I need help!!
The truck is roaming all over the road. I put everything new under the front end and had it aligned. I have the caster set at 4.5 degrees with the top tilting back and the wedges thicker at the back of the axle.


If I go over a bump or let off the gas from fast acceleration it wants to go off line.
I don't want to go to a modern suspension but if it is this dangerous to drive, I may have to.


Please help, should I add more caster or am I missing something.

 

That's odd to me...
I still have my '56 front end intact if you'd like to put it to some use let me know.
I changed mine a week ago to Mustang II IFS from CPP and so far so good.
Paul

 

I was told that the wedges are to be thicker at front as that will put the top of the spindle tilting back. Hope a front end person will chime in and help us.

 

The wedges must be installed with the thick end to the back. If the thick end is to the front it will take caster out by tilting the axle forward.

Rogers, if everything is installed, adjusted, and aligned properly, you shouldn't get that much wander.

A few questions:

• Is the front suspension pretty much original? I mean did you use after market springs or axle?
• When you installed the wedges, did you use spring alignment bolts with longer heads?
• Have you checked to see if the rear end tracks straight behind the front end?
• Did you lower the front or the back?

 

By placing the caster shim with the thicker portion to the rear of the axle will increase negative caster and cause wander and failure of steering return to center. You need positive caster of 3 to 4 degrees which means the caster shim should be placed with the thicker portion toward the front of the axle.

 

Only if the axle is located above the spring would you install the shims with the thick end forward. This would tilt the axle back adding positive caster.

If the axle is located below the spring, in it's original location, you would install the shims with the thick end rearward. This would tilt the axle back adding positive caster.

 

Here's a helpful diagram showing the tilt of the axle to achieve positive caster. As mentioned, with the axle under the springs, fat end of the shim goes to the back.



When you said everything is new up front, does that include king pin bushings, spring eye pins and bushings, steering box rebuild? Any slop in any or all of these components will cause the symptoms you describe. The more play in the various pieces, the symptoms multiply.

The other question is what other modifications have you done to the front end or the truck in general? Lowering? Removing spring leaves? Dropped axle? Tie rod drops? ???

 

Also bias ply tires, not enough toe in can result in tramlining (following seams/crests in the road). And don't underestimate the importance of good quality shocks! Wayne is spot on, how much free play do you have at the steering wheel? Caster is important to the wheel returning to straight ahead after turning, less in maintaining straight ahead when driving straight. When in good condition the beam axle front suspension is quite good. Also check the rear springs for eye bushing and pin wear.

 

left side of truck notice the shim on the bottom. I have new shims to put in the shim you see looks like it was stock showing neg caster





drivers side no shim.




one of two new shims from mid fives I now see clearly (ya right!) that the large end of shim does go in the back to push the rear of the axle down hence pulling the top of spindle back for positive caster. Clear as mud this is one of those things that you have to stop and think about if you are not around it all time.

 

I stand corrected, Thank you. I guess age has a distortion/dyslectic effect with the memory and keyboard. LOL

 

I can see no reason the '48-'56 trucks would have had negative caster from the factory. If the axle is installed with negative caster, it could be installed backwards.

 

The way I had it explained to me years ago by a old school front end mechanic is... negative caster is like caster wheels on the front of a shopping cart. - Very easy to turn but not stable. (I'm sure you've seen how they wobble at times). Positive caster is like a Chopper motorcycle.- Very stable but not quick to turn.

 

Sorry it took a while to get back but I have been under the truck most of the day today.
Here's what I have: a new Toyota power steering box, new 3" drop axle for Mid. F., removed 2 springs, new cross tie-rod and ends, king pins and spring pins (front and back). Everything seems to be tight as far as bolting on, but I can still take the right wheel and move it just a little. (1 maybe and I mean maybe 2 degree flex)
I fixed some of it today. The horseshoe linkage that connects to the drivers wheel (I don't know the name) was a little loose. It was moving up and down created some play from the left and right wheel. I tightened it up and it fixed about 80% of it.
Here are the two things it think could be causing the 20%.
1 - My linkage running from the gearbox arm to the horseshoe piece on left spindle(don't know the name) is tilted just a little. So when I go over a bump, it could theoretically cause the wheels to move just a little as if I where turning the wheel. But I would think this would happen to any of these trucks if they go over a bump.
2 - I had to put those aluminum connecting blocks between the cross tie-rod ends and the spindles since I lowered the front end. I'm wondering if these are flexing on me. Maybe I should find someone that makes stronger ones.

 

Paul
Thanks for the front end offer but if I can't get this right, I may go down the road you just went down.

 

I thought the tie rod drops from MF (round ones) are steel not aluminum
Nostalgia Sid Dropped Ford axles, Spindles and tie rods. Guthrie Oklahoma sells steel ones. Dropped axles of 3" or more usually needs the steering arm (the U shaped piece that is bolted to the left spindle, that has the ball the drag link, the rod from the pitman arm on the steering box attaches to and turns the wheels) to be dropped as well. Call Sid, he is the best dropped axle guy in the business, he will give you the full 411. I don't know if he drops the arms separately from one of his axles tho. It not a simple operation to drop the arm, it must be bent twice to keep the ball stud vertical and the ball must remain in the original front to back position.
If everything is new, there should be negligible free play in the front end With the pitman arm lock in place. With the wheels pointed straight, jack up the center of the front axle until both wheels are off the ground. Put a large C-clamp on the frame tight against the pitman arm (the arm on the steering box that swings back and forth when you turn the steering wheel) one on each side so it cannot move. Now grab each wheel at 3 and 6 o'clock on the tire and try hard to move the wheel like steering it. They should not be but a tiny amount of movement. Try it on both wheels. If either moves any amount enlist a helper to do the same while you watch from underneath (SAFETY NOTE: place a jackstand under the frame behind the axle on both sides before crawling under a jacked up vehicle!) to see what/where is moving. If both wheels move adjust the jack so only one wheel is off the ground and recheck that wheel. If it still moves see where, then replace the jack to raise just the other wheel and check it. You may have a bad or mis-adjusted wheel bearing if only one moves, but the linkage does not, or a mis-assembled or mis-adjusted drag link ends if the play is in the drag link.
Note there should be the same number and thickness caster shims on each side. If not, the axle may have been improperly installed or someone was attempting to compensate for a twisted axle (A known issue with some of the later Mor-drop axles done after the original owner sold the business, and with some of the 3 piece tube center assembled axles.
When adding shims be absolutely sure the spring centerbolt heads protrude thru the shim pack an ample amount to fully seat into the corresponding hole in the center of the axle spring seat. Mid Fifty sells spring centerbolts with extended heads for use with the shims (not longer bolts just longer heads to go thru the shims into the axle).
I might suggest calling Mid Fifty and ask them to send you one of their excellent FREE catalogs. The drawings photos and parts descriptions will help you to identify parts by their correct names. It's a lot easier to understand problems and help when the parts are correctly identified, and will help you to learn a lot more about your truck. Who did the work on your truck?