Custom Carbon Fiber Brushless RC8T Pics

[lutach]

The trucking industry uses such an epoxy and the joint will stay together even after a crash. A few if not all the new over passes are joined with epoxy as well.

[Ryu James]

so here is the history of the Carbon RC8T so far.

version1: 5mm Carbon chassis. looked badass but jumped like crap cuz the chassis was just way to stiff. super silent setup due to sound/vibration absorption by the thick carbon

version2: 3mm 7075 alum chassis. this ran pretty good overall. add lots of weight though since i am not able to mill the chassis and it didnt look that great. it sure did jump better though. much louder than the carbon chassis.

version3: 3mm RCM chassis and RC8T brushless conversion kit. sound is inbetween the carbon and my own alum chassis. sounds good. neither quiet nor loud. esc is not ideally mounted. and worst of all - no mechanical brakes. better than version 2 in quality in appearance but lack of mech brakes is a big hit.

so needless to say there will be a version 4. i hope to nail it with this one. have you all started to get an idea of what a perfectionist i am? or anal? whatever you want to call it. anyway, version 4 i am just going to go all out. its going to be a carbon chassis, 3mm this time in hopes of some flex for good jumping and, the front kickup will be there cuz i will fuse the front end from the stock chassis to the 3mm carbon one. also, all cuts, milling, and holes i am going to have professionally done with a CNC. it will take some time and money but at least i will end up with the Rc8T i set out to build. or at least i better or i could be very upset....

version3 pics (water droplets cuz i just finished a killer snow run)

[rootar]

james the front center chassis brace goes in the cent of the tabs, there is a different ball you press into the chassis brace to get it to fit. also why did you choose to mount the esc off the back of the center diff when is alot of room on the chassis behind your battery?

looks good, and mechanical brakes arent needed.

[Ryu James]

thanks rootar,
i have already moved the chassis brace after talking with Mike. and i mounted the esc where it is for better l/r balance but i dont like it there so i am going to move it behind the battery today. i am also putting im mech. brakes today. i think it will be sweet when done.

take lots of build pics for this noob.

[Ryu James]

Originally Posted by BL Dreamer

take lots of build pics for this noob.

already was planning on it. i will post them all when finished.

[Ryu James]

here is the build pics of version 4 as promised. still needs some adjusment though. because the center diff sits so high off the chassis with the RCM conversion i had to use 3 shims on the servo stands and 1/8" of spacers on the servo arm and the servo still doesnt sit high enough. so i am going to somehow try to make the setup work without the huge center diff shim.

i also had to use a Tekno long shank pinion after making the spacer so that the motor can didnt rub the brakes. anyway, the pics tell the story for the most part.

i also move the esc behind the battery. looks much cleaner.





2 pices of 3mm carbon glued together for a 6mm piece. just enough to clear the brakes now. one side had to be ground down to clear the brakes. 2 screws hold the piece against the motor and the other two screws hold themotor to the mount.

[Ryu James]

a couple more pics. the things seems to drive great now. havent been able to test on track yet but will soon. love the mech brakes finally.






pic of the shims and nut used for spacer on servo arm

[MetalMan]

Aluminum may be a better material for the brake spacer because it is thermally conductive - as is the motor mount. CF won't transfer any heat, so your motor might run a bit warmer than with an aluminum brake spacer.

Here is something else to consider: you could use a smaller servo for the rear brake only to save weight, and then mix in motor brakes since the motor brake tends to get transferred to the front anyways (this is what causes these conversions to push with motor brakes only). With this setup you can tune the braking from your radio without messing with any linkages. It's just a thought, and this is the setup I am using on my 1/8 buggy.

[Ryu James]

so this weekend i had it on the track finally. it did seem to run hotter than normal. after 20 minutes of hard driving my motor temp was 144*, esc was 135*. this is on an indoor track so ambient temp was roughly 70*. this is alittle warmer than i like to see so i may try the alum suggestion but i dont have any thick enough right now.

i have made some adjustments since the last pics. i got rid of the center diff shim so that the brake servo lines up without all the shims and also this really lowered my CG. i am able to run 13/46 gearing now for less rotational weight.

the thing drove amazing at the track. after a few suspension tweaks it was perfect and absolutely nobody was even keeping up. there was a lot of interest in it. hope this spurs others to build their own 1/8 conversion since it is in its infancy here.

anyway, i am pretty pleased with it right now and dont plan to make any changes to this current setup for a little while. i still want to build a carbon chassis that will work so i will be building a milled 3mm carbon chassis with kickup. i think this will provide the flex that is needed. i also now have the tekno chassis for the RC8T and it looks very nice so i plan to try that soon also, maybe with a complete separate build though.

[Spencer!]

im not sure if anyone has mentioned this before about the kickup on the front section of the chassis but carbonfiber can be heated and bent the trick is rapidly cooling it off to maintain strength and shape. Just remember to much heat can hurt you where as not enough heat will not ruin anything.

I also made a carbon fiber chassis (4mm) except mine was for my 8ight buggy...
here is a picture from way back when it was still in building/planning stages and investment in a neu motor

[Ryu James]

so i tried the idea of heating up the carbon to bend it and it worked but it also ruined the integrity of the carbon as i suspected. its still pretty tough but i dont think it will hold up off a big jump. its actually really strong if i push on the nose upward but if i push against it downward i can hear it cracking. i could probably break it with my hands. however, most of the force put on the kickup is in an upward motion so it might hold. this chassis has become just a test/throw away chassis so i am not too worried about it. i am going to order some 3 and 4mm pieces to find the best mix of strength and flex. this 5mm piece is just too stiff.

you can see in the pics that the layers of carbon have slightly separated and the outer layer has bubbled away from the others. also, this produced a large wrinkle on the surface that i tried to dremel down but it still may affect how the front diff case mounts up. might not sit real flush.

i think with some practice this could be done without ruining the piece at all. i didnt think to try it a few times on some other scraps before doing it on the chassis. oh well. thanks for the tip.

[pb4ugo]

Originally Posted by Spencer!

im not sure if anyone has mentioned this before about the kickup on the front section of the chassis but carbonfiber can be heated and bent the trick is rapidly cooling it off to maintain strength and shape. Just remember to much heat can hurt you where as not enough heat will not ruin anything.

I also made a carbon fiber chassis (4mm) except mine was for my 8ight buggy...
here is a picture from way back when it was still in building/planning stages and investment in a neu motor

The epoxies used in CF are not thermoformable. The only way to have a structurally sound bend in it is to mold it there.

[pb4ugo]

Originally Posted by Ryu James

this is completely true and apparent after trying this out. i do have a source now that is going to make a custom matched tool so that i can get some carbon sheets with the kickup angle molded in. these will be absolutely awesome and should be available for retail purchase. i will know more soon.

Didn't you buy this piece from Dave Inkel (D.A. Graphite)? He used to do chassis back in the day with the kick up molded in. I spoke with him about doing it for me a couple years ago and he said he could if I sent him the form. I never did because I decided it would be cheaper and more fun to do it myself.

[Spencer!]

yes molding it that way from the start in the initial mold process is going to better and more structurally sound. However slighty heating and bending it 6-7 degrees should not hurt unless to much heat is added and the epoxy begins to bubble or distort.