3 and 4 link suspension help

[elmer91]

Anyone have experience setting up a 3 and 4 link? I downloaded the calculators from Pirate, but every thread asking for help was either "search" or a fighting match over what means what, this works better, etc. I gathered some advice from all of the threads, but the main problem i am finding is what i should shoot for as far as output numbers (Instant Center, Roll axis angle, Anti-squat percentage, etc).

If anyone has any advice, or has found a good thread about it, anything is appreciated.

[timido]

The roll axis angle is important if you drive it on the street. You want that number close to zero. Too much anti squat you wil hop. Not enough anti squt it will squat and unload the front end. The problem with the calculators is all the numbers change when the instant center changes like going up a hill or down a hill. I read for days. Some say 100%AS some say more some say less. Makethe brackets where you have higher or lower holes to change the Anti squat

[elmer91]

thanks! i have read to keep the anti squat between 65 and 135%, with a goal of 100%. have heard you want it at 0%, at 80%, and a bunch of other numbers. The roll axis angle wont matter much since this is offroad only. now time to get back reading and messing with the numbers.

[tbshakie]

I did a rear 4-link using the pirate calculator and have been very very happy with it.

http://www.ohio4x4.com/forum/showthread.php?7569-CJ-5-Project

Here is two builds of a 3 link front:

http://www.ohio4x4.com/forum/showthread.php?5908-Is-a-3-Link-front-possible-in-a-weekend

http://www.ohio4x4.com/forum/showthread.php?4506-Leaf-spring-front-to-3-link-and-coils-Jydog

There was a really good discusson on the board on optimum link separation, anti-squat etc. when I find it I will post up. I used the info in it for my build.

[tbshakie]

Not the one I was looking for, but another front 3 link:

http://www.ohio4x4.com/forum/showthread.php?7655-Project-No-Lift-YJ&highlight=suspension

talks about anti-dive for a front 3 link

[elmer91]

Thanks for the links! looks like they will be helpful.

[tbshakie]

there was a very good discussion on Ohio 4x4 7 or 8 years ago that discussed link separation at the axle vs. at the frame, ant-squat etc. I cant seem to find it. it was a summation of what people read on pirate along with real world advice from people who have built several suspensions. I will keep looking.

[blazerbrad]

I've been on the trail with most of the rigs that tbshakie linked, all except the rig doing the suspension in a weekend....it probably still looks the same today:D. They all appeared to work well on the trail with no weird hopping or anything.

[Nuts]

Calculator smalculator! You'll spend hours doing math and trying to "get it right" on paper, then once you actually start trying to make the numbers happen on the vehicle you'll find out EVERYTHING is in the way and almost none of the calculations can be mounted where they're supposed to be. So with that said, and what has worked for me is to make the uppers 70% the length of the lowers, make the vertical seperation have the distance on the frame that it is on the axle, and try to get the uppers as close to 45* as you can. Then put everything else where it"ll fit.

[elmer91]

Nuts, I want to do it just the simple way, with little calculations, but im doing this as my senior project for college, so they will want to see the numbers part of it. probably just gonna put some good numbers in the calculator, then move the stuff around as necessary.

[twiztedzuki]

Calculator smalculator! You'll spend hours doing math and trying to "get it right" on paper, then once you actually start trying to make the numbers happen on the vehicle you'll find out EVERYTHING is in the way and almost none of the calculations can be mounted where they're supposed to be. So with that said, and what has worked for me is to make the uppers 70% the length of the lowers, make the vertical seperation have the distance on the frame that it is on the axle, and try to get the uppers as close to 45* as you can. Then put everything else where it"ll fit.

I laughd also when read this, gotta b a jeeper

[Nuts]

Nuts, I want to do it just the simple way, with little calculations, but im doing this as my senior project for college, so they will want to see the numbers part of it. probably just gonna put some good numbers in the calculator, then move the stuff around as necessary.
Are they going to come out and measure the rig? Just steal the calculations from a werock forum and show them. Then throw it away and go put **** where it'll fit on the buggy,jeep,whatever.
I laughd also when read this, gotta b a jeeper

Probably, but everybody was new once so no shame in asking for help. Unless your screen name rhymes with yellow jacket, then your mind works totally different and nobody will have a clue what you mean! :D

[elmer91]

Slowly getting everything figured out. in the process of mocking the 4 link up. Does any one have a 3 link front that i could come look at? i know i can find pics online, but i do better if i can see one in person.

[Nuts]

Saw a link to this on hardline.The guy was asking for help, but already has a good start. Theres a lot of calculations and modles in it. I wouldn't do anything suggested there but some of it might help you out.:beers:

http://www.4x4grace.com/vBulletin/showthread.php?t=13619&page=2

[mckeddie]

Calculators are worthless. You will never know your true roll center, or anything else. And like said above, nothing will fit where it needs to go.

We tend to use the same method Adam used above, except we keep the vertical separation of the frame end about 75% of the axle end. We've found for going fast, get the links parallel to he ground, for climbing, it seems that if your links have a Little slope in the rear, it tends to hook and climb better. It's a super scientific approach, I know, but it woks. We usually try to keep the lowers close to 36" too.

[tbshakie]

I agree with the rules of thumb that mckeddie. but the calculations are not worthless. Will you be able to get thing perfect.....No. you will have to compromise. by running the numbers and all the scenarios, you will be able to choose where the compromises will be in your system and not be surprised on your first wheeling trip

also, the top links should be 75 to 80% of the length of the bottom links.

[elmer91]

I wouldnt be using the calculators if i didnt have to. I have to show there there is technically math involved with all this to show to school. i basically followed this (http://www.therangerstation.com/Magazine/winter2007/4_link_tech.htm), which came from 4 wheeler magazine. then fudged the numbers some to make them better for what im gonna turn in to the professors.