• Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

3-link v.s. 4-link

Either that is a 54" tire in the pic, or it's more like 2' off the ground than 4'. The bottom of the drivers front is about even with the center of the passenger hub. Assuming a 31" tire that would be 15.5" off the ground?
 
4 feet eh?

Anyway, I notice the Dana 30 under there. Still using the stock UCA mounts? There's your source of deflection. Like I've been saying before, its really not an issue, but its there and has a bearing on link design and joints/bushings used. This binding occurs between the links, not just a spherical joint.
 
The key word was "travel". There is a down as well as up... Plus the shot of the front end was one that we limited to keeping the bumper level. The first photo that has the rig picked up from the rear tire shows the travel better.

I had to bump stop the front more than you would expect to when the 33s went on as even with the Bushwacker cut out fender flares, the tires were hitting.

At any rate, no matter what, the front end does not and will not bind until I replace the frame end SREs with rubber based joints. It will limit the flex but it will also reduce the amount of noise in the cabin. The downside to a front end that is all SREs is that it is profoundly noisy. Every bump gets transmitted into the cabin due entirely to it being all metal.

It can be argued then that my front end will then be in a bind. But, as of this date, the conversion has not happened and it does not bind. The shocks currently limit the travel...

Would I recommend a 4 link over a three link? Absolutely. If three links were structurally sound, then the axles would have come from the Factory with only three links.

If you consider the amount of money the Factory would have saved over the millions of vehicles with the 4 link suspension, it boggles the imagination. Manufacturers only put in what they know to be the safe minimum number of components. To think that an after market person knows more than the Designers is a tad conceited on the part of the aftermarket person.

So, in a nut shell... I do not support three link suspension s as I feel that the integrity of the suspension is compromised by the removal of the fourth link. That being the case, feel free to use what ever suspension you like. For me, I will stick to the 4 link.

It works.
 
O-Gauge Steamer said:
Wow. Just wow. I run a LA 4 link and can get about 4' of travel out of the front end before the one of the rear tires lifts off of the ground.

"Bind"... I do not think so as long as the links use high misalignment spherical rod ends. If what was under discussion was links using the stock rubber type of joint, then yes it will bind dop to the joint, not the number of links.

And yes, it is my rig that SolarBell is referring to........

Plus, the rear antisawy bar had not yet been removed when the photos were taken.

A couple of shots taken right after the lift was in but before the rear sway was removed:

98Flex7.jpg
[/URL][/IMG]

98Flex4_zpsd5f4b41d.jpg
[/URL][/IMG]

Bind?
Click to expand...

Solar said you had front and rear sway on but your pic shows that there is no front sway connected and you said rear was connected. Just wanted to point that out.
 
So we agree that this binding does exist? Because that is all I have been saying. Its there, but with a source of deflection it takes care of it.

As for the 3 link being unsafe debate, look at the amount of rigs on the trails and racing running 3 links without issue. I'm sure the reason you don't see them factory equipped on vehicles has to do with costs. 4 stamped sheet metal control arms and weak control arm mounts are cheaper, lighter, and easier to produce than 3 heavier duty links with the mounts to make it strong enough. That and of course not many people buying brand new vehicles are interested in the road noise transmitted through solid joints, so they use rubber bushings anyway (again, bushings are more inexpensive to produce there) I suppose we can consider ford radius arms a "2 link" and those rarely have issues from the factory. Just a formed steel arm mounted by a large stud at the chassis end.

Everything I mentioned holds true. If you need to hear it from someone else search for "parallel 4 link bind" on Google. I'm sure there is plenty of info out there.
 
Too true. My Wife's 96 Bronco has the radius rods and through history, they have proved to be reliable. But... It is a completely different approach to what is on the Jeep. And, it has limitations insofar as travel is concerned.

In the 20's and the 30's a number of cars came with radius rod front suspensions but then, they were street vehicles that had, at best, 6" of travel (or so, do not quote me, I would have to look it up...) as they were usually associated with transverse leaf spring front ends such as the Model T Ford. The transverse leaf was used not only as the suspending unit but located the axle from side to side. The front ends went by hairpin and Curtis for nomenclature for the most part. Hot Rodders today still adopt the suspension for it's looks. Not for it's performance. Although the Hot Rod Industry has largely replaced radius rod with 4 link, they are, by their design, travel limited. Consider the application.

The photos posted, here, were taken within minutes of the suspension being installed. The rear sway was in place, I removed it when I got the rig home that very day. The front sway is clearly visible but had been disco'd for the photos. It has since been replaced with a Currie AntiRock as I can no longer get on the ground to use standard disco's. Poor health...

Anything can be debated to death. What I have works. Perhaps others out there do not. IMO, for a lifted XJ to have a non-binding 4 link, the links must be long as it reduces the angular error the SREs as being asked to handle.

But then, that is just my opinion and we all know what that is worth...
 
All this just from me explaining that joint/bushing choice is related to link design. I never said a properly built 4 link would flex like a shopping cart, you seemed to have been taking this as a dig at 4 links. Like I said in the first post, they both work great when done correctly.
 
I've seen stock uppers fold like tacos more than once, so to argue that the factory setup is stronger than the 3 links being run by so many is conceited at best. The 2 stock uppers riding on 10mm bolts are far weaker than 1 1.5"x1/4" wall dom link running 7/8" Heims held in by 5/8" bolts. And the integrity of the stock passenger side upper mount is questionable at best. If the factory design was the best thing out there, why would anyone modify it?
 
Poly Performance 3-link. Bolt on except for welding one bracket to the axle. Drove great on the street, worked perfectly on the trails. If I ever built another XJ, I'd buy it again.
 
I may be wrong, but I think a rubber bushing is ultimately a source of bind rather than deflection...
The bind point in a 4-link is going to be dictated by joints (misalignment tolerance) and link length. A 4-link will bind, sure, but it may bind well past the point where other things limit the travel. Like shocks, fenders, bump stops (hopefully), oil pan clearance, whathaveyou.
A 3-link might not bind but it might not be relevant in the real world.
Some trucks, newer Dodge comes to mind, do run a 3 link - but links and mounts are built for it. You shouldn't just take a control arm off a stock XJ and call it a three link...
That said, I think you could look at the clamp strength & shear strength of a single large-ass bolt & see for yourself if it's better than the 2 10mm bolts the factory XJ uses. Just make sure you are taking into account that those 2 10mm bolts are hard as holy hell - spec'ed at 65 foot lbs for the nut vs the usual 37 for a grade 8.8 10x1.5 bolt.
All this being said... I'm not an engineer and there's bound to be one or two people who know better and maybe one who disagrees with me here. Hopefully some of this was useful to somebody though...
 
yossarian19 said:
I may be wrong, but I think a rubber bushing is ultimately a source of bind rather than deflection...
The bind point in a 4-link is going to be dictated by joints (misalignment tolerance) and link length. A 4-link will bind, sure, but it may bind well past the point where other things limit the travel. Like shocks, fenders, bump stops (hopefully), oil pan clearance, whathaveyou.
Click to expand...

I'm not speaking of binding at a certain joint. I'm speaking of the binding that occurs between links. The rubber bushing needs to be there to "squish" ever so slightly. Not a binding that occurs during misalignment.

I'm not saying that this binding will hinder flex or anything, I'm just saying that a bushings need to be incorporated into the design. That's it. People seem to think that when I say "bind" I mean their jeep will bind so badly it will flex like a shopping cart. That is not the case.
 
yossarian19 said:
I may be wrong, but I think a rubber bushing is ultimately a source of bind rather than deflection...
The bind point in a 4-link is going to be dictated by joints (misalignment tolerance) and link length. A 4-link will bind, sure, but it may bind well past the point where other things limit the travel. Like shocks, fenders, bump stops (hopefully), oil pan clearance, whathaveyou.
A 3-link might not bind but it might not be relevant in the real world.
Some trucks, newer Dodge comes to mind, do run a 3 link - but links and mounts are built for it. You shouldn't just take a control arm off a stock XJ and call it a three link...
That said, I think you could look at the clamp strength & shear strength of a single large-ass bolt & see for yourself if it's better than the 2 10mm bolts the factory XJ uses. Just make sure you are taking into account that those 2 10mm bolts are hard as holy hell - spec'ed at 65 foot lbs for the nut vs the usual 37 for a grade 8.8 10x1.5 bolt.
All this being said... I'm not an engineer and there's bound to be one or two people who know better and maybe one who disagrees with me here. Hopefully some of this was useful to somebody though...
Click to expand...

What? Are you basically arguing that 4 is better than 3 just because more links must equal stronger suspension?

It has more to do with the use of the jeep. If you want to start doing jeepspeed or other high speed stuff, then upgrading to a 4 link is smarter. Yes, a 4-link is technically stronger if you're constantly hitting things with the front axle at high speed. Plus the bind isn't a big issue because you're not flexing the suspension as much as you are making sure the whole axle goes up and down smoothly

For street driving and rock crawling, a 3 link is perfect. 3-link gives you the ride of a long-arm, while also having the advantage of no binding when flexing a ton. Plus there are less parts to come into contact with the driveshaft and whatever else under there.
 
So the bushing needs to deflect front-back? Side-side is fixed by the bolt whichever joint you run, twisting the bushing runs out of misalignment much quicker than a hard joint. I'm just trying to follow what you are saying, not intending to argue.
 
sunburned said:
What? Are you basically arguing that 4 is better than 3 just because more links must equal stronger suspension?
Click to expand...

Not arguing a single darned thing. In fact, I was going out of my way to point out that 3-links come from the factory, too, and that *any* suspension design can be done well (or it can be done craptastic)
 
yossarian19 said:
So the bushing needs to deflect front-back? Side-side is fixed by the bolt whichever joint you run, twisting the bushing runs out of misalignment much quicker than a hard joint. I'm just trying to follow what you are saying, not intending to argue.
Click to expand...

Yes it is a front to back deflection. Surely you hear of radius arm bind right? You know how those suspension designs require the use of bushings at the axle end to compensate for the binding. Same with a parallel 4 link but on a much less severe scale.

A flex joint at one end of each arm is plenty as well. Most joints out there have about 30-40 degrees of misalignment, and the bushing can safely misalign itself a bit too. Plenty for any practical application.
 
Guys..
Just one quick question..
Are the 3-link and 4-link suspensions just another type of longarm suspension ?
I don't know what the name of the other system is that you normally get with liftkits.
 
You must log in or register to reply here.

Similar threads

ehall
steering overhaul
Replies
16
Views
320
ehall
ehall
F
Axle Swap Advice
Replies
14
Views
248
XJ_ranger
XJ_ranger
Winterhawk
3 1/2" DPG Ultimate hybrid lift question
Replies
0
Views
108
Winterhawk
Winterhawk
B
Passenger Side Riding Low - Any remedies?
Replies
1
Views
2K
Tim_MN
Tim_MN
M
XJ brake upgrade
Replies
7
Views
162
RCP Phx
R
Back
Top