Jim.

I think the tires accent the panel, and give a bit of attitude.

Black walls are the way to go and I like the little bit of shiny stuff with them.

 

Thanks Tom for the kind words. Bias tires do have the "look" that I wanted for my truck.

Matt, thanks for your advice on caster angle. I'll have to look for a shop that works on big trucks. Our little town doesn't have one, but there should be one in our general area. It's interesting that you said the caster angle should be the same on both sides. I asked the young man doing my alignment why there was a shim on only one side. He said caster angle was supposed to be unequal but agreed adding a 4 degree shim to both sides might be helpful. He was unsure, however, if there could be two shims on a side, (the original 1 degree shim plus a new 4 degree one).

Jim

 

On independent front suspensions usually the right side will have a bit of a lead in caster usually in the 0.3° to 0.5° range.
But these trucks are not independent front suspensions and even the specifications state 0.5° maximum variation side to side, ideally there should be NO variation in caster side to side on a solid beam axle.
Your young tech likely has little or no practical knowledge and is just regurgitating what he has been told.

See below specs for the 57's the 56's should be similar if not the same. And should work for the 56.

The F100's state 2.5°- 3.5° caster. With a maximum variation of 0.5° side to side. I Like 4° to be a minimum to use for caster as it has better turn in and return and it's better at keeping the vehicle tracking strait , plus caster decreases overtime in light duty beam suspensions so never a bad ideal to start out a bit high.

Caster or lack there of will affect your vehicles handling more than any any other alignment setting and it is the one that get's ignored the most..
Lack of it will lead to wandering and just a feeling of general lack of stability.
This is even more critical in these old trucks where the steering system always has some slop in it unlike modern rack and pinion systems.

 

Matt, thanks again for your detailed response. I'm not positive, but I think my toe-in reading was something like 11/16 of an inch on one side. I should have asked for a print out. I'm hoping to get my caster angle issues sorted out before the snow flies. It sure seems like increasing the caster angle is going to help make my truck even more enjoyable to drive.

What about king pin inclination? Mine were replaced by my mechanic friend, but he's not an alignment guy. My truck's alignment was adjusted twice, but no one ever mentioned king pin inclination. Is this something that needs to be checked? Thanks

Jim

 

The kingpin inclination or steering axis inclination is the angle, measured in degrees, that the kingpin if off from perpendicular to the ground (looking at the vehicle from the front), kingpin inclination reduces tire scrub when turning and helps to keep the vehicles tracking strait.
As you turn the wheels with inclination you actually lift the vehicle up. Since you have lifted vehicle up it wants to go back down because of gravity. This helps keep the vehicle tracking strait.

King pin angle should be 4° at 1° camber in these specs, this is a check to insure that the steering geometry is correct for the tire size used and that components have not been bent/damaged.

Kin pin inclination should be checked after a restoration to insure components have correct geometry and are not damaged.

These solid front axle trucks really need to be done by a tech that has experience with solid front king pin axles. And in today's world the only ones left that have that are techs that work on medium and heavy trucks.

I'm not likely not explaining this very well. So I defer to this You tube video that does a much better job.

 

As an addition not many people ever get these old trucks properly aligned and then wonder why they are all over the road as they certainly were not when new. This many times leads to swaps to IFS systems so they can keep their truck between the ditches. The issue is not the original suspension but not being properly aligned. These old manual steering set ups had a lot of play to begin with from the factory making wheel alignment more critical than in modern cars. Alignment settings for modern cars do NOT work on these set ups and the original settings need to be used, many current auto techs default to settings used in IFS set ups, this not any where near optimal on these trucks.. I doubt there are many if any auto techs left alive that know how to properly align these trucks these let alone shops that have the tools and equipment to bend beam axles.

The settings on these trucks is similar or the same as modern heavy trucks with king pin solid front axles. The techs in heavy truck shops pretty much work on nothing but solid front axle suspensions and are well versed and experienced in correcting them for optimal operation. So this is the best recommendation I can give for getting your truck aligned, find a heavy truck shop and let the guys that work on this stuff day in and day out do your alignment.

 

Hey Matt--I'd for sure be sending some reputation points your way if the site would let me, but it doesn't. Thanks anyway for all your help!!

I contacted the most well known big truck shop in our area, but they said their equipment couldn't be used on a small truck like mine. I then found a spring and alignment shop willing to look at my truck. They say they work on old solid axle trucks all the time and have the ability to bend axles. The guy, however, said they use shims to correct caster and bend axles for adjusting camber. Does that sound right? Thanks.

Jim

 

Some very good information above. These old trucks can drive very nicely when set up right

 

Yes it does, shims are the standard for minor caster corrections on a solid axle with leaf springs. Generally the only time you would need to bend a solid axle to correct caster is if either the cross caster was not within specification, or could not be corrected with shims, or on a vehicle with lateral a leaf spring such as on a Model T , Model A etc. And of course in Twin I beam suspensions.

The shops than can still do this are few and far between now. Generally cross caster does not change unless the axle suffered a significant impact ( hard hit curbing, big *** pot hole etc).
I have seen cross caster corrected with a pair of big *** pipe wrenches and a couple 6ft snipes and a burly tech.
The tool for fixing cross caster in Model T's was not much more than this. See example at the link.
https://www.modeltford.com/item/2691AW.aspx
And then of course there was the tool shown earlier.

The way to correct chamber in most all king pin axles is to bend them.


Some techs like to add in some cross caster to compensate for road crown, this is a practice I don't really like and is a left over from years gone by. When the interstate hyway system was built it was all built to the same specifications and had a fairly consistent road crown and was pretty much the only paved high speed hyway in most of the nation. Cross caster served a purpose then.

Nowadays roads are built to all different sorts of crown specifications depending on, expected average rain fall, snow fall, road substrate base, surface material, expected traffic etc, so cross caster can be a hindrance as road crowns can vary drastically within a few miles. In PS equipped cars this is not a concern but it can be tiring in a manual vehicle.
Neutral cross caster will always result in a bit of a pull to the right due to the road crown which in my mind is not a bad thing, I would rather have the vehicle wander off to the right if I lose attention than cross the center lane in to opposing traffic. But that is me.

The cross caster limit in the specs I listed is pretty small, to the point of basically being unnoticeable so I would shoot for no more than the 0.5° cross caster but that is me..

Also consider 4° as the about the minimum amount of caster you want . The higher the degree of caster you have the more the vehicle will want to track straight. This comes back to the king pin inclination thing, as you increase caster the vehicle will be harder to turn as it will be trying to force the tires down further as demonstrated in the You Tube video and they will want to return to straight ahead

This also becomes a bit of a balancing act, if your truck is only driven on city streets at slower speeds then you can get away with just a couple degrees of caster and have a bit lighter steering, but if you do any amount of hyway or long distance driving then you want more caster to keep the truck tracking straight so you are not constantly correcting it to keep it from wandering all over. Here most of my driving is either hyway or higher speed surface city streets and the terrain is pretty flat and the roads straight. So I like to have more caster either at the upper limit or slightly over spec. How you use your vehicle and what conditions it sees will dictate how much caster would best work for you.

As noted higher amounts of caster increase steering effort this also wears steering components faster due to the greater effort needed to turn the wheels. But if you are doing more straight line or hyway driving or live in the mid west/prairies then it is off set as you are not doing as much turning or steering corrections.

I'm glad you found what sounds like a shop that knows what it is doing, these places are getting harder and harder to find.

Do let us know how it works out.

And I'd glad to help out

 

Having found a shop that works on vehicles with solid beam axles and king pins, and with the excellent guidance I've been given here, I should be all set. The specs for my truck call for maximums of 4.5 degrees of caster, 1 degree of camber, and 1/4 degree of king pin inclination. Are these the numbers I should ask for? I have read elsewhere on line that caster could, in some cases, be set as high as 9 degrees. I'll have the springs checked too. If the springs are found to be out of spec, should they be corrected before the wheel alignment is done? Thanks.

Jim

 

Manual steering is excellent off road and on dirt/gravel when everything is in good nick, my slick drives straight as a train on good highway and needs less effort to turn the wheel than my Ranger.

One thing to watch out for though, if the front wheels hit a boulder or something like that just right, a manual gearbox will spin the steering wheel from lock to lock the spokes can break a wrist or fingers. I heard the wheel hum like a box fan once, that's how fast!

 

You can run as much caster as you want off feel you need to. if you want to run 9° you are than welcome to. Since your truck has 4.5° as the upper limit go to 5.5 or 6° even. I would think your your king pin inclination is more more than 1/4° as the scrub radius would be huge.

If the springs are out of spec they should be corrected before the alignment.

 

Matt, Just to set the record straight--you are correct on the king pin inclination. The column for degrees of inclination reads: 8 (with the symbol for plus or minus) 1/4 degree. I "saw" 8=1/4 degree. I didn't know what the 8 was, but thought the inclination must be 1/4 degree. Getting old for sure--and I tutor kids in math--scary isn't it?

Jim

 

Ya getting old sucks your eyes tend to miss stuff
I hare having to grab my reading glasses evey time I open a book now as my arms are no longer long enough so sometimes I get lazy, don't bother putting them on then wonder why I miss read or misinterpret stuff, doh.

With a King pin inclination angle of 8° which is pretty high you wont need as much caster so in this instance your upper limit should be 5°.

If you refer back to the video as you increase the king pin angle (inclination) the tries will wan to move down further when turning the wheel, so this will increase steering effort but provide better tracking. So you will not need as much caster to get same strait tracking affect as on an axle with a lower king pin inclination (KPI).

With the KPI on your truck, it will track better than the equivalent 57 F100 with the same amount of caster.

Your caster was way way off spec so it is no wonder it was all over the road.
It must have been interesting to drive. lol

Also Bias Ply tires need more caster compared to a radial as bias ply's tend to follow/bump off road irregularities, where as radials will travel over and absorb them. Caster settings for bias ply's are generally higher than for radials for this very reason, to help keep the vehicle tracking strait, over road irregularities.

This is some of the reason that people find these old vehicles wander all over place when they reinstall bias ply tires after having radials as the caster should be adjusted to the upper end of the factory specs. Most tech's have no clue about this and use generic caster settings for Radials if they do not have the factory spec's as many of these guys have zero experience with bias play tires and are not aware you should not use radial alignment specs for bias ply tires.

This is why it is always good to bring a copy of the alignment specs to the shop and get them to attach them to the work order for the tech and always get a print out of the spec's when they are done. If you want more caster I just cross out the caster specs on the factory sheet and write in my own.

With solid axles each model had alignment settings that is liked best the old school alignment techs knew what worked best for each one with the equipment they had and they always test drove afterwards to make sure it was good. The post alignment test drive is something that is rarely done now as the computer tells them exactly what the specs are so it must be good and usually is.

 

I called the spring and alignment place today to make an appointment. To my surprise, the guy answering the phone asked if I could bring my truck in today at 3 o'clock. I dropped what I was doing and said I would be coming. It took about an hour to make the trip. I arrived 10 minutes early, and that's when it got interesting.

I no sooner got parked and out of the truck and there was a guy already outside by my truck asking if my keys were in the ignition. When I said, "Yes", he jumped in my truck, drove it through an open door, and onto a lift. In seconds my truck was up in the air and a second guy on a ladder was working the steering wheel while the first guy (the owner) was under the truck looking for problems. It was like a pit crew operation.

The owner said my springs were fine and he wouldn't recommend messing with them, but the steering box needed to be adjusted and there was way too much movement in the king pins. I mentioned that the king pins were recently replaced. He said that unfortunately didn't change the fact that there was way too much movement, and he showed me what he was talking about. There was indeed very noticeable up and down movement.

I mentioned that what I really came for was caster shims. The guy said he had the shims and could easily put them in for me, but thought with the king pins and steering box corrected, they might not be needed. I told him my caster numbers were 1.7 and .7 degrees respectively, and that as much as 4.5 degrees was recommended, but he seemed unimpressed.

The owner took down some contact information to set up the next appointment, and I gave him permission to order what might be needed for the king pin fix. He said actually replacing the pins might not be needed given that they were new. He wanted to have new pins available, however, just in case. He assured me that I wouldn't be charged if the new pins didn't turn out to be needed. He thought maybe the king pin repair could be done with shims.

I was out the door and on my way back home at 3:01 P.M. I looked at my watch. I've never had an experience like this at a garage--These guys spent less time diagnosing my problem than it probably took Matt to write just one of his thoughtful responses to this thread. It was a beautiful day, however, for a 100 mile drive, and my truck handled so much better than it had going to Truckstock.

Does anyone think there is a connection between king pin movement and my truck's tendency to wander? Also, why would there be movement in newly replaced pins? The movement was demonstrated with the axel lifted to take the weight off the tires and then a pry bar and block used to move the tires up and down. Thanks.

Jim