Suspension- to all of you who build cars/go-karts/buggys etc

little_sparky said:
So by that i'm guessing that 500lb is way too stiff.

I weigh 160 pounds (80kg)
bike weighs 100 pounds (50kg)
with gear add 20 pounds (10kg)

Equals around about 300lbs; divide by 3 wheels gives me 100lbs and will have two shocks, does that mean they should be a 50lb rating?
Click to expand...


Depending on the amount of suspension travel and front to rear weight balance you have in the shock, for discussion we will assume equal balance front / rear
lets say 4" from topped out to fully compressed and you want to be about 2" compressed at ride height, 50# per inch spring would be about right.

(A 50# per inch spring with 100# on it would compress approx 2")

You may have to experiment or put some scales under the tires to get the actual balance / weight per tire.
 
Yea I would scale it. Take a scale and two shims the same thickness of the scale. Sit in it, check weight, rotate them, check weight, rotate.

Your not going to want it to stiff I would not think
 
Okay thanks heaps guys! And so this weight calculation should include the weight of the tires? Because they are heavy!

And The only thing is, I havnt really seen any that are 305mm long with a 50# rating, so maybe I should be looking at bicycle rear suspension?

Thanks, little_sparky
 
Last edited:
Your shocks only need to be as long as they need to stroke. How much travel are we talking? Are these for the front? The shocks on my buggy front end are only 18in long and my front end will travel 22in before the heims bottom and the camber gain is massive.

My math might be off but 300mm is bout 12in yea? http://www.ebay.com/itm/FORSA-SHOCK...Parts_Accessories&hash=item23457e5c4d&vxp=mtr

Lotta Harley's, street bikes like suzuki, and import scooters have 12in shocks. I would lean more to scooter shocks my self. And dont worry so much about the weight. Just a rough idea of where you need to be. Unless your spending 500+ on a custom set or at least 400 on some fox or radflo air shocks, you will be lucky just to be close. Then lean the shocks to tune your comfort in. IMO
 
What do you guys think of these shocks?
http://m.ebay.com.au/itm/251317832904?nav=WATCHING_ACTIVE

200lb rating, 55mm travel, my question here really is
1. Is this enough travel? I'm not looking for anything in particular I just want to make sure that it takes the load when I hit a small bump or go up a gutter.
2. Will front suspension cut it as rear suspension? Is there any difference?
 
to get an answer to your question would require more information. i would suggest you do some more research on the subject. there are good websites out there with lots of info on the subject of coil over shocks. you will need to know the total weight on the rear tires, the distance from eye to eye on the shocks and mounting angle of the shocks. try pirate 4x4 web site and also art morrison chassis works .looks like a fun project,good luck
larry r
 
I know this is an extremely old thread, but since it wasn't really answered directly I'll try it. what you made is fairly simple. you don't really need to overthink it. the shocks you want can probably be easily and cheapily gotten on a gocart site or ebay. get a cheap one, if it is too stiff or too weak than get a different one and just test them out by jumping on it. for example look at this video
at 21:59 he literally just jumps on it to test the suspension. it's not rocket science, there is no need to overthink it. be prepared to only tack weld it enough to test it and be prepared to make mistakes , the end result does not need to be perfect, the more perfect you try to make it the longer it will take, 4 years seems like a really long time for how small of a scale this project seems to be. the channel " Creative Channel" has 5.5 million subs, go through their videos and you will see a bunch of ideas to help you, do not copy his techniques though, for example this guy is in a 3rd world country, he is welding galvanized steel, this will kill you, it's well known. also he uses very thin flimsy metal for all his projects so unless weight is a problem I would go up a size. also I've seen it where the fabricator drills 3 different holes in a row so they can adjust the shock distance to stiffen or soften the shock. I have basic body work and 2k paint spraying knowledge so I know that bondo and some 2k primer will easily hide any mistake you will make.
 
I'm going to give a second example to state my point , in this video he welded in supports for a set of shocks and then he jumped on the suspension and he realized it was too stiff so what he did was he simply looked into his box and found softer shocks and installed them and then he tested it by jumping on the suspension again, it's at timeframe 7:55

Also an important note: this guy is obviously from a third world country because nobody told him that you cannot weld galvanize steel. So just basic welding safety never weld galvanized steel or use brake cleaner both will produce fumes that will literally kill you. At the very least wear a respirator with a fresh set of cartridges and have a fan blowing the fumes away from you and always use a flap disc to grind away the galvanized coating but just be smart and use regular steel not galvanized that's super dangerous
 
brino said:
@eksine ,

Welcome to the group!

-brino
Click to expand...
Thanks I actually only registered to help answer the suspension question. I literally haven't had to work with suspensions but I have a tiny bit of basic welding down. Unless you guys want to know the reason why and how to fix Honda automatic transmissions that failed from 1999 to 2006+ I actually have no clue how to use a metal lathe, or if you guys need help with body work or spraying 2k car paint or Photoshop , I'm pretty much useless here
 
You must log in or register to reply here.
Back
Top