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Losi Comp Crawler Axle to Axial SCX10 Swap

losi comp crawler axles opener

What are some of the qualities we typically desire in an RC crawler? Okay, there are a lot, so I’ll spare you the guessing game and get right to the particular traits I have in mind–ground clearance, low gearing and strong drag brakes. If you have any experience crawling you know the benefits of the aforementioned characteristics, but you may not realize you can fairly easily get all three–rock clearing ground ground clearance, hill climbing low gearing and drag brakes for precision driving–with one modification. As I’m sure you’ve already guessed, the one mod that does it all is the swapping in of Losi Comp Crawler axles under an Axial SCX10 (oh, the title was such a spoiler).

losi cutaway losi steering

The Losi Comp Crawler axles do not use traditional ring and pinion gears. Instead they use what is called a worm drive. The absence of a tall ring gear allows for a very trim axle shape. This greatly increases ground clearance since there is no big center “pumpkin.” This ability to drive over what others would get hung up on is a huge performance advantage and probably the main benefit of switching to Losi Comp Crawler axles.

The Losi axles also provide really low gearing. If you need climbing power, these axles are a great choice. The worm-drive ratio is 25:1. This means the axles will rotate once for every 25 times the driveshaft spin. In comparison, the stock Axial axles use a 3:1 ratio. That’s a huge difference. The downside is your once somewhat-fast scaler will make a turtle look like a Lamborghini. So, if you need/want speed, these axles may not be for you. For example, if you use Axial SCX10 as your hiking partner and need it to cruise along at your walking pace for extended periods of time, even with a gearing change and a high-zoot brushless setup, these axles may not suit your needs. If, however, you compete on technical coureses that have a lot of difficult obstacles, these axles will give you advantage over the competition.

Unlike most other gear arrangements, worm drives do not free spin. They must be powered to move. This means the Losi Comp Crawler axles provide instant drag brakes. Not only are the drag brakes instant on, they are as strong as you’ll ever need. If you want precise control on hills–going up or down–the Losi axles are a good choice. If you do comps with your scaler, these axles will, again, give you an advantage.

Losi offered its worm drive axles in the previously mentioned Comp Crawler and its more sport-tuned Night Crawler. The Comp Crawler was sold as a pre-built “Race Roller” while the Night Crawler is available only as a RTR. While there are a good number of differences between these two crawlers, Losi Senior Project Manager Richard Trujillo confirms the axles are identical. Richard points out that the Night Crawler uses a molded plastic steering setup, but whether you use the Losi steering links–plastic or aluminum–is entirely up to you. Richard also added that Losi offered a Heavy-duty Worm Gear Set that had a 21:1 ratio. This set has been discontinued, but you can sometimes get lucky and find them out there.

rc-recycler axles

If you’re still reading, you’re probably sold on the idea of installing Losi Comp Crawler axles under your Axial SCX10. Great! Oh, but wait, now there is the problem of getting a set of these axles. Unfortunately, the Losi Comp Crawler has been discontinued. The Night Crawler is an option, but a new truck will set you back $300 and you only need the axles. Time to cruise the buy and sell forums? The problem with picking up a used Comp Crawler or Night Crawler is that you will still be paying for more than you need and you run the very big risk of paying good money for trashed parts. The solution I used is a company called RC-Recycler that specializes in used RC parts–all sorts of RC parts. Not only do they have a huge selection, but you know you are getting exactly what you’re looking for. Speaking of looking for something specific, make sure you source the latest version Losi offered as running changes were made to improve the gears.

losi comp crawler rear scx10 install

While the Losi axles aren’t a direct swap, per se, they are pretty close. My swap was both easy and complicated at the same time. The rear axle was easy because I had already converted my SCX10 to a 4-link setup. Removing the stock axle and installing the new axle took a few minutes. I mounted the shocks to the outside of the mounting tabs instead of between the two tabs for a double-sheer mount. The lower links are still mounted double sheer, so I do not believe any real durability is being sacrificed. If you decide to install these axles, you may or may not have to experiment with different length links–not really a big deal.

losi comp crawler front axle install

In front, I have a chassis mounted servo setup (Hand Brothers Off Road) that has a 3-link with a panhard bar configuration. The front required a little bit of tinkering to get right. And, then some more tinkering when I realized I didn’t get it right the first time. Also, as I did on the rear axle, I mounted the lower shock to the outside of the axle tabs. While the front took longer, I believe I have the new setup working better than the old.

losi comp crawler performance

First impression? Holy smokes there is a big difference in gearing. Other than some brief runs, the first real test of my new setup was at a weekly scale competition at RC Madness in Enfield, CT. The axles worked great, but the lack of wheel speed killed me. It was just too slow to pop over some obstacles, and I had already switched from 2S to 3S for the extra voltage. I have a Novak Crawler 18.5 brushless motor installed. This motor has served me well, but a 13.5 or faster brushless system may be in order.

While I had underestimated how much I’d miss the wheel speed, the benefit of the added ground clearance was immediately noticeable. A truck that gets hung up less is simply a more capable rig–less equals more in this case. My SCX10 was a pretty dialed in scaler before the axle swap, but I could see how the extra ground clearance paved the way so to speak for even more performance potential. On many courses, other trucks scratched and clawed their way in an attempt to make progress, racking up penalties along the way, while my truck often made its way like it was cruising on asphalt.

For the next comp, I installed the biggest pinion I could squeeze in without a spur gear change. This small alteration made a big difference. I may make further changes, but I am holding off until a motor swap is made. I may even switch to a 4S setup. I did notice the axles got very hot after a 10-gate course. I plan to clean out whatever grease in there now and use a liberal amount of high-quality marine grease. Worm drives are inherently inefficient and heat is a byproduct of that inefficiency. Even though the gears in my mind were spinning thinking about doing this or that for the next time, the worm gears played a big part in me taking first place overall in Class 2. This comp was a trophy event, and while I didn’t take first on any of the individual courses, I was consistent enough to get the overall win.

Spring Fling

Overall, I have been very happy with this modification, and I’d certainly recommend it. Just know what you’re getting into. Read this article a few times and make sure this mod is right for you and how you use your RC truck. RC-Recycler delivered a high-quality product that was in the exact condition described (mine barely had a scratch on them) and they did all of this promptly and for a fair price. I’m not sure if the final cost was higher than I could have found from a private seller, but knowing I wasn’t getting scammed was well worth any potential price increase. If you’ve bought used RC gear or have done trades, you know all too well that descriptions aren’t always accurate. Using RC-Recycler removes that variable from the equation.


Some photos supplied by Losi and RC-Recycler

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  1. Great article Matt, I might give that a try when the funds are available. Thanks for the wisdom.

  2. Matt Higgins, as in ‘RC Car Action’ Matt Higgins? Or am I confused, which is entirely possible!
    Great info Matt. Thanks for the heads up. I’m looking to purchase an SCX10 as my next rig when my Wraith/Hilux is complete.

    1. You are not confused. At least not about this. 🙂 I am the same Matt Higgins. I am no longer with the magazine. I just work on RC Truck Stop which is 100% independent. Thanks for the kind words and for checking out the article and site!

  3. I recently did this same thing with an SCX chassis I had laying around. The chassis had originally been setup with Tamiya TLT axles, and performed well, but I plan on finishing this rig as a wrecker.

    After experimenting with what I had, I wasn’t happy with the bulky look of the TLT’s, but didn’t want to pay big money for a set of ‘scale’ axles. On RCCrawler, I was offered a set of these axles, and the gears just started turning. The worm-gear setup is ideal for this type of build. Good torque for pulling another rig, auto-locking axles for winching out a stuck rig, and the improved ground clearance and scale appearance are just the icing on the cake.

    Currently, I am waiting to complete one final piece in my wrecker’s future driveline. While I would love to make a local turtle feel like a Lamborghini, I want to get a bit more speed out of this rig without sacrificing these axles. So, I’m gonna be dropping in the tiny Nightcrawler transmission in place of the Axial unit. Combined with a decent speed/torque motor, the result should be exactly what I’m after. Nothing crazy fast, but nothing painfully slow either.

    Curious for your thoughts… 😉

    1. I think your setup is ideal. I recommend doing a double check that you have the most recent version of the gears in the axles and to add a high quality grease while you’re in there.

      1. Thanks for the tip, I’ll make sure I take a look at the gears and get them greased up before I get too far ahead of myself on the build.

        Thanks again! 😉

  4. I have done kinda the same thing but with the losi stock trans, I am getting motor temp issues. I have tried a wide variety of gear ratios with very little change. I have done the normal checks as far as making sure there are no binds, clicks, etc. Any input would appreciated.

    1. So you changed the axles and trans to Losi? If so, check the stock axle gears. You made need to replace them as they could be worn and/or the old version. Also, troubleshooting would call for you to try a different motor and maybe even a different speed control in an effort to isolate the problem.

  5. What a well written article. Thanks for all the info. By any chance, do you have any videos running with this axle? Sounds like they will fit my style of driving. I just ordered a set and can’t wait to give the worm drive a try.

    1. Thanks, Eric. I believe I do have video of this truck in a comp and I happened to take first, so it did do well. I unfortunately haven’t finished editing the footage. I started, but got pulled onto other projects. I’ll get working on the video again soon.

      1. Thanks again for the article Matt. I got the Losi axles and love them. I also made a couple videos with the axles on my SCX10. Search for “RACE730” on Youtube if you’re interested. Also, if you find the time to post your video I would like to see it. Cheers!

          1. Some people may be hesitant to try the axles unless they’ve seen them in action. Go ahead and embed the videos. That would be great.

  6. Thanks Mate this website was a great help when I was building my new Class 2 comp truck to Losi running gear. I bought a new SCX-10 chassis and started from scratch with the build, I ran all Losi gear including the transmission and diffs. The hardest part of my conversion was positioning the transmission and drilling new holes to suit, the transmission needs some washers to be packed under it to get the height correct. The diffs were straight forward and I run about a 45%/55% wheel base setup coming in just over the standard wheel base of a Honcho. Because of the Losi transmission and a 2100KV 28mm brushless motor on 3S it’s speed is just slower than a Honcho with a geared down 35T motor. The one draw back I have found in running the Losi diffs is the steering angle, a well setup SCX-10 comp rig will have 50*+ steering up to 70* with an XR-10 mod. This means more reverse penalties for me. I would love to send you some pics for you to show alternate setup on your page. You have my email address please email me if you would like some sent to you.

    Thanks for your site,


  7. Hi you have a nice rig there. I have the same set up but would i be able to run a fusion exceed pro 6.5t brushless combo in my rig or is that too powerful for the axles. If it is too powerful is there any way of changing the spur and the pinion to make it go abit slower. Havnt run in it yet because didnt want to completly wreck my axles as u said they were discontinued

  8. Hi Matt,

    Thanks for all the info on your site great for a person like me starting out with trailing and crawling.

    Can I ask please where you get the bumper on the red Honcho and does it provide you with better clearance up fount compared to the stock honcho bumper.

    Also I have seen from your site that to much articulation is not a good thing. Would taking the bump stops out of the stock shocks give the truck to much articulation or just about the right amount?

    And last for now I have noticed on my RTR honcho that the steering link attached to the servo horn is catching on the found cross member is there a way to fix this? I guess it might be a design flaw.

    Many thanks,

    1. The bumper on my Honcho does offer a good approach angle, but as an actual metal bumper it serves as a solid mount for a winch. The bumper was made by DH Fabrication.

      I would try removing the bump stops for testing. You might end up cutting them in half. A lot of it depends on the terrain you’re on and your driving style. Overall vehicle setup matters too. A really low CG allows for for articulation.

      I would use a file to quickly clearance the cross member for clearance. It seems to be a problem on some SCX10s. Easy to fix, but must be addressed.

  9. Hello sir saw your article and it inspires me to build my scx10 with losi crawler axles my question is what size length on the links did you end up using. I can’t seem to get the right pitch on my axles too much cogging thanks

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