traxxas nitro xo-1

[Sharkey]

i recently purchased a brand new traxxas xo-1 rolling chassis from fleabay. since they came out ive wanted one for a project, and being the last chassis i used for an odd project is now 10 years old and is pretty worn out i figured now was a good time.

so its not going to be any old nitro engine. a couple of years ago i got a chance to build an os fs40s-c 4 stroke. these motors were originally built around 12 years ago, they are an airplane 4 stroke that was converted for cars and trucks using a different profile camshaft and stiffer valve springs. they never really got popular because they werent a bolt in and had a fairly low power rating and max rpm. its been well proven that with a proper header and a carb change can double the output and increase the rpm. ive had mine running in a nitro tc3 for a couple years now, it pulled as hard as the .21 i had in it prior, the downside was lower rpm and top speed. ive got mine to consistently hit 26000 rpm, so its now not giving up much to a .28, and has far more torque.

ill be clear, my intentions arent to go 100mph, i know its not going to happen. i didnt choose the motor to go into the car, i chose a solid platform to put my 4 stroke into. the car is well designed, i liked the layout a lot better than the 1/8 scale gt cars.

for now, ive gotta brush up on my cad drawing skills. i have a cnc mill at my disposal and will be making a lot of custom parts for this.

 

[Sharkey]

i got some parts machined today. first pics are of the spur gear hubs

im using the xo-1 spur gears still, and going to run hpi thread on pinions for a nitro rs4 3 along with a 3rd gear pinion i machine. those will be used on a clutchbell ive yet to machine. while i was doing cad drawings i decided to do engine mounts, and a simple thing turned complex.

 

[Sharkey]

couple more pics. i got the transmission shaft made and the transmission mocked in place.

just a little mocking up, trying to get some ideas for brakes and a center bulkhead. im up in the air if im going to stick with the car crankshaft or move to the longer airplane crank and build a different flywheel. it may work better for the brake setup.

 

[Sharkey]

been slowly working away on it, haven't got much done to show off. ive got a center bulkhead drawn up but i haven't gotten a chance to cut it out, likely wont till the weekend. i have got a brake setup designed. im going to use the savage stainless steel brake set. its not really known for its braking power in a savage, however its very smooth and should provide plenty of brakes for an onroad car.

ive been working away on the flywheel and clutchbell, its just slow going. my lathe is small, it works great on aluminum (mostly what i cut) however steel over 1" diameter takes a long time to cut. to this point i figure ive got 6 hours into machining the flywheel and clutchbell.

the flywheel is done as far as the lathe work goes, i need to get it into the mill and cut the hole for the crank and the clutch shoe pins. the 4 strokes don't use a standard collet, the crank has a flat cut into it so i have to cut a D shaped hole in the flywheel. the clutchbell is about half done, i need to finish turning the outer diameter, cut the center and thread it for the pinions.

 

[Sharkey]

after a couple hours on the lathe tonight i finally have a complete clutchbell

i think ive got about 4 hours into that clutchbell. ive gotta look into some better boring tools, what i have just takes too long.

 

[Sharkey]

somebody on another forum noticed, so im letting the cat outa the bag. it going twin engine.

i figured with so much room in the chassis that twin 4 strokes would push this up a notch. now the engine on the left side (cloest to the camer) isnt the motor im going to be using, i bought it online and it turned out its not an fs40 surpass. i am able to convert it for for car use, however it wouldnt be the same as the other motor. i have got a proper fs40 surpass on its way, i haven't decided weather im going to sell the non surpass or save it for another project (fs40 in a savage?)

right now im just busy machining parts still. ive already got a 2nd flywheel machined, need to machine another clutchbell, and still need to design pilot shafts. ill be cutting out the center bulkhead tomorrow and hopefully doing the finish machining on the flywheels.

 

[voo2doo]

Gonna be a nice one!

J

 

[Rossco]

That's gunna sound nice...

 

[Sharkey]

so a little update, although no pics. i received my fs40 surpass, and lets just say it was a clear case of why you don't by used engines. was very clean on the outside, however inside looked like it hadn't ever had after run put in it, and it sat with old fuel for 10 years. it was gummed up so bad i was unable to get the sleeve out, i had to soak the motor in solvent for 2 days, then had to hammer the sleeve out, destroying it and the piston. i did however manage to use the parts from both the mis-purchased fs40 and the gummed up fs40 surpass, along with the new parts to convert it to an fs40s-c to build a matching engine to what i already had. a very round about way to get one of these engines, but oh well.

hoping to make a bunch of progress on this project. ive got a long weekend with nothing planned.

 

[voo2doo]

That's gunna sound nice...

Hey mate...been a while.
J

 

[Sharkey]

spent most of the day working on it today and made some good progress. i now have the transmission finished, the center bulkhead is bolted in, brakes are mostly figured out, and the driveshaft is cut to length. i started making a pilot shaft, however didnt get very far on it, just enough to do some more mock up for pics.

hoping to get both pilot shafts made tomorrow and finish the 2nd clutch bell off.

 

[Rossco]

Hey mate...been a while.
J

Hey James....
Yeah..it's been a very long while...
Been flat out like a lizard drinking with work...all the better to save for this addiction hey

 

[phildogg]

I'm liking this project. I owned a x0-1 but ended up selling it, didn't care much for it. Seemed to pull to the left on high speed passes. messed with it checked everything i could think of and then sold it. I like the mechanical brake idea. Would allow for a brushless airplane hv esc to be used.. I haven't seen the four strokes in along time . I remember when they came out the had it in rc car action in a t-maxx. looking great here.

 

[Sharkey]

haven't had a lot of time again, but i did manage to get some more machining done tonight. the slots are now in the chassis and the motors are mounted.

it was time to put a little more of the car together to figure some more stuff out. the fuel tanks and throttle servo are just sitting in place right now

 

[Sharkey]

ive had some questions about the milling machine im using, i figured id post some pics and a video of it cutting my top plate.

the rear portion of my top plate after cutting

everything i got cut today. the top left is my intake manifold and manifold adapter, a brake spacer, and the top plates.

the top chassis plates sitting on the car

and as a bonus i thought id post a video of the mill cutting the rear section of the top plate

 

[voo2doo]

Great project,great engineering!
J

 

[Sharkey]

well not the big update i was hoping for. i tried to get all the parts powder coated this weekend, turns out the blue powder i thought was going to match the traxxas blue was too far off. i had to order some other powders and hope to have them by the end of the week.

none the less i do have some pics

thats the new brake setup. im now using savage dual red fiber discs. those brakes are strong enough to do a complete front flip with my extended chassis savage, they should be plenty of braking to stop this car.

the receiver battery and aluminum hold down. the battery is a turnigy LiFe 1450mah, no need for a regulator with it. the hold down is pocket milled so it sits down on the battery, no way it can come out of there.

i did get some parts coated. flywheels and clutchbells are done in semi gloss black and the top plates are chrome smoke, its a very close match to the factory chassis and top plate.

 

[voo2doo]

Looking sweet Sharkey. Keep the updates going.
J

 

[Sharkey]

powder coating is now finished and the car is going together for the final time.

still waiting for a few parts to show up to build the throttle and brake linkage, and i need to build some brackets for the telemetry rpm sensors.

 

[Sharkey]

ive been slowly picking away at it and im almost done.

at this point its very close to done. the linkage is all done, exhaust is done. im not entirely happy with the exhaust, however i was limited on space so i had to compromise a bit. it comes out in the channel under the car as you can see in the underside shot of the car. i still haven't built mounts for the telemetry rpm sensors, and i haven't hooked servos or put the temp sensors in, so i still have a few things to do. i also need to figure out a starter box, the one i have isnt going to work out (associated for nitro tc3, set up for a sideways mounted motor). i tried it on an ofna pink starter box, also doesn't look promising. im hoping i don't need to build my own starter box for this beast.