Custom RC8T carbon fiber chassis question.

[Ryu James]

i am building a RC8T brushless conversion and am going to make my own carbon fiber chassis. my question is this; the stock chassis has the slight angle up on the front end. i cannot find anyone who is willing to make a custom cf piece with a bend in it like that. so i will just have to use a straight piece, which will work, but i am wondering if this will effect how the car performs, handles, or anything like that. anyone tried this before?

obviously i cannot bend the carbon fiber but i have thought about just using a 4mm alum. sheet. can 7075 alum be bent ever so slightly? if so, how is this done? do i just heat it up?

[gtxracer]

Yes, 7075 can be bent slightly, but it will be hard to do. The 6061 aluminum is pretty easy to bend, but I would never use it for a chassis. I made a chassis for my first gas RC, a Kyosho Sandmaster, which came with a PLASTIC chassis. We had to have a machinist make the bends. We were hitting it with a hammer and it only bent about 30 degrees, which is around the same angle most chassis's use for kickup, which is what you're describing.

Kickup, sometimes called kickback, or the angle up in the front of the chassis, helps absorb bumbs, collisions, and landings. You DO need it, so don't just make a flat CF chassis. The way CF is made, it is layed down in sheets and uses a epoxy to dry and harden in it's place. It takes many layers to make even 1/8" sheet. It can also be very flimsy. It IS possible to make a CF chassis with kickup, most people just don't want to take the time to do it.

My advice? Use the stock chassis and make yourself a CF battery/radio tray. That's what I plan to do agian. Here's a CRT I had. The radio plate and battery trays were made by nl12 here on the board. I plan to have a similar design:

[Ryu James]

Originally Posted by gtxracer

Yes, 7075 can be bent slightly, but it will be hard to do. The 6061 aluminum is pretty easy to bend, but I would never use it for a chassis. I made a chassis for my first gas RC, a Kyosho Sandmaster, which came with a PLASTIC chassis. We had to have a machinist make the bends. We were hitting it with a hammer and it only bent about 30 degrees, which is around the same angle most chassis's use for kickup, which is what you're describing.

Kickup, sometimes called kickback, or the angle up in the front of the chassis, helps absorb bumbs, collisions, and landings. You DO need it, so don't just make a flat CF chassis. The way CF is made, it is layed down in sheets and uses a epoxy to dry and harden in it's place. It takes many layers to make even 1/8" sheet. It can also be very flimsy. It IS possible to make a CF chassis with kickup, most people just don't want to take the time to do it.

My advice? Use the stock chassis and make yourself a CF battery/radio tray. That's what I plan to do agian. Here's a CRT I had. The radio plate and battery trays were made by nl12 here on the board. I plan to have a similar design:

thanks for the tips. i have a 7075 alum plate on order but held off on the cf. the RC8T kickup is only 7* actually. very slight. but i already have all the motor mounts, battery tray, etc. i am going to try to use the stock chassis first but if it doesnt work then i will cut my own from the alum i guess.

btw, what kind of truggy is that in your pics? where did you get those beadlocks? look very cool

[BL_RV0]

That is a CRT. The beadlocks are maximizer x75 offset beadlocks.

[MetalMan]

How about a hybrid chassis? 7075 up front to take care of that kickup, and 3mm-4mm carbon fiber for the rest of the chassis to keep weight down and rigidity up.

[gtxracer]

^^^ What he said.

I liked the LPRs better

[Ryu James]

Originally Posted by MetalMan

How about a hybrid chassis? 7075 up front to take care of that kickup, and 3mm-4mm carbon fiber for the rest of the chassis to keep weight down and rigidity up.

i was thinking the same thing but not sure how to best mount the two pieces together. any suggestions?


a company called matrix concepts does something like this although they still use all CF but i was thinking something along the same lines but with alum for the nose piece.

http://www.matrixconceptsinc.com/

you can see in their pic of the losi CF chassis that the kickup is a separate piece screwed to the main chassis.

i was talking with Danny from TEkno and he said the MatrixConcepts chassis is actually 3 pieces and that quite a few guys use them at ARC Raceway where he races. he said surprisingly they hold up very well. he said he has seen them come down on the 2nd peak of a double and hit dead center on the chassis, in stead of clearing the jump, and not skip a beat. i would have expected to hear stories of them snapping in two. after he told me this i felt a little more open to trying the CF for a chassis.

also, the piece i am getting would be 5mm 1k weave. it is still lighter than a 3mm alum, or a 4mm milled alum chassis. the 1k weave is a bit stronger than a 3k weave due to finer weave i am told.

anyway, we'll see.

[lutach]

Have you tought about laying up your own carbon fiber plate with the kick up? It's not that hard to do.

[MetalMan]

But to lay carbon fiber you at least need a strong vacuum pump, and even better would be an autoclave. A vacuum pump wouldn't be too hard to come by, but then other materials would be needed - vacuum bag material, thick rubber adhesive tape to seal the bag, mylar, wax for the mylar, and of course the carbon fiber cloth and epoxy resin. Two identical pieces of aluminum or some other metal with the kickup angle would be placed on both sides of the carbon fiber cloth, and clamped together to make the desired shape.

Mr Constructor in Germany has done a lot of 7075/carbon fiber integration. I will try to find his website and post it later after I get home from work.

[lutach]

Originally Posted by MetalMan

But to lay carbon fiber you at least need a strong vacuum pump, and even better would be an autoclave. A vacuum pump wouldn't be too hard to come by, but then other materials would be needed - vacuum bag material, thick rubber adhesive tape to seal the bag, mylar, wax for the mylar, and of course the carbon fiber cloth and epoxy resin. Two identical pieces of aluminum or some other metal with the kickup angle would be placed on both sides of the carbon fiber cloth, and clamped together to make the desired shape.

Mr Constructor in Germany has done a lot of 7075/carbon fiber integration. I will try to find his website and post it later after I get home from work.

www.ace-cars.info

I've seen very good plates that were done with just glass, cf cloth, wax and some weights to put on top of the smooth glass surface. You can also try and make a 2 piece mold out of fiberglass with the kick up first and use that instead of the 2 chassis method.

[_paralyzed_]

the price on the matrix kit doesnt look bad, maybe just buy that

[Ryu James]

Originally Posted by _paralyzed_

the price on the matrix kit doesnt look bad, maybe just buy that

i need a TEkno RC shaped chassis, not the losi. also, i need to put the screw holes in myself. the matrix is already drilled out. but youre right, the matrix chassis looks nice.

[Ryu James]

Originally Posted by lutach

www.ace-cars.info

I've seen very good plates that were done with just glass, cf cloth, wax and some weights to put on top of the smooth glass surface. You can also try and make a 2 piece mold out of fiberglass with the kick up first and use that instead of the 2 chassis method.

i found this site.

http://www.hunterdogs.org/GeneralInf...COMPONENTS.pdf

it sounds possible but...hmm. where could i get all this? i would rather just hire someone to do the custom piece. you guys know anyone?

[lutach]

Originally Posted by Ryu James

i found this site.

http://www.hunterdogs.org/GeneralInf...COMPONENTS.pdf

it sounds possible but...hmm. where could i get all this? i would rather just hire someone to do the custom piece. you guys know anyone?

Good place to buy carbon fiber is ebay. I have a few other places, but the price per yard at them is around $30-40. I have bought plenty of carbon fiber on ebay and I haven't had the time to do any of the things I want to do with them.

[pb4ugo]

Originally Posted by MetalMan

But to lay carbon fiber you at least need a strong vacuum pump, and even better would be an autoclave. A vacuum pump wouldn't be too hard to come by, but then other materials would be needed - vacuum bag material, thick rubber adhesive tape to seal the bag, mylar, wax for the mylar, and of course the carbon fiber cloth and epoxy resin. Two identical pieces of aluminum or some other metal with the kickup angle would be placed on both sides of the carbon fiber cloth, and clamped together to make the desired shape.

Mr Constructor in Germany has done a lot of 7075/carbon fiber integration. I will try to find his website and post it later after I get home from work.

Using a FoodSaver for vacuum bagging CF works very well. FoodSavers can be bought brand new for $100 and at a yard sale for $10. Use a wood (for ease of shaping) form for the angle and finish it nicely with poly and mold release wax. Lay it up on top in quasi-iso orientation, use some peel ply and cotton batting on top for the excess resin and insert in double sealed FoodSaver bag. Draw the vacuum and double seal the other end. Surely not as good as pre-preg in an autoclave, but leaps and bounds better than a wet cure and only a shade behind a professional vacuum bagged set up.