Cheesing the Chassis - Lightening an R/C's Chassis

Cheesing the Chassis - Lightening an R/C's Chassis
How to drop weight and improve performance on your R/C.

R/C chassis lightening and modification has been discussed on about every R/C forum since the infamous Jang introduced the chassis modified and competition eating Ultimate Stampede and Rustler. Inspired by Jang's efforts, I gave it a try and netted impressive results on all my R/Cs but with a different approach. To date I have done about a half a dozen chassis for my R/C's and for friend's cars and believe my "Cheesing" or skeleton'izing method to be a great alternative more complex modifications. Jang's method was more focused on cutting away pieces from the edges of the chassis, my "Cheesing the Chassis" method prolifically punches holes or ovals in the chassis to achieve a similar weight reducing result while retaining what I believe to be more skeletal strength for bashing. Although you don�t have to wait until all the basic upgrades are completed, lightening your chassis should be considered more of an advanced upgrade and is best performed after you have some time behind the throttle.

Which is better?
Jang's modification is without a doubt lighter, however I would lay money that mine will take more of a beating in the long run - as of Decmber 2008 this chassis is still running strong. The Ultra-Rusty modification as an example has taken many very ugly 40+MPH tumbles without breakage running brushless systems. I have an email from Jang stating he believes his chassis modification to also be almost as strong as stock, so I will let you be the judge on which method to go with. Were my modification stands out is that you do not need to be a genius with a Dremel tool or even have one, as my method involves either simply drilling holes or doing a connecting the dots routine with your Dremel tool.

Weight Reduction Expectations
On pretty much every modification I have done using my Cheesing the Chassis method has netted at least a 20% weight reduction in the chassis. The Rustler chassis for example are 195 grams stock without any hardware, after my modification the weight drops to 150 grams. That's a huge 45 gram weight reduction or the equivalent to about 18 large chassis screws. with little noticeable increase in chassis flex.

Tools and expertise you need
Safety glasses, heavy gloves, pencil, ruler, drill, a 3/8" drill bit, a Dremel Tool, a metal cutting wheel (#542 cutting shaping wheel works best), and a 1/4" steel shaping bit (such as the #115 high speed cutter), a fine grit mini-drum sanding bit is also handy for finish work. Metal Dremel bits work best for the cutting task. Do not use the stone or emery cutoff wheels, these will blow apart while cutting plastic like a grenade throwing off shrapnel. Do you need a Dremel tool? No, but it will REALLY help to get the job done quickly with the best results if your cutouts are oval shaped. A $300 Proxxon Mini-Mill will allow you to do this with outstanding speed and precision.

The assumption here is if you already own these tools, you probably also posses the expertise to use said tools. The Dremel work requires the ability to cut a straight lines and use the shaping bit to clean up the edges, if you can manage that you are in good shape. You do need a standard amount of eye to hand coordination, a Dremel type tool with the bit mentioned above (if you are cutting ovals), some sandpaper, a drill, some drill bits, and time to complete the project without feeling rushed. I would set aside two nights to have the time to do a good job.

Performance Expectations - Why would I want to do this?
The easiest answer is - power to weight ratio. There is a reason every race car, truck, and motorcycle is stripped of every non-essential part and/or replaced with some lighter carbon fiber part. The motor, brakes and suspension all have less weight/mass to manage and therefore can perform faster, accelerate quicker, and handle better. It is the same idea with RC cars. The lighter the RC car, with all other things being equal, will out maneuver and out accelerate the heavier car. The less your R/C weights the less it will handle like a big turd and more like a performance vehicle. The general idea is to lighten the car by removing the non-essential weight; i.e. everything which does not effect durability.

Durability?
If strength and durability are key in your driving styles you may want to skip chassis modification. Contrary many beliefs, lightening the chassis even if done correctly will minimally reduce overall durability, if done incorrectly things get very ugly. If you are a really heavy basher and are set on reducing weight, target dropping a 1/2 oz (13 grams) with a simply battery tray perforation. This will still net about a 7% overall chassis weight reduction of the stock 6.87oz (195 grams) stock chassis. Use this weight reduction to offset some strength enhancements such as a Swami Brace. Remember you are trying to remove excess and unneeded weight, structural vertical cross members are required to assure chassis strength. As of this date I am still using the same chassis on my Ultra-Pede and have only replaced the Ultra-Rusty chassis once (50+ mph curb hit that nothing would have survived - very bad).

The Approach
Start by removing all the electronics, unscrewing and freeing the chassis so that it can be completely stripped. This will make it much easier to work on. The next thing is take some time and really look a the chassis, flex it, see how it moves, figure out what areas function as braces, which are load bearing, and which serve little purpose. On the Rustler chassis, screwing in the top deck and adding a rear ESC plate greatly strengthens the chassis - so don't freak out about the flex. The vertical braces running each way on the chassis should not be modified. The bottom of the battery tray provides little actual strength and can be perforated or ovalized without any problems and include handy molded guides in the bottom of the tray that make this part a really easy modification.

Once the battery try modification is done, shedding weight on the Stampede gets tricky and in involves careful drilling and very tricky Dremel work - I would stop at the battery tray on the Stampede.

On the Rustler there are more areas that can be perforated or ovalized to shed weight.

1. Battery Tray

2. Front chassis

3. Front bulk head

4. Side wings

5. Trimming the motor mount area such as you would for a heat sink.

6. I have not done this area again since my first chassis, I think it weakens a key structural area to much and was the site of my first and only breakage (a 50+ MPH crash).

7. Top Deck

Planning is essential on this project, especially if you want it to look cool after you are done, so take the time to map out what you are going to do� and please, use a ruler and marker.

Making Holes & Cuts
Ovals and holes seem to be the easiest to create and finish. A 3/8� drill bit was the perfect hole size for the Rusty and Stampede and provided an easy start for the straight forward process of drilling two holes and connecting the dots with the Dremel tool. After all the rough forming work is done using the Dremel, you can expect to spend a night hand finishing with sandpaper all those cuts to look like they came from the factory mold although I normally smooth out the cuts and knock off the edges with a #115 high speed cutter and call it good enough.

Final Weight In
With the Jang's 3.02 lbs. Rustler being a lofty original goal, I decided it was time to throw the Ultra-Rusty on my digital kitchen scale and figure out where it weighted in. First let me say the Ultra-Rusty is a different purpose built animal than Jang's waif like racing Rustler. Mine was built for bashing durability, speed, my amusement, and on occasion, racing. I was pleasantly surprised that with all my upgrades that that were actually adding weight such as a wide conversion, nitro Rusty shock tower, full bearing and carriers, adjustable camber links, high torque servo, diff ball slipper, and the Mamba Max brushless system, just to name a few, the Ultra-Rusty weighed in ready to roll at 3.40 lbs (without the battery) and just under stock weight. I guess my method of "Cheesing the Chassis" and trimming the transmission housing really worked and balanced out the weight additions nicely. There is still a ton I can do if I want to start trimming arms, leaving out redundant screws, drop the RPM bumper, and loose the front wing, and the biggy switch from the heavy weight Dirt Hawgs to more race oriented lighter tires. Some of those weight reductions I just don't think I will do, because I do need the extra strength and durability that those extra ounces provide.

Happy Dremeling!