I have a line on a well priced set of 12" travel coilovers for the rear of my rig. For a 60-70% street driven rig on 37s, what are the pros and cons of switching to a 4 link in the rear? The obvious one is more travel and flexibility off road and a better ride on road, but I'm not sure what the potential down sides are. I had planned to do more reading, but this has changed my timeline a little and any help is appreciated before I spend more money on the project.

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Ride quality is huge on the street. It rides way nicer on the street than my 11 leaf pack did. Rode better with softer Springs but had a ton of sway. Also there is no axle wrap at all so no worries with a hard accel. Being spooled it no longer jumps around turns, just smoothly let's the tire spin with out the hops the leafs allowed. Off Road is pretty obvious. Dirt roads with washboard are so much better too. My father in law was attempting to keep up with me on a very long dirt road once. He broke a front shock in his 2005 F- 150 in that attempt and couldn't go nearly as fast due to the bouncing. The road to Holy Cross is easy and comfortable to go as fast as I want. I wouldn't second guess doing a 4 link again. Easily one of the best things I've done to my bronco for street and off road. DO IT!

Thanks, I was hoping you'd chime in. Kirk, you may also want to check out the replies to the other places I've posed this. Nothing surprising, but they just went up this AM.

http://www.colorado4x4.org/vbb/showthre ... -vs-4-link
http://classicbroncos.com/forums/showth ... p?t=246354
http://www.pirate4x4.com/forum/general- ... -link.html

I would like to hear more as well.

I hear sway can be a bit extreme on the road without a sway bar setup on the rear. Is this true? What about weight in the back? What if your carrying allot of gear around, camping/hunting/ etc? I would love to do this as well but the simplicity and adaptability of the leafs are hard to beat.

I know jeeps landcruisers and icon broncos are all linked in the rear and seem to do just fine but see they run sway bars as well.

Not high jacking but curious to the advantages.

I invite anyone to ride in my bronco for sway concerns. My Springs are pretty stiff so there is very little sway on the road. My load carrying capability is great. I've had over 800 pounds in the back several times and it handles the weight great with less sag than the leafs I had. Really I have yet to find a negative to the 4 link. Mine isn't even set up super great. I put quite a bit of thought into it but didn't work on the calculators too extensively.

Chris, one of the reasons I'd like to do coilovers is the ability to change preload to accommodate additional weight for long trips. Jason, I have to admit that your rig sways more than I'm used to, but my current setup corners really flat and handles well for a lifted rig. I'm guessing I'll be wanting sways with mine since I street drive it quite a bit more than you do yours. The level of stability your truck has does speak to how well it runs despite not having bars. 4-links are a fairly common setup for street use-just look at how many Jeeps are running around with factory coil rear suspensions. I'm wondering if the handling compromise is to run a less triangulated 3 or 4 link and a panhard/trac bar similar to Digger's setup.

My big thing is that my Bronco has moved outside the norm, which is good, it's quickly becoming what I want in a all around vehicle. I've been daily driving it for over a year now, commonly load not only my camper and bronco trailer, but I also towed my flatbed w/ project 33x2 on it down to the springs. Over the last two weeks I've been scouting really hard in it, put well over 100 backroad miles on it in very demanding conditions, most of that time was in 4 high w/ some low mixed in when it got really nasty. I'm not too concerned with body roll, I don't hit corners very hard, even with the camper it's okay wth the current leaf setup.

So... is 4 link for me?

Your rig, to me, is all about utility and simplicity. My opinion is that a 4 link is not for you. There would be no real world advantage you would see. You would get a nicer ride but in the end I don't feel a 4 link would add enough for you to go through the hassle of setting one up properly.

Awesome discussion so far. I'll toss in a few thoughts for what it is worth.

I would expand the conversation to include any arrangement of linked/coil suspension vs. leaf springs, including 2-link, 3-link/torque arm, 3-link/ radius arm, 4-link & 5-link.

Coils vs. Coilovers is another option to consider. Both have advantages and drawbacks.


Really the only reason to continue to run leaf springs is that they are so bloody simple to mount and cheap to replace. A linked suspension is 3x more complicated but the payoff is that you can divorce spring rate from suspension geometry from joint options, etc. The biggest downside to leafs is their internal friction. It plays hell when trying to adjust damping and spring rates because age and condition of the leafs are always changing the internal friction component.

Coil/linked suspensions on the other hand give you vast opportunities to do great things or screw it up royally. The biggest thing to remember is that most linked suspensions are built with race parts (like rod ends) and race parts are not designed for longevity or good ride quality because that is not important to a race car. This is why the OEMs use bushings and ball joints in their designs. They have to be concerned with more factors than a race car builder.

You should have ZERO concerns about sway and load handling. Those are just factors in the bigger equation. Load handling comes from spring rate. If you think you will be hauling 800 lbs, you would chose a spring rate geared towards, say 400lbs. That way your ride height would be within 1" of the designed nominal regardless of loading. You could also choose a progressive rate spring to help maintain ride height under an increasing load. BUT the truck sitting perfectly level takes a backseat to good handling when loaded.

Sway (roll stiffness) is determined by CG, roll center height, spring rate and distance between springs. Anti-sway bars are added last in the design when your package limitations prevent you from getting all your roll stiffness from the geometry and springs alone.

Personally I like track-bar equipped suspensions (if everyone hasn't figured that out already). Traditional 4-links usually have straight or slightly triangulated lowers and triangulated uppers. Lateral stiffness, which is key to good handling, depends on how triangulated the links are and how stiff the joints are. This is why race cars and trucks use rod ends. They have no compliance, so they are very stiff. However, now lateral stiffness is tied to longitudinal stiffness. With a track-bar equipped suspension, you can achieve different rates for lateral and longitudinal stiffness, which is helpful because you can make the suspension soft in the direction of travel for absorbing bumps from rocks and bridge seams and stiff laterally for good handling. Same goes for torque arms. I used ball joints on the rear mounts of my torque arm to make launches responsive, but bushings in the long arms to absorb rock hits.

Kinder - You shouldn't have any concerns with a multi-link suspension. Yours will just look slightly different because the geometry and spring rate would have to be adjusted for your wheelbase and loading.

Our conversation awhile back has had me thinking seriously about a track bar equipped rear suspension for the reasons you outlined above. It seems like there would also be better potential to control things like axle steer since you're also divorcing the front/rear and side to side movement of the axle through it's swing path. Also, can you speak a little more to coils vs. coilovers? My understanding is that the main differences is in the packaging, but I could see benefits to having the shocks operate on a different path than the springs.

This is a great thead. I have been thinking about rear link set up also.

My buddy is selling his off road only Toyota and buying a Razor side by side, he said the ride is way smoother and he can cover more trails in a day vs. the slow and clunky truck.
That made me start thinking about upgrading the Bronco to ride much better and make the off road experience more enjoyable.


J.E.

Cool stuff. Thanks so much for the expert info.

If/when your stuff is available, let us know. I know I'd like to support the local economy.

x2. How do we get our grimy hands on these? I really like the idea of having some extra cushion in the suspension joints, and am a huge fan of anything that's sealed against grit.

Here are their ball joints:

http://www.amazon.com/s/ref=nb_sb_noss? ... IS%20JOINT

Their web site:
http://www.spcalignment.com/home/291