Building a Rock Crawler 101

[jamesbernatchez]

I wanted to post a semi informative thread about rock crawling since it seems to be getting so popular. Im sure alot of people would find this useful. Maybe we can pin it to the top so its easy to find?

Welcome everyone to the addiction that is known as rock crawling. This post is to help inform you about getting started in rock crawling. Im going to assume you know a little about crawling. It can be done very cheaply or it can get very expensive. But no matter what road you choose there is fun to be had The great thing about building a crawler is there is no right way to do it. There are some basic parts you will see throughout many different builds though that are a staple of rock crawling. The info below pertains to 2.2 class vehicles although some(motors, speed controls, servos, etc. will carry over to the Super Class Rigs.)


#1 - 2.2 Class Rigs

These rigs are called that because of the 2.2 size rim that is used. They are around 1/10th scale and use the same scale bodies. These size rims are found on most stadium trucks. The rules state that a 2.2 class competition legal rig must have a wheelbase no longer than 12.5 inches. The width must also be no wider than 12.5 inches. 2.2 rigs also are only allowed 2 wheel steering. The rear axle must be locked out.

Axles: One of the staples of rock crawling is the Tamiya TLT. This is pretty much the basis of most custom rock crawlers. People purchase this in order to use the axles and hardware. You will want to lock the diff inside the axle case for rock crawling. There are a few ways to do that either by JB Weld, hot glue, or adding another gear to the diff. JB Weld is permanent while the others can be reversed with little to know damage.

Chassis: There are soooo many aftermarket chassis' that it would be insane to list them here. A few popular ones that come to my mind are Bender SW2, Bulu 2, plus more that I cannot think of. These are all competition worthy chassis. I personally have a SW2 and love it! You can check out www.bendercustoms.com for that chassis.

Links: The best option is to get some all thread rod and some traxxas rod ends and go nuts! This way you can make custom links to suit your wheelbase. Its very simple to do and cheap. You can even sleave them with aluminum tubing or graphite rod for that trick look. On the other hand you can use the stock TLT links for upper links and Traxxas 105mm links for the bottom.

Transmission: One of the most proven transmissions and one that most people rely on is the Traxxas Stampede/Rustler/Bandit tranny. It is effective and is easy to find. You will want to lock the diff to give the front and rear axles equal power.

Driveshafts: These connect from the output on the tranny to the output on the axle. You will need two driveshafts. Ones that are effective and pretty cheap are Traxxas sliders. People have used driveshafts from the pede, revo, jato, etc with success. The pede driveshafts are probably the most used. One thing to mention is you will need yokes, which is how the driveshafts are attached to the tranny and axles. Traxxas makes plastic yokes along with there metal yokes. For a crawler I reccommend the metal yokes. They cost alot more(usually around $15-20) but are well worth it in strengh. The plastic ones under the extreme torque and stress of crawling are likley to snap while the metal ones should never break.

Shocks: Youll find that the "standard" is usually around a 4" shock fully extended. Duratrax, Integy, and Traxxas are a few companies that make shocks that work well for crawlers and scale vehicles alike.

Tires/Wheels: Most people run Proline Moab 2.2's for rock crawling. They are the best overall I feel. Some people like the grip of Masher 2000's also. There are a few different options from Proline and Imex so search around and see what works best. As far as wheels, many people use front electric stampede wheels all around. Cheap and effective. Any 2.2 size wheel will work but some might need adaptors so as to not rub at full lock. www.RC4WD.com makes some nice beadlocks also. They come in a few different widths. They are more expensive then plastic wheels but there is one thing that is great about them, you NEVER have to glue your tires. The bead of the tire is held in by the outer ring of the rim. This lets you play with weights in the rims for a better center of gravity. You can run cut foams, airsoft bb's, stick on lead weights, lead shot, etc. There are many options. To many to cover here.

Brushed Motors: In a crawler you want torque over speed. Slow is better(usually). Many people run lathe motors. These come in 35, 45, 55, 65, and even 75 turns. The more turns the more torque but the lower the top speed. I think for crawling a 45 or a 55 turn motor is great. Plenty of torque for when you need it but also it will be able to give you wheel spin if needed. For a bit more speed and still some decent torque look at silver can motors. They are pretty cheap and are a good all around motor. I would personally use a silver can motor for a trail rig, something that will see a bit of everything. Mud, water, rocks, etc.

Brushless motors: These are pretty new to rock crawling. People have found that they weigh less than a lathe motor(2 ounces compared to 6 or so ounces) and have just as much torque. These require a brushless compatible esc inorder to use them. The common brushless motor that is being used is a 400 size outrunner. There are different kinds and im just begining to use them myself. So far I have nothing but praise for them. One thing to note about these motors is because there are no brushes to wear out they are more efficiant then brushed motors and that in turn can lead to longer run times. For more info and a great place to purchase brushless motors and esc's visit John at www.holmeshobbies.com He has been running brushless in crawlers for a while now and is a great guy to deal with.

Speed Controllers for brushed motors: The nice thing is that almost any electronic speed control designed for a car/truck will work in a crawler with a brushed motor. Some favorites to use are Novak Super Rooster, Novak XRS, Mtronics lineup of esc's, and others. One thing to note is what the BEC is rated for on the esc. Many esc's BEC is around 1 amp(Novak XRS for instance). The higher the better. If your running two high torque servos along with the motor then you want something that will be able to power everything at once. With a low BEC....Trying to turn 4 wheels(if using 4 wheel steering) could take all the power away from the motor and vice versa. Im running a Super Rooster and a Novak XRS and havent had any problems with either in my 2.2 rigs.

Speed Controllers for brushless motors: Again, brushless motors need a specific speed control for them. One of the most popular is the Mamba 25 by Castle Creations. It was designed for 1/18th scale vehicles but works great in a crawler too. Its a very small lightweight esc and can handle small brushless motors no problem. Im using one in conjunction with an outrunner brushless motor in a rig I have and it is everything I hoped it would be. For more info on these check out www.holmeshobbies.com

Batteries: A big part of your setup is your batteries. They come in all types, sizes, and capacities. Im gonna focus on NIMH battery packs. These are widely used in elelctric rc cars. A standard 6 cell pack is made with Sub C size cells. They come in capacities up to 45oo now. The higher the capacity the longer the runtime. The downside of Sub C size cells is that they are heavy. I personally run a 6 cell Sub C pack in one of my rigs. I run it over the front axle to get as much weight as possible up front. Some people run 2/3 batteries or even AA size batteries. Im running custom 7 cell AA 1650mah packs in my tuber. There are many options. One thing I recommend with all batteries are Deans connectors. They have alot less resistance then standard Tamiya plugs. Check out www.cheapbatterypacks.com for Custom packs for great prices!

Servos: Any standard size servo will do.....but a good servo will last on the rocks! You would want to look for something with at least 80oz of torque for a 2.2 rig. I personally run a 200oz and a 133oz servo respectively on my rigs. Id rather have more than enough power than not enough.

Radios: Any 2 channel radio will work in a 2.2 class rig. I personally run Spektrum radios and receivers so I dont have to worry about frequency conflicts. A cheap radio that works is the Traxxas TQ2 or TQ3.

Bodies: People run 1/10th scale bodies on there trucks. Jeeps, Fords, Chevys, Dodges..it doesnt matter. As long as you like it.



#2 - Super Class Crawlers (Work In Progress)



Websites

www.thecrawlerstore.com - Everything you need for crawlers
www.RC4WD.com - Aluminum beadlocks along with other items
www.holmeshobbies.com - Brushless motors and speed controls
www.ultimatehobbies.com - TLT Kits
www.bendercustoms.com - Competition chassis and accessories
www.rcpcrawlers.com - Everything you need for crawlers
www.cheapbatterypacks.com - Place for everything batteries


Pictures always help me get motivated to build so I figured I would post some pictures of my crawlers along with some of my past scale vehicles.

2.2 Rig Pictures










Scale Trucks(2.2 and 1.9)

[cpee]

very nice jbn this will help my quet as i will countinue to ask question chris

[Radejr]

This is from great information I have been wanting to create a crawler from scratch just not sure of all of what i needed to get this will help!

[tq_racing]

This has really helped out. I want to build my own crawler from scratch and this has helped give me a few ideas.

TQ

[Kafer_Girl]

with the popularity of crawles these days i wonder how long its going to be before a company like HPI to Tamiya has one on the market.

[tq_racing]

I just have one major question, the shocks are they just standard t-maxx shocks, are those the right size?

[ElectricThunder]

Originally Posted by Kafer_Girl

with the popularity of crawles these days i wonder how long its going to be before a company like HPI to Tamiya has one on the market.

Tamiya has the TLT-1 Rock Buster , and has for some time I believe. I guess the TXT-1 can also be used for rock crawling too in stock, or relatively stock, form; just like it's little brother.

Add the 4WD upgrade to the HPI Wheely King and you can probably rock crawl with it too...although its main purpose is....wheelies.

Of course, none of these are tubular chassised rock crawling machines like james has (which are really nice!).

[tq_racing]

Where can one go about finding a tubular chassise? I would like to find the specs on one and make it myself, im really into the design side of things.

Thanks
TQ

[Radejr]

Most of the tube frames are custom built from people which I am going to do just using design ideas from other people after I get my parts so I can get the dimensions down. You won't really find a descent chassis for cheap that someone has made.

[tq_racing]

Thats understandable, guess I will just have to get all the parts together then start bending.

TQ

[jamesbernatchez]

Originally Posted by Radejr

Most of the tube frames are custom built from people which I am going to do just using design ideas from other people after I get my parts so I can get the dimensions down. You won't really find a descent chassis for cheap that someone has made.

Yeah most are built from brake line or brass rod. They can get expensive. The red one I bought was $175 used...not bad for the quality of it though. Well worth it in my opinion. Check out www.bluemonster-rc.com as he is the person who built it. There is actually a build up thread on it. The tube chassis didnt look like that in the begining.

TQ- yep, standard maxx shocks would work well for a crawler.

[zack221]

Here is a place to get tubing if you want to make your own.

http://www.mcmaster.com/

[savage100]

Very usefull. I am trying to get a sw2 crawler (i still have to convince my dad to let me get one) and this is a big help. Oh and what chassis is used on the blue land cruiser?

[Smib]

This is great, I have been wanting to make a crawler for a while and this should help.

[Radejr]

McMaster is actually who I have been thinking about ordering from I am not sure though if i want to go with 3/16 or 1/4 brass tube. My work has ordered a few things from them and they have a very fast response time if you order over the phone. I already have my Oxygen Mapp Gas bottles and solder. I have some 1/4" brass tube right now I have been practicing on soldering I am getting pretty good. I think I am going to create a 1/10th scale full rollcage circle car with 1/4 for strength reasons, but I was thinking maybe 3/16 for the rock crawler just because its not gonna be hitting things really just light rolls if anything.

[suckfish]

Guys this is awesome information, now I have a starting point.. Start from Scratch..

[suckfish]

Junfac Tracer "Roller" or a Bender Customs SW2 "Roller".. Guys you have me ready to jump into crawling which would be the more popular chassis? Also what about the Tamiya Ford F-350 High-Lift Kit, how popular are they? Thanks for any advice

[savage100]

The junfac uses the stock tlt tranny and doesn't work well for crawling. I am getting the sw2 and you will need a pede tranny. The high lift is not a very good rock crawler. Since it is a sale truck, it doesn't rock crawl as good as the sw2 or junfac.

[tq_racing]

Ok got a stupid question or two.

The TLT does it start off as a 1/18th scale

And then the wheel base, thats from the center of the axle to center of axle right?

Thanks
TQ

[awnelson]

The only thing about a TLT that is 1/18th is the body. The rest of it is really 1/10th and that's what makes it a great doner kit.

Wheel base is from center of axle to center of axle.

Wheel width is outside of wheel to outside of opposite wheel.

[MarkieMark231]

Looks awsome. Anyone know of where I can find some vids. of these monsters in action?

[suckfish]

just check out some of the sites posted at the top of the thread.. Some of them have excellent vids

[suckfish]

http://www.bendercustoms.com/chassis.htm very cool

[savage100]

Originally Posted by awnelson

The only thing about a TLT that is 1/18th is the body. The rest of it is really 1/10th and that's what makes it a great doner kit.

Wheel base is from center of axle to center of axle.

Wheel width is outside of wheel to outside of opposite wheel.

Actually if im not mistaken the tlt is 1/18 scale and you get longer driveshafts and turnbuckles to make it into a bigger crawler. And if you go to www.rccrawler.com and go to the video section in the forums they have a bunch of cool videos.

[savage100]

Thanks to the help of this i ordered my sw2 crawler last night . I will do a thread if i figure out how to downsize pictures. Does anyone know how?