1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Custom 1/10 200mm Rally Car build, with center diff and carbon fiber chassis!

Discussion in 'OFF Road Build Projects' started by Low Budget Hobbies, Nov 10, 2017.

  1. Low Budget Hobbies

    Joined:
    Nov 10, 2017
    Messages:
    19
    Media:
    8
    Likes Received:
    13
    Hey guys!
    New to the forum, not new to R/C. Been in the hobby for 5 years and I'm very excited to show you guys my latest creation: a rally car!

    I have already finished this project unfortunately so there isn't a lot to "follow along" on here, I didn't think about creating a forum account until after I decided to create a youtube channel and by then the car was ready done.
    This is a custom 1/10 200mm wide brushless electric rally car using a mix of Redcat Lightning EPX parts, Redcat Tornado EPX parts, an Arrma Fury BLS transmission, various parts from Hpi, Helion, as well as a couple hand made carbon fiber and steel parts. My intention when starting this build was to build the ultimate 1/10 200mm rally car, something that was more capable than any 1/10 200mm wide rally car on the market today both RTR and in kit form, more durable, and more reliable. Most 1/10 touring car-sized rally cars look really cool and are reasonably durable but are held back by lack of suspension travel, low chassis, and fragile drivetrain components not ever designed for off road use. As far as I know there isn't a 1/10 rally car that has a center diff or slipper clutch that 200mm or 190mm wide bodies will fit on. I wanted a vehicle that could duke it out with an Hpi WR8, a vehicle that I have wanted for a really long time but never bought due to lack of bodies and tires that will fit the vehicle. Larger than 1/10 rally cars such as the Traxxas Rally and Thunder Tiger ER4 don't have as many bodies that will fit on them and are much much larger than your average 1/10 vehicle. After a couple hours of planning, sourcing parts, and ordering, the build was underway.
    Like my username implies, I didn't want to spend a lot of money on this vehicle (although I did end up spending a lot more than I would have liked). I don't have a lot of money I can just dump into an R/C car, so the budget for the build was planned accordingly. I went with a low-budget 1/10 brushless system. I paired a rebranded HobbyWing (rebranded as Leopard Hobby) EZRun 60a ESC with a Gool R/C 4 pole 5200kv motor. The motor is very powerful and HobbyWing EZRun's have been renowned around the world for being great reliable low-buck ESC's. The car is badly under geared, even running a Castle 32P 28T pinion and a Kimbrough 32P 44T spur gear the car's top speed isn't very impressive for a brushless vehicle and the ESC and motor run very very cool. The BLS transmission stock provides enough gear reduction to run SCT wheels and tires, and on this car the output cups go into diffs that are geared 3:1 (approximately) and then the output cups off the diffs go into small wheels and tires. Even with the pinion and spur geared 28/44 (which sounds absurdly high, I know) and with a high kv motor it just has too much gear reduction. It is more than enough speed to have fun with, as the car gets up to top speed very quickly and feels very powerful and lively to drive. If you set up a road course with cones or run the car off road I am very certain you will have a huge grin on your face because I sure did! [​IMG] However if you just do boring speed runs up and down a street, forget about it. It'll beat a stock brushed Rustler, but thats about it.
    For a steering servo I went with a Power HD 1501, which was inexpensive but works quite well in this lightweight little car. I've run dozens of these servos in various vehicles and they have been very reliable and perform adequately. The suspension and steering components are from a Redcat Lightning EPX with the exception of the shocks and shock towers, as those are from a Redcat Tornado EPX. The shock towers are the CNC machined aluminum upgrade shock towers, not the stock Tornado shock towers, and won't bend very easily. I was unable to bend them by hand on the bench. I didn't try to bend them with pliers but trust me, they are strong and look great. The front Redcat Lightning dogbones have been upgraded to CV shafts to allow more down travel in the suspension without risk of them breaking, however the rear dogbones have been just fine running more down travel than the front (as the rear doesn't need to steer) so those are still stock factory steel dogbones.
    The transmission is from an Arrma Fury BLS, yes the one with plastic gears. The differential does a good job keeping the transmission in one piece in this light little car, and my logic was if the plastic gears shredded under brushless power I would upgrade them to metal. However, I have put around 5 packs of hard running off road through the car and have had zero issues. They simply are not strained very much with the small tires and gear reduction the front and rear diffs provide. The car is running a Castle 32P 28T pinion gear with an Associated 3mm to 5mm shaft sleeve, and a Kimbrough 32P 44T spur gear. Against my will of keeping the stock slipper clutch assembly in order to fit this spur gear I had to run an Exotek slipper clutch eliminator made for an Associated B4. However, with the center diff the car is able to bleed power under stress and I haven't had any issues not running a slipper clutch. I'm still a little skeptical about it, but it is holding up very well. This is the highest gearing I could find that would fit the car. I did try running 2 hardened steel 29T Mod 1 pinions at first as you can see in the studio footage, one on the motor and the other on the input shaft on the transmission, but after 3 min of running they destroyed themselves. Ironically the strongest pieces in the driveline disintegrated. The pinion gears had a 5mm D shaped cross section, nothing new there, pretty much standard fare. However upon closer inspection the input shaft on the transmission has an 0 shaped cross section, so the "spur" pinion gear was oscillating around the shaft and wasn't completely centered, causing it to self destruct. My bad.
    The chassis is made out of 3mm carbon fiber, hand crafted by myself. No fancy CNC machining here or use of an expensive mill or lathe, just a Chicago Electric angle grinder (read: Harbor Freight), a drill, and some patience. It turned out really well and I am very proud of it. The chassis is very strong and should stand up to a lot of abuse, and even though the holes were drilled by hand because I used the stock Lightning EPX chassis as a template they are very very accurate. The front skid plate raises the front bumper so the front tires have a better approach angle over obstacles, and the rear body mount was made out of angled steel and reinforced with steel rod.
    The body is from Amazon and is made out of PVC. It is cheap in every aspect. The tires are licensed Pirelli rally tires and they are mounted on standard 12mm hex 0mm offset wheels. The body is actually 190mm wide instead of 200mm, hence why the wheel stick out from the fenders a tad. There isn't any rubbing issues fortunately, but the body was advertised to be 210mm wide and it obviously is not. I guess that is karma for me not buying a licensed body.
    This is a very fun car, but I wouldn't call the project a complete success. The car is a great basher, but because more down travel was incorporated into the suspension the car does have a little positive camber on all 4 tires in order to keep the rear dogbones and front CV shafts from binding up. This does make the car less agile than I would have liked and a little more sloppy in the turns. The limited gearing options also does hold the car's top speed back, and the car isn't as capable as a WR8 like I had hoped for. However, the car is very fun to drive, is more capable than any other 190 or 200mm wide rally car I have ever seen, and the parts that are prone to breaking can be found online. Overall I think it is a great basher, and whoever gets it will surely enjoy it.
    If you want it, it's for sale! Here is an eBay link: https://www.ebay.com/itm/292324800007?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1558.l2649
    Thanks for checking it out, and let me know what you guys think! Next time I embark on another project (Most likely will be a 1.9" Scale Truck) I will for sure create a build thread for the car and send photos as I go along. Thanks again!
     
    sweet rc, Ecordian and Antho11 like this.
  2. Antho11

    Antho11 Studio Forums Elite
    ELiTE MEMBER

    Joined:
    Jun 21, 2013
    Messages:
    3,516
    Media:
    115
    Likes Received:
    1,134
    That’s a really cool car. The rally RC category has such a large potential, it just needs to become more popular.
     
  3. Low Budget Hobbies

    Joined:
    Nov 10, 2017
    Messages:
    19
    Media:
    8
    Likes Received:
    13
    Thanks man, yeah I've always thought the rally section of off road R/C's has been underrated. In my opinion it is so much cooler driving around an R/C that looks realistic like a rally car or SCT or scale truck versus something that looks like a toy, like a buggy or stadium truck.
     
  4. Ecordian

    Ecordian New Member

    Joined:
    Nov 10, 2017
    Messages:
    2
    Likes Received:
    0
    Not too big into rally cars myself, but that thing looks fun!
     
  5. Low Budget Hobbies

    Joined:
    Nov 10, 2017
    Messages:
    19
    Media:
    8
    Likes Received:
    13

Share This Page