Hi guys!!

I have an old Traxxas T-Maxx that I've converted to electric drive, I've stuck with the old aluminum chassis and just making that work with the electric conversion since I had an idea stuck in my haed all along that I would want to make a chassis of my own and now is the time.

Last sunday the car ended up looking like this



And now is a good time to start thinking of making a chassis better dedicated for the electric conversion. I'm going back and forth in my head batteling whether I should make it out of carbon fiber or aluminum and I thought that I better ask someone else for advice.

What worries me about carbon fiber are two things. How will it stand up for wear and what happens if I land the truck wrong.

Starting with the second question, if I decide to go with carbom fiber I will buy a 3mm carbon fiber plate (prepreg) and simply cut it into the size and shape I need. How will that cope with a hard hit? Lets say I jump at speed and land on something that hits the side of the truck, how much force will carbon fiber sustain??

And second, the first question, since it's a monster truck it rides quite high, meaning that it doesent really drag the chassis on the ground that much but it kick up a lot of dirt, gravel and rocks underneath the chassis. The old chassis looked like this after a while



Note that the aluminum chassis are not the reason for the truck braking, thats caused by bad shockabsorbers that ment that a bad landing on the rear broke the rear skidplate and then another bad landing caused the truck to become two

Hope I'm not confusing you too much and that you can help giving me advice about this.

I do have an idea of making 1mm aluminum plates to mount underneath the carbon fiber chassis to make it more bash resistant. If anyone else have any other ideas or advices please share them with me =)

Hi Swede,

I have had similar thoughts to my own RC car chassis.  The main problems that I saw on mine were that the chassis cut directly from flat plate would have most of the strength cut out of it if I just followed the form of the original chassis.  Because the strength in CF is 'along the thread' it meant twill that is generally used in pre-made plate gave equal strength in unnecessary directions.  Also, pre-made plate did not allow for any contours which also give strength, nor reinforcing for cut/narrow areas.

My idea was to make a buck out of MDF based on the chassis including any improvements/modifications, then make a mold from that (the usual sealing, painting, etc).  Using a mold would allow the underside to be nice looking, flat and planned.  For lightweight skid plates I was going to use an old trick given to me ages ago ... icecream container lids cut into sections!  Very slippery, very light, very cheap, very expendable.  On my real race car I actually use old chopping boards cut into strips.  The main reasons are they can be heated and bent, they are very slippery and they don't grab the asphalt like our old steel bash plate that they were 'protecting'.

When building the layers I was going to use (approx.) 2 x twill laid straight, then 2 x twill diagonal to prevent twist, then 1 x unidirectional along the chassis, and some tow from scraps in the sections that were weakened by cutting, and more & scraps for reinforcing, then topped with 2 x twill for looks.

Because heat from batteries and motor might be a problem, I was going to use post-cure resin, and definitely epoxy because it will be wet quite often.

BUT, mine has the suspension components bolted onto strong section of chassis.  It looks like your suspension both front and rear bolt onto extension arms that bolt onto the chassis.  This seems a strange design to me, and I would consider laying stainless steel arms into the laminate as mounting points for those arms.  The main reason here is that I do not know how the CF would handle the constant abrasion from the minor movements that those bolts must produce, and the compression that you would produce in tightening those up.  Unless of course you can come up with a better way of mounting them, or incorporating them into the layup.

Good luck, and take all my advice with a grain of salt!