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Link Suspension Set-ups

ha ha ok how about a quick easy to understand explaination of each of those terms. :D This thread could become a beginners guide to link suspensions.
 
Paxx said:
ha ha ok how about a quick easy to understand explaination of each of those terms. :D This thread could become a beginners guide to link suspensions.
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there isn't really a "quick easy explanation" to imaginary points in space that affect your suspensions actions and reactions :haha: They tried that in my Chassis Fabrication class, and most of the kids sat their sort of staring at the teacher. Only a few of us that had ever heard the terms previouslly had a clue what was going on. Even afterwards, I'm not convinced all the teachers got it.

Yeah watch, now since I don't feel like trying to explain one of the guys will come along and explain it so simply, ha.


Anti-Squat is a suspensions reaction to the transfer of weight. The more anti-squat in a system, as power is applied it will counteract the vehicles want to shift weight to the rear. go to the drag strip and watch most modded up cars with 4 links out back. They will actually, LIFT the rear end of the car instead of squat on it. This is anti-squat at work.
 
ha ha anti-squat is one of the two that I did understand out of the above. CoG is easy enough. The others though leave me scratching my head.
 
IC is the point in space where the single pivot would be (as viewed from the side) if the 4 link was replaced with a simple swingarm (like those on the rear coil sprung GM trucks from the 60's). The difference is that the IC of a simple swingarm stays in one place while the IC of a 3-4 link moves around thru the travel cycle. Playing around with ExcelCAD (thanks guys!) will really help with seeing how this works.

RC is the point in space that the axle rotates around when articulating. It too can move relative to the axle and/or frame as the suspension cycles.

Then we get to Roll Axis. There are two different RA's, one applies just to the front or rear axle (& helps define where the RC for that axle is), and one applies to the whole vehicle.
 
Hey thank you for the info and the link. This should be enough to get me started for sure anyways. I appreciate all the patience with my noob questions :D
 
Hey paxx if you dont mind post up your e-mail address and i'll shoot you over a whole bunch of documents with terms, pics, and other info that i have collected.
 
Make sure and post up when you get things figured out for the most part. I'm going to be linking the rear of my K5 (or what's left of it) in the next year.
 
Hey, my e-mail is down still, so i'm going to type up everything here if that is cool. These are not my own words; it is just some research found mostly on pirate. you guys can critique it however you want, because i'm still learning also.

3 link front with panhard bar:

Make the frame end of the Upper Control Arm(UCA) adjustable to help adjust for anti-dive. Anti-dive is similar to anti-squat of the rear.

Try to make the UCA parrallel to the chassis, and the lowers close together at the chassis and go out to the axle, keeping tire clearance when turining in mind.

With a single uper link on the pass. side, you want the link to slant down from the chassis to the axle, but if on the driver side, you want it to slant up from the chassis to the axle. The horizontal location is important, once you get the side view geometry figured out with the anti-dive you want, you can get the optimal horizontal placement using the link geometry, tire size and gear ratio. This does not matter to what side the diff is on, when the link configurations are designed right it will counteact the chassis tendency to load one side (or give one side more traction) when under power.

For the the UCA most put it on the pass side, as level as possible and as perpendicular to the axle as possible and you should be fine from a term called jacking. This happens under braking from a non centered upper link..

Most people use bushings at the frame end of links, and hiem joints at the axle if it is a daily driver. They say this helps for a better ride and the hiems will last longer.

make sure caster is set-up well, steering, panhard, lowers, toe-in, springs, clearances, etc.

I'll post up the rear 4 link stuff this weekend..
Cory
 
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I dont have time to reply or read through this entire thread...not right now anyways...


Short and simple:

Radius arms suck. I had a radius set up on the front of my buggy and it was terrible. I am building a 3 link with pan hard right now.

If youre not running full hydro, you will need a panhard.

Considering how crappy the K5 frames are, you might want to consider a parallel four link with a panhard to distribute the load over both top links. I dont know if you could build the upper link mounts on a 3 link stout enough to hold up.

Randy Ellis built jaunblazer and knows WTF he is doing. He has probably built hundreds of link suspensions. Copy his. End of story.

If Evolution is telling you to run radius arms, find another shop. They might be able to build bad ass heims, but a radius arm suspension isnt much better than leaves.
 
I went down and spoke with the guys about the suspension. I was told that their radius arm suspension would be very stable and handle great for most types of wheeling and when it came time for some flex there was a pin that could be pulled on one of the links that would allow for some massive wheel travel. Has anyone heard of something like this before?

I would also really like to see a couple of pics of a radius arm set up so I have an idea of why it is a less desirable option. If anyone could post up a pic or a link that would be great. (especially of flexing pics showing where the binding occurs)
 
oh another beginner question. Is the panhard considered one of the 3 links or is it a fourth link?

also what is juan's username? maybe I'll shoot him a pm and try to get some good pics and measurments.
 
Dude dont go there haha.
I dont even see when you could put a pin that would make a radius arm setup flex more:haha:

I know a guy that runs a radius arm setup and it works awesome for him. I know nothing about them so if it were me for the front I would do a 3 link with panhard as stated above.
I htink a dual triangulated 4 link is best but it would be very tuff to fit it on the front of a K5 frame.
For the rear it is the best setup you could have IMHO.
 
Paxx said:
oh another beginner question. Is the panhard considered one of the 3 links or is it a fourth link?

also what is juan's username? maybe I'll shoot him a pm and try to get some good pics and measurments.
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Its a "fourth link".
In a 3 link link you have 2 lower links and then one upper link that keeps the axle from wraping. The panhard is there to prevent side to side movement.
 
Paxx said:
I went down and spoke with the guys about the suspension. I was told that their radius arm suspension would be very stable and handle great for most types of wheeling and when it came time for some flex there was a pin that could be pulled on one of the links that would allow for some massive wheel travel. Has anyone heard of something like this before?

I would also really like to see a couple of pics of a radius arm set up so I have an idea of why it is a less desirable option. If anyone could post up a pic or a link that would be great. (especially of flexing pics showing where the binding occurs)
Click to expand...

The radius arms bind because the mounts on the axle end are fixed. This is hard to explain (or understand without a visual) but think about the rearmost points of the radius arms for a second. They are flexible joints that can pivot, right? So when the suspension cycles there is no problem.....but on the other side of those links (the fixed side) there is a BIG problem.

The suspension will travel in an arc, not straight up and down...agreed? OK, so you have two connections to the axle on each radius arm to keep the axle located properly under the truck. When the suspension articulates (one wheel up, and one down) those connection points are not traveling in similar paths of motion. In fact, one side would actually need to "spin" on the axletube to prevent binding.....this is what that pin is about. They are probably doing a "sleeve" over the axletube on one side to allow it to rotate freely. If they don't, the axle will need to TWIST (like a swaybar) to allow the suspension points to travel in their prescribed arcs of motion......which is impossible!!!

I'm sorry this is so hard to explain, but if you could build a simple model to play with you'd easily see how a non-sleeved radius arm setup is incapable of articulating.



:usaflag:
 
So with the sleeve system you could get some good flex then right? I just don't like the idea of having to get in and out of my truck to pull a pin several times a wheeling trip. Thats part of the reason I'm going to run flanges, so I don't have to get out to lock my hubs lol.
 
You need to read more and decide for yourself what is the best. Radius arms certainly dont work at speed, and barely work for crawling when compared to other suspension setups that can be built.

Any kind of suspension that uses a pin sounds like junk to me. Im sure it can be built stout and work OK, but the point of going to a link suspension is to put more power to the ground. Im sure you also want to accomplish other goals with your suspension also, and you knowing those goals will certainly help.

This whole thread is a shot in the dark right now. It doesnt sound like you have talked to anyone else but the person that is singing the praises of the crappiest link design ever. Call around and talk to other people. Then again, it also almost sounds as if you have your mind made up and we're all wasting precious time in our lives trying to educate someone that doesnt want to learn.

Greg has hit the nail on the head with the synopsis of the radius arm suspension.


K10'sBROinSLO: Take your leaf spring advice and preachings to another thread. You obviously havent progressed to the point that you need a link suspension and thats perfectly ok. Dont ruin a good thread with rambling.
 
blk87K5 said:
K10'sBROinSLO: Take your leaf spring advice and preachings to another thread. You obviously havent progressed to the point that you need a link suspension and thats perfectly ok. Dont ruin a good thread with rambling.
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hey..hes just saying that you dont always need links..and that leafs can be sufficient. There are very few people who need a link setup. dont just think that just because sherly jones has them across the strret that you need them too. i'm sure we'd all like to be linked.

and dont say that that guy hasnt progressed. maybe he wheels with what he's got. i think progression in off road has a lot to do with when to know to stop. to put it more simply.. to progress doesnt mean to put the best stuff on your rig.

i see where your coming from just be easy on others.
 
K10A'sBROinSLO said:
Sorry for the hijack. I just have to argue for the heck of it. I dunno how much flex your kind if wheeling is going to demand, but this leaf setup is all off the shelf or outta the junkyard parts and he pretty much only carries a tire if he wants to. Climbs decent too.

Leaf springs can work well too. Flame away. :D
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Only carries a tire when it wants to? Basically unless you spend high dollars on a set of custom leaf springs, a leaf sprung suspension can only be "Tuned" by shackle length. A 4 link can be adjusted(if you build it right) from here until next sunday, and if you have coilovers, forget about it, adjustability until next month.
 
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