My First Crawler Build

[Cooper]

Hi all. I thought It would be kind of neat for me to post my build as I get and install new parts on my RTR AX10. Please keep in mind that this is my very first build and that I am completely new to rock crawling. All of my experience in R/C cars has been of the nitro type. I do welcome all forms of criticism, be it good or bad. What little I have learned already has been from a combination of hours of reading and posting questions here, and driving it on the local rocks.

-Cooper


I started with the bone stock RTR Axial AX10 kit. It cost me right at $327.00 from our local hobby store (LHS) called Hobbytown USA. I purchased the RTR kit because I did not have the spare parts laying around to build it and ... well.. I wanted to play with it, not look at it!

Here is the basic RTR kit:
PART #AX90002 - AX10 SCORPION RTR

Features

• Wheelbase: 304mm~320mm (12”~12.6”)
• Width: 254mm (10”)
• Height: 156mm (6.125”)
• Weight: 1588g (3.5 lbs)
• Complete ready to race/crawl out of the box
• 4WD
• 27T Electric Motor
• 20T pinion paired with an 87T spur gear gives you a quick rock racer ratio, or install the included 14T pinion for a slower rock crawling ratio.
• True Beadlocks: No Messy Glue!
• Hi-quality Composite Plastic and Metals
• Durable (ESC) Electronic Speed Controller: Hi-quality durable forward and reverse speed controller.
• Hi-Torque Servo help hold your line when rock crawling
• Solid Rear Axle lockouts improve ground clearance when crawling
• Slipper Clutch: Reduces gear wobble for a more efficient drivetrain. Allows a motor to work more efficiently and greatly enhances the durability of the drivetrain.
• Aluminum Chassis plates with a molded nylon skid plate provide a solid and rigid chassis
• Ultra compact and lightweight transmission
• Open front diff for smaller turning radius, or install the included front locker for more traction when rock climbing!
• Rear axle is locked for better traction.
• Full Ball bearings
• Overall gear ratio range from 15:1 to 74:1
• Transmission: 2.6:1; center mounted
• Differentials: Front - gear differential; Rear - locked (spool)
• Transmission: Single-speed
• Tires: Axial 2.2 Rock Lizards
• Wheels: Axial 2.2 8 Hole Beadlocks (Satin Chrome)
• Suspension: 3 Link
• Drive Shafts: Universal front and rear

Chassis

• Wheelbase: 304mm~320mm (12”~12.6”)
• Width: 254mm (10”)
• Height: 156mm (6.125”)
• Weight: 1588g (3.5 lbs)
• Articulation: 70°
• Ground Clearance: 79mm (3.125”)

Body

• Length: 438mm (17.25”)
• Width: 181mm (7.125”)
• Height: 133mm (5.25”)

Electronics

• Radio: 2 Channel
• Servos: 1 Hi-Torque (Standard Size)
• Forward/Revers ESC
• Motor: 27T 540/550 Size

[Cooper]

I was really excited so I got it up and running as fast as I could. The first thing I did before I even started it however, was to check all the screws and make sure none of them were lose. I know this can be a big problem in most nitro kits, I'm not sure how common it is with crawler kits tho.

After everything checked out just fine, I put a fresh battery in in the battery tray and controller and took it for a test run...

It drove like CRAP! Yes, it would crawl, but it wobbled so bad and had so much torque twist that it would pull the wheels of the ground when barely touching the throttle, and you could not keep all 4 wheels on the ground when turning. The front tires looked like they were about to fall off and vibrated so bad that it could have been used as a scale model paint mixer.

If you look at this picture you can see that the RTR kit does not include the nice anodized green parts like the Kit version does. Instead, it comes with plastic nylon lower/upper control arms, and steering bar/linkage. This steering linkage turned out to be the main culprit of the awful vibration and crappy steering response.



I remedied this by buying a reverse steering kit for roughly $30.00:


It only took about 5 minutes to install, it's pretty straight forward:


The wobble is gone! It does not let the the front tires bow into each other when trying to approach climbs at angles now. I can actually steer better at a dead stop and It just feels better to have metal there instead of that flimsy plastic.

So there it was, it wasn't much, but it was my first upgrade to my first rock crawler.. and I was addicted. The whole time I was thinking to myself, yup, i need to strip this green off and polish it up.


More updates and pictures coming.

[Cooper]

Well, as I stated before. I made my own 30 degree lower control arms. And I must say, they hardly cost me a thing and they turned out very nice and work like a champ.

i started off with a set of Traxxas turnbuckles, you can get them in various lengths and I used 116-118mm ones. Check them out here for only 9 bucks a set. http://www3.towerhobbies.com/cgi-bin...?&I=LXDDY3&P=M



I then proceeded to bend them to a 30 degree angle, using a handheld tubing bender that I got from lowes for less than 10 bucks a few years back:



To do this, I simply remove on ball end on each turnbuckle, and set it flat in the tubing bender. Then proceed to crank down on the arm until the markings on the bender lined up at 30 degrees. I repeated this process with all the turnbuckles, and they came out quite nice and all nice and even.



I placed them on the chassis just to make sure they were lining up and worked just right, I also had to make sure that they did not alter my drive line angle.



Im quite happy with that. What do you guys think?

This is a before shot of the driveline angle with the same turnbuckles before I added the 30 degree bends to them:



Yeah, big improvement there. I forsee punisher shafts in near future.

[Cooper]

What little I have done did improve my suspension but It still had some torque twist going on, so it was now time to work on the wheels.

I started off by dismounting them from the vehicle, being very careful not to lose that pin that goes throgh that shaft and rotates the main nut. If you do lose one, a good temporary fix is to cut down a large paperclip and slide it right in there. Works like a charm until you can get new ones.

Well, here's the stock rock lizzards. I will eventually get a set of rock claws, but im saving up for a nice ESC and Chasis at the moment, the stock wheels keep me crawling and having fun for now.


The beadlocks have 6 small hex bolts one each side, there are 2 rings that make up the bead lock, give you 12 bolts total. I keep a little magnet on my workbench, It's actually an old speaker, to hold onto small metal parts like these.



Next, I remove the beadlock rings and drilled two small air holes on the backside of the rim, on opposite corners of each other:



Another angle:


Now, the next part was just a brain fart I had, but It actually helped. I personally dont like actually hearing the BBs roll around in the wheel, it makes my teeth hurt and reminds me of getting a mouthfull of dirt. So, i wrapped a little bit of the original foam around the inside of the wheel, trying to cover the plastic. That's what made most of the noise, the BB's hitting the plastic wheel itself, while It was revolving.


It doesnt have to be perfect, Foam can be a pain to cut if you dont have a really sharp blade to cut it with, and I keep my pocket knife sharp enough to shave with, but this is how it looks:


Next I mounted the tire back onto the wheel and bolted on the beadlock ont he backside of the wheel. Then I began to fill each wheel with exaxtly 5 ounces of Airsoft BB's.



After getting the 5 ounces in each wheel, I bolted the front bead lock back onto the wheel and listened to the much quieter wheel as I rolled it across the garage floor. The BB's can still be heard, but it's much quieter than before, it's tolerable for now.

For those who are curious of the BB's, here is a picture of the ones that I used, I picked them up at walmart in the sporting goods section for $8.oo:


Then I slapped them on the truck and played around with it, getting used to the new weight difference. Wow, this really helped lower my center of gravity, and overall climbing ability. The tires really grab the rocks now that they are not full of air and foam.

[Cooper]

I think I will get some of the stick on wheel weights and give them a shot as well. Im curious if there is a big difference other than the noise.

[g11nslinger]

i also got the rtr kit to start with and now its has been tricked out almost to the fullest but for weight in the front tires go to youre local tire shop and git about 6 sticks of the stick on lead weights 2 full strips on each front works great and makes no noise if i could ever find out how to load pis of my crawler on here i would show u my rtr so if anyone has a pointer on loading pic s thanks

[Cooper]

I picked up an Integy 55t motor for roughly $20.00 at hobbytown usa yesterday. Wow, what a difference in climbing power. There is NO more torque twist hardly and the acceleration is much easier to handle now. It used to pretty much jump when I tried to roll into the throttle on climbs. Now it just crawls.



This was a very easy install. Simply unplug the red and black wires at the quick connects and then unbolt two screws on the front of the motorplate, they are hex heads as well. Use another head head to get the main gear off of the old motor itself and and reverse the process to install it. It only took about 10 minutes. If you are not sure which side is red and which side is black when putting the connectors on, look for a + sign near the leads, that is where the red wire goes.

[Cooper]

Thanks for the tips Slinger, I like the BB's because they do what they are supposed to, but I just cant stand that noise. Im deffinately going to pick up some stick on weights in the next day or so. And you say 2 sticks per wheel? How much weight are you adding total?

As for pics, I took them on a Cannon powershot digital camera. It's new and has alot of buttons that I havn't quite figured out. It's a 7.1 megapixel camera so the quality should be pretty decent. It Has a small memory card in it, and I take the memory car out and plug it into my multi read in my computer. If you dont have a multi reader, you can get a usb cable that plugs right in. Then I save the pictures on my computer, normally C:/Mydocument/pictures, or however you may have it on your computer. Then i use a website call photobucket to host my pictures. Check it out at www.photobucket.com, it's totally free and you can even use them to host videos for free as well.

[Cooper]

While i was playing with the truck, i was thinking of other ways to improve the center of gravity and So, I began to hack. I'm rather proud of myself, I went 2 days w/o cutting or welding on the thing. I think that's a new record for me.

First I completely took off the battey plate:


Then I smoked two cig's, drank a mountain dew and cursed at the hot weather here in the south. Then, the ideas starting rolling in. It didnt really matter how I hacked it up. I was eventually going split pack, so I had some ideas for the battery plate itself.

The battery plate is held on by 1 small screw on each side of the plate. Then there are two small tabs that fit into two small holes on the battery plate. Like so:


Ignore the body mounts in the wrong place, it was another idea i was working on.

I then cut the battery plate into 3 different pieces. ( Muahahahaha! )


I then mounted them on the support that the original battery plate was attached to, but facing opposite directions:


Then I mounted the ESC and Receiver on them, Like so:


Now, the front is a little different. I actually took two spare servo mounts and mounted them onto... servo mounts.
It's ugly, but I havnt polished or finished it yet. But doing this allowed me to take the center section of the battery plate and mount it perfectly level and on top of the front axle:


After more grinding and some cleaning up, I ended up with this, until my split packs come in:


And here is what the battery tray has become:


and




Not bad, for my first crawler so far.

[Cooper]

Well, I noticed I was having a big of binding witht the shocks so I made a small atleration to them, it made a world of difference in the overall flex of the rig.

Before:


After:


This was done at all four corners, and I replaced the shock oil with 30 WT.

[Cooper]

Well, this was my first day working on my frist crawler, i'd really appreciate some feedback on what you guys think about what I have done so far. I know the battery plate looks ugly, but i didnt have time to remove the anodization and polish it out today. But It's only temporary, until my split pack comes in. Eventually I will aslo move the ESC and Receiver to the 4 link plate that i will be installing when I start on the 4 link suspension. This was just to give me a little more advantage while crawling and not rolling over on it's side everytime i wanted to make a turn.

A guy at hobbytown here built a small rock climbing spot and was bragging about his scorpion, so we both set up a small course and went head to head. Guys, I made this fella really made with how easy i was climbing all over the course. I was taking lines that he couldnt even get started on with ease.

[Cooper]

And for those of you who love the flex shots, this one if for you, from one addicted fan to another.

Before:


After:

[Cooper]

That's the end of my first day of modifications. I have alot more plans, and lots of stuff coming my way. VF Dig, 2.2Rock Claws, Custom Tube frame. Split Pack, Sidewinder or Tekin ESC, 4-link suspensin and much muc more. What do you guys think so far?

[hustlercrawler]

looks like a great start to me welcome to the addiction lol

[Browncoat]

Looking good!

One thing you should consider, since you're taking things to the next level, is upgrading your wiring connectors. Deans plugs are a good choice, as are the Traxxas heavy duty connectors. Those Tamiya-style plugs have been around since the 70's and aren't the greatest.

Also, it's easy to get addicted to the "flex factor". Generally, you want to limit your flex to the 50-60 degree range. There's a variety of ways to do this, so do a search on the forums for different ideas. I'd say you're venturing into the 70-80's, which is too much.

Consider mounting your ESC and Rx on the upper links or even the rear axle. You still have them mounted near the highest point on the chassis. Granted, they don't weigh much, but it's always a factor. While you're at it, think about lowering the lexan body. I'm sure you'll have to do a hack job around the wheel wells, but the end result is well worth it.

[Browncoat]

Also, you should mount your lower links inside the chassis frame. Not only will this protect them against scraping the rocks, but it will give you better triangulation...which translates to better stability.

[pencrazy]

Originally Posted by Browncoat

Looking good!

One thing you should consider, since you're taking things to the next level, is upgrading your wiring connectors. Deans plugs are a good choice, as are the Traxxas heavy duty connectors. Those Tamiya-style plugs have been around since the 70's and aren't the greatest.

Also, it's easy to get addicted to the "flex factor". Generally, you want to limit your flex to the 50-60 degree range. There's a variety of ways to do this, so do a search on the forums for different ideas. I'd say you're venturing into the 70-80's, which is too much.

Consider mounting your ESC and Rx on the upper links or even the rear axle. You still have them mounted near the highest point on the chassis. Granted, they don't weigh much, but it's always a factor. While you're at it, think about lowering the lexan body. I'm sure you'll have to do a hack job around the wheel wells, but the end result is well worth it.

x2 try to get everything as low as possible

[Cooper]

Awsome, Thank you both for your input.
What is the average ground clearance for these rigs?

[Cooper]

Just placed another order with TCS, New Hot Bodies skid plate coming, as well as my split pack with Deans and my Delrin tabs to set them on the axle itself. Should be here in 3 days so. Wooohoo. Now to find me a comp. chassis.

[Cooper]

Can anyone tell me the proper way to measure flex on these? Is there a quick way other can building a miniature scale articulation ramp?