Alignment Advice

[flint54]

So, I'm going to check my toe-in using the "bungee cord with bar" method

I saw around here somewhere (measuring and comparing side to side distances

between front of tire and back of tire), and I'm now wondering if this should

best be done with weight on wheels or weight off wheels? The wheel center is

high enough that the bars are unaffected by bulge. Also hampered because

I don't have a straight shot at the rear of tires - LCA's block that path. I may

have to plumb (or framing square) down to the floor and measure there.

Comments?

[ncm1]

This may be a little too elementary, but all I did was use a tape measure in the back under the control arms and in the corresponding spot in the front. Once the two measurements were the same the deal was done.

[Geonovast]

Do not jack up the truck at all. Not by the frame, not by the axle. It must be sitting at driving stance.

[87Warrior]

I suspect you are referring to the method I posted, which is a slight variation from the recommended ORO alignment method.

 

What I did:

- Find two levels and bungee them to the center of outside of the wheel (set the levels so they are both 'level')

- Measure the distance between the levels right at the tire tread

- Repeat the measurement process for the front and rear of the tire

- Adjust tie-rod so that the distance between the front and rear of the tires is 1/16-1/8 less than the rear

 

Having a helper hold the tape will make this really easy if you don't have enough clearance at the back of the tire due to control arm or driveshaft interference.

 

My method is a slight variation of the ORO method pictured below. I used the levels to make sure my measurements were taken at the same spot, front and rear of the tire.

 

I have never tried this on a stock rig so I imagine there would be interference out back. As Correy mentioned above, you must keep the truck on the ground. You could use a plumb-bob to drop the rear measuring point further down, or you could clamp something like old wooden rulers (a square would work fine too) vertically to your level bungee'd to the wheel. However you go about it, make sure the the measurement point is the same for the front and rear. When I did it, I measured from the inside face of each level attached to the wheel.

[flint54]

Thanks for the replies!

 

Experimenter that I am, I've done the check with the axle lifted only enough to barely

clear the tires from the floor and I've got it dialed to within 1/16" toe in. Tomorrow I

will check it with full weight on wheels to see if and how much it changes. Will report

back my findings. Weight on wheels makes best sense since that's how it's operated.

 

Now then, using the angle table so prevalent, I measure 8 degrees caster. There are

no driveability issues, and I'm inclined to do nothing rather than shim it back to the

upper spec limit (LP D30) of 7 degrees. Am I missing anything?

[HOrnbrod]

Now then, using the angle table so prevalent, I measure 8 degrees caster. There are no driveability issues, and I'm inclined to do nothing rather than shim it back to the upper spec limit (LP D30) of 7 degrees. Am I missing anything?

 

Not necessary to do anything, but in your case it's a simple matter to remove one of the thin shims (.95mm) behind each LCAs to get your caster spot on @ 7*. In my case after a 3" lift I had to insert one thick (4mm) shim behind the LCAs to get the caster back to 7*. Are you measuring caster with an angle finder on the ball joint flat?

[flint54]

I'm measuring angle with a digital inclinometer on the round flat

spots where the tubes abut the pumpkin. Get 86.1 degrees. Then,

using the conversion table for LP diff, get 8 degrees. I think I should

add shim to lower the angle, which would lengthen the LCA reach

and rotate the diff forward, and reduce the lean of the caster line.

Since it steers very smoothly and tracks straight, I'm inclined to

leave it alone rather than adjust. My lift is only ~2 inches.