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Medusa said:
I and a significant number of S&N Fab customers must have some really poor antisquat :flipoff2: Seems to work OK from our perspective.
Click to expand...
Shaddup jack :flipoff2:

I said typically.

A lot of link placement as Woody said depends on what you have available to you.


And a lot of the S&N guys like the large AS numbers. They just run tight center straps.

Jack, did you ever use the 4 link calculator on your rig???
 
Yes, I did, and as expected the spreadsheet shows a lot of antisquat. I, however, don't feel it when I am driving and to date no one watching my rig climb has ever said "man that has a lot of antisquat".

I don't claim that my suspension or the S&N Fab design is perfect -- in fact I would never be so bold as to make such a claim, like some have based on that spreadsheet ;) By all means if you are deisgning and building a suspension for the first time, you should get all the information available to you. In my opinion, first-hand experience and being around suspension systems shoud count for more than a spreadsheet based on design principles created for flat-track race cars. I have seen rigs with "good numbers" that perform badly and I have seen a lot of suspensions work very well with what many consider to be too much antisquat. So franlky, I don't pay any attention to the numbers, and suggest that others not get hung up on them either.

And BTW, my rig climbs as well without the limiting strap as it does with it :D
 
For what it is worth, my calculator numbers came out at "0" as in No anti-squat and by God, it actually has none either.

Don't claim to know all about that stuff, that is what Ed was there for, but I will say, I could not be happier with the performance of my 4-link.

It is dual-triangulated, has about 4" of vertical separation in the front and 6-7" in the rear,


I need no sway bar or limiting straps and it seems to work just fine. I am sure not needing the sway-bar is also a by product of front leaf springs and the stability they offer.
 
No one's suspension is perfect.

That is why most of the design of suspensions have more to do with what you can do vs. what you should do..


That is what is so cool about doing stuff like this. Grog's system works well. (no AS)
Medusa's system works well (high AS)
Woody's system works well (~ 80% right woody??)
My system seems to behave nicely (when I am not repairing it :flipoff2: ) At about 90% AS


I do believe that figuring out where the links can go and then modeling the suspension (and using the calculator) from there is a good idea.


I know people that have "serious" problems with rear steer, roll steer and other issues that still love the links. And would never go back to leaves.

Even with my growing pains I would not go back to leaves. This link stuff is too much fun ;)
 
Anybody got one of those 3d things that shows were the links or most commonly located from top and side with measurements?

Measurements of seperation is between where the links are connected at either end?
 
Below is my information in the "link suspension for dummies" thread on PBB. I will also add I am not into those spreadsheets for AS #s, as the COG forces reacting on the chassis and the suspension change with angle of the vehcile climbing/decending. Just build it and make it with some adjustablilty. Make the links long and I like to make them close to the same length (mine are 36") to keep from crating lots of axle roll.

-I would recommend a Tri-4link or 3link wishbone, for the rear. If planning front I would also recommend unless physically impossible due to driveline configuration.

-Place the converging Links on top of the axle with upper tri or wishbone, OR at the lower crossmember for lower links. This will keep your roll center fairly high. You can do both for a double Tri-links.

-Keep the tri links angled as much as the chassis you are building will allow or axle. It hard to go with a hard fast number here because widths of chassis and axles vary so much. Example: my 48" on center widthed chassis isn't going to allow for as much as a regular sized frame.

-Keep the remaining links wide on the axle attachment point. This will allow for more stability. Here again you have to account for the tire throughout their travel and if they steer. Just like leaf spring, you don't want the tires rubbing a lot on the links, so would be OK, but I like none.

-Vertical separation is important to take the torque rotation from the axle under power, and even more important with portal axles. Place the lower link attachment points at the axle so the brackets are not lower than the axle tube. You can go lower but will take away clearance and hang up on stuff. Then place the upper axle mounting position fairly high, again you chassis setup will dictate this a lot (especially in front under the engine). See how much compression you want, what the links will hit and make slightly lower. Once under the rig it will be clear how much, and too much isn't necessarily a good thing.

-After all of the above, you should have the axle mounting placed, or a good idea where they will go, then focus on the chassis. The lowers should be placed in the chassis to be tucked away so you have good clearance and don't get hung up. This would be either frame mounted or cross member mounted. If you have to build lower because of chassis clearance issues build a ramped mount.

-The last set of links to place are the chassis upper, all others you should have a good idea where they go from the above text. Here is where I would build in some adjustment to the suspension. All other points can be solid mount with no adjustment because they take into account other thing for best placement. Make a attachment point with several (3 min) holes that are on the same arc as the link at ride height. You will also see that the body or chassis will dictate the location of this bracket and will probably allow for some positions that have less link separation that at the axle and maybe one parallel. These adjustment holes will allow for some tuning of your anti-squat and IC. They will allow for smaller adjustments than if the lower chassis mount was adjustable.

-Lastly build strong brackets, especially at the chassis and convergence of the tri link or wishbone.

That will give you a good start. This is by no means the be all end oll of building a link suspension I probably left out a ton of stuff. Look at a lot of different suspensions and you will get a good idea. You really have to see what will fit with your chassis and axle, and go from there. Unless your are building a full on tube chassis from the ground up, your configuration will dictate a lot of how the links will end up. This is even the case when building custom chassis, its just easier to move stuff when building from scratch.

Take a look at my site and you can see mu link setup and my adjustment brakets. Oh and Good luck.
Click to expand...
 
Awsome write up, I read through it several times and now I am really starting to grasp all the terms and what the design base is.

Kinda like four link for dum dums.

Even those calculators seem useless unless you understand the basic design.


Thanks
 
This is some awesome info. I've been looking into 4-links for a little while and just can't convince myself I can do it. This helps alot! Is anyone running off-set Toy axles with a 4-link? I really can't do a complete drivetrain swap, it wouldn't look good in divorce court. A fuel injected 2F, sm420, 3 spd t-case, 4.11 or 4.88's with a 4 link stretched to bumpers would be an fun ride and I could keep my antique tags!!!

Mike
 
Guess I should'a checked there first :doh: . Have you had any problems with the structural integrity of the frame or anything? Which springs are you running? Can't wait for the write-up on it. A J@*P buddy of mine is building a similar 4 link for his CJ7 from a kit that he is buying for $1500.00 :eek: . I think he's getting hosed, but at least he has a kit to work from.

Mike
 
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