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The question I hear the most is: “I want to turn my truck into a rock crawling beast…what are the things I should do first?” Some of these people don't even have a truck and are still debating over a TXT, a Clod, a Juggernaut or something else similar. I have put together, what I feel, are the 10 best modifications you can make to a truck that is already capable right out of the box, the TXT-1. Best part of this list is that it uses parts you already have, the stock parts(mostly). With a Dremmel and a few other tools and products you probably already have, you can finish this list of mod's in no time flat!
1. Lock the Diffs! Perhaps the most important modification any crawler can do is to lock the differentials. All you need to do is open up the axles, remove the diff carrier and glue the spider gears together. I, like many others, use JB Weld to hold these gears together. It is the most proven “cold weld” on the market and I will bet that the metal or aluminum parts will fail before the JB Weld will! One word of caution: DO NOT get any JB Weld in the axle tubes of the diff carrier!!! When you slide the axle shafts back into the tubes, the shafts will be bonded to the carrier if there is JB Weld in the tubes. If and when, you break an axle….and I assure you that you will….you would then have to replace the axle shaft and the entire carrier. BE CAREFUL!
Note: If you have to ask what a locked diff is….please proceed to the on road car web site!
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2 and 3. Narrow the wheels and cut the tires tread pattern. TXT tires are very wide. Too wide in fact. The tread pattern, which is a common “Chevron Pattern”, is fine for a monster truck but is not very desirable for rock crawling. By narrowing the wheels, you effectively increase the sidewall and pull the side biting lugs down onto the sidewall, increasing lateral stability and traction. You also increase the contact pressure point of the tire due to making it more narrow. After narrowing the wheel, you'll want to cut a new tread pattern in the tire. I just used a pair of side cutters and removed parts of the long lugs, leaving large voids. This increased the flexibility of the tire, as the long lugs really keep the tire from conforming to rocks. I have been narrowing wheels for some time but after reading how to do it perfectly at mudcow.com, I can now do it with precision, tomake the prefect crawler tire! I used a band saw to cut the outer most rings off of the TXT wheels.
After doing this, which is the most critical part, you are home free. I used a Dremmel to smooth out the areas that the saw chewed up and mounted my tires back on. You need to use plenty of CA glue, as the wheels have lost their inner bead for the tire to seat into. But don't worry, the glue will hold it in place. This narrows the wheel by about an inch and make for a near perfect rock crawling combination. As for the tread pattern, just cut any pattern you feel necessary to gain traction and flexibility. Don't cut too much rubber off, as the construction of the tire still needs to be in tact. Remove small amounts at a time and test them. If you need to remove more, then do so. I don't use any foams, however, if you choose to cut a lot of the lugs off, you will then probably need some type of light foams. |
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4. Get rid of the servo skid plates and convert to conventional steering links. One of the biggest problems with the stock TXT, is the servo skid plate that seems to hit rocks before the tires ever come close. It hangs out so far that your approach angle becomes nil. A quick and easy way to remedy this problem is to fabricated up a little servo mount. I used some light weight aluminum and used the existing mounting holes on the top of the axle. It is very secure and I just used the stock servo mounting blocks to hold the servo in place. It sits very far back from the front of the tires, increasing the approach angle to 90 degree. I have placed the servo so if it encounters a rock, it will be pushed back and will actually hit the top suspension link ends, reducing any type of rearward movement. I then made some homemade steering links and attached them to the steering knuckles. I put the links on top of the knuckles, increasing clearance. You can do this to the rear as well. What I did on my TXT was to make the links so I could easily lock out the rear steering or put on the servo and mount in a matter of minutes. You can see in this picture how I made, basically, the same set up as the front but I have attached the drag link to the axle housing to make a lock out. All I need to do to make 4 wheel steering, in minutes, is to attach the servo on its mount and hook the drag link to the servo. |
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5. Shave the bottom of the axles. Get out the Dremmel with the sanding drum and grind off anything that is hanging down or that might hang the vehicle up while crawling. This is a judgment call you have to make as far as how much to shave off. I typically get rid of everything unless it is vital to vehicle strength. You can see that there is nothing hanging down under the axle, not even link mounts, which is my next point. |
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6. Move suspension links to top of axle. Not only have I moved my link to the top of my axle housing, I have also completely rearranged the mounting points. My lower links are now on the top axle link mount. I have also stacked two link mounts on top of each other to enable right height adjustment. I then mounted both links to one pivot point on the chassis end. This gives tremendous flexibility and keeps the weight of the rig over the center of the axles when totally twisted up. Obviously, this set up gets the links way up out of harms way. It is rare that I scrape the links on rocks. |
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7. Lengthen the wheel base! I have found, as most rc crawlers have, that a wheel base of anywhere between 14 and 15 inches is optimal. I got some ¼ solid aluminum rod to make my own links. Make sure you get long enough lengths of rod so you can cut them down to what ever size you want. It's very simple to do. Measure twice, cut once, and you'll have perfect link. Drill and tap each end, thread in some threaded rod and you're ready to screw on what ever rod end link you have for your project. Many people use the Kyosho 1/8th scale rod ends but I prefer the XTM X-Factor ends. They are simply huge, tough and work well. Once you have finished the links and stretched your wheel base, you will find new climbing abilities you never knew your TXT was capable of. No more flipping over backwards on steep ledges and the infamous “TXT Wave” will be kept to a minimum!!! With all this extra wheel base, you probably have found that you are now getting high centered much easier, right? Number 8 may be the best mod you can make to the TXT-1!!! |
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8. Cut your chassis for clearance. Plain and simple, all of these rc monster trucks that incorporate a center tranny with drive shafts, have a chassis that hangs down ridiculously low. Not good for rock crawling at all. I always envied the Clods that have no center tranny! I wanted over 5 inches of clearance too. It would be easy to raise the ride height of your rig and gain all kinds of break over angle clearance. You'll also be tipping over on your side all the time due to the higher center of gravity. I know!….that TXT chassis looks too nice to cut on. But here is how much I removed from the bottom of the chassis. I actually cut even more off, after removing these large pieces. Overall, I took off over one inch of aluminum. Well worth it though, as I increase break over angles considerably! I still can't believe the difference it made when crawling through even the biggest rocks. To accommodate the tranny, I had to move the whole tranny up in the chassis.
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You can see where I drilled a new hole above the stock hole to mount the upper tranny mount. I then got out the trusty Dremmel and shaved off all of the lower mounting plastic from the bottom of the tranny. I fabbed up a tranny skid plate from aluminum and the tranny now rests on the skid plate. Your measurements need to be very accurate so the skid plate will secure the tranny from any movement. |
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I now have Clod type clearance of 5.25 inches. Not bad for a TXT-1!!!!! And now that you have raised the tranny higher….make sure you adjust your ride height accordingly to keep that center of gravity low! |
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9. Run your battery packs up front. The battery packs we use are the heaviest piece of equipment you will add to your truck. The TXT has a battery tray that sits relatively high in the chassis and is in the rear of the truck. When climbing steep terrain, the trucks weight shifts to the rear so if the batteries are already in the rear, it is just adding to the weight out back. This weight tends to pull the truck back, causing the lighter, front end to want to come back to meet the rear end, ending in a backwards roll over. Getting the batteries up front in the chassis and keeping them a little lower will really help in keeping all four tires on the ground during steep ascents. I only run one stock motor in my TXT tranny. I reverse wired the motor and was running with the batteries up front. I then mounted the battery tray by moving the tray to below it's mounting points, rather than on top of them. I had to remove some plastic so the upper links would not hit the tray. Overall stability has been increased 10 fold. You can see that there is hardly any weight now at the rear of the truck! |
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10. Gear Down, Go Slow. It may be number 10 on this list but it should be one of your first mod's. Rock Crawling is a slow moving sport and the only way to move really slow and maintain excellent torque is by gearing down. Do yourself a favor and get some Robinson Racing 9 Tooth Pinion Gears or gear. I only needed one on this project because I am using one motor to keep the rig ultra light weight. With the 9 tooth gear, you will become a more controlled and better crawler. While this does make a huge difference, you still might want lower gearing! There are several ways to go about it. On another rig I have built, I used X-Factor axles that use a ring and pinion gear that allow a gear ratio half that of the TXT axles. The truck will not even hit 1mph with the X-Factor axles, 9 tooth pinion gears and Magnetic Mayhem motors. You can also opt to get a Traxxas E-Maxx tranny. The use of a spur gear with more than 70 teeth, will net you some pretty awesome crawl ratios. One more option would be the use of some type of gear reduction unit. You can find them for boats, airplanes, helicopters or even submarines. Two crawler buddies of mine told me that they have seen submarine gear reducers that net 1,000:1 ratios!!!! Now that is low!!! |
With these ten, relatively simple tips, you can transform your TXT-1 Monster Truck into a Crawling Machine. The best part about these tips is that you can perform all ten for less than $20! Some of the tips will take some time but those are the ones that will increase performance the most. Take your time, plan out your modifications, measure twice and cut once and you will turn out a crawler that will surprise you and your rock crawling buddies!
This article was written by Dirk Digler. 
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