LMF5000

Well, my plan so far is to run it until I break something that needs access to that cover. In the meantime I'm pondering what to buy. Maybe the sprue with that cover so I can Dremel a slot into the screw with reckless abandon. Maybe some extractor bits so I can try getting it out more elegantly. Pobably some longer hex bits so I can drive the screws in straight next time and avoid this problem going forwards.

Well, this is a first for me. I stripped the circled screw. With exactly zero miles on the chassis. I was actually happy that the BR came with hex hardware - I thought it would be a more enjoyable build experience than the usual Philips head screws because they were less likely to cam out and strip, right? Not so. The screws holding down the pinion/spur cover were tight, because my screwdriver uses changeable magnetic bits so it's a tad thicker than one with a fixed bit . When the screw is approaching fully tightened, the sides of the screwdriver foul against the sides of the spur cover so I had to have with the screwdriver at the slight angle for that screw and the one opposite After first assembling it the first time, I removed the cover piece again to rotate the brushless motor to try different positions for wire clearance. Screwed all the screws in, tightened them fully... and the marked screw was feeling a bit different. At first I thought I'd stripped the plastic so I thought I'd remove it to check... but nope. The head is completely rounded. So far I've I tried the rubber band trick, supergluing a bit to the screw (the glue just broke off), hammering in the next size up torx bit (I couldn't hammer hard enough to get it to sink in), all didn't work. What can I do? The buggy is completely driveable, but it's going to be a big problem the first time I have to remove that cover for maintenance. It's a deeply recessed screw so cutting a slot with a Dremel will definitely destroy the plastic. And this is a 3mm screw and was VERY hard to screw into the plastic.

My servos, not stalled but moving at full speed, were drawing about 0.5A. If most BECs can only supply 3A, then I'm going to guess most servos won't draw anywhere near 3A when stalled. Let's take a pessmistic case where you only had a tiny 1000mAh lipo with a conservative 30C rating - that's 30A of max current, so worst case a stalled servo will use 10% of the battery's capability. If you have the more typical case of a 3000mAh or larger battery with a 40C rating, that's 120A max current, so the worst-case servo is only 2.5% of the battery's current capability. In short, in my opinion (and speaking as a real-world engineer), it's not worth thinking about. Plus if you're accelerating at full throttle your steering will likely be mostly straight so servo load will be very very little.

That is a very good point, and one that I was wondering about myself. It appears some (not all) coreless servos can also achieve similar speed (example) for as low as €28. But I couldn't find a conventional (brushed) servo that could manage 0.08s/60°, at least on tamico. So I'm thinking maybe it's an innate advantage of brushless that they can achieve that kind of speed more easily than conventional ones (maybe less rotating mass since a brushless just has to spin the inrunner motor magnet, a coreless just has to spin the copper wire, but a conventional servo has to spin the entire armature). I'm not discounting that I might have missed something - have you found any similarly fast conventional servos in your own searching?

In one of my other threads, someone had suggested investing in a good servo to complement a high-end build. I had already been eyeing the entry-level brushless servos on tamico. They're 3x the price of a good (waterproof, metal gear) digital servo so I was hesitant, but that discussion convinced me to take the plunge. When I was doing my research, I couldn't find any really good quality side-by-side comparisons online, so after buying I decided to set up a side-by-side comparison video to help others make a more informed decision. As a mechanical engineer I tried to set up the experiment to eliminate as many variables as possible, so both servos are being driven from a Y-harness on one channel so they're getting exactly the same signal at all times. I used a receiver instead of a servo tester to reflect real-world conditions. If you keep the sound on, at the end you can also compare the noise made by the two servos individually. Here's the video. First 15 seconds compare the speed, next 20 seconds compare power consumption:

Decision made - I ordered the TT-02BR. My rationale was the following: - the TT-02B was tempting (and really cheap at €91!) but would have been boring for me, basically a repeat of my TT-01 - the Manta Ray styling wasn't my favourite. That and the Top Force are basically the same chassis as my TA-01, so again not much in the way of new experience (about €140) - the DF-03 Dark Impact (€170) was another tempting one, but it's a 20-year old chassis (released 2006) and parts availability is an issue, some reports of the plain plastic tub breaking at the front and the aluminium main shaft gear wearing - the VQS (€210) was really, really tempting because it's the only one with a center diff (and for €8 I could buy the gearset of the egress to eliminate the center diff if I melted the original center ball diff). It looked like a good, fun, complex build with planetary diffs (never saw them before), universal shafts, the center ball diff, and a brushless-friendly exposed motor layout similar to the TT-02B. Ultimately I decided not to get this because I read about the handling/layout/capability being "vintage" (whatever they meant by that), doubts as to whether it could handle the power, and doubts on continued availability of parts - the Super Avante (€250) I pondered for a very long time and read the instruction book half a dozen times. Ultimately I decided there's not enough of a value proposition there. The features are similar to the DF-03 (ball diffs front and back, metal shafts, no u-joints) but it's wrapped up in a convoluted highly-packed chassis that makes maintenance time consuming. Even fitting non-Tamiya brushless motors and ESCs could be a challenge since their wires emerge from a tab or at a right angle instead of straight out the end like Tamiya brushless and all brushed motors. Then there's the need to undo 2 screws and 2 clips to get the battery out, the need for a low-profile servo, and the amount of play in the stock steering system (from YouTube videos), and lastly the limited steering angle due to the spacers. All in all I never really considered this one - I looked at the BBX (€250) and ruled it out because it's rear wheel drive. I feel like that would hamper how well it could put the power down. - Finally, I bought the TT-02BR (€270) plus a metal motor mount and metal steering upgrade, fancy brushless servo and rather than my existing motor I went for a new sensored 80A ESC/4100kv motor combo. Sensored so that it doesn't have the low-speed cogging of sensorless motors, and a tamer 4100kv setup to comfortably withstand 3s. This BR is based on the TT-02B platform so has excellent parts availability, but has all the fancy upgrades - fluid-filled differentials, universal joints, upgraded dampers, a lot of metal and some carbon-fiber parts etc. Funnily enough it doesn't include the tyres, so I bought the type-Ks (similar to the ones on the DF-03). Like I wrote earlier the TT chassis have extremely simple drivelines (just 6 gearwheels including the pinion) so in my opinion efficiency should be high (less gear tooth interfaces and bearings that contribute friction) and the number of things that can break is more limited. We'll see how it goes 😁

Thanks! Which part is 1.9" - is it the outer diameter of the rim (= inner diameter of the tyre)? Can I fit stock Tamiya tyres (like the ones that came with the CC-02) to aftermarket beadlock rims? After making this post, I discovered this article which answers a lot of my other questions - https://www.eurorc.com/page/100/choosing-the-right-rim--tire-size--110-to-18th-scale

After much consideration (and not being convinced by the TT-02's plastic diff gears), I've zeroed in on the TT-02BR. Unfortunately tyres not included, so that's a further cost, but on Tamico the TT-02BR is the same price as the Super Avante, and seems to have much more performance-oriented parts which easily exceed the cost of the kit if bought separately. Would the TT-02BR happily handle a brushless setup for bashing - or is it a better strategy to get a stock TT-02B then upgrade things after they break?

Hey, I use chatGPT sometimes too (the open ai equivalent to the copilot)! Great minds 🤣

Back when we had physical hobby shops in my country it was easy to buy wheels. Just walk into the shop, pick one that looks like it'll fit on the model, pick tyres that look the right size, maybe take an original rim with you to check the offset, and done. Now that we have to do most of our buying online, I'm finding it more challenging because a lot of listings don't include key specs like the outer diameter of the rim or the inner diameter of the tyre, or the offset of the hex attachment (to know if it will rub the suspension or tie rods etc). Some listings don't even show the back of the rim to see if it's a hex or other attachment style! Can someone help me learn how to find compatible wheels and tyres (especially on tamico.de). For example, let's say I buy a buggy and I want bigger wheels and/or tyres for more ground clearance and that are also less spiky so I can run on tarmac, how would I do that? Are there some overarching standards where all wheels of a certain type will fit all models of a certain type?

Interesting experience. I've never replaced a servo except due to my own stupidity (I was spinning the output by hand, spun the servo horn really fast, and when it got to the end of its travel it hit the stop and the momentum of the motor made it break a few teeth on the plastic gear immediately after the motor pinion - which is why I only buy metal gear servos now; the other servo I broke because I took it apart out of curiosity, disassembled the potentiometer and broke off a few of the fine fingers of the slider so the controller was getting no position signal after that). I think my NSX is still on its original Futaba S3001 despite being frequently driven at 80km/h on a sandy track. However I've been very curious to try a brushless servo. The cheapest one (€60) specs wise is twice the speed of a good brushed servo (€30). You've convinced me to add it to my cart 😁.

Interesting take - I've never had a brushless servo (nor even a digital one for that matter). What makes brushless servos worth the €60 (compared to €20 for metal gear waterproof digital brushed)?

Thanks for the replies so far! TT-02B seems to be winning, with DF-03 runner up. Is there a reason nobody's suggested the VQS? Any significant disadvantage?

Those are some very wise words. Especially about the build being a small part overall (though I buy tamiya specifically for the build, else I'd be buying the more performance-focused brands hehe). Why do you think manta ray and thunder shot are worth considering? I had discounted manta ray because it's basically the same innards as my TA02, and both of those seem to mount the battery transversely using a hole with rounded corners, so I don't think my lipo fits.

That's exactly what I was thinking! Yesterday I priced a TT-02B with the recommended upgrades from the previous thread (metal center shaft, metal motor plate, ball bearings, steel pinions etc). By the end it was approaching the price of the dark impact. I think the more sensible approach is to start stock with only ball bearings (since they are a pain to change afterwards, and since they improve battery life, speed, and the life of the gears and parts), then see what breaks and upgrade only those things to metal. My TT-01 went 50mph (80km/h) with the 6000kv motor on 3s using the stock plastic driveshafts after all. I only upgraded it to a metal center propshaft because the plastic one would bend (buckle) and noisily slap the sides of the tub past a certain speed.