55.2-59 Porterbuilt Alignment

[davecarney2]

Any of you guys have experience doing an alignment on the PB dropmember? I will end up taking it to a shop depending on how close I can get it but sure seems like a ton of camber. I am just not sure where all the adjustment points are. Any help with this would be greatly appreciated.

[mr48chev]

Air bags or springs?

Bags you figure the stance that you want to drive on the roads with 90% of the time and note the pressures and that is where you have it sitting when you align it.

Springs the ride height is set from the get go.

I'm an old school front end alignment from the days when "tech" was a school. As you were a mechanic who graduated from a Tech school.
In that I don't like this broken suspension look of negative camber that so many rigs run now I want the tires standing straight up with 1/4 degree more + camber on the left than the right.
Trouble is that Nowadays guys are all into the ricky racer thing where slamming around a corner is more important than how long your tires last or even not having uneven wear on them after a few thousand miles.

From what I can find the Porterbuilt setup is a mix and match setup parts design wise and it probably isn't productive to try to emulate the specs from a production ride. It seems that over the years their crossmembers have advanced a lot in design from the early ones that they first sold.
I'd go for 0 camber on the left -1/4 on the right and 3+ caster with 1/16 to 1/8 toe in to start. That is if you are running big rims and wide tires. The difference in camber between sides is to correct the drift to the right on crowned roads thing. The more crown your local roads have due to rain or snow fall amounts the more difference you might need than a guy living in Arizona or New Mexico where they might not put as much crown in the roads because they don't have the rainfall that NC does. Done right you should be able to run down a straight stretch of freeway hands off (hovering over the wheel) for a good ways with out having to make corrections.

[dsraven]

without going through your build to see pics of what you have there I would assume on that style of front end you would add shims behind the upper control arm pivot shafts to get the camber/caster where you want it, at ride height, with the rear suspension also at ride height and the tire sizes/wheel offsets (on the front spindles) you will end up using finally.
to do a proper alignment the tech will need the truck to be more or less complete, weight wise, or the suspension pinned squarely at ride height.
hopefully your lower control arms are going to be parallel to the ground at ride height because this affects how the tires move in and out as the suspension moves up and down due to the arc the ball joints travel through as the suspension moves up and down. this is also a relationship between upper and lower control arm length and some front ends are set up so the upper control arm, which is usually shorter to aid in this effect, is already started it's travel past the midpoint of the arc when the lower control arm is at it's mid point. this is so the tire will automatically lean in a bit as the suspension moves upward because the upper control arm is shorter so it runs a shorter arc and therefore the spindle will lean in as the 2 control arms move through their arcs. this keeps the tires from rubbing the fenders when the steering is also turned and the edge of the tire gets closer to the contact point with the fender.
the toe in would be done with the steering box gears adjusted first (because the steering box gears are cut so they are tighter in the middle of their lock to lock travel so the steering doesn't feel sloppy at the mid point where most of the driving is done) and then the box (rack if equipped) would be centered, lock to lock, and then strapped/locked in that position so it can't move during alignment. the steering wheel would be adjusted, after the alignment, to be centered as well. toe in is done to each side tie rod with the steering centered to provide a steering box/rack that is centered when the wheels are pointing the truck straight down the road.
a reference will be done to the rear axle as well to ensure the rear axle is parallel to the front axle and frame so the truck doesn't track sideways down the road. an alignment on a vehicle with a new suspension system should really be done by a shop that has a 4 wheel alignment set up for this purpose.
hope that explained stuff for you.

[mr48chev]

Porterbuilt does use shims and that was one of the attractive features when he first designed it and showed it on the board.
He has come a long ways since then and some of his crossmembers have changed though several versions to improve the design.
http://pbfab.com/

[davecarney2]

Thanks for the input. I do plan on taking it to a shop before I drive it much but would like to drive it around the block some to get the kinks worked out and the 10 miles or so to the shop without tearing up my new tires too much. Top bolts that mount the upper arms just don’t leave much length for shims. That’s what threw me thought maybe I was missing something and there were some elongated holes I wasn’t seeing as I didn’t assemble it.

[joedoh]

looking at your pictures, it looks like you are raising it as far as possible, which will arc the upper control arm over center and pull the top of the tire in. in four (five?) words, you shouldnt do that.

there are three important heights with an air ride suspension, laid out, ride height, max height.

laid out is what it sounds like, except it requires a little planning. the air bag should squash completely, the last breath of air out at the point the truck hits the ground. if it doesnt, if there is still space in the bag when its laid out, you will need more air/psi to lift the truck than would be required with a squished bag, because you have to fill the empty volume first, before the truck lifts. the upper control arm usually has some angle to it at this point and will pull the camber negative, because the upper is shorter than the lower.

ride height is a little more arbitrary, but usually is about half travel on a bag. if you have 10" of lift from laid out to max height, ride height will be at about 5". another good way to set ride height is when the lower control arm is just about level. camber will be about zero or slightly negative, because the upper and lower are about level. the spring rate at half travel is relatively soft, so you will want gas charged shocks to damp the oscillations.


max height is alllll the way up, suspension locked mechanically by either the upper arms hitting the frame or bag mounts, or the ball joint at max angle, or the shock topping out. increasing pressure stresses the mechanical interference without giving any more lift. ride is impossibly harsh because the spring rate is super high and the shock cant do its job. camber trends toward negative again because the upper control arm is over center on the arc.


a lot of people look at the half travel ride height and say, no, I need it higher than that. but thats isnt how your suspension is set up, you would need to move the entire suspension down in relation to the frame to have a higher ride height, and then it wouldnt lay out the way you like. and even at 4-5 inches of travel at ride height, you will still clear almost all obstacles and still have another 4-5 inches of height adjustment to clear bigger bumps or make turns if your wheels hit the fenders at full lock. i promise if you try to drive at max height it will ride terrible and you will ruin your tires. porterbuilt knows their stuff,. set the control arms at about level and set your camber there, you will have enough adjustment.

it takes some driving and practice to figure out the sweet spot, I had a channeled mazda that tucked about 3" of tire/wheel at ride height, but could still make all turns outside of sharp 90 degree ones.


good luck!

[davecarney2]

That’s an old picture. Truck is just about road ready. Few issues I’m working out. I have no intent of riding all the way up. Auto programmed the e level puts the ride height at approx 4 inches. Nate at PBFab answered my questions to. I just wanna get it close enough to drive it around near the house while I work the bugs out and to the alignment shop. Seemed like a lot of shim but we shall see when I get to it. Thanks for all the input guys. Would love to see a picture with the shims in just to satisfy my curiosity before I do mine trying to do as much research as possible. Don’t wanna shred my new tires.

[GreasyLikeaBurger]

your biggest issue with "guess-timating" the alignment will be setting up your ride height first. And then adjusting it around that. I assume PB sets up there ride height camber near zero, or a little negative by a degree or two. It doesnt take much of a shim to move camber minutes or a degree. Just a little bit of fiddling around and getting it right. You can basically eyeball camber from the side or front, or lay a straight edge against the edle of the rim and use read the degree, most phones have a level gauge that will get you in the ballpark. Toe is going to be the one that will shread your tires faster or feather them. But its prettty easy to get a base toe setup with just a tap measure.

[joedoh]

Originally Posted by davecarney2

That’s an old picture. Truck is just about road ready. Few issues I’m working out. I have no intent of riding all the way up. Auto programmed the e level puts the ride height at approx 4 inches. Nate at PBFab answered my questions to. I just wanna get it close enough to drive it around near the house while I work the bugs out and to the alignment shop. Seemed like a lot of shim but we shall see when I get to it. Thanks for all the input guys. Would love to see a picture with the shims in just to satisfy my curiosity before I do mine trying to do as much research as possible. Don’t wanna shred my new tires.

gotcha, I am with greasylikeaburger, camber alone isnt what shreds tires, its toe in or out, although incorrect toe coupled with camber is a real killer. use 4 bricks, two 2x4 and a tape measure to set toe, like 1/8 toe in is enough to keep you from tramlining or wandering. I stole the picture from cautrell but this is how. you have to raise the 2x4 a bit with the bricks to keep the tire bulge from affecting it.

[mr48chev]

Doing it the way Joedoe works similar to the way you check toe in with the Quick trick alignment setup I have. It even came with matching tape measures.

You do want your bars high enough that they are square against the wheel/tire though as they may be pulled off a bit when they are aganst the bulge of the tire.

[dsraven]

Another easy way with less stuff involved
Jack up enough so you can spin tire
Use a flat screw driver or a stick with a nail sticking out of it to mark a line on the tire as you sponge it by hand. Fo both tires about mid width. Set the truck back down and use a tape to measure between the scores lines. I have used a bit of paint on the tread before as well so the line shows up better. With the weight of the truck on the suspension you get a better reading for the.

[dsraven]

Sorry. Not sponge the tire. Spin the tire. Auto correct......grrrrr