Straight axle alignment woes

[Sam_Fear]

I finally fixed my 63’ F100’s egged out axle hole - had it reamed and bushed. It’s good a tight now. Also replaced a weak spring and put new shocks on. New slightly taller tires on the rear and curently some used truck tread on the fronts too.

So, it used to pull to the right constantly until halfway through a right curve, then it would flop left. After the axle fix, the first run was scary. Wandered and hitting the brakes made it weave side to side. Adjusted the rear brakes and added some toe in - helped a lot. It still was a little wandering every once in awhile, but not bad.

BUT there is a stretch of highway where the road is a bit tire track dipped from heavy truck traffic. It wanders unless I am on the center line or on the white line.

I kinda measured the caster at about 2 degrees. Changed in some bigger spacers and am probably at about 6 now. Haven’t rechecked the toe. It got better, but kind of darts into corners but doesn’t seem to want to straighten out on its own very well. I’m not sure if my camber on the fixed side is correct.

This is where I’m at now. Any suggestion?

This weekend I hopefully will get a chance to measure everything better to see where I’m at.

Oh yeah, it doesn’t help that my gear box is shot and has a good 6” of slop in it.

 

[Blue Eyed Devil]

Sounds like a lot of contributing factors. Double check the camber just in case, but that shouldn't be an issue unless something with the repair affected it. Get at least 7 degrees caster in it (I usually set mine around 10). Set the toe 1/8" in. If those tires are old and hard it definitely isn't helping, especially with a heavier ply truck tread. Finally, sort that steering gear out. All the proper suspension geometry in the world won't help a worn out box.

These things all need to be done, but do them one at a time with checks in between. That will likely give you the main culprit.

 

[Bamamav]

For sure needs more caster the way it sounds. More caster will help it to track straighter, but nothing will help 6" of slack in the steering box.

 

[lazarat]

I had the same problem with my original 53 front suspension. The road from my house to gal pal's house was so bad I could let the car steer itself by just letting go. Plus squealing on turns.

It was the camber. I had the king pins done and recently re adjusted all the way back to 0 adjustment Not much room to adjust, its like a quarter inch turn, and used a level to see how they lined up. Much better, watching tire wear.

 

[Tripper]

Are you using a steering damper? [S

BoB

 

[Sam_Fear]

Are you using a steering damper? [S

BoB

Pfft... no. I have thought about it, but I don't want to make the pig any harder to turn! A new gear box would probably help more.

 

[Sam_Fear]

Sounds like a lot of contributing factors.

Yeah, and I changed a lot of things all at once out of necessity.

Double check the camber just in case, but that shouldn't be an issue unless something with the repair affected it.

Whatever jacked up the bore might have messed with it? The way it was egged looks like maybe that tire took a hard hit at full turn. Machinist didn't find anything off, but they do robotics normally, he owed me a freebie.

Get at least 7 degrees caster in it (I usually set mine around 10). Set the toe 1/8" in.

Ok. I was thinking 6-7 caster was about the limit. I'm going to remeasure and shoot for 10.

If those tires are old and hard it definitely isn't helping, especially with a heavier ply truck tread.

Just got my new fronts to put on. Still LT's, but have a car tread. I run radials, not bias ply.

Finally, sort that steering gear out. All the proper suspension geometry in the world won't help a worn out box.

These things all need to be done, but do them one at a time with checks in between. That will likely give you the main culprit.

New box... I know. It's in the works now. But I should be able to let go of the wheel for a second and not have it wander off unpredictably. So I want to get this sorted regardless.

ONE. THING. AT. A. TIME.

Thanks for the detailed response! Hopefully I can get on it in the next few days and report back.

 

[bob w]

I know BED uses 10 degrees of caster. I've built dozens of hot rod since 1959 and have used 5-6 degrees. An egg shaped kingpin bore is not uncommon in well used straight axles, specially trucks. The truck alignment shops used to just heat the area and beat it with a big hammer. There is also another technique that I can't remember but you might find it by searching the HAMB.
I also know BED considers steering dampers a crutch. I agree. But thousands of them are in use and I don't think they increase steering effort. I've never used one or driven a car with one.
But first, you need a tight steering box. If you are driving undulating county highways, that much slop will make the truck undriveable. Like the '55 Chevy panel truck I sold to a hippy in the late '60's. He couldn't even drive it home at 30mph. Worn out steering box.

 

[Sam_Fear]

The new car tread tires helped a lot! Still ned to recheck the caster/camber/toe but it’s easily drivable and stable at 70+. (I usually don’t go more than 60 in it)

I had the whole fixed already. A machinist that works dor a robotic builder owed me so I had him bore it and press kingpin bushings in top and bottom. Tightened it up nicely!

I’ve drove it for years with that sloppy steering and it was always predictable. Eventually it just started flopping to far when it did flop. Before I couldn’t afford the cost of a good gear box so I dealt with it - no one made rebuild kits for the 61-64 so they cost a lot of gold.

If I can’t get the box tightened up with a rebuild kit I may try a damper.

 

[Blue Eyed Devil]

New rubber always makes a big difference. Glad to hear you are on the right track (literally!).

 

[Old Iron]

Good to hear you're getting it under control

 

[donsrods]

The new car tread tires helped a lot! Still ned to recheck the caster/camber/toe but it’s easily drivable and stable at 70+. (I usually don’t go more than 60 in it)

I had the whole fixed already. A machinist that works dor a robotic builder owed me so I had him bore it and press kingpin bushings in top and bottom. Tightened it up nicely!

I’ve drove it for years with that sloppy steering and it was always predictable. Eventually it just started flopping to far when it did flop. Before I couldn’t afford the cost of a good gear box so I dealt with it - no one made rebuild kits for the 61-64 so they cost a lot of gold.

If I can’t get the box tightened up with a rebuild kit I may try a damper.

I was going to make the same suggestion Tripper made about a damper. None of our cars leave our shop without one, they make a world of difference, and you don't feel any more resistance at all.

If it were me, I would pick up one for a Jeep, they are a little heavier duty than the hot rod versions. Also, I bet that slop in the steering box isn't helping, have you adjusted the threaded adjuster to take up any slop ?