nbTMM
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Posts posted by nbTMM
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On 8/23/2019 at 5:05 PM, jupitertwo said:Yeah, it’s a little odd that it’s just the Super Coppermix is reversed. Somewhat disappointingly the other side isn’t the flip, with everything else reversed and the Coppermix the right way
It's a Japanese 1:1 racecar/driftcar thing to mirror the main livery so it is perfectly symmetrical
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The design flaws add character and give us and the aftermarket something to do
I hope the cc02 does have weaknesses.
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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.
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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.
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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.
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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
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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.-
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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.
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9 hours ago, jupitertwo said:How’s the internals coping with those wheels? Did you upgrade them?
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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Trialled equal length front and rear suspension to complete the whole monster buggy thing I've got going on with this TT02B. These ZD Racing '105mm' (95mm hole to hole) shocks are awesome for $25AUD per set of 4. Still needs work as the mounting points for the upper suspension arms are slightly higher in the front due to the kickup, so using a rear tower messes up the front end geometry. Another carbon rear tower re-drilled to suit the front should sort that
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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.
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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.
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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.
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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.-
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On 7/30/2019 at 8:43 PM, Mad Ax said:I have a Turnigy GT5 (same as a FlySky FS-GT5) which is indeed a 6-channel wheel controller and is cheap at around £60, however I can't find how to set up dual rate via a switch. You can independently set dual rate on throttle and steering using the menu on the handset but that won't be idea for operating functions while driving. I've had a quick search online and I can't see that anyone has made this work.
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.-
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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.
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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.
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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..
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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.
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On 8/13/2019 at 6:42 PM, Mad Ax said:Like for example could the endbell be adjusted in motion to adapt motor timing to the conditions? I don't know if any current tech does this. I guess that's part of what the above gets at, among other things.
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.-
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What's better than having three TT02 chassis? Four, of course.
I guess that makes this now a TT-02RR Type S
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On 8/10/2019 at 9:28 PM, Honza said:Doesn't "metric 48p" mean 0.5? Since 48p is about 0.53 metric - It's too big difference, but 0.6 metric is interchangeable with 42p (some Traxxas gears) an 0.4 is almost same as 64p
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.
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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-
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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
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I hope the cc02 does have weaknesses.
Advice for a beginner wanting to get into building
in General discussions
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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.