klampykixx

this should be #10

klampykixx

now?

klampykixx

sweet.










next is to make a mount for the transmission to sit on.

i had a browse through ebay, and discovered the stock gear pitch is 32p. so i can get a larger spur, but none that have a small enough I.d. that it will sit snug on the shaft. so i think ill get it going as is first, then see how it goes torque wise.

Ill be using an 8ch Tx so will definately be able to control brake and throttle independantly if required, so perhaps if i run into clutch issues, i could go a harder spring and heavier shoes so it does have to rev up a bit harder to get it to engage?? or would i be rathering a heavy shoe and a light spring to engage at lower rpm?

meno1103

iTrader: (6)

A heavier shoe will swing out sooner, and a softer spring will let the shoes swing out sooner as well. Going with a heavier shoe and stronger spring will basically cancel each other out, unless one has a much bigger change than the other. I'd look into what type/brand of shoe is more heat resistant first, then look into an adequate spring.

xristoz

How is your build going do you have any updates for us?

klampykixx

Sorry for the delay, i didnt get the notification that someone had replied.. odd... anyway,

firstly before updating, i have a Question regarding the engine itself.

How hot does the outside of the motor get? if the glow plug is at 270~ is that fahrenheit or celsius? im in Australia, so have no idea of fahrenheit.. lol

reason im asking, im considering starting a scratch built chassis out of brass/solder (not brazing) and im concerned that the motor will melt the solder joints if i do go this way. regular electronics solder (60%tin/40%lead) melts at 182 to 183 degrees C.

now, 183 degrees Celsius is 361 degrees Fahrenheit so i think im pretty safe, but id like to double check anyway.


on to updates. > pretty much only collecting parts atm, and ANNOYINGLY either my cat/wife/son has shifted one of my brake calipers and i CAN NOT find it anywhere... problem with that is that its just as expensive to purchase new parts as it is to buy a complete new kit.. $60 later....

xristoz

Why don't you screw the engine to the chassis? What happens if you want to remove the engine for some reason in the future. Screws are easy and fast to remove.

klampykixx

you're absolutely correct, the chassis that exists in the pics(and that the engine is screwed to) is steel and i very much dislike working with steel at this scale. i just don't have a small enough welder to work with and i don't have brazing gear.

what i do have, is lots of brass tube, solder and a small torch. but the solder i have has a melting point of 180degrees celsius.

now, glow plug temp is supposed to be about 250-280*F which apparently is equal to ~140*C so its under the melting point of my solder, but will the crankcase be that hot too or just the glow plug??

what im getting at, id be happy to build a complete new chassis/cage out of brass tube/solder but dont wanna risk it being weak at operating temps as 140* is very nearly its melting point.

does that make sense??

ThePanda

iTrader: (68)

if you tune your engine right it should run between 225 and 250 degrees f as a general rule, but things like fuel and air temp do play a role in engine temp. it should not go hotter than 250 or you could damage the engine

ThePanda

iTrader: (68)

i dont know how well brass tubing joined with solder would be. i think that there would be to much strain on the solder joints maybe?

klampykixx

nah, the soldered chassis is plenty strong, you can bend the brass before breaking the solder joint if done properly. plus, i plan on (at least attempting to) recreate my jeep XJ chassis.

but its only strong when its cool. im not sure how it goes with temperature hence my current question. i know the engine will get to approx 250*F at the glow plug, but what about on the outside of the crank case? does it get the same temp there too? even with a small thermo fan blowing air past all the time?

ThePanda

iTrader: (68)

since nitro engine temps are usually taken from the glow plug i think that is where it would be the hottest.(the combustion chamber is right underneath) Where the engine mounts are located i would think that it would be cooler. the pull start housing is made out of plastic, and that is bolted right onto the crankcase so it cant be to hot or the plastic would melt.

You could always test the solder joints by heating them to the Max motor temp and seeing how much force they will withstand, compared to one that is not heated.

I am pretty sure that it would be safe to run the motor on the brass tube frame you mentioned, As the crankcase should be cooler than the glow plug.

Anyways cool build.

klampykixx

cool. thanks, and its good news im hearing from numerous forums/facebook.

i think what ill do regardless is actually make the mounts so they bolt to the chassis and also bolt to the motor where before i was only going to make them bolt to the motor and be part of the chassis. this way, i can make them from aluminium which will also help in reducing the heat transfer to the chassis as well.

will also make it easier to get the motor in and out if required to.

thanks for the input. ill start a build thread and link it here when i get to it.

ThePanda

iTrader: (68)

separate engine mounts is what is used universally throughout rc, it makes changing gear mesh easier too.

looing foward to the build.

meno1103

iTrader: (6)

On aluminum-chassis nitro vehicles, I can normally pick up the car from under the chassis and carry it after running a full tank, sure it is a bit hot but it doesn't burn. The cooling head? Yeah no, not going to try carrying from that or making contact for anything over half a second.
I would definitely say to go for the fan idea, maybe make it a front mounted 'radiator'-looking setup.