Wheely King Crawler Conversion

[Webbage]

I'm trying to plan a Wheely King crawler conversion. I'm a bit bamboozled by all the trick parts available from the US and don't want to make any mistakes as I'm in the UK and importing the stuff is time consuming.

My Plan so far is to take the WK from stock using these parts:

TRA4928X - Traxxas Output Yokes (EMX,TMX.15,2.5,3.3)
TRA4951X - Traxxas Heavy-Duty Drive Shaft (EMX, TMX, TMX2.5)

ST85252B - ST Racing Concepts Aluminum Hub Carrier (Blue) (Wheely King)
ST85256S - ST Racing Concepts Aluminum Front & Rear Shock Towers (Silver) (Wheely King)
ST85257B - ST Racing Concepts Complete Aluminum Steering Linkage Upgrade Kit (Blue) (Wheely King)
ST85264CB - ST Racing Concepts Extended Wheelbase Rock Crawling Kit (Blue) (Wheely King)

AXI30500 - Axial Heavy Duty Differential Locker

I am also looking at:

Novak Rooster Crawler ESC
Novak Fifty-Five 55T motor

But I have to get these in the UK (more pricey but I keep my UK warranty )

That ought to get me started I'm thinking. But there are some niggling things that worry me about the setup...

I want to axle-mount the steering servo, to remove the flex in the steering system, and also to allow me to easily flip the setup around so the battery is at the front. If I get a multi-channel radio set I may even convert it to 4-wheel steering . I looked at this This Steering Kit from Mico/rcguy and it looks like the ideal solution, but I have a question. It says you need to turn the shock/link mounts through 90-degrees.

I found that plate on, HERE, has the shocks mounted weird on the stock axle mounts. Wouldn't that strain the mounts in funny directions?

I'm unlikely to compete with this truck (I'm learning the ins and outs on this beast atm, then I'll purpose build one if I want to get serious).

Is there anything else you guys would suggest for add-ons or mods?

 

[CharliesTheMan]

HPI just released their own servo mounts for the wheely king. https://www.rcnitrotalk.com/forum/showthread.php?t=59009

 

[Webbage]

As far as I could see that's the parts from the Rock Crawler kit that turns the servo round in the central housing, allowing you to steer the opposite axle using the steering links, meaning that the car is effectively rotated around the other way. The problem with using that system is that you still have all the 'give' in the steering arms, and also the steering is less efficient.

Axle mounting the servo seems to be the way 99% of people go with crawlers to give the servo maximum leverage against the steering. apparently once you start using grippy tires and diff-lockers it becomes an issue.

Thanks for the pointer though

EDIT: I just got a mail from RCGuy at Mico engineering and he's been incredibly helpful. He pointed to the same article (at rccarreviews) and explained how the shocks and links are fitted, and how the whole thing is setup, and also put my mind at rest re: the mounts. Apparently you don't have to skim the aligning ridges off the axle

Also that article uses Traxxas and Tamiya spares (I really should learnt o READ these things!) that I can source in the UK so I can do it without ordering too much from overseas!

I still need some other replacement alloy parts for it though as I am not 100% confident that the plastic bits will stand the rigors of time.

 

[Webbage]

Thought I'd update you guys on the progress of my new baby.

I've got a 4-link rig mounted to the chassis, in the end I went for using Traxxas links, 5139 (116mm) for the lower links and 5138 (106mm) for the uppers.

The 'Gearbox' end of the chassis. I couldn't put a through-rod right through the chassis for the upper links here, which was kind of annoying. I'm a bit worried the individually attached top links will twist the plastic chassis.

The 'Motor' end of the chassis. I put a through-rod right through both the upper and lower links here. I suppose 3 out of the 4 wasn't too bad, it's certainly allowed the chassis to retain, and probably better, the stiffness it had with the original plastic parts.


I also bought a set of long Traxxas props off the T/E-Maxx.

The props have been an interesting prospect, as I can't get hold of any Traxxas end Yokes at the moment (the splined parts that fit to the diff/transmission shafts). I've discovered with a bit of encouragement by a 3mm drill bit you can drill the HPI ones out slightly over 3mm so that they fit and work with the Traxxas UJs.

The props went back on just fine and work pretty well in spite of my 'modifications' to the HPI yokes. The oil is Tamiya shock oil, that I was using to aid the assembly a bit, Traxxas prop UJs are a real PIG to get into the shaft yokes.

I've currently got on the way a set of diff-lockers and 2 Axle servo mounting plates from RCGuy (Mico Engineering) in Canada.

To Fit the RCGuy Servo plates, you are required to turn the link/shock mounts through 90-degrees (so that the bottom 2-poisition mount is facing 'inwards' rather than 'down'). This works pretty well, but you have to mount the shocks up a bit funny (sort of 'inside' the inner side of the axle mount) and I'm a bit worried about straining the axle mount the wrong way. I'll see what I can do with that and maybe make a custom shock mount for it.

I'm also waiting for some Alli metal stock to turn up from Folkstone Engineering Supplies. I intend to make a rail for each side to fit along between the top shock mounts to allow me to have the shocks mounted diagonally backwards as they are on the AX10 (this helps a lot with articulation apparently). It will have multiple holes for each shock, so I can play about with different angles to see what gives the best combination of the shocks working and the suspension being flexible. It will also facilitate me mounting linger shocks in future.

Does anyone know where I can get HPI's recommended 15 Tooth pinion gear and 96 Tooth Spur gear from to gear this puppy down? I had a look a while ago but they were out of stock everywhere I looked.

I'm planning on getting some ProLine Moab or Masher 2000s for the rig. I want to fit some Beadlock wheels, but I'm totally bamboozled as to what wheels will fit and what will keep the wheelbase legal. I'm not planning on comp-ing with it but there's no harm in getting it right, I may want to upgrade it later

 

[CharliesTheMan]

I hope you've done away with the stock motor and gone to a 55 turn lathe motor. It's only $20, and will take it from a basher to a crawler and give much more precise throttle control, as well as A LOT more torque.

You need to go with a 2.2 inch wheel. As long as it's not an amazingly terrible offset I would think that you should be ok. Smaxxin is running axial beadlocks on one set of his tires and they're working good for him. I have some axial beadlock wheels and axial rock lizard tires for sale if you're interested. The tires and foams have never been out of the package, the wheels have been used twice. Everything is in great shape.

It's looking great though, glad to have you here on the forum with us.

 

[Webbage]

I hope you've done away with the stock motor and gone to a 55 turn lathe motor. It's only $20, and will take it from a basher to a crawler and give much more precise throttle control, as well as A LOT more torque.

It's in the plan, I just wanted to get the chassis and suspension worked out before I got into the electronics. I eventually plan to fit a Novak Fifty-Five and a Rooster Crawler ESC to it to give her the legs. I'm also gonna get a Futaba 4EX radio set so I have 4 channels to go at. I plan on 4-wheel steering, using a servo on each axle.

You need to go with a 2.2 inch wheel. As long as it's not an amazingly terrible offset I would think that you should be ok. Smaxxin is running axial beadlocks on one set of his tires and they're working good for him.

I'm just a bit confused by all the different offsets and hex fitting and stuff. I think the standard WK uses a 12mm hex, and they supply 14mm ones with it as spares. 2.2 wheels also seem to come in different widths. It's all so confusing! :\ :surrender

A set of plastic beadlock wheels will probably do for a start, but ideally I'd like to get a set of billet aluminium ones, they look shiny and are a lot more robust.

I have some axial beadlock wheels and axial rock lizard tires for sale if you're interested. The tires and foams have never been out of the package, the wheels have been used twice. Everything is in great shape.

Generous offer but it's a long way to catch the bus I'll pick some up at the UKRCRC Nationals if I can, hopefully there ought to be a couple of trade stands there. If not, I'll grab some from Modelsport or somewhere like that.

It's looking great though, glad to have you here on the forum with us.

Good to be aboard

 

[CharliesTheMan]

Visionary Fabrication has some aluminum beadlocks that are narrow and in the wheely king offset. I have a set of MDS aluminum beadlocks. The MSD baedlocks that I have are offset, and they make the track width just a lil bit wider. Basically, crawler wheels are narrow for a few reasons. One is that is makes the track width more narrow, which is good when you're running in comps because it makes it easier to get through the gates. You're not allowed to touch the gates, so as you can imagine, the narrow trucks have more room to work with. Another reason is that a narrow wheel wraps the tire in more, which brings some of the tread down to the sidewall, giving the tire much more sidewall bite.

Now about the rear steer. I see with everything else, you've set the truck up so that if you want to enter competition later, you can. I think that's a great idea. I had absolutely no intention on getting competitive, but when I discovered how much I enjoy crawling, it was only natural for me to want to attend gatherings in other places and crawl with a bunch of friends, which is what comps are for. So, if you're going to be thinking about entering comps later, I wouldn't do the rear steer. There's another mod that you can do that will be comp legal and I think will give you much more advantage than rear steer.

That mod is rear dig. With rear dig, you can lock the rear wheels and pull with the front wheels, which drastically reduces your turning radius. Locking the rear dig also allows your truck to climb vertical obstacles that would cause the same truck without dig to flip over backwards. With the dig on, it allows the front wheels to climb vertically and loads the suspension so that it pulls the rear end up the vertical wall, and then pulls the truck over the ledge. Rear dig has three modes that you change with the transmitter, that is rear dig (mentioned above), rear freewheel, where the front tires pull and the rear tires roll freely but aren't driven by the tranny, and regular mode, which is just normal 4 WD. Thr VF Dig is one of the best there is for an axial tranny, but I know companies make them for the wheely king setup as well.

VF Wheels http://www.visionaryfabrication.com/sales/index.htm

VF Dig Example Video

I have a set of MSD beadlocks (billet aluminum), and they are absolutely beautiful, but they're in high demand and it's hard to get them sometimes. I'll send you a PM with information on a great place to buy crawler parts though.

I think the Mayhem Engineering has some of the prettiest wheels out on the market today, and the price is amazing considering the work that goes into them. Here's a special page on the wheely king wheels that they sell. Something else, when you buy from a good company like that which really takes care of the customers, as opposed to some of these big companies that just put out parts as cheap as the can and have no customer service, you can talk to them about the right wheel for your application and things like that.
http://www.rccrawler.com/forum/showthread.php?t=120696

 

[Webbage]

Now about the rear steer. I see with everything else, you've set the truck up so that if you want to enter competition later, you can. I think that's a great idea. I had absolutely no intention on getting competitive, but when I discovered how much I enjoy crawling, it was only natural for me to want to attend gatherings in other places and crawl with a bunch of friends, which is what comps are for. So, if you're going to be thinking about entering comps later, I wouldn't do the rear steer. There's another mod that you can do that will be comp legal and I think will give you much more advantage than rear steer.

Good advice, but the great thing about the Wheely King is rear steering is easy to do AND UNDO. I can always swap it out and fit rear lock-out shafts for a comp if I need to. It'll take all of 10 mins to do now I know how the axles come apart.

I just always wanted a truck with 4-wheel steering, I used to lust after the Clod Buster when I was a kid It's all in the name of science, and as I said, it's far from a one-way road, I can always undo it easily, I do my mods that way.

It's a pipe-dream at the moment anyway as I need a 4-channel radio to use it, and one with channel mixing to pull it off really well, so I'm gonna fit the plate for the servo and fit lockouts on the back for now.

That mod is rear dig. With rear dig, you can lock the rear wheels and pull with the front wheels, which drastically reduces your turning radius. Locking the rear dig also allows your truck to climb vertical obstacles that would cause the same truck without dig to flip over backwards. With the dig on, it allows the front wheels to climb vertically and loads the suspension so that it pulls the rear end up the vertical wall, and then pulls the truck over the ledge. Rear dig has three modes that you change with the transmitter, that is rear dig (mentioned above), rear freewheel, where the front tires pull and the rear tires roll freely but aren't driven by the tranny, and regular mode, which is just normal 4 WD. Thr VF Dig is one of the best there is for an axial tranny, but I know companies make them for the wheely king setup as well.

A dig is certainly a handy thin to have and I'd like to fit one in the long run, but a quick search turns up nothing I can buy to do the job as yet. VF asked if anyone would be interested, but they as yet have turned up nothing for sale. I know they are only a small shop so it's probably taking a while. I don't currently fancy the idea of making my own.

I think the Mayhem Engineering has some of the prettiest wheels out on the market today, and the price is amazing considering the work that goes into them. Here's a special page on the wheely king wheels that they sell.

Those are a work of art. I gotta have a set... but maybe later. I'll sort some good tires and cheapo wheels out first to get myself started, then consider upgrading later when the cash surfaces.

 

[CharliesTheMan]

what's your wheelbase now?

 

[Webbage]

I dunno yet, I haven't got the axles built up and re-attached yet. My RCGuy.com lockers turned up today (totally stunned, 2 working days to ship from Canada to the UK), so my Axles are off the rig, one is rebuilt and the other is waiting to be stripped and built up again.

The guide I followed states it's under 12.5" (2.2 max wheelbase) and over 12".

I presume you mean from wheel-centre to wheel centre? I'll have a measure when I get my other axle rebuilt with the lockers in and hitched up to the chassis.

Something else I really and strongly considering is plating the sides of the chassis with aluminium plates, or buying aluminium billet side plates from a US maker. The plastic starts to look way too flimsy when you start taking out the parts that stiffen it, like the battery box, and the 'front' servo tray.

That brings me to another interesting point. I'm sticking to stick packs (har, har) at the moment, where's the best place to mount them? I've seen some rigs with them slung under the chassis, some with them on the sides, and some even with them tied to the top links!

 

[CharliesTheMan]

I think the top links is probably one of the best choices. If you have any stick packs from a 1/18 mini, that uses 2/3 A size batteries, they will give you the same power yet they will be a lot smaller. Basically, you want them down close to the axles. With a crawler, it's all about low COG. If you look at crawlers from two years ago they were jacked up for ground clearance, and if you look at them today they're slung very low with droop suspension, etc... That's because the lower the COG, the better it will crawl. I have all of my electronics mounted on the top links to bring the weight lower on my axial. The worst thing that you can do is mount the battery up high on the chassis.

You can buy a performance chassis for the wheely king for 50 bucks or less, and that would solve a lot of your problems. You could also make it out of a delrin type material. Smaxxin has a wheely king and that thing is DIALED. I was amazed at it when he brought it to my house, that's how I was bitten by the crawler bug. He used a cutting board like women use to cut fabric on for his chassis. It's plenty strong and lightweight, and it worked out great for him. He did it as a temporary mock up and it came out so strong and worked so good, he decided not to use the aluminum that he originally planned to use.

 

[Webbage]

First test build was completed today and I can say it was a moderate success. The articulation is good, but with the shocks in stock position (vertical) it leaves about an inch of travel it can't use. I'll fix that when I build the shock mount rails for it. in the mean time here's some pics!

I put the shocks on with no springs to see what they acted like, I notice some people run springs and some don't. I found the ride height was too low, and it beached in the middle easily. The long wheelbase means it's pretty easy to leave it high and dry on the middle of the chassis.

The motor and ESC are totally wrong for this kind of work too, but I knew that. They'll get pulled eventually in favour of Novak crawler gear.

,

I'll post some detail pictures of the suspension when it's on its second fit, as it's not looking especially photogenic at the moment

 

[CharliesTheMan]

Too much articulation can be a very bad thing. Most guys with axials are having to limit their artuclutation, so you might be ok where you are. Droop shocks have to be setup in a certain way, and if you wanted to run droop I would suggest trying 60 weight oil with an internal spring above and below the piston in the shock. This would give you a semi droop and still leave you with some ground clearance. You need to address that battery issue before anything else, that's going to be the main thing that will hold you back from having the crawler as capable as you want it.

It's looking great though, and you're building it yourself, that's what is really important.

 

[Webbage]

Too much articulation can be a very bad thing. Most guys with axials are having to limit their artuclutation, so you might be ok where you are.

Interesting. From some of the pictures on RCCrawlers.com you'd think that the amount of articulation was a 'size of my thingy' ideal. I can see how twisting the chassis too much would put a lot of stress on it, it also would mess up your centre of gravity on the stock chassis as you'd end up hanging the body out too far from the axles.

Droop shocks have to be setup in a certain way, and if you wanted to run droop I would suggest trying 60 weight oil with an internal spring above and below the piston in the shock. This would give you a semi droop and still leave you with some ground clearance.

Right then, I'll try setting mine up with the stock shocks and springs set off at an angle and see where I get to. That's the next project after I've rebuilt this phase with properly trimmed up screws and nylocs.

You need to address that battery issue before anything else, that's going to be the main thing that will hold you back from having the crawler as capable as you want it.

Slung it up there out of the way for testing purposes. Just wanted to see how well the suspension worked to start with.

Trouble is I still haven't worked out where the hell to put it :\

I had clearance issues putting it above the front top links, because there's a couple of cross-braces above there.

I suppose I could swing the whole thing round, there's a cavity above the rear axle atm where the battery box was. But then I'd have to reverse the motor wires from the ESC or I'll have a forward drag brake, which isn't too helpful! Is this no problem?

It's looking great though, and you're building it yourself, that's what is really important.

It's great fun man, it's made me think hard, swear hard and dig out tools I haven't used for an age. my Dad's been really good, he used to teach metal and wood work so he's pretty handy, which is good because I'm a putz sometimes I had to make the connecting part from the axle top to the top links myself, and it took quite a bit of plying to get it right. I had to pop the ball joints out and replace them with some nylon bushing to take some of the flex out of it as it was a bit TOO flexible

 

[Webbage]

Got my better top link mounting pieces made up tonight (as seen in bottom pic), and mounted on the truck axles. Decided to go all out for a second test build to see what the effect of adding the springs and more rigid top links had. I also played with re-siting the battery as well as turning the chassis around the other way. (I plugged the motor in backwards - seems to work okay ).

For the moment the suspension is sorted, just needs rebuilding with proper screws and nyloc nuts. I'm concentrating on re-siting the electronics and battery better now. Any suggestions anyone?

Yay for more Pictures!

 

[CharliesTheMan]

When you do flex shots to measure articulation, instead of twisting the chassis sideways, leave the chassis vertical, and see how much flex you get with the suspension. That would help us get a better feel of your rig, and help me be able to offer better advice. It's hard to tell now, as it looks like your axle is almost parallel to the chassis, and the chassis is what's twisted up.

 

[Webbage]

Grr now he tells me, it's dark out

I had to set it up on the bed in my room, and the tyres are all covered in crud. I'm gonna be picking the blades of grass out of the bed for days after this

Aaaanyway. The chassis isn't quite vertical, because I lost one of the preload collars for the springs so one of the rear springs is missing the collar. I doubt the links are perfectly centered up either, all that's stuff I've gotta tune up when I do the final first build.

 

[Webbage]

I solved the ground clearance issue by moving the shocks to the holes in the end of the chassis. It's lifted the whole trucks by about a half inch and it'll romp over anything now. Trouble is it's a little top heavy because the main body/chassis is sat a ways up above the wheels. I found an effective way of mounting he battery on the axle top links (which will ultimately need a plate making up that fits on the top mount) and I have also mounted the electronics down inside the chassis over the front axle. There's very little actual weight up top but the sheer height still seems to make i unsteady, probably the transmission is what's screwing it up :\

In short, the suspension geometry is spot on now but the ride height is too hight, but if I put the shocks back to stock it gets stuck everywhere that sticks up. Am I looking at having to get/make a comp chassis, and maybe even a custom transmission (easiest way to get a dig, as far as as I can tell) to ultimately get this right? If so I may as well leave this as a rock capable fun truck and start looking at a serious comp beast... maybe?

 

[CharliesTheMan]

I think you're getting to the point where you can decide if you want to spend a lot of money to try and make this into a capable crawler, or spend about half that on an axial and be a lot closer to your goal. If I were you, I would sit down with the WK and think about every part that you need to improve, and write that down in a list. Then look at the price of the axial. If you're still running stock electronics in the WK, don't worry about listing electronics with either one, because they will cost the same and that will save some writing, researching, etc...

Those flex shots are a lot better. I know you probably don't want to hear this, but in the pics (which I think you've moved the shocks since then) it seems to be your shocks that are limiting your suspension travel. I don't know what a lot of the guys with Wheely King crawlers are running, but the Losi Crawler shocks are wonderful, and I bought my whole set for $42. If you find that you can run axial shocks and that will help you out, let me know, I have some extra one that I could help you out with.

As far as ground clearance, what does your belly height measure at? Once again, I haven't done a lot of research on the WK like I have the axial. With the axial, around 2.5 inches seems to be the magic number. Most guys are giving up some ground clearance in favor of low center of gravity. Your chassis is designed with a good bit of weight up high. Is your battery still mounted in the chassis? If it's anywhere above the axles, ever mm that you raise it up is going to throw off your COG even more.

 

[Webbage]

Yeh, the shocks are definitely the limiting factor. The articulation stops when the shocks bottom out. There's probably another half in of travel in the links.

Clearance with the shocks mounted below the stock mounts is way up, like about 3.5 inches approx. With them in the stock place the clearance at the belly about 2.5 inches, but it grounds to easily. As I described before though, with the shocks in the stock mounts it grounds in the middle going over narrow obstacles. Now that MAY be down to lack of fine control because of the stock electronics (which truly suck for crawling) but I feel if you get something stuck under the belly of the beast and it lifts the wheels then you are screwed whatever setup you have!

The critical limiting factors are the upright transmission and the resulting tall chassis design. With everything else slung low on the truck, the height of the motor is kinda crappy.

Right now it'd be great for bashing around and scrabbling over rocks and it's a lot stronger and more capable than the stock WK was out of the box. You're talking sense regarding the situation I'm stuck at now. I have these choices available to my mind:

1. Keep going and turn the WK into a full-on WK crawler. It'll never be ideal but it'll be cool to have. Ultimately though it won't be that satisfactory. TBH I'm pretty much there already save for the electronics package.

2. Use the tranny and axles off the WK to build a special. I have a cool idea for a really simple chassis that would give it the ability and weight distribution necessary to do comp work with.

3. Keep the WK as it is (maybe add a decent ESC/motor) and buy all the parts to build a special from scratch. It's expensive and would take a long time to build up the parts. I'd also have to import nearly all of if from the US which has the potential to cost me a lot of money in import duty if I get pinched by customs.

I'm swaying towards 2 at the moment, but ultimately I'll probably end up doing 3 via 2 and replace bits of the WK with higher spec parts as I go along. How robust are the AX-10s? I looked at one but they look kinda plasticky. I mean the WK is almost all plastic but it's also cheap, the AX-10 isn't so much...