Ray_ve

Last steps, battery box repair and the test drive! The battery box had splits and breaks on both sides. I decided to repair this by extending the box, so it would also accept the 8.4V stickpack that came with the car. So new extended side covers were moddeled, printed, and glued in place with epoxy glue. And then, the long awaited test drive!. Because of the large diameter tires, and the gearbox uses a 21 tooth pinion with the motor directly bolted to the box, it is fast! Well, at least compared to the original. With a silver can it is about 2x as fast, with the 35T motor I use now, about 1.5x as fast. It also steers well.... at low speed! The test drive revealed a design flaw that is very logical.... once you see it in action. Because the chassis is much higher compared to original, and the speed has increased, any attempt to turn while at more then half speed will result in the car flipping on its side! If a NiMh 8.4 pack is used, it will also do a full 1.5 tunr flip because of the battery weight high from the ground, with a much lighter weight 2S 2200mAh lipo it will only tip over.... Hence the reason I changed it to the 35T motor, its there to reduce speed as part of damage control. So.... to wrap things up: this has been a very fun and interesting build for me. And despite its handling problems, it is still a fun truck! I will not use the original body for this truck. I found a complete and in very good condition big bear chassis, which only needs a body and wheels. Since I have these left over from this truck, I'll use those to build a complete and original Big Bear. Frankenbear will get a polycarbonate bear body, thise can take some abuse. And bumpers with lights are still on the drawing board. Who knows, maybe with some repositioning of the gearbox to get the chassis lower, its handling will improve. But I plan make it a complete car, So some time in the future I'll post it with its new body. And if anybody is interested, I'll do a topic on Basherbear, which is (as the name implies) the big bear lookalike I use for bashing and recreational driving.

Found the specs of the ESC, and indeed, it should work per your description. Strange that it glitches while USB power is also present, that should not make any difference. When power by USB, is the ESC still connected and on and hooked to the battery?

Maybe it would be usefull to put some pictures here of the setup. I believe you use an Arduino Mega 2560? And what ESC do you use? Can you use a multi-meter to verify the output of the ESC BEC voltage going into the Y cable? I would expect this to be typically 5V , 5.6V or 6V (thats the values I've seen in most ESCs). Not 7.4V which would be direct battery voltage. If the ESC indeed outputs 5V to the Y lead, It should not be connected to Vin as Vin is the pin for the external power supply, rated for 7 volts up. This is because there is a power regulator on the board that will convert the Vin voltage to 5V. But if the ESC BEC voltage is already 5V, this regulator will not function properly and the arduino may show all kinds of unexpected things due to brown-out/undervoltage. Especially if the steering servo starts drawing current when moving. If the ESC BEC voltage is 5V, connect it directly to the board +5V pin which is a few positions toward the power connector I believe. If the ESC BEC voltage is higher then 5V, but not at least 7V, connect it to the 5V pin via a few diodes. Each diode should drop the voltage by 0.6V.

Ordered a 3100KV brushless+ESC, to see how that compares to a silvercan. A 4300KV was too much for my DT-03 and destroyed it, so I'll try the 3100KV in Basherbear first. If succesfull, maybe get a second one and put 2 in the bullhead. Or move it to the konghead.

Ordered a Marui Big Bear polycarbonate body for frankenbear, and a Marui Samurai body, from our buddies at teambluegroove. Still need to decide what color to do frankenbear. I'm thinking a PS-62 orange body, which is the color of our royal house, with big bear decals in red-white-blue instead of the original yellow-orange-red. Something completely out of my comford-zone, but for frankenbear that is OK. Edit: ooooh PS-61 metallic orange!!!!

I like the extra heatsink, which make/brand is that? Have you decided on a color yet? Or box-art black like mine? Agreed that they still drive great! But mine is mostly a shelf-queen as I dont want to risk any damages or bad gears which cannot be repaired anymore.

Let me know how it turns out, very interested as I want to strengthen my old bbear tires.

For me it was the Calvin and Hobbs Lamborgini. Took some work but came out great with this artwork.

On with the front suspension. To get the front suspension on the same height as the rear, One could simply make longer uprights that the big bear frotn suspension uses, bit this would put the steering servo into a very high position compared to the original mounting of the steering point. Another problem I had was that the new front wheels are also 12mm hex, while the front axles on the big bear are of the same type as the lunchox: stationary, not rotating. So I decided on a whishbone suspension, and had our aliexpress friends send a set which are ment to be on a Kyosho Javelin I believe (since I was already using Kyosho shocks anyway). I still had a set of 4WD axles and 12mm Hexes from my Corvette, so these could also be used to rotate and mount the wheels. Started the front suspension by moddeling and printing a plate that sits below the front chassis and bolts into the servo mounting holes, and a U bracket that holds the plate at the front and bolts into the original suspension swivel holes using the original M3 rod. The steering servo mounts to this plate, and another shaped piece extends further down to hold the lower whishbones. The upper adjustable bones screw into the U bracket. Here is the steering servo, missing its servo saver but you get the idea. Steering rods are now 3mm rod, coupled with ball links. This is the view from the front, with the shocks in place. Finally, the chassis was now on 4 wheels, with the bottom of the chassis sitting about 2x higher compared to original. Next post, the battery box repair and the test drive!

maybe 100mm will just fit the big bear tires too. I'll need to measure that!

First thing after stripping the bear down, had to think of a way to get a new gearbox. I believe it was somewhere on this forum, google pointed me to a thread that said 'Why not put a grasshopper gearbox on it?'. Thankfully, I still had a lunchbox gearbox, so I thought I would give it a try! Moddeled and printed new suspension arms that would fit the lunchbox gearbox, and join with the chassis. Then, a trail fit. Heee, not even half-bad! Next, suspension. I also dug up some oil-dampers that belonged to my long discarded Kyosho Nitro Corvette. Since they could not go into the original positions, I made a strengthener plate to hold them at the end of the chassis. It is fixed to the chassis using double-sided tape and 2 screws were the original springs sit. And offcourse, no car is complete without tires! Found these great shevrons on aliexpress. 130mm diameter and 70mm wide. Original bears are 110mm by 80mm. And adapters for the gearbox, as these are regular 12mm hex. And when it is all together: A sturdy gearbox, ball bearing equipped offcourse, and new tires. Job done on the backside. And because of the way this is mounted, no hole drilling in the chassis. This mod is reversable. Only one tiny issue...... the back end sits a lot higher from the ground with this gearbox and bigger wheels, so the front suspension is now too low. Next post: Front suspension.

Dug up the original Big Bear tires from one of the many boxes of parts, to get a Marui big bear to pose with Frankenbear and Bullheadclodbear. And made a start on the promised Frankenbear topic in the Marui Section. This weekend is nice weather, so hopefully Basherbear will also see some action! (Yes, I have 4 variants of Big Bears... I'm a little silly that way.)

As promised, I'm starting a build overview of Frankenbear, a heavily modified Big Bear I'm working on. This project started with the car that got me back into RC cars, a few years ago. My first love (and those are the hardest to forget), a Marui Big bear. https://re74.imgur.com/all I bought this car cheap, and although rough looking it was a runner so I had a few runs with it. When the nostalgic feelings were satisfied, I decided on a stripdown to see is what real state of the car was. As we all know, after 30ish years, thing start going south. The tires were in 1 piece, but dry. The gears in the gearbox about half-way worn. The chassis had splits in the battery box, both sides. The body itsel, despite its bad paintjob, was in 1 piece! Score! So it was time to have some fun modifying this old beast. To do list: - New tires.... somehow. - New gearbox and/or gears. - Fix cracks and patch it up. -Ball Bearings! For now, this post mainly shows the differences between a regular Big bear, and Frankenbear. More posts on the build details will follow when I recover the data from my laptop. Left: Original Big Bear, Right Frankenbear with a Team Bluegroove body from my other bear: Basherbear! And as a glimpse from my latest creation, original bear vs. Bullheadclodbear (working in the body, its in filler primer now)!

Absolutely buy an ultrasonics cleaner. I got one too, and its so much easier and faster to the toothbrush. One of my best buys ever!

True words. People here are quite friendly, I only seldomly encountered disputable language here like 'who can paint my body' 'how do I paint my Willy' and don't get me started about the person talking about 'frontend stiffners'. Or maybe that's just my crazy mind going into high gear!

Thanks! These tires are a little wider and higher compared to original. These 130mm diameter and 70mm wide. Original I believe something like 110mm by 70mm. But I'll dig out the originals and put a picture in a build thread since more persons are interested in this. Aliexpress Brand xxxxxx. The same type as shown here in the last post of the page: https://www.tamiyaclub.com/forum/index.php?/topic/39344-the-postman-brought-me-thread/&page=515 No, but I'll make one and put it in the Marui section. Maybe this weekend if time permits.

Craziest thing ever, he must get a lot of returns that way!

Replaced the Johnson silver can in Frankstein Big Bear with a 35T Absima motor. It was too fast with the can so more turns should slow it down a bit. Also placed one of the cheap ESCs in it, So it starts resembling a working car again. Still need a receiver and a body. Edit: Combined with another hardly used johnson can I still had, I now have a nice pair that can go into the Dual Hunter. They have the same current draw and the same pitch when connected to a bench power supply, so should be OK with minimum speed difference.

For me in the Netherlands, with limited time to pick stuff up, I typically use Tony too. Also because of the free shipping, tell a Dutch person something is free and you've got their undivided attention. Edit... hopefully this will continue to be a good service after Brexit..... as stuff from England will be treated as 'from a foreign country' with possible tax and handling charges....

If they cannot deliver the first time, they will try a second time the next run. And if they cannot deliver again, they typically bring it to a pick-up point and leave it for 2 weeks so you can pick it up yourself. Very strange that they send this back..... Must somehow be related to the contract they have with the Austria postal service or something.... It is not normal procedure in my opinion... I'm typically very happy with the deliviry guys from postNL in my area, great guys.

Looks great! No idea these were collector items. Some time ago, I also saw a Marui Big Bear, new in sealed box, 1200 dollars. And if you fancy a clodbuster, with some spare shocks: https://www.ebay.com/itm/Original-Tamiya-Clodbuster-4x4x4-monster-truck-Nice/264157299697?hash=item3d810083f1:g:8AUAAOSw-k5cR0l5:rk:22:pf:0

Ah, saves me the trouble, Thanks!

Yesterday evening I put electronics into the Dual Hunter and took it for a spin. For a truck that I want to use as a basher, the resulting ride was less then impressive..... The 23T Carson motors that were included with the car are just very very bad. I think they were badly overloaded at the previous owner, because they had very dirty black commutators when the car came in which I cleaned up a bit, but the brushes are probably bad too. Overall speed was disappointing and a lot of speed difference between front and aft gearbox (maybe these motors have timing? Dunno..). I also managed to hit a curb (I excel at that!), not even at full speed, and the servo saver broke and 1 servo mount pillar broke off with the piece of the chassis the mounting screw sits in and is now missing. I'll search for it at the end of the day when there is still some light. Repair is easy enough, as the chassis is symmetrical and I can reverse the chassis and have a new point to mount the servo pillar, if I can find it. Maybe I can even find a way to mount the metal DT-03 servo mount I still have somewhere, or 3D print something better that mounts at both sides. That would greatly improve things. I also have 2 as-new silvercans left over, and 1 metal servo saver horn, so I'll use those for now. It also needs a good battery tray to mount the lipos I have, which are plain rectangular ones not stickpack-type and this chassis is made for stick-pack only. I have those on order, hopefully they will arrive in 3 weeks time. So, some TLC for now, suck up the shame, and improvements and upgrades to follow. To be continued!

I've been looking at brushless before in the past, got very confused by all the numbers, ordered one with 4300KV (big numbers are better...right?) and put in into a DT-03. Destroyed the car in minutes. So let me get some stuff straight, as my knowledge of brushless is limited. Please correct me if I'm wrong in any way! A non-sensored brushless motor has its RPMs vs Voltage expressed in KV. They are typically also advertised as waterproof, as they can be fully sealed with only the 3 wires coming out. From standstil they also have a minimum RPM as rotor position is unknown to the ESC when engaging, causing a non-smooth pullaway from standstil. Timing is neutral, reverse rotation is swapping 2 out of 3 wires. A sensored brushless motor is expressed in Turns rather then KV, with winding numbers ending in .5. They are typically not advertised as waterproof, as they have the non waterproof sensor cable coming out. From standstil they are smooth as the sensors tell the ESC the status of the rotor. Timing can be adjusted by turning the endbell. A brushless 'equivalent' of the silvercan is about 2300KV or 17.5T. A nice more RPM and torque upgrade from a silvercan, given the same battery, would be a 3300KV or 3500KV? I see 4-pole and 2-pole brushless advertised. A 2-pole is typically more a '380' motor in a 540 size can, and a 4-pole is 'true' 540 size (bigger rotor)? Because brushless has more torque, you do not need to change the motor pinion to one with less teeth?

I agree that the 'open' construction on brushed motors make them vulnerable to dirt. Since I mainly drive on hardened roads, I don't have any issues with that, but with trail and beach running like you do it will be an issue. And the closed construction of the motors will be a big plus side. I am very intresested how your bullhead runs on the brushless setup. Keep us updated!