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About nbTMM

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  1. The basic recipe for a speedrun car is pretty simple. You want >6degrees caster in the front suspension, >2deg toe in at the rear suspension, belted or foam tyres, and shim everything in the suspension to remove slop. Run slightly stiffer springs and heavier shock oil than you would for on road racing. Spool/locked front diff. Tt02 (non type s) suspension is kinda clunky out of the box as it is close to 0deg everything alignment which makes it very unstable at high speed. The open gear diffs make it spin like a top once it loses control. The advantage is that it is cheap so it's not the end of the world whe you crash it, and some of tricks from the above recipe are easy to implement. At the very least you'll want some aftermarket 3degree toe rear hubs/uprights, lock block in the front diff, flip over the upper front suspension arms to get a bunch of caster, and a 5mm ID shim set. Get a tt02 kit that comes with CVA shocks and fill them with 1000cst oil (kit oil is 400cst which is too thin). Standard chrome springs are ok for starters but you might end up wanting slightly stiffer ones. 0deg camber and 0deg front toe is fine for speed runs so there is no need to turnbuckle mod everything as long as the plastic links don't have slop. No need the upgrade the propshaft unless you get a dud and it's unbalanced. Driveshafts should probably be replaced with metal universals when you get >100kmh. With those mods, you have a car that drives pretty straight by itself. The only thing left to do is add power and gear it properly. The Tt02 is somewhat limited on gear ratios but you will be able to get a final drive ratio around 4.7 without modifying the gear cover. You need the spur gear adapter from the high speed gear set, yeah racing adjustable motor mount and aftermarket spur/pinion gears. If you mod the cover you can get down to an FDR around 3. Even with an FDR of 4.7 you should still get well over 100kmh with an >8000kv motor on 2s or >5000kv on 3s.
  2. Put in some nicer geometry rear suspension (modified roll center, ball jointed upper arms) and loosened the diff to tame the rear end in my RWD TT02 drift project. Also started building another chassis so I can get back into speed running - built from spares taken off the drift car and the left over parts after upgrading my TT02RR with a Type S kit.
  3. For me it's because i'm time-poor for running (need a commitment-free weekend, appropriate weather, daylight), but time-rich for building as that can be done most evenings. Also having what would seem like a virtually limitless budget to a kid, there's always the urge to continually upgrade/change what I've got instead of run it a hundred times over in the stock configuration as most kids would. I'll often hold off running a car because I'm waiting for a certain upgrade part to arrive.
  4. Fresh water generally does not bother sensorless motors or batteries as it not very conductive and batteries and motors normally deal with huge currents. They will not care that a few milliamps of current is flowing through some water when there are normally tens or hundreds of amps flowing through the main circuit. What will be a show stopper is if water gets into the low current circuits of the receiver, ESC, hall effect sensors on a sensored motor, or steering servo. When that happens you may find your car turning or accelerating out of control, or if the sensor system is effected the ESC could apply the wrong sequence to the motor causing the magic smoke to be released from motor, esc and/or battery. The problem with the sprays is that you can't always get it into the parts that matter. Better off fully dismantling the parts and applying epoxy resin to fully encapsulate the electronics. You'd probably also want to put dielectric grease into the sensor connectors in a sensored system.
  5. I don't think you can. I have the GT5 myself and the functionality of ch3-6 is extremely limited imo. The only 'feature' it has for the aux channels is for four wheel steering and even that is pretty clunky as you have to operate it via the scrollwheel/menu system. Maybe someone makes a steering controller that you can put at the receiver end to use an aux channel to adjust the D/R of the steering channel. I think of the GT5 more as a decent 2-channel radio with gyro, model memory and 4 bonus aux channels that have very basic functionality, rather than being a serious 6ch radio.
  6. Mine is 1310g without a body shell but with battery, a Turnigy Graphene 4600mAh shorty pack (206g). It's pretty much a stock type S but with the blue chassis (glass fibre reinforced but the same weight as black one iirc), 64dp gears, the blue alloy and carbon hopups you can see, a standard diff with lock block in front and an oil diff filled half way with 3000cst in the rear. Could probably slash a few more grams by changing the steel turnbuckles and screws to aluminium or titanium. I'm sticking with steel for now as i'm a newb and prefer it to be durable. Light weight body shells around 60-70g are common. Most tamiya body shells are 100-150g because they have very thick polycarbonate to make them durable.
  7. Adding to the above, you'll need to modify the spur gear cover (to fit a larger pinion gear) if you want to run a FDR below ~4.7, which will be required if running 21.5t and probably also 17.5t unless your local track is tiny. Adjusting the FDR is a lot more work than other chassis as the rear diff cover (and therefore suspension), as well as the spur gear cover and the motor itself have to be removed in order to change the spur and pinion gears. It is less work if you only change pinion gears, but if making a big change you will need to do the spur as well since the TT02 only allows limited adjustment before the motor body or pinion gear interfere with the chassis or propshaft. All the cover screws are threaded into the plastic chassis, so if you aren't careful you will strip out the chassis over time. Luckily the chassis is a cheap replacement part. Type S fixes most of the short comings with the 'standard' TT02 suspension. The main adjustments you will still lack is rear toe (fixed at 3deg), front caster (fixed at 4deg but can replace c-hubs to get 6deg), and droop screws - you will have to rebuild the shocks to adjust droop. The number of holes in the standard shock towers is also lacking in order to adjust ride height independently of spring/shock rate, and there are only 2 options for mounting the upper arm to adjust camber gain / roll center - the inner hole of which is just about useless as you get almost no camber gain (which was the main problem with the standard TT02). To be competitive you'll need a spool or very stiff front diff and a looser rear diff. You can achieve this using grease in the standard diffs however it is inconsistent as after some time the grease gets flung off the gears and the diff becomes looser. What you really want for TC racing is a spool/locked front diff and an oil filled rear diff. The standard diffs will leak if you fill them up with anything less than really thick oil (>200K cst). A decent oil filled diff with o-ring seals is expensive for a TT02 (hopup 54875). 3racing make a cheaper one but apparently it isn't very good quality - although I haven't personally tried it. Put a lock block in a standard front diff (not the tamiya one, it's too heavy) or simply epoxy glue all the internal plastic gears together, or run something like 1million cst silicone oil. You'll need to lower weight at every opportunity - light weight body shell, low profile servo, shorty/lightweight battery pack, minimise wiring lengths, carbon battery strap and front bumper mount - otherwise you'll find yourself at close to 1500g when other cars are running close to the minimum weight of ~1350g. A lot of the aftermarket aluminium hop ups will subtract more performance at a racetrack from being heavier than they will add from being stiffer than the standard plastic parts. The aluminium hopups that Tamiya offer are generally justified in increasing racing performance.
  8. I only ever rounded Tamiya turnbuckles when using steel wrenches. Changed to an aluminium wrench and no more problems. You want a wrench that is wide to distribute the force so if you don't get it on there perfect you don't end up with only 10% engagement between wrench and turnbuckle like what often happens with the thin stamped steel tamiya wrench. Poor engagement = rounding the part with the softer material, or both parts. You can continue using your rounded turnbuckles by filing flats onto opposite sides and using needle nose pliers to turn them, or file them down to exactly 3mm and use a 3mm wrench. Given that turnbuckles only cost a few dollars, I'd just replace them, then take the time to line up the wrench properly every time or invest in a better wrench to prevent rounding them..
  9. All in due time . Already feels way better than before, even with the cvas, probably because the standard tt02 suspension has so much friction damping "built in". The type S has very little due to all metal hinge pins, so the cvas are doing all the work . Makes me want to try retrofitting a standard tt02's lower arms with metal pins, just to see how much it can be improved.
  10. That's what ESCs with boost/turbo currently do. The endbell on a brushless DC motor (what RC cars have) just houses 3 hall effect sensors which are used to tell the ESC what the position of the rotor is, hence it knows when to switch the 3 electrical phases to the motor. Physically rotating the end bell makes the ESC think that the rotor is in a different position and hence retards or advances the timing of the electrical control. Physically rotating the end bell or simply adding or subtracting an angle in software achieves the same thing. So if you have 20 degrees boost starting at 5k rpm and ending at 20k rpm it's like someone is sitting there monitoring the rpms and seamlessly rotating the end bell up to +20 degrees as the rpms increase from 5k to 20k. On a 540 size BLDC motor you can widen the power band slightly and increase efficiency over that range by perhaps 10-20%. Not a huge difference but better than nothing. I think the point of the OP's video was more that they increased the efficiency above 85% for 20-100% of the motors usable rpm range, versus existing motors that are only >65% efficient over that range. Existing motors are already quite efficient once the motor is up to speed. Hence for stop start traffic the efficiency would be increased 20% or so by the proposed motor design. Of course, you could also just introduce a gear reduction so the motor gets up into it's efficient range at a lower speed, and sacrifice top speed, or add an automatic gearbox with more than 1 ratio. Reducing size, weight and cost of manufacturing is a big deal for 1:1 cars, so if something can be eliminated that's a very good thing, hence why most EVs run fixed gear ratios as the added weight, complexity and efficiency loss of an automatic gearbox isn't justified when you could just install more batteries instead. At the moment range is given more consideration than the actual efficiency of an EV. Tesla's Model S already operates with decent efficiency over a wide rpm range, and key to this is the use of an induction motor. It still has a fixed gear reduction however as the induction motor is built for much higher rpm than typical wheel rpms. Unfortunately, induction motors don't scale down in size very well, hence why no RC cars use induction motors (and I don't think many if any popular small 1:1 EVs). The motor in the smaller Tesla model 3 is a BLDC motor somewhat more like a really big RC car motor. The same problem as the Tesla Model S is true for RC cars, a little 540 size BLDC motor wants to spin at say 15,000rpm to make peak power when we only want a few thousand rpm at the wheels, hence a gear reduction is used. Making a small motor that turns at low rpm and produces a great deal of power on a low voltage isn't practical/possible. Similarly, efficiency at very low rpms (<20% of max rpm) is rarely a major consideration for RC. The tech in the video looks interesting but I doubt it will make it to RCs as it's too complicated for negligible gain in a racing context where you don't care if the power/efficiency band of the motor is somewhat limited. RCs are largely driven by controlled racing series, simplification, light weight and low cost. It's hard to beat what we already are running for that.
  11. What's better than having three TT02 chassis? Four, of course. I guess that makes this now a TT-02RR Type S
  12. 32dp and 64dp are so close to 0.8mod and 0.4mod that they might as well be the same so people used the names interchangeably. Where things go astray is that the preferred imperial size between those two sizes is 48dp and the preferred metric size 0.6mod. while both numerically divide the larger/ smaller sizes, they are not the same since the scales are inverse - choosing the number inbetween is like choosing halfway between 0.5 and 1 on one scale and halfway between 1 and 2 on the other, and 1/1.5 does not equal 0.75. Therefore 48dp and 0.6mod are incompatible as 48dp has finer teeth. 48dp is close-ish to 0.5mod and 0.6mod close-ish to 42dp, but not like 32dp/0.8mod and 64dp/0.4mod are. 42dp and 0.5 mod are not common, at least in the RC world. Naturally in the US they preferentially use the imperial names so some genius (moron) thought to market 0.6mod gears as "metric 48dp" so customers would have some idea about how big they were without needing to be familiar with the module scale.
  13. I don't think so. For V1 turbo you need this one https://hobbyking.com/en_us/turnigy-trackstar-turbo-and-waterproof-esc-programming-box.html
  14. Got some big boy shoes for the TT02B. I sense a lot of parts finding their mechanical limits in the near future. Worth it tho
  15. Yes, just needs longer turnbuckles. You can also just reuse the standard plastic tierods with the aluminium steering upgrade since the TT02B already uses 4.8/5.0mm balls for the tierods. That's what i'm doing and I don't see any point in upgrading yet since I have no desire to adjust the toe from 0 degrees. Like so (my aluminium steering parts are not tamiya brand but are functionally identical)
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