WK to Crawler Conversion… Cheap & Simple!

[themerc64]

Here are a few ideas for a simple low budget crawler conversion for the HPI WK. My plan was to use as much of the original model as possible, including electronics. Also to try to make the conversion without any cutting or drilling, so those without the tools or skills could make this an easy build. I also tried to make sure that all needed parts are readily available from most any RC outlets.
Sorry this is not a step by step narrative, but I think most of you will figure it out from the pictures. I will try to update the details when I get some time. Also search the other WK threads for some more great ideas. Maybe we will get a WK section on the forum with all these good ideas.

To start with... Prices are from Tower Hobbies and can be found for less online

(1) HPI 10820 Wheely King RTR $189.99 I bought two for $360 out the door, locally

First… Making the WK 4WD. Here is the parts list for the 4WD conversion… Prices are from Tower Hobbies and can be found for less online

(1) HPI A431 Diff Case $4.79
(1) HPI A850 Diff Bevel Gear Set $4.79
(1) HPI A855 Diff Final Gear Set $5.79
(1) HPI 6819 Silicone O-Ring P-3 (RED/5pcs) $1.45
(1) HPI 86810 Gear Shaft 5x6x29mm $7.69
(1) HPI 86813 Drive Shaft 6x82 (2pcs) $12.99
(2) 10x15x4 Ball Bearings $0.99ea
(4) 5x11x4 Ball Bearings $0.99ea

Parts Total for this step $37.50

Second… Making the WK a Crawler. Here is the parts list for the Crawler conversion… Prices are from Tower Hobbies and can be found for less online

(2) Traxxas #2680 Screws, 3x25mm RH ST (6) $1.45 x2
(1) Traxxas #4951 Half shafts, long (heavy-duty) (external- splined (2) & Internal-splined (2))/metal u-joints (4) $7.69
(2) Traxxas #4928X Differential output yokes, heavy-duty (2)/set screw yoke pins, M4/10(2) $4.79 x2
(2) Traxxas #5138 Turnbuckles, 106mm (front tie rods) (2) (Includes installed rod ends and hollow ball connectors) $8.59 x2
(2) Traxxas #5139 Turnbuckles, 116mm (rear toe control links) (2) (Includes installed rod ends and hollow ball connectors) $8.59 x2
(1) HPI 6993 Spur Gear 93 Tooth (48 Pitch/Carbon Fiber) $3.89
(2) Tamiya 9804179 Lower Suspension Stay from TLT Kit $2.79
(1) Integy Matrix 55T lathe Motor $18.49

Parts Total for this step $79.70

Grand Total so far, less shipping and taxes $307.19 and RTR too!

Third… Whoops, did I say No Cutting?

I ended up modifying the servo mount so I could swap the servo to the other side of the chassis and keep the stock linkage. Very easy to do, just mirror the stock cutout on the opposite side of the mount and shave down the lugs where the servo attaches to the mount. You need the servo to set back in some so the servo horn will clear the inside of the chassis. A small mod is needed to the servo horn too, so it will clear the chassis. I will get some details up on that soon in case the pictures don’t give you the idea.
I also am still looking for a part number and or source for the lower steering link. It needs to be longer due to the stretched wheelbase. A 3x150mm threaded link will be needed, or just fabricate a link of your own. As you can see in the pics, I have just extended the link on the axle end. This will be changed out before it sees any use.

More to come…

[chip cross]

sweet how does it crawl i got one waiting for parts from lhs to make it a 4x4

[themerc64]

Here are a few more...

[themerc64]

Here are a couple more...

[NickRummy]

Looks good! What did you do for the upper shock mounts? Also it looks like both your upper links and lower links mount to the same spot on the chassis? I like how you flipped the shock/link mounts on the axle. I had mine flipped too but I ended up putting them back and mounting my lower links on the bottom part of the axle. I'm thinking the links being on the bottom might help the truck slide over rocks better. When I had my links mounted to the top of the axle like yours it seemed like it might be easy for the axle to get hung up.

[davcom]

very cool.

[themerc64]

This not being a serious crawler I was not planning on going all out on it. I am looking to make a functional skid plate from something easy to find around the house. Nothing is set in stone yet, so the link positions could change. The lower links were to be mounted lower on the chassis, but the links bound up really badly. The axle link mounts could be used differently as seen in some of the other WK threads. This is still a work in progress and updates will be posted. Thanks for the comments guys...

[cotharyus]

What is the bracket you are using to attach the top links to the axle? I struggled with this quite a bit, and settled on something that I'm not entirely happy with because I couldn't find any think channel material to fab something with laying around.

[NickRummy]

What is the bracket you are using to attach the top links to the axle? I struggled with this quite a bit, and settled on something that I'm not entirely happy with because I couldn't find any think channel material to fab something with laying around.

http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXGKG9&P=7

[pbfrk4life]

WOW! Great thread!

What is the total wb now? How much did all this end up costing?

[Kranberry]

how much did it end up costing ya for the conversion?

[Randy77]

great info, been looking at the WK as a possible truck for Momma to play with.

[themerc64]

Chip, It's not running yet.

Nick, 3x25mm screws into existing chassis holes, The links on the chassis worked out pretty good that way, and I will probably remove the lower tabs on the axles, but I am going to wait until I make the skid plate first.

cotharyus, It is a TLT lower link mount.

pbfrk4life, WB is just over 12" and I still need to add the cost up. I upgraded the motor to a 55T Integy, so I need to figure that and whatever I use for the skid plate in. I will update the cost soon. I am building a couple other rigs at the same time, so I get sidetracked too easy!

Thanks to everyone else for the comments, share the good!

[warp speed]

I know I have not posted much on this site, but I have been lurking longer than I have been registered. I have the Wheely king and love it. I too also stretched mine out to make it a crawler. I just made links longer than the stock ones. I was looking at the way yours is stretched and where you have your links positioned. I think you will find that as you compress one corner, it will cause the axle to turn, or not stay straight in relation to the frame. Almost as if you turned the wheels left or right. This is caused by both upper and lower links sharing the same pivot point, and both links mounted on top of the axle.
Otherwise it looks good.

[NickRummy]

I used 3mm hardware too. I might change my lower mounting points but i'm not sure yet. I'll have new shocks in a few days. I put it through it's paces last night :D

http://img.photobucket.com/albums/v486/yellowfox/Wheely%20King%2003-07-07/DSCF9788sm.jpg

[Big Mike]

You're gonna hang up a lot here, where I've put arrows:http://img66.imageshack.us/img66/7760/crawl1ruz5.jpg
Also, the inboard link mounts being on the same plane is going to bind up the suspension. But your only option looks like moving them back to the original mounting holes. Or raising the top inboard mount points - IF there's a spot to move them to.
It also looks like you could shorten the upper links some and make the axle rotate inward and sit straight up and down - so the input shafts are not canted upward like they are now.
If you're ok with it the way it is, you've got the lower holes to mount a skidplate.
Looks real good so far. Just the wheelbase stretch should make it perform a lot better.
Looks like the stock WK chassis is not going to be very modifiable. At least you can spot new holes in a stock TLT chassis...

[FossilJunkie]

I know I have not posted much on this site, but I have been lurking longer than I have been registered. I have the Wheely king and love it. I too also stretched mine out to make it a crawler. I just made links longer than the stock ones. I was looking at the way yours is stretched and where you have your links positioned. I think you will find that as you compress one corner, it will cause the axle to turn, or not stay straight in relation to the frame. Almost as if you turned the wheels left or right. This is caused by both upper and lower links sharing the same pivot point, and both links mounted on top of the axle.
Otherwise it looks good.

I'ma have to agree here. Do a quick search on 4-link design, everything you need to know has been posted, and helped me a lot when I build my first one. Best way to mount your links is equal spacing (same distance between mounts on the axle and chassis) Other than that, yea, looks like a skidplate is a must, yer gunna get caught up of that piece in the middle a lot.

[Big Mike]

I'm confused now -
It looks like there are six links in the front, four in the back? Is this an optical illusion or something?

[FossilJunkie]

I'm confused now -
It looks like there are six links in the front, four in the back? Is this an optical illusion or something?

I was wondering the same thing...

[NickRummy]

I'm confused now -
It looks like there are six links in the front, four in the back? Is this an optical illusion or something?

One in the front is a steering link.

[FossilJunkie]

interesting. Never have I seen a WK in person... Guess that explains it a bit!

[themerc64]

Thanks for the words of wisdom guys. I have set up a few 4-links before and this surprised me too. I did not plan to set it up this way, but I had binding issues before going this route. This works fine and no bump-steer either. I will try this before going back to my original plans. Yes it's hanging low and I plan on making a center skid for it to. This one is purely for fun and keeping things simple. Give something new a try and you too could be surprised!

[themerc64]

Here is a center skid I made for a stretched PTI Goliath Crawler...

[pbfrk4life]

what did u make that skid plate out of?

[themerc64]

And there is still travel left in the shocks. The axles are clocked on the C ends to induce the pinion angle. Look at the stock pinion angle. The C's could be rotated, but I was trying to keep from cutting and drilling. There is no ill effect from this pinion angle and it adds some clearance.

[themerc64]

The skid is aluminum covered with thin Kydex plastic. Here is another view...

[Gula]

Looks like a cheap alternative for a strech"thumbsup" From what it looks like in the pictures you have posted that your axle will try to rotate itself. I think if you would rotate the shock mount 45 degrees and mount a link to it on the lower hole that it would eliminate that. I think that way you could also mount the lower link where the old one used to be and the upper too. I dont have my WK in hand right now so I'm probably wrong but that's just my 2 cents

[themerc64]

Yes the axle does rotate some, but for as much as it travels it is very little rotation. The link mounts on the axles are keyed and really only go on two ways, but others are mounting them different ways. There is a lot of good stuff out there for the WK. I tried the lower links mounted lower on the chassis and all I got was binding and almost no travel. I may go back to mounting the lower links differently, but I am giving this a go first.

[Gula]

Take a small piece of wide rubber band and cut it to fit in between the non keyed portions of the axle. Once you tighten the screws which should now be paralell to the ground, it wont move and your set.

[cotharyus]

The link mounts on the axles are keyed and really only go on two ways, but others are mounting them different ways.

Yea. There's a suggestion of a rubber band, you could use part of an old inner tube, or, I went with some pieces of molded nylon I happened to have laying around to turn those mounts. Either way, it's not something that's too hard.

[cammok5]

would the Parma Ford 90s Bronco body fit the WK w/out stretching to much. it be a cool mudder with swamp dawgs.

[Coolhand]

Now that the WK is coming out in a 4WD model, I was thinking of snagging one to attempt a build ... I assume all the below would be unneeded?


(1) HPI A431 Diff Case
(1) HPI A850 Diff Bevel Gear Set
(1) HPI A855 Diff Final Gear Set
(1) HPI 6819 Silicone O-Ring P-3 (RED/5pcs)
(1) HPI 86810 Gear Shaft 5x6x29mm
(1) HPI 86813 Drive Shaft 6x82 (2pcs)
(2) 10x15x4 Ball Bearings
(4) 5x11x4 Ball Bearings


That bit of the ladder frame they're talking about hanging up ... is there something within? I can't quite tell but it does look like it ...

Looks nice!

[Cslax06]

It looking pretty good so far.

Could you give me an idea how soft the stock WK tires are? Grip wise?

[pbfrk4life]

Now that the WK is coming out in a 4WD model, I was thinking of snagging one to attempt a build ... I assume all the below would be unneeded?



That bit of the ladder frame they're talking about hanging up ... is there something within? I can't quite tell but it does look like it ...

Looks nice!
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Actuially they are not comming out with the 4wd wheely king in the US only europe. Which is total bs if you ask me.

So you will need the parts to convert it. The parts are only about $60 or so if your a smart shopper.

[themerc64]

Coolhand,
Yes the bottom of the tranny and outdrives are in there. My skid plate will take care of it just fine. I made a template last night and now I need to scrounge up something to make it out of.

Cslax,
The tires are pretty firm, but we will see?

I dont want this to come out the wrong way, but when I posted this thread I was just trying to share something different to try with the WK. I appreciate everyones input, but I wasn't fishing for improvements. This is all supposed to be fun no matter how anyone chooses to build their own models. If we all did things the same way it would not be as much fun. There is good and bad ideas to learn from in all the threads on this forum. I do wish we had a WK thread, but people need to do a search on a topic or model before asking redundant questions or offering redundant advise. The search function is a valuable tool when used correctly! Share the good...

[pbfrk4life]

Hey, no matter what anyone says, you did a great job on this truck. Your guide was very well done, and it will help show new comers that a WK can be a crawler for not much money. It also givs good instructions on how to do it.

I dont think they were trying to bash you or offend, but help. This is an internet forum where people come to get and give opinions. As long as you are happy with what you have then what anyone else says shouldnt matter.

[cotharyus]

Looks good themerc64 - though I'm still waiting on parts for my wk conversion, so I am a little green over here. For my part at least, thank you for the post. While most of my truck will be different, I did pick something up from you. :)

[80'sBIGFOOT]

I just got a wheely king. Converting to crawler. I am trying something different I guess. I am using all stock but a couple of things. What did you use to make the drive shafts longer?? With what I am doing the wheel base will go to 11.25" from the 9.25" (center to center of wheels) All I need is Longer Drive shafts. Around 1" longer than stock. Thought I would ask this question here. Guy is selling me his wheely king for $230.00 advantages= 4 wheel parts, 19T Motor, Upgraded Steering Servo and ESC. I personally think it is a deal. Upgraded Parts and Spare Parts and 4 WHEEL DRIVE!!!:D :D :D

[pbfrk4life]

I just got a wheely king. Converting to crawler. I am trying something different I guess. I am using all stock but a couple of things. What did you use to make the drive shafts longer?? With what I am doing the wheel base will go to 11.25" from the 9.25" (center to center of wheels) All I need is Longer Drive shafts. Around 1" longer than stock. Thought I would ask this question here. Guy is selling me his wheely king for $230.00 advantages= 4 wheel parts, 19T Motor, Upgraded Steering Servo and ESC. I personally think it is a deal. Upgraded Parts and Spare Parts and 4 WHEEL DRIVE!!!:D :D :D

http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXSP55&P=7

buy that and you are covered.

[80'sBIGFOOT]

WOW that was easy. THANX!!! Just Curious Will I be able to get more than 1"?? Looks like i will.:mrgreen:

[inv3ctiv3]

Wow I think you convinced me! I just need to sell my X-ray M18 and my Tamiya F201 and I'll buy a WK!

[80'sBIGFOOT]

Yeah These Thing ROCK. I am somewhat new to RC. But my Opinion if you are new and want a CRAWLER the KING is the way to go. You get everything electroncs, etc.. You do not have to buy extra stuff. aside form 4 wheel parts. Personally Tamiya is just a OVERSIZED Model KIT:flipoff: Opps!(that might make some people mad);) ;)

[NickRummy]

Whoever was asking about the stock tires. THEY SUCK FOR CRAWLING! haha They are as hard as a tow motor tire. Seriously. They aren't bad for trail riding but they have no flex at all. An upgrade in tires would probably be one of the best upgrades to make the WK a crawler.

[themerc64]

Well the skid is on and the body is trimmed up...

[NickRummy]

Looks good! what is the material and why is there that funny bend towards the axle? Wouldn't it have been better to keep it pretty smooth? Seems like that might hang it up.

[themerc64]

Nick, it is made out of .060 styrene. There is a method to my madness... if it was left flat the ends would have really got caught up on things. The axle really travels high with the links set up this way. I intended to leave it flat to start with, but there is always more Styrene out there. Be different!

[sleek6mt]

thaNks for sharing man

helps alot

[e-hills4x4]

looks good

[themerc64]

The whole thing was feelin a little stiff still so I changed up a few things looking for some rear droop. I would like to soften the front a little more too, but the stock springs are softer than any other springs I have seen. The skid was ditched because of the Styrene cracking were it was bent at a 90'. Kydex wont do that, but with the links moved down it wont need one now. Next up, cutting the Chevron Tires!

[NickRummy]

Ever think about using polycarbonate? It's strong and slides on rocks easily. Heat bends easy too.

[slowcrawl]

Themerc64 I have a question: with your "cheap and simple conversion what was the wheel base measurement? Thanks..

[themerc64]

slowcrawl,

As it is now... 12.25"

[revoracer99]

i am looking to build one. but i cant do any fabbing. i think i will run into problems with the servo any ideas????

[slvrf150fx4]

The truck looks great. I am working on this project right now and i have just about everything i need. But i was wondering what odds and ends parts i need like the new screws and ball ends. I am was wondering if there are parts that you bought that i will need to complete this project. because i want to get everything i need first before i start this part of the build.

Thanks for any help with this.

[themerc64]

Most everything is listed in the thread.

[themerc64]

Changed over to weighted beadlocks and M2K's and really needed a servo upgrade. Found a good deal on an Integy C22433MG 6.0v/0.13s/144oz-in for $25 Also got around to installing the Ofna servo arm I bought for the front pivot.

[balang_479]

very nice... looks professional.

[cammok5]

you shouyld mount the servo on the axle

[BJoe]

Hey Eric, do you have any kind of bearing or bushing in the servo arm you're using as a bell crank? I may do something like that in the future on my WK.

[themerc64]

I shoulda woulda coulda done a lot of things, but the idea was to keep it simple. No cutting or fabrication for those that can't. These are just some different ideas to put out there. If the servo was on top of the axle in my set up, there would be no room for the axle to travel. It's fun to be different too.

[BJoe]

X2, I work in a LHS and I try to build things with stuff we have in stock instead of buying parts online or major fabbing for that reason. I think the most tool intesive mod I've done is the body mounts for my Pede with the HPI Ram ST/MT body. I used a Dremel but it could be done with a miter box and hand saw.

[SeanD]

BJoe:

A while back you asked about an aluminum bellcrank used by themerc64. I fabbed a bellcrank out of 1/8 aluminum plate and I put a bushing in as well. You can't see the bushing but its a piece of brakeline. There is no binding whatsosver plus I added a nylon washer under the bellcrank for futher reduction in friction and slop. It works great.

To any who are wondering, I switched the bellcrank to the other side of the diff because when I did the chassis reversal I opted not to move the servo from its stock position. (I will be mounting the servo over the axle soon enough and will make the shift at that point). I fabbed a new bellcrank mount from aluminum and bolted it to the diff case. It was actually quite easy. Here is a picture:

http://i124.photobucket.com/albums/p14/seand_photos/IMG_6776.jpg

Sean

[my96on22s]

Where Did Some Of The Guys Buy The Rear Sterring Servo Mount That Fits On The Axle? Thanks

[vinny1957]

Getting the parts needed to make my WK a crawler and noticed on the list that starts the thread there is no pinion gear change. Is this correct? Other threads show a 96t spur (this list has a 93t) and a 15t pinion. No change needed for pinion gear?
Thanks

[themerc64]

vinny1957,
I had to leave something to the imagination of others. I am running a 12x93 and a Integy 55 turn. Remember this... 1 on the pinion is equal to 3 on the spur.

[vinny1957]

Thanks!

[2Crawlers]

Where did you get the bearings that cheap?

[rm25x]

Good thread, I am looking at getting a wk for a larger trail truck. I like that for the price its rtr, and won't take much to build it to run how I want. HPI has a winner here.

[BJoe]

I like that bellcrank set up you've got there Sean, does that mount flex as much as the stock one?

[SeanD]

I've since moved onto an axle mounted servo but when I did use the aluminum bellcrank, I had no flex.

Sean

[julian]

Here are a few ideas for a simple low budget crawler conversion for the HPI WK. My plan was to use as much of the original model as possible, including electronics. Also to try to make the conversion without any cutting or drilling, so those without the tools or skills could make this an easy build. I also tried to make sure that all needed parts are readily available from most any RC outlets.
Sorry this is not a step by step narrative, but I think most of you will figure it out from the pictures. I will try to update the details when I get some time. Also search the other WK threads for some more great ideas. Maybe we will get a WK section on the forum with all these good ideas.

To start with... Prices are from Tower Hobbies and can be found for less online

(1) HPI 10820 Wheely King RTR $189.99 I bought two for $360 out the door, locally

First… Making the WK 4WD. Here is the parts list for the 4WD conversion… Prices are from Tower Hobbies and can be found for less online

(1) HPI A431 Diff Case $4.79
(1) HPI A850 Diff Bevel Gear Set $4.79
(1) HPI A855 Diff Final Gear Set $5.79
(1) HPI 6819 Silicone O-Ring P-3 (RED/5pcs) $1.45
(1) HPI 86810 Gear Shaft 5x6x29mm $7.69
(1) HPI 86813 Drive Shaft 6x82 (2pcs) $12.99
(2) 10x15x4 Ball Bearings $0.99ea
(4) 5x11x4 Ball Bearings $0.99ea

Parts Total for this step $37.50

Second… Making the WK a Crawler. Here is the parts list for the Crawler conversion… Prices are from Tower Hobbies and can be found for less online

(2) Traxxas #2680 Screws, 3x25mm RH ST (6) $1.45 x2
(1) Traxxas #4951 Half shafts, long (heavy-duty) (external- splined (2) & Internal-splined (2))/metal u-joints (4) $7.69
(2) Traxxas #4928X Differential output yokes, heavy-duty (2)/set screw yoke pins, M4/10(2) $4.79 x2
(2) Traxxas #5138 Turnbuckles, 106mm (front tie rods) (2) (Includes installed rod ends and hollow ball connectors) $8.59 x2
(2) Traxxas #5139 Turnbuckles, 116mm (rear toe control links) (2) (Includes installed rod ends and hollow ball connectors) $8.59 x2
(1) HPI 6993 Spur Gear 93 Tooth (48 Pitch/Carbon Fiber) $3.89
(2) Tamiya 9804179 Lower Suspension Stay from TLT Kit $2.79
(1) Integy Matrix 55T lathe Motor $18.49

Parts Total for this step $79.70

Grand Total so far, less shipping and taxes $307.19 and RTR too!

Third… Whoops, did I say No Cutting?

I ended up modifying the servo mount so I could swap the servo to the other side of the chassis and keep the stock linkage. Very easy to do, just mirror the stock cutout on the opposite side of the mount and shave down the lugs where the servo attaches to the mount. You need the servo to set back in some so the servo horn will clear the inside of the chassis. A small mod is needed to the servo horn too, so it will clear the chassis. I will get some details up on that soon in case the pictures don’t give you the idea.
I also am still looking for a part number and or source for the lower steering link. It needs to be longer due to the stretched wheelbase. A 3x150mm threaded link will be needed, or just fabricate a link of your own. As you can see in the pics, I have just extended the link on the axle end. This will be changed out before it sees any use.

More to come…

can u put links on the bottom were the arrows are pointing

[themerc64]

Do what and where? I really need to post some updates of my WK. Been too busy playing with it!

[deadmechanic69]

good idea with the lower links but what about your trany