4 link critique

J.P. · Jan 2, 2013

Sounds pretty good you will also want to make sure that on the frame end up and down is 6 to 8 inches apart. Mine are just shy of 6. You will also want to look at a sway bar mine was fine with leaf springs on the front but once I got coilovers in each corner it got a little body roll. But overall worked fine without. But a sway bar will take it to the next level.

J.P. · Jan 2, 2013

My lower links on the rear are 40 something inches. They are 1/2 DOM tube 2.5 OD I have gouge marks from hitting rocks and have not bent them in the past 3 or 4 years. And I ride a couple times a month on average.

kturner · Jan 2, 2013

socsmm6 said:
I read the petersons article. I have always heard make links as long as possible but not sure how long is "as long as possible". are they talking 3, 4, 5, 6 feet in lenght. the longer they are the easier they will bend.

I also use the petersons formula ,and have had great sucess with it. I have never worried too much about the lengh of the links,like you said the longer they are the easier they will bend.

socsmm6 · Jan 2, 2013

the way it sits right now (home brew leafs in front and dual triangulated 4 links with 1/4 eliptical springs in rear) it climbs pretty good with just a little wheel hop. the biggest problem I have is it wants to flop everytime you get on a side hill. trying to get it lower and trim up a top heavy exo cage.
having a hard time getting good seperation on the axle end at the front, everything is pretty close. I can move the uppers at the axle up some but it will cut into the up travel a good bit. not really sure what you may need the most of.
thanks for the info

TBItoy · Jan 3, 2013

socsmm6 said:
the way it sits right now (home brew leafs in front and dual triangulated 4 links with 1/4 eliptical springs in rear) it climbs pretty good with just a little wheel hop. the biggest problem I have is it wants to flop everytime you get on a side hill. trying to get it lower and trim up a top heavy exo cage.
having a hard time getting good seperation on the axle end at the front, everything is pretty close. I can move the uppers at the axle up some but it will cut into the up travel a good bit. not really sure what you may need the most of.
thanks for the info

A top heavy rig with soft springs can't really be fixed with suspension geometry alone, unless your links are at steep angles, I'd bet that you wouldn't see much difference.

Fire Freak · Jan 3, 2013

My lower links are 53" eye to eye 1 1/2 x 3" rectangle tube 1/4 wall with tractor lower link rod ends 1 1/8"

offroadwerks · Jan 3, 2013

Triaged's on Pirate 4x4's version of 4link calculator is what I always used. Seems like 80% anti squat and as close to 0 over steer is what I would shoot for. Some link mounting points just can't be changed for whatever reason. Get some basic measurements from vehicle and plug them into calculator, adjust numbers that can be adjusted on vehicle to get as close to 0 over steer at static ride height. You are usually limited with uppers at frame but all other link mounts can usually be moved. I've been pretty satisfied with the ones I've done. Everybody who gave me a hard time about using or trying to figure out a calculator and just put links where they fit usually flopped like a dish rag and blamed it on the shocks etc....it pays off to do your homework. Good luck :dblthumb:

cushmaneaglerider · Jan 3, 2013

TacomaJD said:
I don't even know what this means, is this the same ancient alien arithmetic that the Mayans received when they were making their calendar?

This is why your truck falls over :flipoff1:

:****:

socsmm6 · Jan 3, 2013

You have seen my 4 runner, so you know it don't matter if I cut into anything. I have been using the link calculator but have been trying to get the anti squat down In the 25 to 50 range. Raising the % is pretty easy but getting it lower can be a pain. I understand to much antisquat leads to wheel hop on steep climbs but not sure what a really low antisquat would lead to.
Been shooting for 0 or negative 1 oversteer. Think I have that one figured out.
Got the cage cut off and the front end removed. Going to try to get the cab off this weekend and make some changes to the frame.

tc1 · Jan 3, 2013

J.P. said:
On my rear 4 link I used calculator stayed confused most of the time trying to figure it out. But with some help from an engineer I finally got it figured out. On the front I took a much simpler approach. Make sure that the lowers are longer than the uppers (30% difference I think Is the Best number)get them as far apart on the frame as possible, top should have around 22 Degrees of triangulation and the lowers at least 10 degrees, make them as long as you are able too and buy the best link material you can afford. Use cheap tube or plastic pipe to make up mock links and make sure nothing binds before cutting up the high dollar stuff. I say this because what is on paper does not always work in real life because there will be something in the way or lack of room.

Well said.

kturner · Jan 3, 2013

Pay attention to the roll axis ! I did one that we double triangulated , and my roll axis was way out of wack! the lowers and uppers converged too close together.A stabilizer helped it alot , but it was never what it should have been to start with.

socsmm6 · Jan 3, 2013

kturner said:
Pay attention to the roll axis ! I did one that we double triangulated , and my roll axis was way out of wack! the lowers and uppers converged too close together.A stabilizer helped it alot , but it was never what it should have been to start with.

what do you mean way out of wack? what do you cosider to close and ideal?

kturner · Jan 3, 2013

If you can imagine looking down on youre suspension links , the point at which the lower links (drawn or extended until they touch together) converge in reference with the rest of the chassis.The point that these links converge is a imaginary line in which the axle will articulate.You want the rear links to converge close to the front of the chassis versus being close to the rear. I didnt have enough seperation on my lower links or on my upper links. So either youre upper links or lower links depending on how youre designing the suspension will need some seperation where they connect at the chassis. My last rig as i said we did double triangulated and the lower links had four inches between them where they mounted to the cross member and the upper links had four inches between them where they connected at the differential so it had alot of body roll.This is why i say the roll axis was out of wack.Make sense ? If you go to petersons 4wheel and off road web sight you can surf through the old tech articles and find a article on four link suspension. Its worked for me so far.

socsmm6 · Jan 4, 2013

On the rear right now the lowers have 8" of separation at the chassis and the uppers have 5 at the axle. It works good but does not feel stable. So a little more separation on the lowers at the frame should help out. That is what I have got planned to do. May have to do some adjustment to get anti squat up to around 80% to start off with.
Thanks

wont work · Jan 4, 2013

socsmm6 said:
On the rear right now the lowers have 8" of separation at the chassis and the uppers have 5 at the axle. It works good but does not feel stable. So a little more separation on the lowers at the frame should help out. That is what I have got planned to do. May have to do some adjustment to get anti squat up to around 80% to start off with.
Thanks

I have always done more separation at axle and not frame