4-link and pinion angle

[robsm88]

Hello guys, I picked up my ART 4-link setup from Nathan and Porterbuilt today. I just have to say, very impressive work going on down there. I am in the process of getting my chassis ready for the GenIII 6.0l and 4L80E. I have basically gutted the truck. I want the chassis completely redone before I drop the motor in.
Ok, so here is my problem.
I initially planned to just flip the rear axle to get my rear drop. So I cut off the saddles, flipped it and popped in the new saddles in place. The saddles were just held tight by the u bolts until I would be ready to drop in the motor and set my angle. Then I would weld it. But I was not happy with that setup and decided on a 4-link with bags.
But now, I need to get the 4 link in and set up. This is a weld in kit. Would it be ok to weld it in with the pinion level? Then adjust the angle with the 4 link when the motor and driveline are in place. I allready pulled off my leaf springs and mounts. So basically, the truck is in the garage and can't be moved to install the engine even if I wanted to until the 4 link is at least tacked in place.
Thanks guys.

[PBFAB.COM]

I would recommend welding it up with the pinion at 2-3 degrees (pointing up), and then adjust when the motor and trans are in. Typically the pinion angle should be between 2 to 5 degrees on the rear of trans (pointing down) and then the angle on the rear diff. pinion should be the same (but opposite) angle (pointing up). If you set it up at zero and have to adjust up to 5 degrees, the four link bracket where the shock mounts will be skewed and the shock will have unnecessary binding.

[robsm88]

Thanks Nathan!

[robsm88]

Ok, looking for some more help.

Problem #1 4-link mount
My frame goes inward as it comes closer to the cab. Opposite as shown in the install on the later model truck in the picture. Even if I weld the 4-link mount as far in as possible on the axle, the rods will be binding againt the frame. The frame where the mount attatches is not square with the axle either. It goes at an angle.
My thoughts so far;
I could shim the front mount out a little with a plate underneath.
or, box the inside of the frame and mount the links inside the frame.

Problem #2 shock mounts
The brackets that ART include for their 4-link have integrated shock mounts. The kit also includes shocks and upper mounting brackets. To use the integrated shock mounts on the 4-link, I would be forced to mount the bags on the opposite side of the frame, due to limited mounting space. Which kind of ties in with the last problem.
I know that you can get the best cornering with the bags as wide as possible. Outside the frame. I have been trying to think of any reason why the 4-link would perform any worse on the inside.

Problem #3 pinion angle
I know Nathan told me to set the pinion angle up 2-3 degrees. I completely agree. Any tips on getting this without a driveline attatched.

Problem #4 Panhard bar
I am looking for a couple pics of good panhard bar mounting locations. The brackets in my kit require the bar to be directly on top the axle. This will bind against the diff when lowered if I set it parralel at my ride height. I think I might need to get a different mounting bracket like the one in the pic. That one would be welded to the axle pointing to the rear, clear of the dif and not bind. Notice how the one from the kit in the last pic points up and does not sit parralel at ride height.

Problem #5 ride height
OK, so I don't exactly know where my ride height is for setting the 4-link mounts or bag mounts. I have no motor in, no front fenders and the bed is off. I want to set the ride height according to where the stock front end sits with the 2.5 drop spindles. That way my steering is set properly while driving. When I do the front, I plan to measure the frame height before installing the bags, so I know where it needs to come back to. And then adjust the bags to sit there when inflated. I think I will wait till after the motor is in to install the front bags though. So if I am level front to rear, then once I install the motor, I may have a little rake.
Thanks again for any tips.

I included a few pics from the article I am using to do this install. Notice, in the first pic, how their frame contours nicley out of their way for the front mount!!!!!!!!

[robsm88]

here are a few pics of mine.

[SCOTI]

The 67~72's I've seen w/a weld-on style 4-link require a 'spacer' to allow the bars to run parallel to the frame (& square to the rear housing).

You would weld the spacer to the frame & then weld the bracket from the kit to the spacer. Search 'valleycustoms' threads. He did an install for a board member & posted some pics. I remember one that showed a good shot of what I'm talking about.

[robsm88]

Great find man!! I swear I searched every 4-link thread on here. That thread is perfect, Thanks.

[robsm88]

Still think it would be cleaner with the 4 link and shock inside the frame. Then just the bags outside.
He used the bracket I was mentioning for the panhard bar. Maybe Nathan could has one I could buy.

[SCOTI]

Originally Posted by robsm88

Still think it would be cleaner with the 4 link and shock inside the frame. Then just the bags outside.
He used the bracket I was mentioning for the panhard bar. Maybe Nathan could has one I could buy.

Yes, mounting the 4 link and shock inside the frame would make for a cleaner install. Typically though, the farther apart the 4-link bars (and springs) are on the rear end housing, the more stability the vehicle will have.

[PBFAB.COM]

Originally Posted by SCOTI

Yes, mounting the 4 link and shock inside the frame would make for a cleaner install. Typically though, the farther apart the 4-link bars (and springs) are on the rear end housing, the more stability the vehicle will have.

SCOTI is right-on (as usual). The four-link will be optimal (in terms of function) on the outside of the framerails... as far apart as possible. It doesn't mean it will not work on the inside, just not as much stability. Sometimes compromises have to be made (in terms of performance) to achieve certain outcomes. I would do all I could, if I were you, to keep the four-link outboard of the frame-rails. If you need some brackets made-up, let me know. I will need either a template or a drawing with dimensions, and we can cut them out on the CNC.

[robsm88]

Originally Posted by porterbuilt

SCOTI is right-on (as usual). The four-link will be optimal (in terms of function) on the outside of the framerails... as far apart as possible. It doesn't mean it will not work on the inside, just not as much stability. Sometimes compromises have to be made (in terms of performance) to achieve certain outcomes. I would do all I could, if I were you, to keep the four-link outboard of the frame-rails. If you need some brackets made-up, let me know. I will need either a template or a drawing with dimensions, and we can cut them out on the CNC.

Sounds like I will be doing it outside then. I will just locate the shock absorbers on the inside. For that bracket, all I really need is the center piece on the mount in this picture, I can make the rest.

[valleycustom]

[PBFAB.COM]

Rob-
I am pretty sure I have a small piece of that DOM... it may need to be threaded... you can have it. And I might as well throw in some gussets for ya as well (save you some precious time with the grinder!).

[robsm88]

Originally Posted by porterbuilt

I would do all I could, if I were you, to keep the four-link outboard of the frame-rails. If you need some brackets made-up, let me know. I will need either a template or a drawing with dimensions, and we can cut them out on the CNC.

Been trying to decide if I should cut some pieces and build a bracket, or have something CNC'd. I will bring the dimensions when I come by.

[70short/step]

Originally Posted by valleycustom

Thought that pic looked familar!

[robsm88]

Hey valleycustom, thanks for that great thread. It has saved me a lot of time and guesswork.

[robsm88]

I did mine a little different. I do not care about laying frame. The only reason I went with bags is for for the 4-link and to get ground clearance when needed. So my mount needed to be a bit lower on the frame to keep links parallel at ride height.