Wheely King CXT

[swhenrik]

My Wheely King with CXT body build thread.

I had a thread going in Newbie General: Wheely King, CXT, camper trailer but I wanted to start again from scratch.

I converted mine to 4wd before the parts were available using a NMT diff, drive cups and center dogbone, and made my own dogbones for the rear axle. But I wanted to add rear steer, and the dogbone I made weren't ball shaped at the end. So I ended up ordering the HPI parts anyway.

I'll skip the pics of the stock WK, since everyone knows what it looks like!

Mock up of CXT body on stock WK chassis:



CXT body on stock NMT tires and wheels:

[swhenrik]

GD-600, shaft filed down to fit standard pinion, dremeled to fit in stock motor mounting plate, and swapped to a 12 tooth pinion on the motor making it 3.8:1:

Attachment 31329

[swhenrik]

RPM Revolver "rear's".... rub on the steering arm:



I cut off the innermost mounting lip, and they cleared fine.

[swhenrik]

I rotated the link mounts on the axle, as many do, and mounted the shocks to the outside of the mounts to get them as far out on the axle as possible for more stability:



The mounts were originally just tightened down on the axle, but the shock was tilting them. I added thin plastic shims between the top and bottom of the axle, and the mount, to prevent the tilting, and it's working out well.

Also the first glimpse of the Imex Claw Dawg's.

[swhenrik]

Next step... custom chassis plates.

I picked up a HUGE cutting board from Walmart... something like 14" x 20". I cut it in half, and screwed the 2 pieces together. I set a stock chassis plate on it as a template to drill all the holes. Then I started trimming a little at a time for clearance, drilled more holes for extra suspension mounts, etc. I didn't get any pics of this process. And I'll never do it again, it SUCKED!

Here's the chassis as it sits now:



Ugly? Yes! Functional? Yes again. I intentionally left it tall under the cab so I could mount things up there, like it I needed to relocate the battery for example. It MIGHT get the top trimmed down once it is more "complete."

[swhenrik]

And with the body on:

[swhenrik]

There is a LOT of trimming of the chassis plates left to do. I would like to get the body to sit a lot lower, but the tires hit the body already at full articulation, which there is probably almost too much for a trail truck:



I will probably lower the body and limit the suspension travel, screwing up some climbing ability in order to make it look better. Adding some large nerf bars would also help fill in under the body. The steps that came on the CXT body would work, but are way too flimsy.

[swhenrik]

The suspension links are all stock, I just relocated where they mount to the chassis to extend the wheelbase, and moved the upper link mount on the chassis up to get the links more parallel. I will be changing things quite a bit yet, but I would like to keep using the stock links.

The tie-rods.... don't ask how I rigged them together. It's not duct tape, but it's not much better! Another area that needs work.

Driveshafts.... are Maxx wheel shafts, JUST the female section, trimmed to length, combined onto the stock u-joint. The male end of the shaft is completely stock. The WK and Maxx shafts are exactly the same in every aspect. I have a set of Revo shafts, but they are too big around and will hit the cross brace for the lower links.

The goal for the truck was to make it work well in the living room! I wanted it to look a little better, and perform a little better, keeping speeds down, and ability to tow a trailer. A hitch is coming.

So far the truck actually works pretty well. Open diffs both ends and 4 wheel steer make it turn incredible compared to 2ws. A JR XS3 radio controls it, with rear steer mixed to front steer at 70% to keep some stability at high speeds. I leave the radio menu in the setting for "servo reversing" on the auxillary channel, so a push of a button switches from sharp steer to crab walk.

There's not much speed left with the GD-600 running 3.8:1 and the smaller tires, may go back to the pinion that came with the GD-600 to return it to 2.5:1. Wheelies are a thing of the past, can't get the front end up if I wanted to. Oh well, I'm getting closer to some of the other goals.

My 2 year old loves pushing trucks around, and over a pile of pillows in the middle of the floor. The mod's to the WK have made it work a lot better for pillow crawling.

[karlos]

Looks good so far. You might try dyeing the cutting board black to make the chassis a little less noticeable.

[swhenrik]

Originally Posted by karlos

Looks good so far. You might try dyeing the cutting board black to make the chassis a little less noticeable.

Yes, I need to do SOMETHING.... I pondered on dying it, not sure how it would take the color though. I wish I could have just found black. If nothing else, this can be a learning chassis and I'll later build a better looking one from aluminum sheet.

[Natedog]

Originally Posted by swhenrik

I rotated the link mounts on the axle, as many do, and mounted the shocks to the outside of the mounts to get them as far out on the axle as possible for more stability.

The mounts were originally just tightened down on the axle, but the shock was tilting them. I added thin plastic shims between the top and bottom of the axle, and the mount, to prevent the tilting....

How about some double-sided servo tape instead?

[swhenrik]

I used plastic for a nice firm filler between the axle and mount, top and bottom, where the gap is. The double sided servo tape is usually a soft foam, which may be better on the front and back where it would be squeezed. But then sticky type adhesives, when being pulled on constantly (even the truck sitting on a shelf), tend to slowly move. A hard servo tape should be fine for the top and bottom shims though.

One thing I was thinking about today.... filling the gap with something like JB weld. The rotated mounts split at the same place the axle tube splits, so each 1/2 of the mount could be permanently attached to each 1/2 of the axle tube..... I'm going to look into doing that tonight.

[swhenrik]

To add 4ws, using a servo mounted by the stock servo, I ordered another set of the steering parts:

85260 servo saver/pivot ball http://www.hpiracing.com/piw4.php?part=85260 will get you another servo saver, the ballcrank for the rear axle, and the rocker/lever that goes on the side of the tranny.

85257 suspension rod set http://www.hpiracing.com/piw4.php?part=85257 will get you the link from the servo saver to the tranny lever, and the ball ends for the link from the lever to the bellcrank on the axle. It also has the link from the bellcrank to the rear steering tie rod that connects to both rear wheels.

The standard tie rod that goes from the lever on the tranny, to the bellcrank on the axle, is too short for the rear. But if you want it anyway, to cut and make longer:
http://www.hpiracing.com/piw4.php?part=86816 Or use 3mm threaded rod.

Some of the required screws will be included, but you'll need to supply a couple more, I believe just some 3mm screws.

Mounting the 2nd servo is another story.... I still haven't gotten pics of my setup. I cut out part of the bottom from an old style Savage radio box for the servo mount, and CA glued it on top of the stock servo mount, with a couple spacers. A little dremeling was required for clearance of the servo horn.

[Natedog]

Originally Posted by swhenrik

I used plastic for a nice firm filler between the axle and mount, top and bottom, where the gap is. The double sided servo tape is usually a soft foam, which may be better on the front and back where it would be squeezed. But then sticky type adhesives, when being pulled on constantly (even the truck sitting on a shelf), tend to slowly move. A hard servo tape should be fine for the top and bottom shims though...

The way I trimmed my housings and link mounts the servo tape is not under any real stress...it is being squeezed and the link mounts are seriously not moving on the axle housing even without any tape, shims, or whatever.

[SACCO]

looks nice.

you might find some darker chassis material here:

http://www.usplastic.com/catalog/default.asp

I would have bought the cutting board too though. I just hate waiting on stuff to come in.

[tltman12]

looks pretty good man

[swhenrik]

An idea I came up with to narrow the WK axles.... some may have seen me mention it in slobin3d's thread, I finally got some pics of it.

On the left, stock Wheely King steering knuckle and parts. On the right is Nitro MT 1 parts.



You can see how much difference there is in the length of the axle stubs. What's not as clear in the pic is that the NMT drive cup is quite a bit larger diameter (beefier).

[swhenrik]

The Wheely King wheel stubs are the same as the REAR of the NMT1. The NMT front stubs are much narrower, and have a larger bearing to get the drive cup inward more.

Here is the stubs with bearings on them:


Part numbers:
HPI A460 - NMT1 steering knuckle/C-hub parts tree
http://www2.towerhobbies.com/cgi-bin...?FVSEARCH=a460
HPI A548 - axle stub
http://www2.towerhobbies.com/cgi-bin...?FVSEARCH=a548
Bearings, one 5x11 and one 10x15 each per knuckle, I use Avid's
http://www.smfstore.com/product_info...roducts_id=176
http://www.smfstore.com/product_info...roducts_id=178

NMT2 parts are similar to NMT1 parts, but not sure exactly the difference. I believe the NMT2 comes with CVD axles. The dogbone style drive cups are needed to work with the stock WK axle shafts (86813). The only pdf manual I have for a NMT2 is from the 18SS and it uses CVD's.

In case anyone is interested:
HPI 85076 - NMT2 steering knuckle/C-hub parts tree

[swhenrik]

NMT hub on the left, WK on the right, you can see the width difference, and height difference:



WK on the left again, NMT on the right, with hex installed:


I'd guess about 3/8" difference in width for each side.

[swhenrik]

The screws are completely different.
WK on the left, NMT on the right, with the shoulder installed on the screw:




The NMT screws are definitely too short, and the diameter of the collar is too small. The WK screws are much bigger where they screw into the knuckle. Drilling the NMT knuckle and threading in the WK screws should work perfect, but I didn't do so as the NMT parts are going back on the NMT!!

The NMT hubs have plenty of material around the hole, they should hold up just fine after drilling.