The Stovebolt Site Forums The Shop Area Engine Shop Wandering 51'

When I first drove this truck home, noticed some play, not alot though, in the steering. Sooo, as I've done in the past, I adjusted the steering box according to specs, tie rod ends I took apart, ball studs were round and in good condition, greased everything, and put it back together. Waiting for my Drag Link sockets to arrive from Craftsman, to finish adjusting that,(my big screw driver was not big enough!). After adjusting the steering box, I began to get road wander on certain pavements, thought maybe I had things too tight, checked steering wheel pull with my fish scale, and showed o.k. Sooo, thats when I decided to adjust the Tie Rod Ends, yes they needed adjusting, but were great internally. After adjusting the Tie Rod Ends, my road wandering is much, much worse. Bumps in the road have no effect on the steering, where as my experience in the past with bumps has related to the king pins. Reading the service manual, it looks as though, if it weren't the Tie Rods, wheel bearings(checked), Steering box, that it might be that the Toe in/Out might be incorrect. Am I looking in the right direction? Thanks!!

Hy CATMAN, you might also check your caster shims [the wedges that sit between the axle and spring] the thick end should be at the rear side, hope that helps.

well when u do a wheel alight me u want a little bit negitive on the drivers side because of the crown in the road the best way to do wheel alignments on a stove bolt is get the old string out .. set your wheels dead a head then tie the string to the rear end and walk it forward to the front of ur truck(on the outside of the truck not under it )and check the relation of your front wheels to your rear wheels ..also sometimes play when you adjust things that are old to stock specs it throws them out of alignment

Isn't positive caster achieved with the thick end of the shim in front. This give the front axle a backward tilt, or positive caster.


Stuart

Inadequate freeplay can cause this. If it is too tight at the center, then it will 'jump' off-center with any little push. Check caster, a little extra positive is not bad, except low speed steering might be heavy, but wandering will be better, and recheck freeplay. Bearing preload should have no effect on wander.

Catman,

I just went through this a bit on my truck. I replaced steering box bushings which helped, but I also tightened my lash adjustment a bit more than the manual called for. That helped quite a bit for steering wheel free play. Changing from the beat old bias ply tires I had to steel radials (used) made a HUGE difference. The truck no longer seeks the grooves/ruts in the road.

It,s the other way around Automarc. Picture a bicycle fork. You can check your tio-in. Raise the front end a little & take a sharp instrument like an ice pick. Put a jack stand or something close to the tire. Put the ice pick on the stand enough to rub the tire. Spin the wheel to make a line all around both front tires. Set the truck down & with the wheels straight ahead have someone hold the end of a tape on the line at the rear of the wheel about in the center. Read the distance between the lines. Go to the front of the wheels & do the same. There should be 1/16 to 1/8 in. less at the front. To adjust loosen the tie rod clamp bolts & turn the tie rod.

Wrenchbender,

I am thinking "bicycle fork" and I see the king pin inclination tilting backwards, just like the fork on a big old chopper motorcycle. If I put the shim between the axle and the spring, with the thick part forward and the thin part to the rear, wouldn't I get this angle...I think I would. This would be positive caster!

http://en.wikipedia.org/wiki/Caster_angle

AND

http://www.procarcare.com/images/shar/encyclopedia/8852MG15.gif

Stuart

Negative.

Wrenchbender,

What don't I understand. Don't all the pictures indicate this is positive caster. With the wedge in from the front, it tilts the axle back which inclines the kingpin so a imaginary line drawn through it comes out in front of the tire.

Did you look at the links. Am I not understanding "alignment 101".

"Caster is the angle to which the steering pivot axis is tilted forward or rearward from vertical, as viewed from the side. If the pivot axis is tilted backward (that is, the top pivot is positioned farther rearward than the bottom pivot), then the caster is positive; if it's tilted forward, then the caster is negative"

Stuart

Did someone mention checking the toe-in? Seems like the most logical way to start, assuming that there isn't excessive wear in any of the major steering components. As Wrenchbender mentioned, it's easy to check, easy to adjust to get a 1/8" toe in, and normally cures the problem. You didn't mention how much toe-in you had but I'd focus on that. If you've already got an 1/8" toe-in then I'd go with the heavier stuff.

Wrenchbender/Fla54chevy3100,

Can you elaborate on an "easy" was to measure toe-in? As I understand it, that means that middle/center/front part of the tires are 1/8" closer together than the middle/center/rear part of the tires. It's pretty easy to tell the middle of the tire by looking at the grooves in the tread. Unfortunately, you can't simply measure the direct line distance between the middle/center/rear point of the tires since part of the truck is in the way (at least in my 49 1/2 ton). If you measure lower than the midpoint than the measurement is thrown off by camber. Is there an easy way to measure the rear of the tire I don't know about? (I've been thinking about using a plumb and marking two dots on the floor to represent the middle/center/rear part of the two tires and then measuring the distance between the two marks).

Thanks
Dave

DW,

The exact, simple procedure for this was laid out five posts up.

I am still wondering about positive caster? I have been to a dozen sites, and they all concur with my thoughts. Stuff like this makes me crazed! Have I had the wrong notion on it all these years. ANOTHER quote from the good old Stovebolt site!


"Redcoat is right on... I had the same problem with a '50 3600 that I had completely rebuilt the front end. I stopped by the alignment shop and he said, without even getting under the truck, "The caster is off..." The axle needs to be "raked back" a bit with caster shims between the axle pad and spring. Made all the difference in the world. Before it felt like someone had replace the front wheels with shopping cart wheels...".


Stuart

I don't want this thread to 'wander' off until I'm clear on positive and negative caster! :confused:


Stuart

Stuart,

I do not know positive from negative caster (1 +/- 1/2 degrees is the setting); however, every Advance-Design axle that I have seen has wedges between the axle and spring with the high part of the wedge dowards the rear edge of the axle.

You want backward tilt of the axle and king pin (Shop Manual); and, the springs are on top of the axle. The wedge tilts the rear edge of the axle downwards - is that backwards?

"To increase caster, place the thick side of the shim toward the back between the spring seat and the spring." (Shop Manual)

Tim

Tim,

You have solved my mental mystery. I kept seeing the axle on top of the springs, which makes the shim affect the geometry exactly backwards.

As usual, apologies are in order for 3B and Wrenchbender.

Thanks Tim, Stuart

Take it to an alignment shop and get real answers and proper adjustments made,
Scott

Thanks a Million to all of you!! You all are great. I will look at the Toe In, then if that fails, I'll head off to the alignment shop.
Thanks Again! Bryan

Harbor Freight has a toe-in alignment tool that works well and is on sale for $10.00.

The HF toe-in tool looks like it registers off the sidewall of the tire. The problem I see with this is that the sidewall is not necessarily straight and can wobble. The afore mentioned method, that is, marking a line on the axial centerline of the tire, while rotating it the full 360deg is the most accurate method. A scriber was mentioned, that will give a fine line and give you the most accurate reference. A white pencil would work but by the time the tire came round full circle the line would be an eight of an inch wide, not to accurate of a reference point.
As far as the horizontal height of your front to back measurement being affected by the caster angle, a little trig will show you that the measurement could be taken up or down a few inches from the horizontal center line and it would be little affected, at least not enough to be noticed by the resolution of a tape measure.
Back tilt of the kingpin is positive caster angle, forward tilt of the kingpin is negative caster angle, PERIOD! Kingpin inclination and camber are best left to the alignment shop, they are a little more difficult to measure accurately in the garage. You could change the Caster at home but the Camber angle can’t be changed with out cold bending of the axel.
Denny Graham
Sandwich, IL

Think of the old style dragsters with the engine in front of the driver, the front axle was layed way back, kingpins were on a slant big time, this made them go down the track straight with little input from the driver. Your truck will be the same. If you have altered the ride height of the truck, your factory caster measurement will be off, add a few degrees if the toe in doesn't work. NAPA can get the shims for about $4.00 each. I added a few more degrees to my '37 and it made a ton of difference for the better. Just remember, the more you add, the harder it will turn when not moving.

Set your toe in to 1/8" in, or close to it, a little off won't make much difference as long as you are toed in. Right now you are looking for a difference in how it drives. The reason for toe-in is to take up the slack in any of the steering joints. Under driving conditions with all the drag and restance of the road and tires, your adjustment should be 0" in or out. Each joint has a little movement and together they should be add up to about one 1/8", yours may be more or less, thats why its trial and error. Joe