SlashBasher

My Feedback: (8)

yeah I think a chassis that long at 3mm would flex. thats why I want 5mm, if my dad can bring home a sheet of 3mm i would try it though, no complaints haha. Not like im jumping it sinces its an onroad car but twin engines is gonna put some stress on the chassis.

Dirty_Vinylpusher

3mm is plenty.
I use 3mm on this car with side bracing.
And this has 200mm dia wheels and a 2-stroke motor, and most likely weighs a fair bit more than your car will.

Just a thought.

Frederik_b

With a "sandwitch" design or other kind of bracingI also think also 3mm would be enough. By sandwitch I mean there is a second plate mounted like 1.5 inch above the bottom plate and held together by spacers.This upper plate can be cut to hold servos and stuff but it also strenghten the chassis a lot.

I think 1/8 scale offroads are already partially like this (holders for steering servo saver holder and servo tray, center diff) but having it all one piece would make the whole assembly more rigid.

Fred

Dirty_Vinylpusher

Wow this thread is on its second page already and the guy hasn't even bought the plate for the chassis yet.

Guess we really love homebuilds here

Bob-Stormer

chassis thickness. Just run a few roll bar tubes around and that will take care of any flex you might have had.

ttr125fan09

My Feedback: (1)

im with bob's idea

SlashBasher

My Feedback: (8)

OK ill go with the 3mm plate and bracing, thanks for all the help so far guys its been great!
you guys really must!

SlashBasher

My Feedback: (8)

Ok so my dad didnt have anything I could use so im gonna have to order it. Hopefully I can order it soon I want to get started so bad!

SlashBasher

My Feedback: (8)

Ok so I was thinking that maybe twin nitros wouldnt be the best idea...it would be awsome but two big blocks would use almost a gallon for one session at the parking lot! What I was wondering is if there is a way I could run say a small 2 stroke engine like a chainsaw engine or a weedwacker engine or somthing but still connect it to the truggy rear end? I think that would be cooler also not to mention the run times I would get. lmk what you guys think.

Frederik_b

I think It would have to be a tiny engine. Thats why I initially wondered what is the smallest possible gas engine you could use (to retain the 1/8 drivetrain) and someone pointed out the small 15cc airplane engines, but those specialized engines looks to be morecostly and not as easily available as weed hackers and chainsaws. And they are maybe not that small.

The smallest weed hacker I saw was like 21cc but thats stilltoo large for1/8. Not only the power, but also the weight, combined make iteven more hard on the drivetrain. Or you could try to find a larger diff online, or make it solid axle?

Fred

SlashBasher

My Feedback: (8)

yeah I could make it a solid rear axle i guess and keep the suspension up front...but without a diff would it have a really bad turning radius? cuz i will most likely only really drive it at a parking lot track guys setup every week in the summer near me for 1/5 and 1/8 onroad cars so.. not competitive but i want to make the turns lol.also wouldnt I have to make the ride hieght higher to clear the sproket on the axle? idk i will keep looking around. thanks for the help.

Frederik_b

If you can't find a diff maybe you could dial in some oversteer to make it easier to turn by making the suspension stiffer in the rear and softer in the front.Then when you turn the rear insidetire tends to lift off the ground so you can turn. Not as good as having a diff tough and might be hard to adjust depending on the car's weight distribution (for instance if the car is rear heavy it might be hard to make the rear wheel lift!)

The sprocket on the rear axle doesnt really need to be that big if you have an lay shaft (dont know what is the correct word for this), that's like having 2 stepsof chains.Your gear ratio could be adjusted betweenthe engine andlayshaft, and you'd keep identical (small) sprockets between the layshaft and axle.

It's simpler with only one chainrunning directly from engine to rear axle, but in that case you would more likely need a larger sprocket on the axle to have an appropriate ratio.

Fred

SlashBasher

My Feedback: (8)

Ya those get complicated fast though. hmmmm maybe like one four stroke or somthing. I like the idea of a 2 stroke though. id. thanks for the help man.

Dirty_Vinylpusher

Wasn't Sam's first cars based around 1/8 diffs and wheels and he ran a small weedwacker motor in them.
The first one was only 18cc.
Don't get fooled in to thinking that you need a lot of cc.
Most little motors will pull their own weight pretty good (and fast)



As for the diff.
I haven't had any trouble with the turning circle on any of my diff-less builds.
See below.


[youtube]http://www.youtube.com/watch?v=5q5cnxoD9gA[/youtube]





[youtube]http://www.youtube.com/watch?v=qwKJslE_ip4&feature=channel[/youtube]

Fabe

As a few have said, you should be ok with 3 mm plate with some bracing. The car I have has dual ~3.5 mm plates with bracing between them and it's solid. Car weighs 22 or so pounds. It also has diffs in the front and rear, which are from a T/E-Maxx. If you go the 1/8 scale differential route, I'd suggest going 4WD to distribute the power a bit, but go for a larger scale diff if you're only going for 2WD.

Cheers!

sam123

My Feedback: (1)

As long as you can keep your build lightweight and 4WD, the 1/8th scale diffs and drive shafts should be fine. I have done something similar to this before and it worked really well, and was quite simple to build. The only issue was that it would eat tires too quickly [:@].

Here is my build if you want to take a look: http://www.rcuniverse.com/forum/m_5682405/tm.htm

Good luck with your build

SlashBasher

My Feedback: (8)

Fabe and Sam your builds look great! i think im going to do the double chassis and a straight shaft from the front to rear diffs. I dont have a welder so how would I attach the sprocket to the shaft? thanks for the help guys.

Fabe

Thanks. Were you thinking of something like this for the shaft front to back? I found a long shaft makes it easy to attach extra "things" on there like brake disks, sprockets etc.

To mount the sprocket to the shaft is very easy if you have one with a hub on it because there is a set screw to lock it on to the shaft. If you don't have one, you could use a keyed shaft and sprocket, but you would still need something to prevent the sprocket from wobbling...a homebrew way is to use tube that fits over the shaft and centers the sprocket from either side. I believe if you choose the engine and diff setup first, then it will be easier to know what ballpark size sprocket we're talking about.

SlashBasher

My Feedback: (8)

Well im not sure what IM going to do yet. But that looks good. im new to this large scale stuff and sprockets and what not lol