brice_arnold

My Feedback: (6)

I'll go ahead an post this here. Some of you might get a kick out of this. This is my attempt at a custom build MRC crawler. I started this project Tuesday night and finished tonight (three days) working on it after work each day. I started with a brand new stock MRC and ended up with my beast. My approach was that of someone who has no experience with crawlers. I also own an Axial AX10 and a recently built Venom Creeper, but don't have much driving time in on these. These two crawlers and the recommended mods were my inspiration for this build. I started with some of the guidelines that I saw posted by Ted and went from there. I got to the point where you flip the tranny around as done on the AX10 and decided it was time to do a custom chassis. The end result I think is a fairly capable machine. I have only played around with it in the living room and I still have rebuild the wheels but just from playing with it, it seems to do OK. Some of the things I was trying to improve on include durability, minimizing torsion twist, lowering the CG, keeping everything clean. And, because I am still learning about crawler geometry I wanted to have plenty of adjustment to play around with. This I think will be a good platform for optimizing suspension geometry as you will see.

1. The chassis model is what I refer to as XA1. I wanted to do a TVP style chassis for simplicity. I haven't seen much carbon fiber and I wanted something stiff, light, and strong. Carbon Fiber fills the bill. I originally wanted to use 2.0mm but all I had was 1.0mm or 2.5mm so I went with the 2.5mm material. This is a little overkill but it is just a prototype.



2. The vertical plates are supported by a single strut in the center of the chassis. There are also two shock struts with slots that allow for side to side adjustment of the shocks. This strut actual pivots on two bushings in the vertical plates this allows everything to move smoothly with the suspension.



3. I picked up the Losi bent links for the lowers and machined and bent the rest of my link from 4mm stainless. I used the Losi rod ends for these linkages.





4. I converted the upper links from the original 3-link setup to a 4-link setup. On the front servo plate I made the plate large enough for a standard servo. On the rear plate I designed it so that I could straddle two of the 600mAh batteries across the knuckle of the axle. The rear plate sits on spacers and the batteries strap to the bottom of the plate with Velcro. This gets the weight of the batteries as low as possible. Much lower than mounting a large battery to the top of the plate. Thanks to Losi for making the perfect sized battery for this.



5.I don't know why but I picked up a billet skid/tranny plate and used that for the build. Eventually I would like to make my own from Delrin or UHMW. I rebuilt the front and rear axles with the HD lockers, front CVD's, Rear lockout kit, and aluminum knuckles. I also trimmed the front steering blocks to get more steering. I highly recommend the front CVD's simply because you do get so much more steering out of these over the dogbone and cups. I also triangulated the lower links. This should help minimize torsion twist.



6. I rebuilt the tranny with billet gears. I also replaced the stock motor with a trinity cobalt brushed motor. So far this motor seems to have good torque but it is too fast. I will need to do something about the gearing or just pick up a holmes motor. I will also need to see how the torque is when I get some weight in the wheels. I had to ditch the gear cover for space. I don't think it will be a big deal because the AX10 doesn't have a gear cover and the driving conditions for these crawlers are pretty mild.



7. Here the tranny is installed and flipped around. This does a better job of centering the drive shaft. It also puts a weight bias on the right side of the vehicle to help minimize the front right corner from lifting due to torsion twist.



8. Linkages, vertical plates, and the rear battery plate are installed



9. I have installed the shocks. I don't really care for these shocks but it's what I have. I used 70 wt oil. The springs are a little stiff but I will deal with it when I get new shocks I would like to look at running without springs. I have seen some people with springless shocks but I need to read up on it because I don't understand it.





10. Here you can see the battery and servo installed. The two batteries are in parallel. The servo is a Futaba 3305 which has 130 ozin of torque. I hope this is enough. If not I have some back-ups with 200-400 ozin LOL.



11. I installed the body to check for clearance. I had to trim the front and rear lip to allow for clearance for suspension travel. I also trimmed the bottom so that it wouldn't hang up on anything. The body nicely wraps around and meets the bottom edge of the verticle chassis plates. It also looks like it will do a decent job of protecting the motor.



12. Here is the bottom with the body installed.



13. I went ahead and installed the rest of the electronics and finished the wiring. I am using the a Castle Creations Mamba Pro ESC. I am using the stock Rx with my Futaba 3PK transmitter.







14. Here are the stock wheels installed. I have some billet beadlock wheels from Losi that I need to build up for this car.



15. Here she is with the body installed. So that's it. Let me know what you think. And be gentle, this is my first crawler build and I am a noob.

t9dragon

My Feedback: (11)

Looks good.......................

The shocks without the springs on them have an internal spring in side the shock.

Mudguppy

Great work Brice,good to see you work on the little guys also,have your front disc set up for the baja and really works well.
Will you be producing these as well or just a personal project ?

James..

hdmm

Very nice work! [sm=thumbup.gif]

BadClownCrawler

Brice like Corey said on HBF, get those chassis plates into production! He ll sell a shizload of them im sure.

Build looks Great. if this thing wasnt so small and such a pita to work on, i d get one. heh.