Gas R/C car

I have already built one robot that i am still improving upon but i needed more speed…

so ever since this winter i have wanted to build a gas r/c car and haven’t really had the money up til about now because i will soon be getting a better job.

i look at some of the systems in the T-maxx cars and saw how simple they are, i will most deffinately be using the steering system which is the simplest i have found anywhere and I am thinking i would like to make it have suspension and maybe 4-wheel drive so it can have fun off road too.

and i need some suggestions and ideas, i dont really have a size in mind i would like to make it much larger then the T-maxx cars beacause i am going to us some sort of small gas motor from either something like a chain saw or weed wacker, or something else which ever i can find cheaper. But i dont really have any specs on any weed wacker motors because i can find them, any one know the average torque and RPMs for one?

i dont know the wheel size, i make make it interchangeable so that on the road i can put large wheels on to go faster and then smaller ones for off road

another HUGE problem is the differential, anyone know of any inexpensive solutions? i was thinking of using one off of a T-maxx which i would figured would be ok because they r hardened steel and made for high motor speeds if they are used in cars that can go 60 MPH+ would it be fine with a weed wacker

if(most likely) i use a weed wacker motor i need a centrifugal clutch to use with, which would means i also need the idle speed of the weedwacker i will use, so anyone know of good places to get a centrifugal clutch for cheap?

I actually need help on “pepping” up a stock $5 car from Family Dollar. Right now we have the biggest motor we can fit in it. What else can we do to make this thing super fast? The car is a Chrysler Powerbook or something like that…we already stripped the decals and started painting it. So, what else can we do?

What exactly are you trying to do? Take a T-Maxx and make it have a bigger chassis with a bigger engine? What is the end goal of this project?

If you are looking at a wheedwhacker engine, I’d suggest you look at a chainsaw one instead. Unlike wheedwhacker engines, they usually have the pull start in the rear so it will be easier for you to adapt something to the shaft in the front. For a centrifugal clutch, I know most gas chainsaws have one, but other than that I’m not sure about any details since I don’t have a gas chainsaw. It is possible (not certain, but you could try) a gokart style centrifugal clutch would work if you made a properly sized keyed shaft (5/8" or 3/4") to adapt to the engine.

These wheedwhacker and chainsaw engines can usually get up to around 7-8K rpm (provided they are the 2-strokers).

why wouldnt i be able to adapt somthing to the shaft if the pull start was in front? and a chain saw is madd expensive : ’ (

and the end goal is like a custom gas powered rc car, u can compare anything to a tmaxx, a fordeplorer is a huge tmaxx with more power and more space

I have a question. Just how big do you plan on having this robot be? And if you want just a fast robot, I’d recommend just using a T-Maxx chassis and an engine that comes with the RTR version. It also has an E-start so it’s easier and more reliable than a pull-start like on other engines. The only thing I’m wondering if you’re going to throw in a weedwhacker motor or a chainsaw motor is can the drivetrain parts of a 1/10 scale monstertruck handle it? You might go through a lot of the gears for the 2 speed gearbox that it comes with, unless you’re going to make a custom gearbox for it and I say KUDOs to you.:smiley:

You wouldn’t have to modify the chassis much if you’re going to use the RTR T-Maxx, maybe just to add a microcontroller to it, because all you would need to control are the servos, one for throttle and one for steering. If you want something bigger to work on, maybe you might want to check out the Traxxas 1/6 scale Monster Buggy.

you should google giant scale r/c, there are a bunch of companies who build cars and trucks powered by zenoah gas ignition engines. you would be suprised how cheap you can get a glow engine for.

i never sed i am going to use the transmission from the t-maxx i sed i am going to use the differential and buying a tmaxx to rip apart would defeat the purpose of me even doing it cuz i would be spending like 400$ on a couple parts that i can get on ebay for like 30$ and i was saying that i may use the differential cuz i was asking everyone else if they think it would work so i dont know if it would work either

I currently own a both a 2.5 T-maxx and a Lost LST, both nitro powered.

I am pretty sure a T-maxx transmission will blow to pieces stock, if you plan on using an engine more power than what comes with a stock T-maxx.

They can also blow to pieces if put under load such as cornering and braking.

I have never seen one in action or in person, but I bet a differential from one of these would hold up:**&P=0

Either that or you could spend some cash buying all metal parts for a T-maxx differential. The only things that are metal in a T-maxx differential are the gears and shaft, everything else is plastic and very prone to breaking. That setup might work, but it all depends on how much stress you put on it.

Look around I am sure you can find a differential much better than a T-maxx differential.

You might be able to find something on this site

i was looking around and instead of like a weed wacker or chain saw motor i would buy a 47cc or 49cc pocket bike motor off of ebay, now that would give it speed and off-roads capabilities :smiley:

Just make sure you know what you are getting into. This project isn’t going to be cheap. Especially when you start getting into 1/4 scale servos and stuff like that.

i kno, i figure maybe 700$ but it will go way faster then the ones you can buy for 700$

the only problem is the differential, i figured for now if i cant find anything that i dont HAVE to have one i can just u a solid rear drive shaft until i can make one, seeing as how it is really easy to make one with one have 5 gears, but then i have to figure out what to do for lubrication because chances are it will just be mounted on a 1/4" aluminum plate

and i need to make a rool cage when i make the main frame so that i dont brake it the first time i take it out and try jumps,

my friend owns like 5 acres and they are all in his back yard and he goes dirt biking there so the jumps will be fun to test it on

If you are going to take jumps, you should make the car as light as possible, but don’t sacrifice durability. For the role cage, do you have access to a welder? Even just a small arc/stick welder should work. If not, maybe an oxy-acetylene torch for brazing? If not, then perhaps a simple roll bar (as opposed to a full cage) would suffice. Find some tubing that has a hole the right size to tap for a machine screw/bolt. Then bend a hoop (leave the ends straight) and tap both ends. If it is aluminum, it is possible that you could just cold forge the threads using a Grade 8 socket head cap screw.

What is the car going to be based on other than the pocketbike engine?
Basically, what off the shelf parts are you using and what are you making yourself? I’m insterested in exactly what the frame, suspension, driveline, and steering are going to be and roughly what the overall dimensions are going to be.

pretty much everything will be made by be or i will be peying someone to machine, we have a cnc mill at skool that i can use that i will most likely make parts on.

i am not sure on yet, i may wait til after the wholething is made to have suspension so Iknow what to buy, in terms of strength because i dont want suspension on it fomr a mountian bike if it is like 100 poyunds, buit i also dont know what the force for max compression is on the T-MAXX suspension is.

Drive Train-
-either a weed wacker, chainsaw or pocket bike motor
-when i make suspension i will have to make drive shafts with U-joints in them, or buy alot from socket sets
-the main drive shaft i don’t know yet because i dont have a engine, when i buy one i will update
-the differential, i may not start out with one because of the intial cost
-to control the throttle i will use a servo
for a clutch i will use a centrifugal clutch made for the motor i will buy(mostlikely the pocket bike motor), the only problem is i think they only come with a sprocket on the output, which wouldn’t be a problem but those sprockets are weird because i bought one once and it didnt fit #35 chain, so i will have to machine that down to a cylinder and weld somthing on or just weld it to the sprocket so that it is a longer perimeter which will make the stress on it less and which will reduce the over all stress because of the larger diamter

i doubt i will have them on when i first finish it but WILL eventually add for saftey

i will use a T-maxx/E-maxx/Traxxas model TQ3 am wire controller, the only problem is that i dont know the maximum range of it, this will be the first item i buy because if i have no way on controlling it there is no use in making it

Steering- the steering will be based on the T-maxx/E-maxx/Traxxas steering system, i may start out with off the shelf parts but will eventually upgrade to machined aluminum part because of the forces on turning at high speeds, especially on uneven ground and in the dirt/sand

Frame-i will most likely use 1/16" walled 1/2" square steel tubingfor the first frame then upgrade once everything is in working order and i have added what i wanted( i have like 30 feet of it in my basement and i made my robot frame out of it which remind you i must is very very strong)

then i will probally use 1/8" walled 3/4" walled square aluminum tubing or use one 1/4" plate to mounted everything too kinda like the T-maxx frame but thicker

i have access to a welder on at home, which is a 90 amp chicago electric gasless flux cored mig welder(i know it doesnt sound like much but I welder the frame for my robot with it and it works wonderfully not to mention the frame hasn’t broke yet after me jumping on it and throwing it around

also at school I can use our dynasty 200 tig welder

also one last thing I wanna add, is that once skool start i will most likely have an internship at a machine shop where i know the owner, i would have had it last year but our conselor is a different story

anything else you would like to know?

ok scratch the motor part above, because i worked for my boss for 5 hours and he gave me a 14 inch craftsman chain saw and it works perfectly, so i will be using that

the biggest problem is the vibration with it, anyone know where to get vibration reducers?

the best part is that it is loud as all hell :smiley: :ahh:

some thing i need opinions on are if i should use the steering assembly from a t-maxx or make my own outta aluminum?

You could start with a T-Maxx steering assembly. I’m just not sure how much of a beating it will take. If it brakes after just a little bit of bashing, you should just make a new one out of aluminum. It would be stronger for when you really go bashing and probably just a bit heavier, but the hard work would definitely be worth it.

And also, how powerful is the chainsaw engine you got? That’s pretty cool that you got it from your boss.:smiley:

For vibration, you can try using like, rubber washers or grommets, or cutting the surgical tubing that came in the kop and put that between the engine and the chassis. That’s what we did for the electronics board this year. Well…it wouldn’t really work that well for vibration, but somewhat for shock absorbing.

i was thinking bout mounting the engine to a board or piece of metal then putting long bolts from that to the car chasis but putting springs between the engine and the chasis and putting a spring on top of the mount and puting a bolt through it all

bolt head
engine board thingy

I don’t think springs are the right answer. I see that as being too wobbly. You don’t need sprung mount, just a vibration insulated mount. I think rubber (like rubber washers) is a better option. Just make sure they aren’t near anything too hot. What is the primary drive off the engine going to be? Chain? If so, you don’t want your mount to be too sloppy where you lose chain tension or alignment.

Also, exactly how much does this thing vibrate? I have a weedwhacker engine and yes it vibrates but not all that much. I have held it in my hand (just the engine) while running it without a problem. (although if you try that don’t blame me if you drop it or get burned or lose a finger or something) Could it be possible that your engine has lost it’s balance somewhere along it’s life?

As with any custom project, please post pictures along the way if you can. :slight_smile:

yea i am most likely going to use a chain see as how it is the easiest to control with movement.

how would a spring mount be too wobbly?

how thick of a rubber washer?

and it vabrates a little bit, deff less then 1/8", and i think prolly less then 1/16", most likely bout 3/64 in either direction, and if you have ever used a chain saw you will notice that it does vibrater a little bit, every small motor like that vibrates a little bit, especially with a small motor reving at prolly 2500+ rpms( i dont know how fast the motor goes yet

also what sized shaft do you think i should use for the back axel.

and what kinda wheel do you think would be suited best for a project like this, maybe just a replacement wheel barrel wheel, or like just a off road wheel?

i can think of lots of options but i want something that i can use on and off road, at first it will be just on road until i get suspension and everything built