a different timing setting may actually be faster because adjusting timing adjusts not only power output but also the kv of the motor and kv can compensate for gear ratio. Putting any kind of wired multimeter in series with the battery will change how the system behaves under load as the resistance of a typical multimeter and leads on a 10A range is in the ball park of 0.1ohms. That may not seem like much until you realise that even a mild motor like a 21.5t brushless draws around 20-30A in it's power band. 30A*0.1ohm = 3V drop across the multimeter! Measuring the peak current while driving will be meaningless for tuning timing as it will just be as much current as your ESC and battery can muster when the motor is stalled i.e. when you punch it from a standstill, peak current will occur. This will likely be 80A+ for 21.5t on 2S with the punch turned up, which obviously does not work if you have a 0.1ohm multimeter in the circuit as the multimeter will drop a tonne of voltage and prevent 80A from ever being achieved. At 6A the multimeter is only dropping 0.6V which while not ideal is somewhat more managable and introduces minimal effect on setting the timing. Ideally you want a DC clamp meter, which measures the current going through a cable without needing to break the circuit.
  4. For bashing on asphalt? First things I'd buy are spare tyres as you will go through many. I don't see the need for a slipper in a relatively light, small tyre 1/10 car. Building the suspension to handle jumps is a compromise in an on-road car because by increasing the suspension travel and raising the car it will traction roll easily on grippy surfaces. Running a lower suspension and accepting that on jumps the chassis may smack the ground might work out better for you. I run my on-road cars around 15mm ground clearance and accept that the chassis will smack the ground every so often, or leap in the air if it hits a stone or sharp lip at speed. Not sure which dampers are required to achieve that ride height on an XV-01.
  5. I actually find front caster has a more profound effect on stability than toe. Positive caster will make the front wheels want to steer in the direction the car is travelling in so the car tracks straight, as long as the servo is not forcing them to steer off course. Some slop in the steering, combined with positive caster therefore makes a car track straighter. Unfortunately, caster is often non-adjustable on many models because the angle is built in to the plastic parts. Most 4WD Tamiyas have very little built in, and require modification to get more. Theoretically, toe in at both axles should improve stability and this is mostly true for 1:1 cars. Imagine the car is travelling down the road and the car starts sliding slightly on the pavement and rotates a little to the left (it's now facing a little towards the left gutter instead of directly down the road). Now the left wheels which were previously scrubbing slightly due to toe in are pointed perfectly down the road and no longer scrub, and the right wheels are pointed even further towards the gutter causing them to scrub even more than normal. The right wheels scrubbing gives a slight braking effect and skid-steers the car to the right, counteracting the slide. However, there is a second effect. If the car starts steering towards the left due to steering slop, a bump/pothole in the road or tyres ballooning and becoming different diameters, the car will experience a weight shift to the right wheels (which in turn causes bodyroll to the right). Now the right wheels experience higher grip than the left wheels and produce a stronger steering force to the left, than the left wheels produce to the right. This results in the respective axles independently steering to the left. If the rear steers to the left and the front axle does nothing, the car overall turns to the right, so toe in at the rear definitely helps stability. If the front steers to the left and the rear does nothing, this makes the problem worse as it causes the car to steer even further to the left, therefore in the case of weight shift front toe in can decrease stability if there is a significant weight shift across the wheels on an axle. That is probably why some people report that front toe out improves stability, instead of toe in. Personally my go-to setup for stability is toe in at the rear, zero toe at the front, and positive caster. Some toe out at the front seems to improve the aggressiveness of the steering, and might decrease straight-line stability slightly although to be honest I don't notice a huge change compared to adjusting rear toe or caster. If there is a lot of slop in the wheel hubs, you may need to slightly toe out the wheel from the alignment that you want, because any driven wheels will toe in under power. As above, servo and servo saver make a big difference too. If you can move the mounting point that the steering arm attaches to the servo saver/horn closer to the center of rotation (effectively reduce the length of the horn), the servo requires more rotation to give a certain amount of steering throw. This may reduce the amount of steering, but reduces the effect of a deadband/centering error from the servo. Some servos just have a large deadband, which is how much the input signal has to change before they actually command the motor to move. This stops them constantly hunting around and burning themselves out. You can test this by turning the steering to full lock and back to centre in either direction, and checking if the centre position is the same from both sides. A servo with a large deadband will stop significantly right of centre when returning to centre from the right, and left of centre when returning from the left. Making sure the steering is mechanically adjusted to center (remove the horn/saver and reinstall centered) with no electronic trim will ensure you have close to even throw to the left and right before adjusting end points. Finally, consider adding a steering gyro.
  6. Just chop the ESC plug off and put a HXT 4mm on it, same as your battery. That's all I run as all my batteries are Turnigy/HK and 4mm is better than XT60 which is in turn better than deans, at least in terms of power handling. XT60 or Deans is safer because you can't plug two batteries together - HXT you can, so keep kids away from a pile of HXT batteries.
  7. I like to think that a lot of Tamiya's customers are probably quite happy to build a car as per the instructions and have it tear up and down their driveway or backyard at 20kmh with the silver can because what they are after is really a remote controlled model, not necessarily a 100kmh remote controlled missile like your average traxxas customer wants. If the build is enjoyable and it can navigate their backyard at any speed, they are happy. If you look outside of this forum, you'd be hard pressed to find mention of fragile gears in a TT02B or many other 'common' flaws of other Tamiya cars. If the customers aren't complaining about it, Tamiya is unlikely to address the 'issues'. On the contrary, Traxxas are constantly pushed by their customers to make ever increasingly unbreakable products. People make youtube videos of their Traxxas cars breaking after crash landing a 20metre high jump at 80kmh and all the comments are "OmG it iS SooOOO WeaK TrAxXaS SuCks!!111"
  8. Started enclosing the tub of this TT02 with some XV01 guards and some foam. The aim is to get it almost fully enclosed once the body is on to keep the dirt/water/stones out.
  9. Yeah those are fish eyes, which are caused by surface contamination that the paint won't adhere to. Maybe the IPA or tack cloth cleaning steps left some residue that the TS paint doesn't like, or it got contaminated with some other type of overspray. Building up a series of very light mist coats before spraying a heavier coat can also help.
  10. On this forum maybe. Outside of this forum I wouldn't be surprised to find that TT01/TT02 see 20-50x the popularity that they do here and eclipse the sales of everything previously mentioned combined, for one reason only; the bodys that they are bundled with. A huge chunk of Tamiyas market must come from people who just want say a Subaru WRX RC car, don't know what a Lunchbox or Grasshopper is, and probably never find out either.
  11. Yeah racing universals. The dog bone drive pins and differential outdrives/cups don't like the torque. They get worn down and bend. I've also had the grub screws come loose on a shaft twice which causes the pin at that end to slide out, first time it locked up the wheel/shaft solid, the car cartwheeled and snapped the shaft at the universal joint. Second time it just mangled the pin (car still ran, but I noticed a clattering sound) and I was able rebuild the shaft by grinding a flat on a new pin. Thankfully both pins on the shafts are just standard pins like wheel hexes use, which I have plenty of. I think the demise of the last shaft was that the dog bone end was able to pull out too far when the wheel drooped which makes it ride on the 'knife edge' part of the slot in the drive cup, causing excessive and uneven wear, making it vibrate more than normal which shakes the grub screw loose and mangles that pin too. I've now cambered the wheels so that the shafts are inserted into the cup as far as possible without bottoming out when the suspension is compressed, and stepped up from blue to red loctite on the grub screws which should hopefully solve that problem. The differential drive cups also see wear - Yeah Racing cups and the Tamiya ones that came with a TT02 Type S are not immune to being impressioned by the pins. Turning down the punch on the ESC would probably also help but I won't resort to that yet as popping wheelies is fun . Yes, should be good to go out of the box and give you plenty of maintenance free running when built with a ball bearing set. The issues mostly come when you start upgrading it to go faster than standard, or crash it hard. Even if you keep it 'stock', parts will eventually wear out or break, and no RC car is immune to that. Replacements are especially cheap right now for a TT02B because it is a very popular kit and most parts are plastic. If you break a plastic part you just purchase the relevant 'parts tree' for a few dollars, and then you have spares of everything else on that tree. The part numbers for everything are in the back of the instruction manual so you can just punch in the number of the part you need into ebay or your local hobby shop to buy replacements.
  12. Nice. If you're fighting stability try putting the standard upper front suspension arms in, but flipped upside down, which brings the upper suspension ball joint rearwards by a fair bit. That gives you a whole lot of caster in your front suspension which will make the steering self-centre strongly. Ideally you'll want to space up the tie rod ball joints on the hubs, because caster tilts the hub backwards and lowers the tie rod ball joint - you want to raise the ball back up to the height it was previously so you don't introduce bump-steer (wheel turns when suspension compresses/droops) due to the tie rods pointing downwards at an extreme angle. I use brass standoffs (like computer motherboards mount on), but you can also just get balls with a longer thread and add spacers/washers. TT02RRfront upper arms can't be flipped upside down without cutting some plastic away which makes them very weak and break (as I found out...). The inability to adjust camber is no big consequence for speed running, especially if only at the front as 0deg camber at the front and a little negative camber at the rear will give you handling that tends towards understeer rather than oversteer.
  13. If you're going for a TT02B, I'd build it first with a set of ball bearings and everything else as standard. The plastic links/arms/shafts/gears/steering that come in the kit will be absolutely fine to get you going. The standard plastic suspension of the TT02/TT02B is almost bombproof. The plastic suspension parts are actually more durable then the metal/carbon parts because they will flex instead of bending/snapping. The rigidity of the carbon/turnbuckle suspension parts will however give you sharper handling, it's a trade-off of durability for performance. You can always add hop-ups later as you desire, and as the plastic parts start to wear out. Putting bigger wheels or a more powerful motor will definitely demand an upgrade of the differentials to metal gears which is not a particularly cheap upgrade. Stronger gears are required with a more powerful motor for obvious reasons, but stronger gears are also required if you put larger wheels on with the standard motor, because when the car gets airborne and then lands whichever wheels hit the ground last are re-synced to the road speed through the drivetrain by the wheels on the ground and that can put massive loads on the drivetrain, especially if the wheels are large in diameter and heavy (= more torque generated). I've done both a powerful brushless motor (about 8x the power of the standard motor) and big wheels (+30% diameter, probably twice the weight of standard wheels) to a TT02B and pretty much immediately stripped the plastic differential gears. Since then it's got GPM steel differential gears front and rear, in addition to the steel propellor joints, aluminium propellor shaft and steel universal driveshafts it's had from day one. Even now, I can see the steel driveshafts are going to be a consumable item - every 5-10 battery packs they are going to require rebuilding or replacing. It would be much more economical to just buy a Traxxas Slash, but where's the fun in that? . I like the challenge of working out which combination of parts to use to keep it semi-reliable, and fixing it when it does break. My suspension is still standard plastic hubs and lower arms from the kit - it has taken a few heavy crashes and nothing has broken yet, maybe I'm just lucky. I suspect eventually I'll break a hub - only when that happens I'll consider upgrading to aluminium hubs. This is it - you can see how much it bogs down in the grass compared to asphalt: only about 35-45kmh in the ~2-3" grass compared to 60kmh+ on asphalt. A completely standard, brushed motor TT02B only goes about 20-25kmh on asphalt and has half the ground clearance, so it would probably wouldn't even move on this grass.
  14. TT02B would be my pick for on-road and a bit of mild off road action (short grass, gravel, dirt) - grass longer than 1.5-2" will have it almost stopped in its tracks with the standard wheels, ride height and motor. Buy some different wheels for on-road use so you don't wear out the spikes on the off-road tyres. It is reasonably durable, but still requires some restraint otherwise you'll be breaking parts - it is a low slung buggy that is designed to be driven tidily over relatively smooth terrain. Parts are cheap and plentiful though and there are zillions of hop up parts to keep you amused and slightly improve it's off-road capability. DT-02/03 and DF-02/03 might be slightly more capable off road, but parts availability is not as good - they are older designs and support is dwindling. Tamiya unfortunately don't really have any cars that are super rugged and super capable off road for all out bashing - that's not really their target market. Most tamiyas are really only designed to cope with a 'silver can' motor (low power brushed motor) and many parts are harder plastics which crack if abused. Newer designs (like the TT02B) have more flexible nylon and glass reinforced parts which cope with a bit more abuse. For all-out off-road bashing, I think you have to look towards ready to run cars from different manufacturers like a Traxxas Slash or similar cars from Arrma, Axial or Losi instead - those can take big motor power with relatively few upgrades, and many of those you could jump off the roof of a house and they would just shrug it off like it's nothing. If you aren't launching it off 1metre+ jumps you should be fine with a Tamiya.
  15. Took the TT02B out for a spin... was still running by the time the battery hit low voltage which was nice for a change
  16. 550/3660 size motors are a huge step up in power. You are looking at more than twice the power at the same Kv compared to a 540 size motor. 3200kV 550 size motor is actually about 6.5turns because larger motors are slower but produce far more torque. The arrma combo is probably about 750Watts on 2S and 1500W on 3S. A 13.5t/3000kv 540 motor is about 250W on 2S. 550 motors usually have 5mm output shafts (as opposed to 3.175mm) which means you need a different pinion gear too. Anything north of about 300Watts becomes difficult to control in a 1/10 touring car so unless the aim is to make a tyre frying basher or do speed runs, stick to a 10.5turn or higher 540 motor. The silver can motors that come with TT02s are in the ballpark of 70-80Watts if I remember correctly. A 21.5turn brushless is actually a little more powerful than a silver can, but brushless motors typically rotate slower when making similar power to a brushed motor so they require different gearing (larger pinion / smaller spur) to be comparable. That said, a 550 size motor and 1/8th scale ESC should fit in a TT02, but you might need a low profile size servo so the ESC can fit between the long motor and the servo. Not sure about the other chassis. You'd probably want the smallest final drive ratio possible (big pinion, small spur gear) to keep the torque down, preventing destroying the plastic drivetrain and allowing a reasonable top speed (>60kmh). This requires cutting the spur gear cover on the TT02 as it only fits smallish pinions from factory. With the stock gear ratio it'll just have insane tyre frying torque and only do 25kmh haha. 3S and 550 motor would probably require metal upgrades to the drivetrain.
  17. It's a Japanese 1:1 racecar/driftcar thing to mirror the main livery so it is perfectly symmetrical
  18. The design flaws add character and give us and the aftermarket something to do I hope the cc02 does have weaknesses.
  19. Depends how hard you run your cars I guess. I use cheap CA/superglue as I want the tyres to stay on when they are spinning at 60kmh+ and the cheap stuff works just as well as the RC branded CA. The wheels usually end up rashed/kerbed by the time that the tyres need changing, so it doesn't bother me that I have to abrasively remove old glue from them. I cut and peel off as much old rubber as I can, then mount the wheel on an M4 bolt in a drill press and 'lathe' the remains off with files and sandpaper. Good quality wheels will last 3 or 4 sets of tyres before they crack or the lip gets to thin from 'latheing'. If you're keeping it to low speeds a rubber glue might keep the tyres in place and be easier to clean off when changing tyres. Also consider bead-lock wheels.
  20. Neither. Buy Wiha or Wera drivers and never look back ;).The only downside is plastic/rubber handles which may not be as good as knurled aluminium when working with oily hands.
  21. Some of the cars which make excellent rally bashers are a bit overbuilt and therefore overweight for competitive racing - 4-Tec especially, XV-01 to a lesser extent. Unless your club runs a higher minimum weight - 1/10 touring racing is usually set to a minimum of 1350g or thereabouts. 4-Tec and XV01 are more like 1500-1700g ready to race. Just about any decent 1/10 touring car will also make a good 1/10 rally car when fitted with longer stroke shocks and softer springs. You may need to modify some suspension parts (cut some plastic away) to allow the wheels to droop 20-30mm below the chassis.
  22. Buggy update. Both diffs were upgraded to GPM steel gears. The rear diff was assembled with a minimal amount of AW grease so it is open/loose. The front diff was filled about 1/3 of the way with 1million cst oil and then up to half way with 100K cst oil to make it a little thinner than 1million. The only thing I don't like about these gears is that the ring/crown gear doesn't have the 4 tabs that key the gear to the housing like the standard plastic gear does, so the torque is transferred from the gear to the case by only the 4 small screws, and whatever friction is generated between the gear and casing. Nevertheless, it doesn't seem to be an issue. I also changed the wheels to Proline Badlands SC 2.2/3.0". At ~113mm these are significantly larger than the standard ~85mm wheels, which increases ground clearance substantially. Being a higher profile tyre the suspension doesn't have to work so hard over rough ground either. The downside is of course that the rollout is increased substantially, as well as the wheels being heavier, and this drastically increases how hard the motor and ESC are worked. With the 7.5t (5100kv) motor on 3S and the timing wound all the way down (~5-10degrees = ~4000kv), boost timing disabled, the ESC would overheat after only a couple minutes of running in grass. I can't really increase the FDR since it's already just about at the maximum the TT02 chassis supports. The 48p 78t spur is as big as will fit. I have maybe another 1mm of adjustment room on the motor so perhaps I could change the pinion from 18t to 17t or *maybe* 16t but I think that would not improve things as much as I need. On 2S and boost timing, it ran great but I wanted a bit more power than that. I found a happy medium swapping the motor for a 13.5t (3040kv), running boost and 3S. This makes about 600W whereas the 7.5t on 3S is ~900W and on 7.5t on 2S ~400W. Speeds seem to be around 40kmh in 2" tall grass and 60kmh on asphalt. The limiting factor now seems to be motor temp rather than ESC temp. After half a pack at full noise in grass the motor was quite hot, I might still need to dial back the timing a little. The other thing I've changed is the suspension. I opted for these '105mm' (95mm hole to hole) ZD Racing shocks. They are exactly the same length as the rear CVA shocks but have longer travel due to a longer body and shorter rod end. Of course, as with any cheap shocks they were not supplied filled correctly so I tore them down, inspected, refilled and bled them properly. The oil that came out seemed about 200cst. The piston is a much tighter fit with the bore than a CVA shock, and the bore overall larger, so the oil doesn't need to be as thick. The shafts had a slight 'turned' finish which caused a zipping sound as they moved in and out of the o-ring seals in the shock body. I gave them a once over with some metal polish to remove most of that finish - I didn't aim to get them perfect because I was worried about completely removing any plating on the shaft. Left is as supplied, right is polished. I refilled them with 350cst which gives quite firm damping - comparable to the CVAs with 800cst. The front suspension was converted to use the same length shocks as the rear. Because the TT02 chassis is symmetrical front to rear, you can mount a rear shock tower to accomplish this, however due to the kickup in the lower front suspension arms, the mounting points for the upper suspension arms need to be higher on the front tower. Fortunately the carbon towers (hopup 54754) have enough material that you can simply align a front tower with a rear one and transfer the front holes to the rear part with a 3mm drill. I'm just using a stock tower for the rear for now, until another carbon one arrives. If you cut down the 'stalks' that the top of the shocks mount to, as short as possible without the shock cap hitting the tower, it reduces the amount of flex in the shock tower to a minimum. The springs that come with the ZD shocks turned out to be just about perfect for a TT02B. At the front I run no spring preload, and at the rear I have almost full preload due to the higher weight over the rear wheels. One final tweak I've made is to drill some holes in the shell just in front of the A-pillars and put a zip tie through to slightly pinch the shell and make it fit tighter to the chassis. This is to increase clearance with the front wheels, since with the Proline wheels if the steering was turned to full lock and the body flapped around in just the right way the tyre could catch on the shell. It didn't damage anything but made a horrible noise. With the ziptie the shell can't flap around much anymore so the problem is solved. I'll shoot a video when it's not a roaring gale outside
  23. I can't imagine the kind of abuse you'd have to throw at a YR shaft in a TA01 for it to break. Small 1/10 wheels loose traction way before enough torque is generated from the motor to bother the shafts. I had them in the rear of a TT02 basher on 7.5t (5100kv) brushless, 3S lipo, often full of dirt and sand and they are still in perfect condition. If the car was involved in a big crash that jolted the front and rear wheels in opposite directions it might be possible to break a shaft. I have a set of Tamiya shafts and they are basically identical in quality and smoothness (to my untrained eyes) as the YR shafts. The Tamiya parts offer less angle before the shaft hits the edge of the cup - not sure if you'd consider that a good or bad thing, although both brands of shafts start to chatter significantly if you push them past say 20degrees or so, they are after all universal shafts. I run double-cardan shafts in the front of my on-road cars because they are a true CVD and don't chatter when operating at an angle.
  24. I run plenty of Yeah racing universals (both the type with the spring clip and the type with the grub screw) in my cars and they are as good as the Tamiya ones imo. Just make sure you thread lock any grub screws well when you get them, otherwise the pin comes loose and they can be damaged.
  25. I already had it running on 5100kv 3S with the stock wheels and the rear diff pinion gear stripped out so I upgraded it with GPM steel gears. With these wheels I got the odd click from the front diff so I upgraded that one to GPM gears as well and haven't heard any bad noises since. Drive shafts are Yeah Racing universals, which I've had one snap already but I think that was my fault for not thread locking the pin properly, so it backed out and jammed up the universal joint. Also running an Eagle Racing alu propshaft which comes with steel prop joints since day one - not sure that is entirely necessary though.
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