Some 4-Link, Rear Setup Questions

[Throwtech]

ok i have bag over axle rear setup and i went a head and 4-linkd it. i used a weldon summit 4-link . when i am driving at speeds of over 40 mph and have thE rear low i hear what sounds like the driveshaft humming. i also feel as if there is a lot of swaying in the rear when a take a corner. please checkout my setup and see what you think, any feedback will be appreciated

[flnole78]

First off I just want to say that the upper links being welded to the cast pumpkin are a bad idea. It's ok if you really know what you are doing and from the looks of the welds, the person who did them didn't know what they were doing.


Now on to your question, the pics don't really tell us anything. we would need shots of the driveline from the side at normal ride height and at the height where you are hearing the noise. But I can take a pretty good guess and say that your pinion angle is incorrect.

you are getting a lot of sway bc your rear shocks are basically useless the way you have them mounted at that angle. They need to be as straight up and down and as close to the wheels as possible to be effective.

[Throwtech]

yes those welds are trash i had a friend of mine weld on the angled bars because he said welding to cast was ok. but because of my bag over axle setup have no room to weld them to the axle. i will remove my bed and take some ew pics

[Throwtech]

and even with shocks removed i grab m bed and rock it side to side and there is a lot of play, is this because the angled bars are at the incorrect angle

[flnole78]

From the looks of it the uppers have plenty of triangulation to them, you typically want them to have between 37* - 40* of triangulation. By taking the shocks off you are making the swaying worse not better. The shock, when positioned correctly, will reduce the amount of sway. So if you take the shock off and get the same amount of sway then that means your shocks are basically doing nothing.

[rstadelmaier]

Quote: Originally Posted by Throwtech

yes those welds are trash i had a friend of mine weld on the angled bars because he said welding to cast was ok. but because of my bag over axle setup have no room to weld them to the axle. i will remove my bed and take some ew pics

Welding to cast is fine....if youre welding cast to cast. Mild steel to cast is a no no. thats like welding aluminum to steel. does your front still have the sway bar? might take that into consideration.

[Throwtech]

i didnt remove the shocks i was makeing an example. with the socks out of he question i am only interested in the 4-link , bag over axle setup i will relocate the shocks later. i am basicly asking is the way the triangulated bars are not meeting at the croassmember and att the diff. instead ok? i know that alot of 4-link setups i have seen are kinda opposite of the way i have them. they met at the center crossmember

[Throwtech]

yes my front end still has sway bar. i dont see how that has anything to do with the play in my rear end

[rstadelmaier]

Just saying...
are the rear bags plumbed with seperate valves or are they tee'd together?

[Throwtech]

basicly this is the s@#$ im dealing with HACK JOB

[Throwtech]

teed for fill but each have their own dump

[gunther19820]

what kind of shape are the bushings in? From the pics looking at the upper bars it doesnt seem like there is any shoulder to the bushing ( the part of the bushing that steps out around the face of the bar end).

Is the rear totally perpendicular to the truck?
Does the rear feel like it "sways" more going into one corner than another.. IE a left hand corner or right hand?
What is your pinion set at?
What is the condition of the u joints?
Is your driveshaft rubbing the cab floor?
With your truck at ride height, what is the angle on your lower bars? (in relation to the ground... are they level, or pointed up or down)
With your truck at ride height, what is the angle on your upper bars? (in relation to the ground... are they level, or pointed up or down)

[rstadelmaier]

Dude just cut it all out and start fresh. That is not safe

[Throwtech]

someone help me please.

[rstadelmaier]

So one fill valve? If so thats your sway issue. air is transferring to the side of least resistance when cornering. Think of.... A waterbed? Ha.

[Throwtech]

i know this is not safe that is why i am tryig to find some help here the 4-link is brand new but i dont know if they even measured anything . idk what to do. my u joints are in good shape the shaft dousnt hit cab floor the floor is cut out the swaying seems to be equal on bolth sides. and the rear end seams to be purp.

[Throwtech]

no now that i look t it it seems that there are 4 valves in front and 4 in rear but i only have 3 switches, front up-down, back up-down, left-right

[gunther19820]

Your lower bars are too long for my liking. I set the forward mounts for the uppers and lowers as close to each other as I can, in relation to how far from the rear they are located.- But this isnt your issue.... this will cause some pinion variance through the range of travel.

-I would also cut it all out and start over. Dont throw the bars out since you have them already, just replace the brackets.
-Run 2 fill valves
-Fix that airline that is kinked.
-Grab a book an d chasis setup, or do a bunch of research on here to see how/why others have set their links up. That way you know what is going on when you do this again.

Also, where do you live? Maybe someone on here is close, and can lend a hand/ charge you to redo the work


Just FYI... those summit links are a tiny bar, and I believe they are Chromoly, not DOM.... they may not like the abuse they will see on a bagged truck. If you have the money buy a beefy link setup from a vendor on here... they are designed for the loads and abuse a bagged vehicle creates.

[Throwtech]

here are some more pics of my hacked pos i am trying to repair

[gunther19820]

p[lease post a link to the summit kit you used... I am very curious about those bar ends

[Throwtech]

i live in so-cal Temecula,Ca. i will just cut it all out and start over. i dont have mush $ so im prob. gunna kceep the bars if anyone is near me please contact me if help is available. i will post or start a thread on my progress, thanks guys. and if anyone has any more insight on what was discussed in this thread please add.

[Throwtech]

summit 4-link, link
http://www.summitracing.com/parts/ART-18987999/

[usmc1833]

in that last of pics you posted is the truck at ride height in the first one?

[flnole78]

The pinion is def off at whatever height the truck is sitting at in that pic for sure, It's pointing up.

Im going to be completely honest. I wouldn't worry about the issues you have with that setup. I would tear it all out and start over. That gas tank xmember is scary. The "brackets" on the front of your upper bars are scary and could be moving on you causing the "sway" issue. They aren't very strong.

Your question about how the bars triangulate pointing toward the rear is perfectly fine as long as there is plenty of triangulation and there is. This setup has way too many other issues to troubleshoot these 2 problems you are having. Please don't drive this truck until you get it fixed.

[baggedout81]

^^c0-signed