Noob questions - buggy

[karte_m0lim]

Hi ..

so plan is to build buggy, two seater, A-arms front suspension and swing arm at back with solid live axle.

it will be used on gravel , grass and tarmac, no heavy dutty offroad..

it should look a like spiderkart grand daddy but slightly bigger as my a$$ is 2 m high and lets be optimistic , 110 kg ..

first I planned to use scooter engine, 500 cc , 40 HP, with built in torque converter and put 3 pairs of sprockets for 3 different gear ratios, and than just quickly swap chains .

but, managed to get suzuki DR 650, around 40 Hp (35 to 43 , depend of source) with 5 speed gearbox and kick starter.

also , friend promise to give me seat ibiza as parts source.

at first, will took seats and tyres from it.

plan is to take front hubs, disks and brake and weld it to swing arm .
idea was also to take half axles , if is possible to joint it together with hub which will be sprocket carrier.

now, problems which crossed my mind ..

first, gear lever.. I have motorcycle engine on gokart and shift lever on right hand below steering wheel, but there is no swing arm.. which will be on buggy and swing arm travel will brake lever ..
I have two ideas but need second opinion.
First, is to use cables and maybe use flappy pedal under steering wheel.
Second idea is to use solid lever with H joint inline with swing arm .... will it work?

To avoid all that , keep engine together on chassis and use full independent rear suspension, but then I need half axles, those form seat ibiza are not same, left and right.. also , is there lateral motion and how to avoid it?

More questions... front suspension from this motorcycle, will it be strong enough for swing arm?
guess car suspension is 2 strong?

next, it is hard to find (at least where I live) square iron 30x30 mm with wall thickness of 3 mm, it is usually 1.8 mm.

will be enough if I use 40 x 40 mm , it is 2 mm ..

thanks

 

[itsid]

What a multitude of questions..

let me start to answer a few..

1) SHIFTING GEARS:
cable would work, Joint will likely NOT..
BUT take a look at PUSH cables (essentially monofilament wire for the most part, very tightly wound coil for some flexible sections all wrapped in a bowden wrap)
I'm not too sure but I'd believe it might just be stiff enough to shift a motorcycle engine both ways (assuming the gear train is still smooth that is)

2) SUSPENSION:
No Lateral movement if you use trailing arms instead of transverse control arms.
(think 914 rear suspension [or google it if you don't have that mental image ])
if the front forks provide enough suspension for the rear depends on the weight and the angle of attack..
tough to make an assumption that's not entirely off what you are imagining there..
sooo I'd say NO and the one from the Seat might in fact be the nicer choice (dialing in on the safe side)

And finally MATERIAL:
DO NOT use iron at all.. steel is what you're after
(yeah I know you meant steel not iron, but we try to keep things exact for the next reader to follow your examples )

40x40 -2 IDK sounds plenty for my ears.. but again... IF it does suffice depends on more than a gut feeling..
frankly I bet you can make a sturdy frame from 10x10-1 if you have a good enough design
(and lots of such tiny tubes crossbracing one another)
but that depends on the what you are going to do..
BTW round tube is much stronger than similar size square tube..
(also the result looks way better) So maybe look what you could find there
(OD30-2 should be about as strong as 30x30-3 IIRC)

'sid

 

[Joe-405]

For the shifter use Morse style push pull cables. They work flawless. That’s what I used to make my paddle shifters mechanical on the buildoff winner this year.

 

[karte_m0lim]

thanks ..

cable, maybe I can use parking brake cable from older vans, its usually 8-10 mm thick or from grass trimmer .. just thinking on loud...

rear suspension , so it is basically independent, two swing arms?
but again, these it means that H joints on half axle should be inline with wishbone joints?

reason I am asking is I am scared of bump steering , well it effects... (yeah, I know, , too much youtube)

and frame.. as I sad, plan is to use spidercart grand daddy as guideline ..
round tube, I am sick of grinding to fit round tube joints...

only store where I can find 30x30 with wall 3mm , they asks 27 euros for 6 m piece.. and I need at least 10 ...

joe , yeah, watched your build, congratulations ..

 

[itsid]

tube notcher!
much quicker than grinding

'sid

 

[Joe-405]

tube notcher!
much quicker than grinding

'sid

Yep. We used one that uses a hole saw and drill. Very affordable.

 

[karte_m0lim]

yes, I have it.. but still ... looks better, but take too much time ..