WK to Crawler Conversion… Cheap & Simple!

[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:



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]

Originally Posted by 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…

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