JennyMo 3526 Posted December 7, 2021 Yes, those deep-dish 1.9 RC4WD wheels really are for much larger/wider tyres - for example I have some Axial BFG All-terrains on mine which are 120mm diameter and 45mm wide, which fit well... I can imagine trying to fit a more narrow/sub 100mm diameter tyre you might struggle to get them to sit well. It's worth looking on Ebay for those [regular width] stamped steel wheels too - you can get a 'copy' of the RC4WD 8-spokes from China, although they tend to sold in sets of 4 of course, and are almost always a 6-stud pattern too unfortunately. Whatever you do, it's going to look awesome I'm sure! Jx 1 Share this post Link to post Share on other sites
Mad Ax 9325 Posted December 14, 2021 No updates to the truck yet, as I was busy racing this weekend, but here's some photos of the Banggood transmission that arrived last week. Apologies for the washed-out photos, I hadn't noticed the exposure was all wrong until I offloaded them from the camera this morning! Anyhoo, here's a nice big plastic spur gear. There's a transmission behind it somewhere, but you can't see it This is what it looks like from behind, in case you were wondering The plastic may be a bit brittle, it wasn't too well packaged and the teeth have some chips, but it should work just fine Comparison photo next to the Ansmann Mad Monkey transmission. They follow roughly the same design philosophy, although the eagle-eyed among you will note the Ansmann is a 4-gear transmission and the Banggood Special is a 3-gear, so the Banggood will need to be mounted the other way around to get the correct drive direction to the transfer case. Flat bottom on the Banggood Special will make it easier to mount, although the screw spacing is different so I'll need to remake my plate. I'll have to do that anyway to reverse the transmission direction. No slipper on the BG-Spesh, which means it will fit better under the good and I can re-attach my home-made Mad Max style grille. But there again, the spur will be the other way around, so the point is moot. Overall this one should fit better in the space available. I've got a day to myself tomorrow while I use up the last of my 2021 leave allowance, so I might have time to get this mounted. I still haven't ordered my spurs for the transfer box, so I can't make it drive until the New Year, but I should be able to make some good progress getting it all together. 4 Share this post Link to post Share on other sites
El Gecko 1344 Posted December 15, 2021 I'm curious on the ratios in those cheapo gearboxes... do you think they'd work for a RWD car or would they still be geared too low? I'm thinking it might be ok since most crawlers have gear reduction within the axles as well (and even further if the axles have portals), but I don't know for sure. Share this post Link to post Share on other sites
Mad Ax 9325 Posted December 16, 2021 16 hours ago, El Gecko said: I'm curious on the ratios in those cheapo gearboxes... I've just been out to the workshop to check. I haven't opened up either gearbox, just marked the spurs and turned them over by hand. I'd say the BG Spesh is somewhere between 2.65 and 2.7 to 1, and the Ansmann (which was from an RTR mid-motor RWD Mad Monkey buggy) is around 2.6 - 2.65 to 1. So the ratios are very close, despite the Ansmann having an additional gear. The spur included on the cheapo is much bigger than that on the Ansmann, but it's a standard fitment so you could put a smaller one on. Not sure how small you could go before the motor contacts the case, but there are some seriously big pinions on the market these days (I run a 65T pinion on my frontie at big outdoor tracks). 1 Share this post Link to post Share on other sites
Mad Ax 9325 Posted December 21, 2021 I had a bit of holiday to use up before the end of the year, so I had Weds 15th to myself. The wife was out at work, the child was at school, and all my chores were done (besides rebuilding the entire house form the ground up, but I thought I'd leave that until May Bank Holiday when it'll be a bit warmer). After lighting the fire and tidying up some working space, I got to work installing the sail winch servo for the tail lift. My original plan had been to install this under the body, but the space is taken up by the transfer case and propshafts, so I figured it was just as well to put it in the cab. I can hide it under a half-interior later. I cut some servo posts from 10mm alu square, and countersunk the transfer case screws so the servo can fit flush. The standard winch drum that comes with the sail winch is a bit cumbersome, but this one came with a crawler winch servo that I got a few months back. It's a bit of a fiddle to fit, because the screw won't turn in the splined to part so half the drum wants to spin around, which is awkward because I had to leave just the right amount of thread left for the tail lift, moan moan etc etc, but I got there in the end. After that I turned my attention to the Banggood transmission. After double-checking that it does indeed turn the opposite way, I lined it up for the cutting of an all-new mounting plate. Share this post Link to post Share on other sites
Mad Ax 9325 Posted December 21, 2021 The China transmission doesn't have a mounting support on the motor plate end, so I was able to make the mounting plate a bit smaller and not feel guilty about it. Finally with the body on, for show. Not too bad for a day's work. 1 Share this post Link to post Share on other sites
Mad Ax 9325 Posted December 21, 2021 I was back in the workshop again on Sunday with these cheap propshafts. They came in the same Banggood order with the transmission. It looks to me like it would be painfully simple to make these things myself if only I could find out where to buy some alu tube with a hex shape in the middle. The best bit about these cheap sliders is how easy they are to shorten - a hacksaw at either end and they're done. The angle here is quite steep but everything fits well enough. Then I had to get busy grinding in a new hole for the propshaft in the body mounting plate. The previous hole was on the wrong side, and as I'd already countersunk the holes for the tranfer case screws, I couldn't just flip it over. This FR4 sheet is a bit nasty when using power tools, especially a Dremel sanding drum attachment - the dust is very fine and irritates the lungs and sinuses. A proper fitted mask with a filter is essential, and I used the squeezy bottle with soapy water to damp down the dust while I was grinding. 1 Share this post Link to post Share on other sites
Mad Ax 9325 Posted December 21, 2021 After that I laid out a mockup of how the electrics might go. There's less space than I expected under the cab, so I thought the little 3S would be perfect, but I'm not sure what power I'll run yet. I don't think it needs a lot of power, it's not a proper crawler, so 2S should be fine, although it will need some torque if it's going to pull a touring car on the back. For a steering servo, I'd used the same Alturn high-torque servo that overheated on my at the Southern Scale Trail earlier this year. The servo stopped working about 30 minutes into the first course, it was drawing enough current to brown out the receiver and it got so hot I burned my hand on the casing. I thought maybe the gears had jammed inside, like the end-stop had been forced past its stop point and it was stalling as it tried to turn back, but the gears all turned just fine. When I hooked it up to the receiver on Sunday, sure enough, it browned it out and jammed solid until the power was removed. So, internal problem, then. I opened it up, still expecting to find some kind of gear problem, but instead found this - a burned chip under the pot. It's completely marmolised the PCB under the chip, so there's no fixing this, sadly. I can buy replacement Alturn gears but I don't think I can get a replacement board. So I threw it back in the junk pile and temporarily installed a metal geared New Power that I randomly got from a local hobby shop a while back. I don't know what the specs are but I doubt it's very good. It'll do for now, thought. Maybe it won't need much steering power? Who knows, it probably wants more steering lock before it wants more steering power. At this point I was starting to run out of things to do, but I did have these little badboys arrive from Amazon (amazingly, a pack of 20 of them delivered nextday on Prime for £10.49). I was going to use my ubiquitous 4mm ID alu tube to make spacers, but the tube is too fat and pressed on the bearings, stalling the pulleys. So I just used regular nuts to hold the pulleys in the right place. 3mm ID in the bearing means they fit nicely over M3 screws. Share this post Link to post Share on other sites
Mad Ax 9325 Posted December 21, 2021 Finally, I turned my attention to the body. I'd somehow managed to fit it too far back and too low down I added an extra strip of plasticard at the back of the body to lift it where it sits on the chassis rails, and cut a strip off the back of the floor panel so the body would sit closer to the front. The pen marks on the chassis rails note where I had originally marked the rear of the body to go. New fitment is much better Glued on some box section. This rests on the FR4 floor panel to set the body height. I still need to work out a neat way of securing it. It now looks pretty mean, I think. It could go lower if I cut the arches - I still haven't decided what to do with the arch, as the other side is missing the front part entirely - but it kinda looks right sitting on top of the chassis rails, like it's had a big lift kit installed. 1 Share this post Link to post Share on other sites
Mad Ax 9325 Posted December 21, 2021 So, there we go. Still a lot of work to do, but it feels like it's starting to come together at last. My gears arrived for the transfer case yesterday, so it should be a fairly quick job to get those fitted, and then I'll actually have a roller. I'll be able to throw a battery in it and take it for a spin around the garden. Unfortunately, there's still a bit of money to spend. That's the problem with these cheap, easy projects - they might be budget builds most of the way, but they still need motors, servos, speedos and all the rest. I have to make some decisions. Ideally I want a proper drag brake and easy forward-reverse running. A perfect candidate for the 1080, then. But it feels like overkill, and it's not cheap. The 1060 is a more realistic proposition but doesn't have the drag brake. Plus I'm not sure if any of my 2S packs will actually fit under the cab, so it might have to be 3S regardless. I want a bit of torque, and I don't want high speeds. At the moment there's a Torque Tuned motor fitted, but that's probably too fast. I really want a 55T motor in their to bring the speed down, especially if I do go 3S. There's a lot of cheap 55Ts on the market but it all adds up. I don't know if the steering servo will be up to the job but I don't have much else. I guess I'll try it with the New Power and replace it if it's no good. Maybe it'll be fine. The sail winch servo isn't working. These are actually really annoying things. They have a 360 degree rotation, but they don't have an unlimited rotation. They'll make several full turns either way. Sadly, that's not enough to get the tail lift all the way up or down, and of course any time I let go of the stick, the servo returns to the centre anyway (full trim and full subtrim don't help here). So my options are to buy a winch controller (not too expensive, but slow delivery from China and in my experience, not too reliable) and use the broken Alturn servo (you don't need the board if you fit a winch controller, just the servo with gears and motor installed), or just buy a winch servo, which is basically a 360 degree servo with the winch controller neatly packaged inside it. A local company sells them for just £20, but they're out of stock right now. Also I still need to find some front wheels. Fingers crossed there's some space in the January budget for all this 1 Share this post Link to post Share on other sites
Mad Ax 9325 Posted December 30, 2021 Another quick update from today - will try not to make this one too long because it was a "first run, first problem" kind of day today and I could easily go off into a "how I will rebuilt this truck entirely from the ground up" if I'm not careful. Anyway - the day began with some RW Racing pinions, 15T and 17T to give a bit of reduction from the China Transmission to the axles. This is the transfer case from Mad Inventor, opened up and spread out with the new pinions. The bronze bushes came with the transfer case but I fitted ball bearings instead. Pinions installed, supplied spacers pushed into place Installed in the case don't panic - I took this photo with dry gears, but I pulled them out to give them a light dab of grease before reinstalling. Share this post Link to post Share on other sites
Mad Ax 9325 Posted December 30, 2021 With grease added, the gears turn smoothly when the cover isn't fitted but they bind with the cover installed. My guess is the 15/17 ratio is just a bit too close. I'm tempted to grab a pair of 16s to see if they are smoother. The gears will actually turn OK most of the time, but they want to bind when the grubs are facing each other. This probably suggests the gears are actually twisting very slightly on the shaft when the grubs are tightened down, so the gears are turning eccentrically and when both grubs face each other the mesh becomes too tight. I tried turning the pinions so I'm not torquing down onto the flat, which did make a marginal difference, but it's not perfect. I also tried installing with the grubs only finger-tight, but although this was better, they came loose on the first test run. Perhaps I could try drilling into the flat and installing a grub pin, so there isn't a twisting effect on the pinion. I tried flipping the shafts so the gears are at the other end (in case there's a tiny inconsistency in the bearing spacing on the cover) but I have the same issue. I'll pull it apart again some other time because it's possible I've missed a fundamental thing and there's a really obvious reason why it isn't happy. Anyway, a pair of 16T pinions might be a better mesh (pretty sure this was how the box was used before I got it). Moving on - I hooked it all up to the output shaft from the China Transmission and gave it a try. Despite being tight, it turns easily enough. With enough bed-in time it will probably loosen up anyway, although that's not an ideal way to treat a binding gearbox. When I ran at higher speeds I noticed an infrequent loud chirping coming from somewhere, which I thought might be the transfer case binding, but when I disconnected the propshaft it still did it, so it must be either in the motor or the China transmission. I think the transmission needs to come apart for an internal check. Even the torque tuned - which to my knowledge has never been run - wasn't happy. It was quite buzzy and arced a fair bit, despite running in the right direction. In the end I popped it in a glass of water to bed the brushes in, but I'm not sure it made much difference. I then hooked up all the propshafts to give it a full test. So those expensive RC4WD wheels don't sit flat on the Tamiya splined hexes (not sure if it's the hex flange on the back of the wheel, or the hex itself, or the big rig axles) and they float around all over the place. The tyres don't sit level either, which I think is predictable given the nature of the wheel. The end result is it kind of looks like a comedy cartoon car with the wheels waving around all over the place and catching on each other because there isn't enough clearance between the rear wheels. With the truck on the ground, it sort of covers ground at a reasonable pace, but doesn't go around corners. The steering lock on the TLT axle is abysmal. I think I modified the TLT axle on my tipper truck build, so I'll dig that out and check what I did. Pretty sure I did some drastic grinding to the drive cup to allow it to turn more without grabbing the axle shaft. All in all, not an entirely successful morning and one that made me decide to push it all out of the way and do something else for a bit - I've been working non-stop on this car for a few weeks now and I'm a bit fed up with it. I'm seriously considering abandoning the comedy RC4WD wheels and going back to conventional duallies on the back. I've found some Lesu off road tyres for £9.99 per pair, that's around £50 plus postage to do the entire truck. Probably need to buy a new rear wheel set as I doubt I have enough to fit on the front. The money spend on the bargain Amazon tyres won't be wasted - my CC01 Hop-Up vs Homebrew rigs are desperate for a softer control tyre. Also need to decide what ESC to fit and buy a winch servo. This is probably the most expensive parts-bin project I've ever done 1 Share this post Link to post Share on other sites
Mad Ax 9325 Posted January 11, 2022 I came back to this again after the last embarrassing effort to make sense of it, with the idea that I might try some different wheels. First I took a picture of it as it stands, with the cheap Amazon tyres fitted on the comedy RC4WD wheels. Then, out of interest, I put on the BFGs I'd just pulled off the Budget Bruiser. Obviously the rear wheels are no good on the big rig axles, but the tyre diameter looks good. Not that it matters, I tried to get those BFGs on the 1.9 wheels before and they weren't having any of it. After that, I went up into the storage area and spent 30 minutes digging my way to the very back where my wheel stash is. I came down with all this. I've already tried most of wheels before, but I read on the internet that the definition of sanity is trying the same stuff over and over again and expecting different results, so I though it was worth a go. 1 Share this post Link to post Share on other sites
Mad Ax 9325 Posted January 11, 2022 The first thing I tried - which I foolishly thought might work well - was TLT wheels. They don't actually look too bad, but they really need a wider hex to push them out - not least because I can't get the shocks on. I tried a touring wheel with an RC4WD tyre to bring the front end in. The Lobster Effect of the narrow rear axles and wide front just looks silly. It didn't really work. It still looks silly. After that I went back to where my head was last time, and fitted some big rig wheels. Now these don't actually look bad either, although I would have to cut the chassis rails and lower the transmission so I can get the body down, because right now it looks like some gangsta's Dodge Ram. I even took off my wider centre brackets which I made to space the RC4WD wheels apart to get a more conventional look to the wheels, but in the end I just wasn't happy with it - I still can't get the shocks on behind the truck wheels. So - in the end, there was nothing for it. I put the RC4WD wheels back on. They're on now, it looks OK. Ideally it needs the rear axle moving back about 10mm, but I don't know how I can do what and still use the leaf springs, and I don't have the space (or, if I'm honest, the inclination) to convert to a 4-link setup. I'm going to have to re-engage my thinking brain... 1 Share this post Link to post Share on other sites
Mad Ax 9325 Posted April 20, 2022 This truck has been sitting on one bench or another since January, while I focussed on the KBF Pro-mod and my Iconic Cup car, and a few other little things besides. I finally figured it was time to come back around to it and try again to make it work. Here's how it looks right now: And here's that painfully-close wheel gap, which closes up when the comedy wheels spin because nothing is perfectly circular in the world of foam-padded RC tyres. And here's the leaf spring mounted on top of the axle. Now, how can we move the axle..? Share this post Link to post Share on other sites
Mad Ax 9325 Posted April 20, 2022 Here's the first thing I made. Actually it's the second thing I made, but it's the first thing I remember to take a picture of. Can you tell what it is yet? Share this post Link to post Share on other sites
Mad Ax 9325 Posted April 20, 2022 That's right, it's an extended hanger for the lower axle links. This moves the middle axle forward about 12mm. You can see my extensions that move the top of the axle forward by the same amount. better pic, with the chassis the right way up. these extensions are made from 3mm aluminium sheet, hopefully strong enough to hold the weight of the truck and payload without bending. 3mm spacers cut to lift the rear axle spring mount by the same amount, so the springs are still level Share this post Link to post Share on other sites
Mad Ax 9325 Posted April 20, 2022 There - that's a much more sensible tyre gap There! I was deliberately going for a compact, stubby look on this truck, so I moved the middle axle forward instead of the rear one backward. I think the length and axle spacing is spot on now, although it looks a bit goofy with the body so high. I think I need to investigate that and lower it down by 10mm or more. There's not much articulation at the front and the arches are already badly battered, so I can cut them out if I need to. I'll have to modify the front axle to get enough steering lock - the TLT axle is notoriously bad. The drawback of all this is that the propshaft angle is now too steep, but that's OK, as I can lower the transfer box when I lower the body. 2 Share this post Link to post Share on other sites
Mad Ax 9325 Posted April 24, 2022 I finished work a bit early on Thursday, and my daughter was away at the parents, so I had no responsibilities for the night. Actually that's not true, I had lots of responsibilities, just none of them involved the welfare of another human being, so I ignored them and played with silly toy trucks instead. My usual thing when I start working on something is to take a picture of the current state. Which is this: The main problem from the previous weekend was the angle of attack for the rear prop was too steep, so I had to relocate the transfer box. Also the floor is too high, and/or the body mounts are too high. The transfer box and floor are mounted using the same screws. The body is located using some strips of styrene box section. And the transfer box is suspended underneath the chassis. At this point my wife got home and managed to convince me that my responsibility to fill my belly with marinated chicken in wholemeal pitta bread was more important than playing with silly toy trucks, so I left it all in pieces and went inside. While munching on toasted wholemeal, I mulled over my options. 1) Put some spacers between transfer box and floor to move the box down so the prop angle is acceptable. However, this puts the angle on the propshaft from gearbox to propshaft at too steep an angle, so I'd have to relocate the gearbox, and the gearbox is wider than the chassis rails, so I'd have to get super-creative. Also I can't lower the body without lowering the gearbox, because the spur gear is touching on the hood. 2) Make new suspension mounts to lift the axles up, thereby lowering the entire chassis. I figured this was best done with some more aluminium L-section, but I couldn't get any at the local hardware store, nor find any online that would be delivered in a reasonable timeframe. 3) Abandon the straight rail chassis and make a more conventional chassis with a lowered mid-section. This doesn't solve the gearbox problem. 4) Eat chicken and drink beer until a better idea happens. I chose 4. I better idea came to me. It was this: stop playing with silly toy trucks and go to bed. 1 1 Share this post Link to post Share on other sites
Mad Ax 9325 Posted April 24, 2022 Sunday morning dawned dry and bright, and I was out of bed early and itching to get building something. After fixing the paint job on the MTX-1 (updates to follow in the MTX-1 thread), I turned my attention to the tow truck. I was only really going to have a quick look at it, then do something else, but I had an idea: I could make all new suspension hangers to lift the axles a little, thus lowering the gearbox and body at the same time, without having to find some new angle section. First thing I did was pull off the left chassis rail to use as a template. Using a ruler, drill press, and my evolved primate brain, I was able to transfer all the necessary holes onto a sheet of aluminium in a way that would allow me to refit the axles with a 13mm drop, although my primate brain is not quite as evolved as I had first thought because I had my new rear extension brackets around the wrong way, so instead of moving the middle axle forwards by 12mm (as per last week's update), I moved the rear one back by 12mm. I didn't realise this until I came to test-fit everything after doing all the cutting and filing. New plate, ready for filing. Two plate, both as wrong as each other. Of course, every problem has a solution. This problem had one obvious solution, which was to start again, and also an easy solution, which was to move my extension plates from the middle axle to the rear axle and sacrifice a little bit of stubbage for not having to make my suspension plates all over again. Here's the new plate, test-fitted. 1 Share this post Link to post Share on other sites
Mad Ax 9325 Posted April 24, 2022 I had to cut into the plates / chassis rails to allow the axle to articulate, but the plate adds a lot of rigidity so that's OK. A bit of extra screwing lower down on the plate should stop the chassis rails from bending - screw holes were made after this photo was taken (I also had to file out a bit more to allow for the swing on the links): This view from the rear shows how the plates bolt onto the chassis rails Rough mock-up of one chassis rail, wheels, floor and body in place You've heard of a half-track. Well, this is a half-truck. 1 Share this post Link to post Share on other sites
Mad Ax 9325 Posted April 24, 2022 After that it was time to add some more screw holes, clean up the edges, then spend 20 minutes in front of the bench polisher filling up the crevices between my fingerprints with aluminium dust and synthetic wax Chassis reassembled. If only it was as quick to assemble this chassis as it was to paste the photo - these photos were taken 50 minutes apart! Still a half-truck, but this time it's a different half 3 Share this post Link to post Share on other sites
Mad Ax 9325 Posted April 24, 2022 So - there you have it! The rear axles have been lifted by 13mm, so the body and transfer box sit lower and the propshafts can now be connected. Next plan: lift the front axle by 11-12mm by making similar brackets, then finalise the body mount solution and make the final trims to the arches, if necessary. 3 Share this post Link to post Share on other sites
87lc2 2666 Posted April 25, 2022 This is looking great! Fantastic custom work. 1 1 Share this post Link to post Share on other sites
Mad Ax 9325 Posted May 1, 2022 Got a bit more done today. After re-hanging the rear suspension last weekend, it was time to re-hang the front. I started by putting a spirit level on the chassis (on the probably incorrect assumption that the plate is actually level to the chassis rails, which I can't get at) and spacing up the front with random things until I had it level. Then I sort of squinted at it a bit and held a ruler in the rough general direction to work out kinda maybe where the front axle would have to go. This is kind of the same technique I use to estimate software development time at work, which has led to me being promoted to a position where I no longer have to do estimates, so I must be doing something right. "About there" is the estimate I came up with. But not really there, because the axle moved before I could take the picture. I made a thing with holes in Then I screwed the thing with holes in onto the chassis rails, and screwed the leaf springs to the thing with holes in. Good job it's got all those holes in it, really. Share this post Link to post Share on other sites