Chris's "Cow Ant" XR Crawler Build

[coliver14]

I've been periodically in and out of r/c crawling for the past decade or so...I started gaining interest after seeing the insane lines that a tricked clodbuster could pull off (anyone else remember those 'Mudcow' videos?). Even though I'm new to the XR10, I've decided to attempt my own custom build using XR axles and designing my own chassis. I've always liked the black and orange look that the XR10 has and I'm gonna try to keep that theme going throughout the build...hence the "cow ant" title.

So far, this is my starting point...
XR10 kit (mainly for the axles and shocks)
Black hex hardware from Tony's Screws
VP Orange Knuckles, C-hubs, Lockouts, Link Mounts, Tranny Cases, Motor Plates, Servo Armor and Ti tie-rod
HH Torquemaster Sport, 55t
HH BR-XL Esc
Futaba S9157
Spektrum DX3E


Haven't decided on tires/wheels yet. I still have a set of Mayhem engineering Evolution beadlock wheels (3.7oz each) but I may be going with a lighter option. Leaning towards white dot Rovers but may sway towards to shaved BC's. Anyways, here's a teaser pic of the goods that came in tonight (thanks CKRC!).



I'll be posting build pics as progress happens...stay tuned.

Chris

[JeremyH]

Originally Posted by coliver14

(anyone else remember those 'Mudcow' videos?)

Yep, sure do!

Originally Posted by coliver14

Haven't decided on tires/wheels yet.

I bet MrVertical could make you a set with faces that would match the rest of your orange accessories...

[scorpion_ax]

nice bunch of parts ....good luck we'll be watchin it progress

[coliver14]

Originally Posted by JeremyH

I bet MrVertical could make you a set with faces that would match the rest of your orange accessories...

I will keep that in mind. Thanks


So I cracked open the kit and started building finally. After opening up the Vanquish stuff all I can say is wow - they make some nice stuff, good machining, nice fit and finish, overall very pleased. Anyways, one thing I noticed with the stock motor plate was how much slop there actually was between the three bearing housings and the bearings. Of course I had read about it and knew that was a reality, but I didn't think it would be a visible gap there - needless to say, I'm glad I bought the VP plates. Aside from having no slop, it was nice to see how much larger the VP bearings actually are over the stock ones...



Going through the instructions and putting together the front axle, I noticed there is a small amount of slop between the drive gear and the e-clip:



Similarly, on that same shaft, there is slop between the idler gear and it's e-clip...



I'm not sure I like this amount of play in my tranny and was thinking about ordering some 5x8mm shims before I go any further. Has anyone else done something similar to eliminate some of the gear slop...or am I just being paranoid?

[JeremyH]

Originally Posted by coliver14

I'm not sure I like this amount of play in my tranny and was thinking about ordering some 5x8mm shims before I go any further. Has anyone else done something similar to eliminate some of the gear slop...or am I just being paranoid?

No, you are not being paranoid. Personally, the slop annoys me too. That side to side play you wont notice, but the rotational slop you will. You can shim the side to side if you'd like, but I doubt you will see much difference.

What I like to do to get rid of rotational slop is to use larger pins (and grind them to fit snugly) as well as loctite the pins in place (using a liberal amount of loctite and letting it dry completely).

[Jakerz]

Originally Posted by JeremyH

No, you are not being paranoid. Personally, the slop annoys me too. That side to side play you wont notice, but the rotational slop you will. You can shim the side to side if you'd like, but I doubt you will see much difference.

What I like to do to get rid of rotational slop is to use larger pins (and grind them to fit snugly) as well as loctite the pins in place (using a liberal amount of loctite and letting it dry completely).

That's a great idea! I just got my axles together with all the Vanquish stuff as well (minus the axle tops) and I'm just going to run the stock gears until they die and go with all axial lightweight gears then. I will be doing this mod though, thanks for the info!

Jake

[coliver14]

Shims are on the way! Kyosho makes a nice set (96643 5x7mm Shim Set) of shims that come in three different thicknesses: 0.1, 0.2, and 0.3mm...the right combination of these should remove any side-to side-slop in the tranny and axles.


As for rotational slop - the stock pins are listed as 2x8mm in the manual. According to my caliper, they're more like 1.99x7.70mm...



So I started looking into machinist drill bits since they come in a large variety of sizes with very small diameter increments. As it turns out, a #45 (2.0828mm) and #46 (2.0574mm) drill bit fit perfectly in the transfer gear shaft and the main gear shaft, respectively. I found these at a local Ace Hardware for $3 each.



The bits sliding through the shafts is very tight - almost to the point of needing to tap them in with a hammer to get them to slide.



Anyways, the idea here will be to cut the drill bits into 8.25mm segments (since the gear pin slot is that wide) and use them as the new pins to minimize rotational slop in the tranny.



I'll have another update and some more pics once the shims arrive. Then, I'll hopefully be able to build these axles to my liking.

[slowride1]

looking great man an good find

[scorpion_ax]

yeah dude great idea on the new pins i may have to use this idea if you don't mind....good score.....i was never good at homework but it loks like you've done yours.

[brazwewn]

Definitely interested in seeing how well the drill bits hold up against the shear force of the gear. Hope it works out for you.

Wes

[concretejungle]

cool idea of getting some beef! Quick question, most are breaking the gears not the pins, right? I still like your insurance policy though.

[Jakerz]

Originally Posted by concretejungle

cool idea of getting some beef! Quick question, most are breaking the gears not the pins, right? I still like your insurance policy though.

I believe that is correct, but I don't think anyone has broken one of the idler gears have they? It's usually the transfer gear that goes to the spool or the smaller transfer gears inside the tranny, and the Axial machined gears seem to fix that problem don't they?

Jake

[scorpion_ax]

Well if it helps the only gears I have broken is a few sets of drum and final drive gears and the transfer gear shaft where the pin goes through it a few times but have never broken any internal tranny gears all stock


Sent from my iPhone using Tapatalk

[Fumbles]

Originally Posted by coliver14

As it turns out, a #45 (2.0828mm) and #46 (2.0574mm) drill bit fit perfectly in the transfer gear shaft and the main gear shaft, respectively. I found these at a local Ace Hardware for $3 each.

Damn nice find - I'm gonna stockpile some of these. Thanks!

[coliver14]

Originally Posted by slowride1

looking great man an good find

Thanks

Originally Posted by scorpion_ax

yeah dude great idea on the new pins i may have to use this idea if you don't mind....good score.....i was never good at homework but it loks like you've done yours.

Lol, use the idea all you want...I can't tell you what to do.

Originally Posted by brazwewn

Definitely interested in seeing how well the drill bits hold up against the shear force of the gear. Hope it works out for you.

Wes

So I did some more homework on this - it's damn near impossible to find the yield strength, not to mention shear strength of M-2 tool steel, which is what the drill bits are made of. I hope they hold up well since they really help with the slop in the tranny.

Originally Posted by RunsWithScissors

Damn nice find - I'm gonna stockpile some of these. Thanks!

I'm probably gonna do the same if I find out they last for a good while.


The pins worked out better than I thought. They are not only a tight fit inside the shaft, but they have to be tapped down into the gears pin slot.


Shims are in!



I used a 0.2mm shim between the gears and their e-clips, which eliminated the tranny side-to-side slop.




Once the gears were good to go, it was time for some grease before the assembly...I use Red "N" Tacky #2, works well and smells good too



...and the front tranny is put together finally!


The next step was to trim the stock steering slide rail and make some room for the VP titanium tie-rod.


I used a dremel cutting wheel for the first attempt at removing the tab.


Then, about 5 minutes later with a dremel grinding rod...voila!



Putting the VP c-hubs on the axle tubes. Ideally, I would counter-sink the bottom holes but I didn't feel like attempting it just yet, since the holes are slotted. So I went with button head screws instead.


After putting the VP knuckles on, I ended up using three 0.3mm shims between the outer bearing and the hex pin on each side to eliminate side-to-side axle slop.


Once the titanium steering tie-rod was on (w/Jato rod ends), I had a complete axle! I'm starting to see the cow ant look also! What do ya think?




The front axle, without motor and servo weighs in at 10.8oz.


And with the S9157 and servo armor installed...



Hopefully, I'll have time tomorrow to build the rear axle and start looking into designing the chassis.


Until next time,
Chris

[losiking1]

Looks really good!! Kinda partial to the orange myself!! Do need to flip that servo though

[jim hall]

Those axles look good with all the vp bling

[coliver14]

Originally Posted by losiking1

Looks really good!! Kinda partial to the orange myself!! Do need to flip that servo though

Thanks! Yea, I'm really liking how this orange/blank is turning out.

What's your reasoning behind having the servo flipped? I've seen alot of XR's on RCC, and it seems it's about 50/50 as far as servo positioning goes. My thinking was that the longer the steering rod, the more perpendicular to the servo horn it will be during rotation. The more perpendicular the steering rod is with the servo horn, the greater the transfer of torque will be through the steering rod to the steering arm. There are, however, obvious disadvantages to this such as more weight and less front axle clearance.

Originally Posted by jim hall

Those axles look good with all the vp bling

Thanks!

I decided to go ahead and mount the front motor and RR battery/electronics mount. The motors I'm using are old 55-turn HH Torquemaster Sports with new springs/brushes. I stripped the labels off them a while ago when I still had my bully, recoated the cans with a spray-on metal appliance coat, then wrapped them a few times each with some electrical tape - not the best protection but it should last atleast until I buy some better motors.




The entire front axle weight surprised me a bit being 20.5oz. Remember, I'm used to bully axles - where front axle "light version" weighs that much without a servo or motor.


When I started building the rear axles, I noticed the instructions show different idler gear orientations for the axles - the gear is shown with the arrow on the outside for the front, and the arrow on the inside for the rear.



Anyone else notice this? If I remember right, the idler gears packaged with the front axle were beveled on one side only. It appears the idlers supplied with the rear axle are beveled on both sides - so the arrow probably doesn't matter. Just thought it was interesting, may just be a typo.

[Jakerz]

lol never noticed that! I just made sure the bevel was on the correct side and went with it. Interesting though, but if you look at the Axial aftermarket lightweight gears they are beveled on both sides as well.

Jake

[brazwewn]

You might wanto to swap around your servo. Get the servo arm closer to the knuckle. This will allow you to run a shorter connector and have less hanging out to get caught on stuff. I really like the color you have their. Cow ants always made me laugh when I was a kid. We would cut them in half and what them scamper off in different directions. Nothing much to do in the middle of nowhere growing up.

Wes