OK........I've been watching and reading all of the posts (past and present) on people designing their 4 link suspensions. And I decided it was time for me to give it my best shot. We're not talking some ho-hum Autocad setup. We're talking full blown 3d modeling.

I and a buddy used ProE and threw every bell and whistle we could think of when putting it together. An output of our design and layout for my CJ7 can be found at:

EDIT (fixed link - thanks to Lance):
http://www.pirate4x4.com/tech/4link/4link.pdf

I appologize up front if we exceed the site's daily bandwidth limit. I just don't have the $$ to pop for a web site. This is a free one. If anyone has a suggestion on where I can post it that it won't get limited on bandwidth, please let me know.

Look it over, both the design and the dimensions, and see if anything seems like it is missing or should be changed.

We worked pretty hard on it to include all we could think of. But my skin is pretty thick......so fire away. It currently does not have a front suspension modeled. That is to come.

One last thing........I have never built a rear 4 link suspension nor have I helped with one. I one of those kind of people that has to analyze the hell out of it before I build it. I plan to start building the final design in the next year.

EDIT: Damned link doesn't work!! Give me some time to fix it! Arrrgggghhh.

http://rse.theshoppe.com/fourlink/
then click on the pdf

Originally posted by bobjohnson
http://rse.theshoppe.com/fourlink/
then click on the pdf

Thanks!!! Glad someone is smarter than me when it comes to that. :rolleyes: Hopefully my modeling/design isn't that sad too!

:eek:

damn.. it looks cool anyway... I need to learn how to do that. to busy with school though.

Looks almost exactly like my link plans. Of course, mine are on graph paper.
My uppers are 41, and the lowers are 43. I was advised to shorten the uppers, to increase antisquat on compression, and decrease antisquat on extension.

Looks like you have 7" of seperation, in the side view, between the uppers/lowers at the axle, but I couldn't figure out the seperation at the chassis. 6" I'm beting?

Nice work, and tell us what you guys are working on for the front.

AntiSquat (here we go.... :rolleyes:...) is 89.8%, huh? So your suspension will SQUAT slightly under acceleration...

Personally, I've come to believe that a bit of anti squat is good (greater than 100%, but not waaaaay up there). Here's my thoughts:

1. As you accelerate, weight shifting to the rear of the vehicle will cause the rear suspension to squat, reducing the angle of your links. Now you have even more squat...

2. On hillclimbs, where it's most important that the suspension does it's job for me, the CG of the vehicle shifts to the rear considerably. Again, this effectively reduces the amount of anti-squat produced by the rear suspension, or increases the amount of squat produced, if the # is below 100% to start with.

Thoughts? :confused:

Originally posted by RightPedal
AntiSquat (here we go.... :rolleyes:...) is 89.8%, huh? So your suspension will SQUAT slightly under acceleration...

Personally, I've come to believe that a bit of anti squat is good (greater than 100%, but not waaaaay up there). Here's my thoughts:

1. As you accelerate, weight shifting to the rear of the vehicle will cause the rear suspension to squat, reducing the angle of your links. Now you have even more squat...

2. On hillclimbs, where it's most important that the suspension does it's job for me, the CG of the vehicle shifts to the rear considerably. Again, this effectively reduces the amount of anti-squat produced by the rear suspension, or increases the amount of squat produced, if the # is below 100% to start with.

Thoughts? :confused:

The C/G changes if you are carrying bowling balls maybe! Just bustin your chops, man:flipoff2: It is a common misconception. In truth is that the C/G stays constant. The effective load transfers to the rear suspension though, giving the effect of more weight in the rear.
Other than compressing the springs further and changing the link angles, it does not effect how the instant center of the rear suspension interacts with the C/G of the vehicle. It is, however, a consideration in how much anti-squat you want to put in it if you want to tune the suspension for hilll climbing.

all I have to say is WOW!

Those drawings also will help people really understand s/as and roll axis. Conveniently, your dimensions are about dead nutz to my rigs specs...my CG is a bit more forward....hmmm...you may have made my decision to go 4link in the rear a bit easier. I really dig those drawings!

Special thanks to your employer for the copy of Pro-E!

Originally posted by four_by_nut
If anyone has a suggestion on where I can post it that it won't get limited on bandwidth, please let me know.


I've placed a copy of the pdf on our server.

http://www.pirate4x4.com/tech/4link/4link.pdf

:cool2:

Originally posted by Lance


I've placed a copy of the pdf on our server.

http://www.pirate4x4.com/tech/4link/4link.pdf

:cool2:

Lance.........your the man!!! Thanks.

AlumCJ......yes, thanks to my employer for the ProE. :cool: As for CG location, I still need to actually MEASURE it the proper way. I intend to before it is all said and done.

The whole drawing/modeling is driven by those tables on the drawing sheets as well as a few dimensions on specific items. I thought it was really slick how it all went together. Now............It's time to put paper to reality.

One thing I did notice, you still get about 3 degrees of rear steer even with the double triangulated setup. Is this because my roll axis is at a slight angle upwards? I think it is, but just wanted to double check.

Originally posted by KingOf_Pain
Looks like you have 7" of seperation, in the side view, between the uppers/lowers at the axle, but I couldn't figure out the seperation at the chassis. 6" I'm beting?


Actually, the seperation at the axle is about 10" (see sheet 2) and at the chassis it's about 7" (sheet 3, 4" above tcase for uppers and 3" below tcase for lowers = 7" total about)

Well.......not quite as much discussion as I had hoped on this, but what are you gonna do? I guess everyone is getting burned out on the 4link stuff.

So...........I decided to model it as a converging link setup today. Changed a couple of numbers quickly and got the following. Click on the "converging_link.pdf" for that setup.

http://www.pirate4x4.com/tech/4link/

I tried to keep the links as close to the same as the double triangulated. AS is about 200% (versus 89%) and rear steer is twice the double triangulated version. Also the roll axis is much steeper. Comment???

Please understand, I am not judging any setup here. I have yet to actually build one myself. I'm only noting what the model is showing and what I think we already knew anyway.

The model is extremely easy to change and shows you quickly what effects specific changes will make.

AlumCJ: I just figured out what you meant by "Special thanks to your employer for the copy of Pro-E". RSE, llc is my business that I and a buddy started on the side. Pro-E license is ours. Sorry......I didn't quite understand what you were getting at the first time. But the designs are for all to use if they wish.

How do you determine COG?

Originally posted by four_by_nut


Is this because my roll axis is at a slight angle upwards? I think it is, but just wanted to double check.

Yes

Originally posted by RightPedal
AntiSquat (here we go.... :rolleyes:...) is 89.8%, huh? So your suspension will SQUAT slightly under acceleration...

Personally, I've come to believe that a bit of anti squat is good (greater than 100%, but not waaaaay up there). Here's my thoughts:

1. As you accelerate, weight shifting to the rear of the vehicle will cause the rear suspension to squat, reducing the angle of your links. Now you have even more squat...

2. On hillclimbs, where it's most important that the suspension does it's job for me, the CG of the vehicle shifts to the rear considerably. Again, this effectively reduces the amount of anti-squat produced by the rear suspension, or increases the amount of squat produced, if the # is below 100% to start with.

Thoughts? :confused:

It doesn't quit work like that. Anything above a 100 lifts on steep hills.
Under a 100 is definitely the way to go.

"(sheet 3, 4" above tcase for uppers and 3" below tcase for lowers = 7" total about)"

Actually the sheet 3 says ABOVE for both links. I knew 1" couldn't be correct.

Looks great to me. I would move the lower shock mounts outward. I've noticed that most of the successful comp rigs are mounting them as close to wheel as possible for better stability.

As for CG location, I still need to actually MEASURE it the proper way. I intend to before it is all said and done.

Every method of figuring the CG that I've seen posted or referred to around here calculates the TOTAL vehicle CG. For purposes of anti-squat, anti-lift or anti-dive, you should use the unsprung CG. On most buggy's, this seems to be at least a foot higher than the overall CG. With this is mind, your quoted anti-squat % is probably on the high side.

HTH

Originally posted by MaXJohnson


Every method of figuring the CG that I've seen posted or referred to around here calculates the TOTAL vehicle CG. For purposes of anti-squat, anti-lift or anti-dive, you should use the unsprung CG. On most buggy's, this seems to be at least a foot higher than the overall CG. With this is mind, your quoted anti-squat % is probably on the high side.

HTH

Ok, couple of questions... First, don't you mean you need to use the sprung CG to figure anti-squat?

Second, how do you find the sprung CG? Weigh the front and rear of the vehicle and subtract the weight of the front and rear axles from each number respectivly, then subtract the sum of the axles from the total vehicle weight? Using the final numbers for the CG formula?

Or just add 12" to the verticle position of the total CG?
:flipoff2:

Originally posted by Nobody
How do you determine COG?

I got this link from other threads on COG topics:

http://www.jeepaholics.com/tech/cog/

KingOf_Pain: Yep, your right. The verbage should actual read 3" BELOW TC for the Lowers and 4" ABOVE tc for uppers. Whoops. That is a copy/paste gone bad! Thanks.

I'm going to try to model this as a parallel lowers and triangulated uppers today (and post it tonight) to see how that effects the variables. And lastly I will model it as uppers and lowers as parallel. The model will blow up with respect to calculating AS (which as we know is differently calculated from triangulated setups), but it should tell us what we want to know.

In the end I should end up with 4 models/layouts showing how each setup varies from one another while trying to keep everything else constant.

Useful???? Don't know. But might help to explain to people what each setup looks like and how things are calculated.

Originally posted by bigbene


Ok, couple of questions... First, don't you mean you need to use the sprung CG to figure anti-squat?

Second, how do you find the sprung CG? Weigh the front and rear of the vehicle and subtract the weight of the front and rear axles from each number respectivly, then subtract the sum of the axles from the total vehicle weight? Using the final numbers for the CG formula?

Or just add 12" to the verticle position of the total CG?
:flipoff2:

Right, sprung weight is the deal.

I have a formula at home for figuring the sprung CG if you know the total CG and the weight of axles, tires, etc. (approx.) I'll try to post it tonight.

I think if you use the old "cam shaft" rule of CG location on a rock buggy or big Jeep, you'll get close enough.

What's the old 'cam shaft' rule?

Originally posted by bigbene
What's the old 'cam shaft' rule?

It is "felt" that the dimension from the ground to the back of the camshaft of your motor is close to the CG location of your rig. Don't know if this is true or not. But that's what they say.

The only camshaft rule I've seen is 9/10 times people talking about camshaft lift/duration/timing don't know WTF they're talking about!

Seriously though ya gotta look at the distribution of mass. Throwing an external cage on and 44" bogger up top will move the body/frame COG quite a bit. (Regardless of where the camshaft is!)

Ken

I don't suppose you would be willing to setup a wishbone a arm on top and a triangulated 2 link for the lowers? I'd like to see how one affects the other and if binding does indeed occur.

Nice drawings nut.

all i can say is thanks, i am fixing to do a 4 link here shortly and this sure makes everything easier to figure out. mike

Originally posted by ECF
I don't suppose you would be willing to setup a wishbone a arm on top and a triangulated 2 link for the lowers? I'd like to see how one affects the other and if binding does indeed occur.

Sure I can throw that version in and see what comes out. Let me make sure I understand the setup first. Essentially you are talking about a double triangulated setup, except that the upper is an "A" where there is one link at the axle and two at the frame. Right? If so, this is essentially what I modeled already with the file called "4link", except that I have about 4" of seperation for the upper link at the rear axle. From a suspension geometry and action standpoint, it isn't much different from that. Looks like that would be real quick to do. I will do it anyway and post it this evening.

PIG: Thanks. But unfortunately, that's all it is right now is drawings. Time to put paper to steel and prove or disprove the theories.

Gunracer1: Not a problem. That is why I posted it. To help out others and to help explain how all of the variables go togther.

Does anyone have any other setups that they would like to see modeled? Shorter arms? Flatter arm angles?

One of the things I struggle with is to be sure that I am modeling what happens in real life. And the biggest question I have had is by just lifting and lowering the rear tires to induce flex, is this realistic? I've tried lifting just one tire at a time and it creates a lot of rear steer. But after looking at the situations involved in flexing, it seems that one tire up and one tire down is the right way to look at it. Imagine a rig going up a ramp with one front tire. As that tire climbs, the body rolls, but the rear axle stays squarely on the ground. So essentially, you have pushed one rear tire up and pushed one rear tire down. The same would apply if you were doing the ramp in reverse. True? Making sure that I model real life is the hardest, and most important part of this whole thing.

Originally posted by Slowzuki
The only camshaft rule I've seen is 9/10 times people talking about camshaft lift/duration/timing don't know WTF they're talking about!

Seriously though ya gotta look at the distribution of mass. Throwing an external cage on and 44" bogger up top will move the body/frame COG quite a bit. (Regardless of where the camshaft is!)

Ken

You're right, but eye ball a sideview shot of a rock buggy or Jeep w/cage and it looks to me like the CG is reasonably close to cam shaft height. Besides, how much accuracy do you need?

Get a close estimate of where this point is, extend it to the vertical point above the front tire and draw the force line back down to the rear tire. Once you have that line, keep your rear link IC below it for < 100% anti-squat or above it for > 100%

Originally posted by four_by_nut




One of the things I struggle with is to be sure that I am modeling what happens in real life. And the biggest question I have had is by just lifting and lowering the rear tires to induce flex, is this realistic? I've tried lifting just one tire at a time and it creates a lot of rear steer. But after looking at the situations involved in flexing, it seems that one tire up and one tire down is the right way to look at it. Imagine a rig going up a ramp with one front tire. As that tire climbs, the body rolls, but the rear axle stays squarely on the ground. So essentially, you have pushed one rear tire up and pushed one rear tire down. The same would apply if you were doing the ramp in reverse. True? Making sure that I model real life is the hardest, and most important part of this whole thing.


You are right on for the real life flex. The rig isn’t getting any heavier or lighter so for ever inch of up travel the other wheel should have close to the same down travel. I think

Originally posted by MaXJohnson


You're right, but eye ball a sideview shot of a rock buggy or Jeep w/cage and it looks to me like the CG is reasonably close to cam shaft height. Besides, how much accuracy do you need?

Get a close estimate of where this point is, extend it to the vertical point above the front tire and draw the force line back down to the rear tire. Once you have that line, keep your rear link IC below it for < 100% anti-squat or above it for > 100%

Sorry guys I'm new to calculating CG and anti-squat . Could you explain further? I have a buggy that works pretty well but you have me second guessing what I've built.:confused:
In real life we're never on level ground so what does all this squat and anti squat do when you're trying to climb #3 at St George? If your links are short and slope up, the tires try to climb under the rig and hops, right? What about the plane from your axle to your IC should'nt it be under your CG ? Help!
And PRO-E?? what ,where and how much?

Cool post!

I have a good request... :D

How about a 4 link with the lower links converging at the t-case and splayed out to 40-45" wide , but with the upper links parallel to each other about 32"apart. The links mounting distance apart is 6" on the frame and 6" on the axle. The links be 36" long while looking at the side profile.

Ride height would be with the links only at a 7-8 degree down. The suspension will have 8" of uptravel at the splayed outerlink end and about 8" of downtravel.

Not that I would ever build it in a buggy front and back or anything.

Originally posted by zags
The C/G changes if you are carrying bowling balls maybe! Just bustin your chops, man:flipoff2: It is a common misconception. In truth is that the C/G stays constant. The effective load transfers to the rear suspension though, giving the effect of more weight in the rear.
Other than compressing the springs further and changing the link angles, it does not effect how the instant center of the rear suspension interacts with the C/G of the vehicle. It is, however, a consideration in how much anti-squat you want to put in it if you want to tune the suspension for hilll climbing.
Dammit! I should have changed the phrase "movment of the CG" to "weight transfer" but got lazy... and just clicked post.

That's exactly what I mean: weight transferring to the rear of the vehicle will compress the springs, decreasing the angles of all of the links and reducing your effective anti-squat. Part of what makes a hill-climbing link suspension hard to nail down. Any pile of tubes will flex it's ass off in a flat rock garden unles you really fawk it up... :D

Zags's point about the CG staying constant, and the weight transferring, can be summarized in this pic.

Originally posted by Air Ride


It doesn't quit work like that. Anything above a 100 lifts on steep hills.
Under a 100 is definitely the way to go.

Anything above 100 lifts? the rear? Would that add pressure to the front tires? Say if you used a limiting strap to keep your rear from coming up too much and your rear axle from going under your rig like Neils red rig. sorry Neil.

rocraven: I wouldn't second guess for a minute what you have built. If it works, go with it!!! Only think about changing it if it doesn't get you to the top of the hill you are climbing! There is someone on this board (and rockcrawling comps) that uses the converging link setup to GREAT effectiveness. It has a good deal of antisquat which he counteracts with a strap to the diff. Do a search using "4 Link" or "God of Suspension" in the search criteria. You'll get more info than you have time to read! There are some really good discussions and explainations covering the question you are asking about lifting the front, walking underneath, hopping, etc.

EDF: I modeled the setup you mentioned. Go to:

http://www.pirate4x4.com/tech/4link/

And click on the 3link_upper_a.pdf file.

Mieser: I will model that tonight and try to post the "results" tomorrow evening. I have to use a converter to get it into PDF format which is at my office.

Originally posted by four_by_nut
There is someone on this board (and rockcrawling comps) that uses the converging link setup to GREAT effectiveness. It has a good deal of antisquat which he counteracts with a strap to the diff.Ken Shupe's comes to mind, as do some Avalanche and SNORT setups. :)

four_by_nut Thanks for the direction to the G.O.S. thread. I can see now no one can give a ideal example of any link. just plenty of opinions & B.S. But at the risk of starting more. What about front link design. Is there a design that is thought to add pressure to the front tires?

If your interested in figuring the unsprung CG height and know the overal CG ( http://www.jeepaholics.com/tech/cog/ ), here's a formula I use:

((Total weight/sprung weight)*CG height) - ((unsprung weight/sprung weight)* hub height)

To get an approximation of the sprung weight, subtract the weight of:

100% of both axles (complete with brakes)
100% of tires and wheels
50% of suspension arms
50% of springs and shocks
50% of drag link
50% of drive shafts
20% of swaybars (100% of links)

from total weight. Remainder is sprung weight.

Example:
5500lbs/3700lbs*38" = 56.49
1800lbs/3700lbs*17" = 8.27

sprung CG height = 48.22"

The force available for anti-squat isn't free. It's a percentage of the torque applied at the rear wheels. When you increase anti-squat, you take away from the power available to climb.

Mieser: I ran your setup last night and will have a PDF this evening to post. I must say..........this is the BEST setup (by the numbers) that I have seen yet. (this is my opinion people, not fact). It has good compromises of all aspects. I set it up with a little longer arms than what you mentioned because I wanted to keep the models all at 100" wheel bases (so as to keep comparing apples to apples so to speak). The rear steer was a little more than the double triangulated setup (7 degrees versus 3 degrees). But AS numbers were lower and the rear axle doesn't want to swing to the side under articulation. I pretty much stays nicely centered. And the links aren't anywhere near touching, even under 40" of total wheel travel (20" up one side, 20" down on the other). Roll axis is a little high, but that can be worked slightly with how the mounts are placed. This setup reminds me of one I saw pictures of on this board. I am sure others have this setup too, but Camo's comes to mind, and I was able to find a pic of it. (see pic). And it appears that Camo's links are much flater than my model, thereby bringing the roll axis to a flatter dimension.

I will post the drawing for this setup tonight for all to see.

I think your first example was just as good, IF you lowered the upper link attachment on the axle 2". Check it out.

Yes that's exactly what I am thinking. In theory it sounds like it is close to the same but could have binding issues. I built a model with a wishbone a arm on top and converging lowers and it doesn't seem to bind but that might just be a crappy model. Anyway I appreciate your work and it's nice to have something totally tech. without all the BS.

Originally posted by KingOf_Pain
I think your first example was just as good, IF you lowered the upper link attachment on the axle 2". Check it out.

You naided it!!! Just made that change (dropped the uppers at the axle end to by 2". This gives them an 8" spread while the uppers at the frame end have a 7" spread. AS is 62%, rear steer is 4.1 degrees, axle shift to side is 3.51", and roll axis is 5.3 degrees. I will try to post this one tonight as well. Thank you for the insight!!! This seems to be a great combination of minimizing rear steer and keeping AS low while at the same time keeping the other variables in a reasonable range.

hehe,

Also you might want to bring the lower links at the chassis together some, so they are triangulated equally with the uppers. Now, it will be exactly like mine. :)

Of course, I copied it off one of the guys here after studying up. Seemed like the best compromise to me, plus I made some changes in link length, at Gordons suggestion.

What about double parallel 4 links with trac bars? Radius arm setups? I don't really know much about link setups. But its really cool to see how the different setups change the numbers.

Mieser: The one I modeled similar to your suggestions is titled "para_uppers_traing_lowers.pdf".

KingOf_Pain: The one modeled per your suggestions (not including your last of moving the lowers at the frame more inboard) is titled "4_link_round_2.pdf". So far I like this one the best (on paper). I am going to also make the mod of moving the lowers inboard more and see how that effects it.

Link is:

http://www.pirate4x4.com/tech/4link/

And click on any one of the pdf files. I need to ask Lance if he can put these on the Pirate site. I'm afraid my free one is going to run out of bandwidth allowance soon.

Feel free to give more ideas and suggestions to try and model. I'm going to try to see if I can create some animations of the movement as well.

Check 'em out.

Feel free to give more ideas and suggestions to try and model. I'm going to try to see if I can create some animations of the movement as well.

How about mocking up one of the SNORT setups:

Like the pic of Camo's that was posted but have the links all on one plane at the frame crossmember side - keep the lowers above the axle centerline and raise the uppers to effect at the axle end...

I wouldn't mind seeing two variations of this setup...

One like Camo's where the lowers are triangulated and the uppers are parallel to each other (again all frame mounts in the same plane)

| / \ | (uppers on the outside)

And the other with all four links triangulated and still share a single mounting plane at the x-member

/ \ / \ (uppers on the outside)

You can't mock up some rockwell's too :flipoff2: I have measurements! :rolleyes: Just kidding - unless you really enjoy this stuff and want to?! Thanks

Matt

Originally posted by Slowzuki
The only camshaft rule I've seen is 9/10 times people talking about camshaft lift/duration/timing don't know WTF they're talking about!

Seriously though ya gotta look at the distribution of mass. Throwing an external cage on and 44" bogger up top will move the body/frame COG quite a bit. (Regardless of where the camshaft is!)

Ken

the camshaft rule, assumes a largely standard car! (i.e. no external cage, no 44" bogger on the roof, no fat guy with an esky {cooler} full of beers) the assumation is a more standard setup

yeah the page is havingt hosting errors!!!

thansk for the link lance!! :D

Originally posted by BJ On Roids
yeah the page is havingt hosting errors!!!

thansk for the link lance!! :D

What trouble are you having? I was able to bring them all up just now without a problem.

wanderingwillys: I will try to work the setups you suggested this weekend. Should be able to post something on them Monday evening.

This model really DOES make it easy to see how different setups react and how they all vary. Granted, real life is going to be somewhat different, but should be pretty close. And you would expect them all to behave differently in real life just as you see them here acting differently.

Maybe we should put names and/or rig names to each of these setups. Can anyone decifer one from another and give a real life example of someone running something like that?

Originally posted by four_by_nut
[Feel free to give more ideas and suggestions to try and model. I'm going to try to see if I can create some animations of the movement as well.

[/B]

How about the same link design as the first one but using a Mog portal axle :D

Tass

Originally posted by four_by_nut
Mieser:

Feel free to give more ideas and suggestions to try and model. I'm going to try to see if I can create some animations of the movement as well.

Check 'em out.


If you can put some animation to these I would really like that. I always understand things better if I can see it work. I would love to go coils or coilovers on my truck some day. I'm reading as much as I can about building a link set up,since I've never done it, so I can try and learn. For some reason though I keep thinking of the set up that Scott (Rockstomper) runs. It seems like that set up works well and might be easier to build. But then again I don't know cuz I've never done it and want to learn how to build a good set up.

Thanks on the drawings... I am also working on a set of drawings but on paper, ther are very simlar to your "XX", I also would like to keep about 100" of WB . When I get some time (right now working too much OT) I have some cheap heim joints & misc scrap Im going to "dummy" up my 4 link XX set up & see how everything works out.
Keep up the good work!:D

Originally posted by four_by_nut


wanderingwillys: I will try to work the setups you suggested this weekend. Should be able to post something on them Monday evening.

This model really DOES make it easy to see how different setups react and how they all vary. Granted, real life is going to be somewhat different, but should be pretty close. And you would expect them all to behave differently in real life just as you see them here acting differently.

Maybe we should put names and/or rig names to each of these setups. Can anyone decifer one from another and give a real life example of someone running something like that?

Thanks Jay!


Matt

Originally posted by wanderingwillys


Thanks Jay!


Matt

I started to try to put in the ideas you had but realized I did not quite understand exactly what you meant. Anyway you could do a MS paint picture or something of what you were saying. This would help me to make sure I understand it better. Or maybe try to explain it a little more clearly and in detail.

All: I am working on an animation of the motion. should have it soon.

well i think i can safely say you are one of the best fawkin newbies we have had in a long time. thanks man, and welcome newbie:flipoff2:

Originally posted by gunracer1
well i think i can safely say you are one of the best fawkin newbies we have had in a long time. thanks man, and welcome newbie:flipoff2:

DAMN!!! That's one HELL of an accomplishment/compliment coming from someone on this board. Especially from someone with over 1800 posts!!! I'll have to try to live up to the billing.:D

I will try to keep working it. But offline I am getting BARAGED (spelling?) with people wanting me to try this and that. I've got more requests than time.

I want to try running wanderwillys idea though. It sounds interesting and WAY different. Just need some clarification on the setup.

Now...........if only I can find that damned link on "How to do an SOA"!! :rolleyes:

I would think that wanderingwillys set-ups would both have really high anti-squat numbers.

I am guessing that in the same plane means mounted at zero distance apart vertically. This would be the same as the 'converging link' pdf already posted.

I can get ProE on some of the lab computers on campus. I am going to try to learn how to model this out for my suspension on the buggy.

With the arms even more level at ride height while having an equal 8" of up and downtravel at the axle should make the rear steering numbers go down and the antisquat go down a little too while climbing.

cool post

I am guessing that in the same plane means mounted at zero distance apart vertically. This would be the same as the 'converging link' pdf already posted.
No. In the "same plane" means that, from the side view, the uppers and lowers are parallel.

With the arms even more level at ride height while having an equal 8" of up and downtravel at the axle should make the rear steering numbers go down and the antisquat go down a little too while climbing.Antisquat depends on your instant center's position relative to the CG of the vehilce. Since the instant-center is determined by the link angles, you're correct... sort of.

ok....So the links are parallel. That makes more sense. My bad.


On my buggy suspension I ended up going with the most simple system that would fit in the space required. Also, the suspension is the most neutral I can make it. The links are parallel while looking sideways, they are the same length looking sideways, mounting distance is the same on the chassis and axle, and they are as level as I can get them.

Simple things for simple minds I guess. Once I started trying to change things around too much I just gave myself a headache :D

I have a little updates on some things.

First..........Lance came through for me and allowed me to post each of these PDFs on the pirate site. They can all be found at:

http://www.pirate4x4.com/tech/4link/

Second........I'm still not sure what Wanderwillys is looking for, but I will wait for his reply.

Third......I did some "if you can't amazing 'em with brilliance, baffle 'em with bullshit" today and did two animated gifs of the rear during articulation. The first one "4link-both.gif" is a shot of the rear flexing when one side travels up and one side travels down (equally). They start at ground level and travel up to 15" per side. The second one "4link-psonly-animated.gif" (nice title huh?) is a shot with just the passenger's side flexing upwards 20". The link setup is a 4 link, double triangulated with the uppers and lowers nearly parallel to one another and AS about 62%, roll axis at 5.3 degrees. Rear steer is 4.1 degrees in the one where one side drops down while the other goes up.

Interesting thing about these is that one has rear steer to the right while the other rear steers to the left. If you think about the static position of the arms (slightly angled up) and how that effects the arcs that are swung, it sort of makes sense. But makes you go hhhmmmmmm.

Take a look and get back to me. :D

Crap.....the second picture exceeded the file size limit. here is a link to it:

http://rse.theshoppe.com/fourlink/4link-psonly-animated.gif

All I wanna know is where the god of suspensions (GFI) is on this one...........









:confused: :confused: :confused: :flipoff2:

four_by_nut,

I know your covered up. this thread has made alot of people
think about what they're doing. If you have time would you try an
"A" link? top of the "A" 4" under yoke of TC. in a johnny.legs of "A" mounted to spring pads solid. then track bar mounted apx 2" inside pads and level apx 8" above centerline of axle. I already know it moves side to side alot because of the track bar.

Originally posted by rocraven
four_by_nut,

I know your covered up. this thread has made alot of people
think about what they're doing. If you have time would you try an
"A" link? top of the "A" 4" under yoke of TC. in a johnny.legs of "A" mounted to spring pads solid. then track bar mounted apx 2" inside pads and level apx 8" above centerline of axle. I already know it moves side to side alot because of the track bar.

I would, but the model does not have provisions for what a trackbar/panhard bar would do to the action. I have simply set it up for 4 link (and some 3 link) setups.

I do intend to extrapolate this to the front end where I expect to have it set up for use with a tracbar/panhard bar. But for now, it is limited to setups that don't include this feature.

Sorry.

And...........yes...........where IS GFI on this one? He must be out cutting and welding on his 4 link setup. :D Or just hasn't got much to add. Who knows.

Originally posted by four_by_nut
Second........I'm still not sure what Wanderwillys is looking for, but I will wait for his reply.


Sorry I took a while - things have been kinda crazy around here - you first thought about frame link placement is correct (all the links at the frame are in the same plane horizontal and vertical)- but the AS value does not have to be super high - especially if the crossmember is not much higher than the axle mounts and the links are long...

Here are the two crude drawings of what I was envisioning - anyone think of the benefits of doing one over the other...

Thanks

Matt
MS Paint to the rescue! :rolleyes:

http://home.off-road.com/~wanderingwillys/xjpics/Willys_Stuff/link1.bmp

http://home.off-road.com/~wanderingwillys/xjpics/Willys_Stuff/link2.bmp

I'm no suspension guru by any means, but if the links are mounted all along a single line like that, wont it totally screw with your antisquat?

It seems to me that the number you are getting for antisquat are too low in that I am aiming for somewhere in the neighborhood of 100 such that more force is applied to the tires. I'm wondering on the 3 link if I just put the links closer together at the chassi end if that would increase the antisquat right? Thanks again.

Originally posted by Heavy Metal Toy
I'm no suspension guru by any means, but if the links are mounted all along a single line like that, wont it totally screw with your antisquat?

Not at all - you are just making the IC become the link mounts at the frame instead of some imaginary point off in space

Anti - squat is just a measure of how much force the "lever arm" of the links applies to the center of gravity of the vehicle (a little simplified but pretty close)

With converging links that are seperated at the frame you still have an IC but if is farther foward than in my example... The usual downside to the setups I drew is very high anti-squat numbers because the axle is usually quite a bit lower than the frame - angling the links upwards and making the roll center height over the front axle much higher than the COG...

If the links are kept very flat - run real big tires with very little suspension lift on a narrow body; AKA: tube buggy - the roll center is also very flat - making the height of the roll center plane at the front axle much lower (possible even lower than the COG depending on the exact measurements)

Make more sense???

Matt

sorry to be a newbie and bring up an old post but i can't bring up
the pdf files.do you need a special program to get them,if so where can i download it?like i said sorry if this a stupid post:confused:

this thread is old, but just another 4link download can be found on the bottom left column of page.
http://www.powerblocktv.com/sites/xtreme/

I think this is the same one that tri ag (ok so it's somewhat close to the user name) has on pirate here

Holy fawk...

Where do you think xtreme got their 4-link calc? Hint: search general 4x4.. :shaking: