Can you help make my triangulated 4 bar work?

Hey guys. I have been beating my head against the wall trying to get my 4-bar setup to be at least half-ass correct in my 59 GMC. I read, read, and studied pictures and diagrams before getting into to this so I could try and do it correctly. I am having major problems getting the top bars laid out correctly.

I have three issues against me here:

1. The frame of this truck is pretty narrow versus the stockish track width. Frame width in between the rails is 29"

2. The truck is designed to sit all the way down on the ground when aired out and the rearend takes up all of the notch when down.

3. The frame on these doesn't head downhill ahead of the rearend like most stuff I see when trying to find a solution, that may have help a little, maybe not.



I can't come up with a way to get the upper bars angled enough to limit rearend side to side motion (at least 30* or more according to all I have read) without running into the driveshaft. I need the front crossmember to hump up in the middle to make room for the shaft and full drop and if I place the front upper bar mount together in the middle on the "loop" portion of the crossmember then the bars go uphill and never intersect the lower bars if extending them mentally when viewing from the side. I see many people just run them this way as it obviously located the rearend in the truck but everything shows this to be the incorrect way to do it. The narrow frame width and cast center section keeps me from mounting the bars close on the rearend and heading outward. Also there isn't enough room to build a bar to run over the center section to mount my bars to, this would get into my new, already raised bed floor at the top of the frame notch.

The truck is designed to drive (ride height) about 4" up from the notch, so even though the bars are slightly downhill in the side view so are the bottoms. The bottoms just barely aim up towards the front when at or close to ride height.

What are your thoughts guys??? I have included some crappy pics, and obviously the top bars are long and uncut at this point, don't want to cut them yet and possibly ruin them until I figure out what I am doing.

 

I think your upper arms are too long, look at fox body mustang, monte carlo rears. might help to visualize options. what if you use a triangulated upper instead of two uppers? Might help in the tight space. I bet you can find a mini truck article for inspiration also.

 

Yeah the plan is for the bars to be about 70% as long as the lower bars, which are 25" so the tops will probably be around 17" long but that doesn't make anything better, I just habe that one top bar lying there in the picture. I don't want to go too short on the top bars so it doesn't change the pinion angle substantially as this thing goes through 10 inches or so of travel. Believe me I have looked at a lot of different things, including the mini-truck sites which are where most of this stuff is found but it's amazing how many improper setups people are driving around on. I also have a mustang rearend sitting here that I look at for reference but it's very different than what I have here.

 

why don't you just run a equal length parallel 4 bar and a long track bar? This will definitely fix any pinion angle gain issues. easy money.

 

Have you trid angleing the bars the other way like mustangs and chevelles the to bars are close to the diff and angle out outsides of the frame' or just use a 3 link with a panhard bar.

 

put the top bars to the center of the rear end, angling out towards the lower bars front mounts, thats how you do it, otherwise you are on the right track, otherwise you don`t get enough angle before running into the frame....its how mosdt mini trucks do it, and don`t look at a fox mustang or a monte, their arms are to short to do what you are trying to do......in order to lay frame and come up to a drivable ride height, the arms have to be almost twice as long as a normal car, otherwise you run into pinion angle issues......

 

There is nowhere near enough room because of the narrow frame width to put the bars near the center of the rearend. There is only a few inches of axle tubes to weld to so the bars will only be at about 15 degrees heading out towards the frame rails. I can't weld them to the cast center section and there isn't enough room for a bar over the center of the rearend because the center sits flush with the top of the notch and that is where my already raised bed floor is.

 

now that its too late,, you shoulda triangulated the lowers and run the uppers straight ahead.

 

why do you need 10" of travel? You going off road?

The pinion angle won't change much in the 2-3 inches of travel you need on the road. If you are building this to "lay frame", pinion angle won't matter much when you are posing. You need to make it right when you are driving.

Another alternative is to make a true 3-link. Place one of your remaining links parallel to the lowers, above the pumpkin. Angle it down so that it it will project a line to cross that of the lowers somewhere near the front bumper. Use the 4th bar as a panhard behind the axle.

 

he needs his pinion angle to work at all ride heights cause if hes smart he will make his vehicle be able to drive at what ever height it is at in case he loses a bag or some toher problem........even if it is only 1 inch off the ground he can get it off the road on the even of a problem........

 

If it was me I would put that top bar parallel to the left frame rail just outside of the cast diff center section, take that 4th bar and run it behind the rear end as a panhard bar....but you may have to extend (rebuild) your frame notch. you have all the parts, just need to scrap the triangulated idea.

 

scottybaccus ya beat me to it

 

I'm with you guys here. I also see how triangulated the lowers would have helped my problem except I plan on having the bags on the lower bars. I would like it to have 10" of lift because I like stuff that can almost sit stock and then go all the way down rather than poorly lifting only a few inches off the ground. I plan to have the pinion angle real good at around 4" off the ground and pretty close 2" up and down from there. The problem isn't getting the upper bars right while the truck is down, that actually seems to work better, but once you raise the truck up 4" the top bars start pointing up and no longer intersect the lower bars.

Now I do have another question, is there any reason I can't run a parallel 4 link with the lower bars outside the frame and the upper bars inside the frame?? They would still be parallel just located in different locations when viewed from above. I would then add a long panhard bar to keep the rearend centered.

Thoughts on that?

I don't get too excited about the actual 3 link as it doesn't seem as strong to me.

 

putting the bags on the lower bars is another bad idea....

 

that 4 link would work as well i would imagine, and the 3 link has been successful on many a asphalt oval car with sticky 10" wide tires and upwards of 650 hp.

 

The bars will have full lower gussets...is there another reason that putting the bags on the bars is a bad idea? Better ride, better lift are my reasons for doing so.

 

where would they mount on top would be my first question.......i have seen bags bend their quarter inch plate mounts.....you`d be suprised what they can do.......doesnt look like you have a very good place to mount the upper, and i wouldn`t mount them to the bars either....but thats me...what the hell do i know......

 

Why not run a wishbone style upper bar? If the lower bars have gussets on the bottom from bushing to bushing then i see no reason why its a bad idea to put them there.


Justin

 

I'm not worried about the bags right now. The upper mounts will be gusseted and will have a bent bar running across from one upper mount to the other and that will be tied into the notch bridge and the crossmember. That part will be all fine, when it's all done.

I don't think a wishbone will help any with this setup. A single mount up front and center doesn't help because the issue is that single mount area will be up to high to clear the driveshaft so the wishbone would still be running uphill.

 

and the hits keep comin, not worried about the bags, hmm.......i`m designing an airag suspension, and i dont have the airbags........they`ll work though......good luck with that......you don`t know how much space they will take up how much lift they will have and all that unimportant stuff............think ur puttin the cart before the horse......why not have all the parts before you try to design something........see alot of redoing your future.....

 

Heres a picture of my frame im building with a wishbone. In your case you would need a tube going over the diff housing because you cant weld to it like i did my 9". heres the picture (not now where near finished in this picture)



Not sure if it will still work but im trying to give you some ideas...

Justin

 

dude I said I am not worried about the bags because I have that part all sorted out. I have the bags, have figured the amount of lift per their location on the bar to achieve the desired amount of lift at the wheel. I have figured out the gusset for the bottom of the bars and a complete reenforcement strategy for their upper mounts to tie into all the important chassis areas. The issue I am having is the upper bar location and angle due to the chassis packaging I have and am listening to suggestions, some get shot down and some are taken into account - mainly a parallel 3 or 4 link at this point.

 

Laidout the issue with that is that I don't have room to build a piece across the rearend for me to mount anything to because it will go higher than my notch and that is where my bedfloor I have already raised is. I would not like to change the bedfloor unless it's the ONLY way to go about this. If I had a piece to connect links or a wishbone to it would make this much easier. At this point I think the parallel setups might be a good bet if I can find some good info to support the idea of having the upper links inside the frame instead of right above the lower links like it most traditional 4 links.

 

By the way thanks for the pic, I like the way you attached the front lower bars to the frame.

 

thanks, well good luck man i know who hard it is to make thinks work in tight spaces...

Justin

 

then get/make a bracket like this and be done, angle upper arms towards center .......

 

donno if that worked...oh well....

 

I appreciate you trying to help but have you read any of the issues I am having?

I assume you were trying to post this:

http://www.suicidedoors.com/4-link-parts/kp-conversion-parts/kp-s10-differential-bracket

That would do nothing for me. I have the ability to mount the upper bars to the axle tubes, which is pretty much what this piece would do. The bars mounted on the tubes don't angle inward enough to make at least 30* (or 70* total difference between the bars) to keep the rearend from moving side to side. Also I can't run them to the center which would make it close because the driveshaft is there. Once a crossmember is made up front that is notched/ looped/ whatever for the driveshaft then the mounting area for the upper bars would be too high and they wouldn't aim down anymore to intersect the lowers. This would not get me desirable results but only a typical mini-truck 4 link with no regards to roll or instant center, anti-quat, or roll steer to name a few items of concern.

 

run it parrallel then and use panhard bar or watts link and call it a day..

btw newer durangos come with some sort of watts link that looks like it could easily be adapted to other rear ends.

and I dont think the bags should be mounted to the lower bars, gusseted or not. post up a drawing of what your planning there so we can get a good look at it, it may be fine but I kinda doubt it.

 

i`m spent.....