Thinking of building a four link set up

[Tyler Bates]

I have a 90 YJ currently with a spring over and was thinking of doing a four link but not sure what all I need to do to make this all work such as measurments and what i will need to do about a driveshaft and all that any help would be great

 

[animus_divinus]

what do you plan on doing that would require a link setup?

 

[Tyler Bates]

what do you plan on doing that would require a link setup?

I want to do away with the leaf springs and build a four link suspension in the rear

 

[Ggg]

Look up T&T customs they have a pretty nice setup. Beefy links, good joints, cross member, skid plate, and mounts etc. It does require welding and the kit works well. I know you said you wanted to build one but there is a lot of math and measuring to get it right if you are starting from scratch. You can do that or get a kit that has been thought out and install it and get back out on the trail.

 

[animus_divinus]

I want to do away with the leaf springs and build a four link suspension in the rear

yeah, but why? leaf springs are the simplest, most reliable suspension you could have, and capable of doing whatever about 99% of the jeep owners want it to do.. unless you plan on building a purpose specific competition rock crawler, theres not much point to it

 

[jps4jeep]

are you looking for a "kit" or are you looking to fab it up on your own? I just finished a double triangulated 4 link on the front of a yj and in the end, materials and air shocks cost about $1300. If I was to do a "kti" I would only narrow my search to two;

1. Clayton
2. Poly performance

for the rear you can get away with running 2.0 air shocks if you move the fuel cell to just behind the rear seats and loose all the excess weight, if not, you should ideally use a 2.5" body. also had great luck with running tj rear springs. depending on where and how you mount the coils/re work the rear frame, you can run a stock spring which most people give away for free.

if your looking to fab from scratch, down load a 4 link calculator, I would not focus too much on the squat anti-squat value rather I find that if particular attention is paid to vertical seperation at the frame and at the axle as well as link angle, those values will fall into place.

 

[Utah_jeepster]

the problem with DYI kits is you have to know center line of the jeep and know center line weight of the jeep to calculate the anti squat out or in depending on what type of driving this jeep will do.
There are several calculating programs available, I like this one from power block TV

 

[Ggg]

Utah jeepster that is exactly why I like the T&T customs kit. It locates off of specific points on the frame so you do not have to do all the 4 link calcs. All you need to do after installing their kit is a 4 wheel alignment.
Don't get me wrong it is a kit and there are compromises. Some people like to do it completely from scratch, I can relate to this. I have used several other kits like those mentioned by Johnny but the best most comprehensive kit IMO is the T&T. I have used the same kit to install 1 tons and only had to use different axle mounts and it still worked great. If this YJ is going to see any street use I would never recommend air shocks. If you have tried to use them on the street even if for only a hundred feet you'll know what I mean. Even for trail use they can suck. For a purpose built rock crawler they work. Coils and shocks, 1/4 eliptical, or coilovers are the only way to go for street or trail use.

 

[jps4jeep]

that was kinda my point Utah, I have found that with less focus on calculating center line, center weight, roll axis, axle steer, squat, anti squat etc.. focusing specifically on vertical seperation and link angle and length, the rest always seems to fall into place. will it be ideal.. no, will it ever be ideal if you calculate those values specifically, obviously not. The ride height and amount of flexability we desire out of these link set ups is not really what they were initially designed to do a 4 link was adapted from other types of motor sports and applied to off roading.

Some values I tend to start my builds around.. I like to start with my upper links about 40 degrees from the diff to teh frame. this will give me the upper link length length I will add about 25-30% of that length to the the lowers and that gives me an approximate lower length. I move those links on the axle tube as far out as I can with out contacting rims, tires, brakes what have you. As for vertical seperation, I find that is I have about 10-12" at the diff and about 8-10 at the frame. These are preliminary value I start with then I will fine tune and tweek them based on the vehicle, frame, clearencing etc.. this is a set up that has worked extremely well in a number of applications that it has been installed.

 

[Tyler Bates]

I knew the four link was going to be difficult but is it worth the time? And will it tdo away with the top heavy feeling

 

[animus_divinus]

sounds like a lot of work for a relatively small increase in travel and a greater loss in strength and reliability vs leaf springs... never seen anything wrong with YJs... seems for the price going into putting links and coils on a YJ, one could just keep that, sell the YJ, and get a TJ

 

[Ggg]

There is nothing wrong with a leaf spring suspension, other than it too has its limitations. To say a 4 link is weaker or less reliable is simply not true. Look at Dodge, Jeep, Ford they all use 4 link suspensions with no adverse effects on strength or reliability. A properly functioning 4 link will far out travel a leaf spring suspension. Don't forget, axle wrap with a 4 link- nonexistent.
There are some special leaf spring setups that will significantly increase the travel but not to the extent a 4 link can provide with the same strength and axle control. I will say if your YJ is a DD then I can see where the cost v/s benefit may not justify the effort and price of making a 4 link. But that is something only you can decide.

 

[Ggg]

Johnny do you have any pics of the 4 link front suspension you made? Also do you have any pics of a 4 link you made front or rear with 10" of vertical separation at the frame?

 

[Tyler Bates]

There is nothing wrong with a leaf spring suspension, other than it too has its limitations. To say a 4 link is weaker or less reliable is simply not true. Look at Dodge, Jeep, Ford they all use 4 link suspensions with no adverse effects on strength or reliability. A properly functioning 4 link will far out travel a leaf spring suspension. Don't forget, axle wrap with a 4 link- nonexistent.
There are some special leaf spring setups that will significantly increase the travel but not to the extent a 4 link can provide with the same strength and axle control. I will say if your YJ is a DD then I can see where the cost v/s benefit may not justify the effort and price of making a 4 link. But that is something only you can decide.

My jeep is not a daily driver I do occasionally drive on the road but rarely, So thats why I was trying to decide if its worth the time and money my jeep also feels very top heavy probabley due to center of gravity but not sure so was just trying to get ideas on what upgrade to do next

 

[animus_divinus]

tyler.. if you do offroad driving for recreation, sport, then leafs will do anything you ask it to.. if you intend to do professional rock crawling for money only then would it be worth the cost and effort to go with links.. and the CJ leaf spring suspension is actually pretty good, might want to look at bolt on leaf kits to get what you want.. but first you have to determine just how much travel youll actually need in the suspension

 

[jps4jeep]

Johnny do you have any pics of the 4 link front suspension you made? Also do you have any pics of a 4 link you made front or rear with 10" of vertical separation at the frame?

I'll check when I get home, I can't access photobucket on my work PC for some reason.

as for the 4 link on the front, I do not think I have a pic of a 4 link front in a jeep, the jeep frame rails are narrow and do not lend themselves to allow ideal settings. all of the front's in jeeps we do 3 link with pan hard. 99% of the 4 link fronts are in buggy applications of vehicles with the front frame re-built. also one full size chevy.

Also, if you are still a full body jeep, to have that much seperate, your lower link will be below the frame rail and you will need to cut holes in teh floor for the upper links.

Like mentioned, I will try to get some pics up tonight.



One of the benefits of link suspension over leafs is ride height. last fall we finished a tj with about 3.25" of total lift orver stock on 42" irok comp sticky's (measure about 42.75" tall at 6 psi.) we were able to rebuild the frames and pretty much get the rig as low as possible. Currently we are working on an MJ that we gutted down to the fire wall and floor boards. we are tubing it and lowering it, also on 42's

 

[Tyler Bates]

tyler.. if you do offroad driving for recreation, sport, then leafs will do anything you ask it to.. if you intend to do professional rock crawling for money only then would it be worth the cost and effort to go with links.. and the CJ leaf spring suspension is actually pretty good, might want to look at bolt on leaf kits to get what you want.. but first you have to determine just how much travel youll actually need in the suspension

Well I appreciate the advice and Im a mechanic for a living, but new to crawling, so not real sure where to go next I love crawling and have a 90 YJ that I love and and would like tocontinue to build. Ive been craling for about a year so so far I have a spring over a body lift 35 inch tires, a ratcheting locker in the rear and thats it and have no clue where to go next so all elp would be much appreciated been having problems breaking u joints so added two inches to my driveline but wont take it out until this weekend to see if it works

 

[jps4jeep]

Johnny do you have any pics of the 4 link front suspension you made? Also do you have any pics of a 4 link you made front or rear with 10" of vertical separation at the frame?

Ggg

Here are some pics in no random order. 3 link front, 4 link rear, 42 irok comp stickies, bone stock 2.5L AX 15 and 5.0 atlas, bone stock CUCV axles with front gears welded.

This was built to be super low and stable. You will see that the rear frame had to be cut out and rebuilt, the floors were chopped, and the amount of clearance needed for the atlas to fit, also note how theshocks were run inside the tub.

Full bump on 42” irok comp stickies, person in the photo is 6’1” or 6’2”.. tall soma gun


Here was the finished product pre bead locks

Now with KMC bead locks (about 3" wider)

 

[Ggg]

Nice pictures Johnny, now Tyler these pics are a good example of a typical custom 4 link suspension and how much you will be modifying your Jeep. The suspension looks to be well thought out and executed, I am not criticizing Johnny's work. The "kit" version 4 link suspensions will be a compromise like I said before, but they will require significantly less modifications. Such as no frame rail replacement, no floor pan mods, and do not require shocks mounted through the body. The kits are more in line with what a novice would want to try for their first suspension. There is nothing wrong with what Johnny has said or pics he posted, just that for a first time 4 link build a custom suspension can get overwhelming which is why I recommended a kit style suspension.
Johnny I was hoping for a pic of the double triangulated 4 link front suspension you said you just finished. Unless that was in a mid or rear engine buggy that would be one pain of a build.

 

[jps4jeep]

sorry, like I metioned, I know for a fact I do not have a pic of a double triangulated 4 link in the front of a jeep, to be honest, I have not personally done it. we are currently working on the MJ I previously mentioned, 4 link rear, but 3 link front. Check out the Slinky Blue Balls build on pirate, Kirby built a double tri 4 link front in a low TJ, but even when done, he said it was miserable trying to package everything together.

here is another of the TJ right as it was finished, and the MJ on it's way to being under the knife.

The cutting started

About 2 months later, this is what it looks like now

[quote author=Twisty link=topic=8387.msg114385#msg114385 date=1301514060]

Dialing in the front 3 link