Wouldn't steep angles from the factory cause drive line vibration and premature u joint wear?
Yes it would. The wrong angle is the wrong angle, period.
Yes, there is some leeway as there would have to be, due to the suspension being a dynamic thing that moves all around under just basically normal driving conditions. So there is a little slack for the designers. But not much.
I still really don't know why modern lifted rigs need the shims more than they used to. I've lifted mine with add-a-leaves and it did not need a shim. I lifted it with a set of stock type 6-leaf packs at 3.5" and did not need shims.
Not that I drove it very long though, as I took them back off after only a week. I was just not going to put myself through all the discomfort of a crappy ride just to get some lift. So I went back to the stock original springs with an add-a-leaf and a 1" block. No taper on the block either, and still did not need shims.
My '68 with slightly sagged 2.5" rear springs and slightly tapered 1.5" block still needed the 6 degrees shims to get rid of the vibration.
I thought I was being particularly insightful when I noted a few years ago that the thicker spring packs were obviously the culprit, by moving the rear end down farther away from the spring eyes.
That was until someone eve more insightful cam along last year and noted that, if 3.5" of lift is 3.5" of lift, the pinion angle should not care how it's achieved if the springs are equally flat on the bottom and the center pin is in the same relative location in the pack.
True dat...
To that end, does anyone have a stock spring pack they can measure the distance between the front eye and the center pin, then the rear eye and the center pin? This way we can put some more data in the mix to compare to the new springs.
This discussion really has nothing to do with the springs sitting high of course. Just that it's a good place as any to figure out this pinion thing. Maybe it's just as simple as how the axle sits when the springs are clamped to it, with the short arched leaves vs the longer, thicker arched leaf on the bottom of a stock spring pack. Maybe there is some rotation as the u-bolts are torqued.
I don't see it in my mind, but that's why we experiment.
That said, yeah, I hate that my pinion angle is jacked with a 3.5 lift. Probably around 10 degrees just eyeballing it with no driveshaft in place yet. Not even sure if 6 deg shim is going to correct it.
Is it just that you don't like shims? I mean, you should not be leaving a bad pinion angle no matter what the root cause. If it's off, fix it. You can't drive on it that way, and pinion angle issues are as old as lift kits. Which is exactly why lift blocks taller than one inch are all tapered. It's very hard to find a non-tapered lift block because they just don't work in most of the real world.
I don't know if one type of spring is better than another yet, but we should be able to get to the bottom of that hole.
Bottom line though is, don't hate it. Fix it.
Worse, my traction bar was welded on at current angle.....
If you correct the pinion angle though, won't that at least help with the traction-bar brackets? Yes, the lift changes the relative distance between one bracket and the other no matter what, but the angle should improve with any corrective measures for the pinion angle.
I would think anyway. Where are your mounts? I'm sure I've seen the discussion, but want to make sure. Are they on the center of the housing top for a single bar? Or at the ends for two bars?
Thanks
Paul
