Duff's monster 4-link install *PROBLEM*

[STD]

Are your lowers higher than the center line of your axle tubes?

 

[u10072]

I sure looks like the lowers are above the axle center-line. The testing point depends on what their goals for the setup was. It appears that ground clearance was a concern and the problem with that is I haven't ever seen a factory style 4-link with that configuration. If it won't safely do 80mph down the highway the geometry is off IMO. A rock crawling only suspension makes no sense-- at least for my money.

 

[mavereq]

i played around with the numbers on the link calculator and it really looks like that was the fix for the oversteer caused by the lack of triagulation. when i moved the link above the axle i immediately went from 2 degrees oversteer to 1 degree understeer. this suspension is definitely setup to be run with a lot of lift.

 

[chuzie]

I will try and answer those questions today when I roll over to the shop to work on some stuff. My rig is 50 road and 50 trail so I hope it is worthy. Thanks for the help.

 

[mavereq]

i'm sure it's roadworthy with the amount of understeer you should have. the problem is that having those lowers above the axle centerline has to put a lot of stress on those joints. if your lowers were below your axle then the the axle tube would be the pivot point when the suspension moves. with the axle lower then the lower tubes are the pivot point.... if that makes any sense.

 

[chuzie]

This should help answer the centerline question...

We ended up shaving some meat off the top of the coil tower and raising it all the way to the floor. It is still high so I have to count on the settling of the coils to get close to the height. I guess we will just have to see what happens. Way too much time and work involved in getting this right. Oh well, such is life.

 

[mavereq]

if it sits much lower your uppers are going to hit your shock bar

 

[chuzie]

Funny you say that. We were trying to develop a plan for bump stops today and noticed the shock bar is currently working as such. I really need to get the other stuff complete so I can test it out and find the bugs.

 

[mavereq]

i'm interested to hear how it handles. most people run shorter uppers (75%). it looks like you have about 9" of verticle separation at the axle and 4" at the frame. i'll be running a really similar setup but my uppers will be about 6-8" shorter and my lowers will be slightly below the axle centerline.

i'll post up a thread in about two weeks on mine. i'm waiting for my dom and a few other parts. i have the axle truss just about complete.

 

[SOLID1970]

How did this work out?

Just curious how this build worked out? I am installing the same system in my 1970 and I am just setting up the rear. By the way, I don't see a spot where the rear bump stops should hit the rear housing either. Also noticed another person using a bar attached to the top of the housing and the frame to keep the rear from swaying from side to side. Much like the bar in the front end. Any thoughts on that? I don't see this offered from Duff's but it looks like a good idea for the street. Thanks. J

 

[chuzie]

Bump stops are a MUST or you will destroy the shocks as they bottom out before the springs fully compress. Duffs is working on a solution.

A sway bar is recommended for highway driving in my opinion.

Look up rodeo or pathfinder sway bar on pirate. i may have a link on here somewhere.

 

[Monster Mike]

its not apples to apples since my suspension in the rear is nothing like yours. however I agree with a few others that posted about the additional sag you should get once you load up your rig and cycle your suspension (preferably on a couple good rock trails) I dont run a hardtop either but I have the 24 gallon sherman tank and the bc skid plate under it. also the protofab bumper w/ tire carrier and 35" tire, rear seat, and a storage box full of trail gear. im currently running 5.5" total lift in front and 7" total lift in the rear and my rig is completely level at about 4.5" of lift over all when measured from axle to frame

 

[68 Broncoholic]

Why not get longer shocks and raise the mount higher or add more angle to them so less travel is used out of the shock.

 

[blazinchuck]

alot of things could have been done from duffs...lower shock mounts on the axle truss, different upper mounts. and even bumper stops from duffs.

i think outboard shocks would have been easier to deal with...4 shocks across the length of axle seems like a waist

 

[chuzie]

With the inboard setup, there is a limit to where the crossmember can be moved. Can't move it up as it is already to the floor. We may be able to move it forward a few inches and then move the lower mounting table from the truss to the axle housing to lower it a bit.

They are aware of the issue and researching a solution. Hope to hear from them soon. As the truck rests, there is about 1" of shock extended.

 

[Casey835]

I saw a few issues with this setup also, and had already decided that i was gonna have to figure out some bump stop set up, probably some limit straps, and sway bar set up. How would a tracking bar work on the rear for sway bar?

 

[68 Broncoholic]

4 shocks in the rear might be needed to keep it from bouncing with those coils. Some use Cherokee coils that are softer and 1 shock per corner.

Can't you just make shock mounts that are lower on the axle?

 

[u10072]

Guys this is a pretty old thread and if you have any thoughts about my 4link question I would appreciate the input. Trying not to hijack the thread but its time someone built a custom built 4 link that worked, looked cool, and worth the money.

http://classicbroncos.com/forums/showthread.php?t=196699

 

[blazinchuck]

4 shocks in the rear might be needed to keep it from bouncing with those coils. Some use Cherokee coils that are softer and 1 shock per corner.

Can't you just make shock mounts that are lower on the axle?

you can, its not hard...but the question really lies with Duff. thats alot of money to spend , only to find out you have little to no up travel-and the only up travel you really have is controlled by the shocks(which really take a beating)

i think chuzie already has one leaking(pass side)

 

[SpareParts]

The problem with any "kit" is that is designed to work for every bronco that is out there with as little modifications possible. I thought about the 4 link kit, talked a great deal with Suzy about it even. I have wheeled with her's and have personally seen how well it works, see the pics below. I think one could build there own 4 link to work better with their rig, but it would not work as well if I installed it on mine or any others. As with thinking out side the box and going to any other type of system other than leafs, you will have to adjust things to your own rigs weight and characteristics.

I stuck with coils for pure simplicity, they work for me. Good luck on the 4 link quest, I'll venture down it someday.