Insufficient Front Caster

[Lembomw]

I just put my car (1930 Tudor) back on the road this past Saturday after rebuilding it (I drove it for only about 150 miles after purchasing it in 2011 when I decided to do the rebuild). I went for a 10 mile shake down ride and found that it was still hard to steer. I had rebuilt most of the front suspension (new front spring and lots of other new parts), put in a Mel Gross steering box and modern shocks. I also have an F-150 transmission with the AA bell housing. The radius rod fell right into place.

Today I checked the toe-in and caster. Both are out. Have a bent tie rod that I did not notice before, so that can be an easy fix.

The caster is another issue. I only have about 3/8 inch between points A and B when it is suppose to be 1 inch (5 degrees). Les Andrews Trouble Shooting Guide says that when the steering is hard and it is insufficient front caster, to adjust front caster. Problem is the book does not say how to do that.

I have searched prior posts on the subject and while there has been discussion I do not find anything to tell me how to get the caster into specifications.

I would greatly appreciate some direction on how to do this. From what I read the caster is an important part of the steering and I am really lost on this one.

Thank you for any assistance you can provide,



Mark

[BRENT in 10-uh-C]

Mark, generally when there is too much caster, then it is difficult to steer yet when the caster is around 0°, then the steering is very easy. What + caster does is take 'darting' away and make the car want to keep tracking straight when your hands are removed from the steering wheel.

Caster & Camber are adjusted by bending the beam. Now, the caster can also be affected by a sagging front spring which effectively increases + caster. A new spring would in theory decrease caster which should make it easier to steer.

I did notice that in your avitar you have larger tires. Are you taking those wider footprint into account for the tougher steering? Also, what is the condition of the steering arm balls?

[Napa Skip]

There are good articles on alignment of the Model A front end, including explanations of camber, caster and toe-in, as well as a discussion on the steering-related differences between contemporary (i.e., 1928-1931) automobile tires and modern automotive tires. If you have access to the MARC and MAFCA club magazines you might try: “Model ‘A’ Ford Front End” by Dick Valot from the Model “A” News (I neglected to note the issue but there are indexes available on line); “Tuning Up A Model A Front End” by Milton Webb in the January/February issue of The Restorer; and “Proper Front-End Alignment Using Modern Day Tires” by Steve Smith in the March/April 2004 issue of The Restorer. Valot’s article also gives easily understandable illustrations and directions for measuring caster, camber and toe-in.

Other articles from The Restorer are: “Front End Alignment” by Merle (?) Smith (March/April 1980), “Servicing The Steering” by Murray Fahnestock (September/October 1966), “Why-What-How” from the Steering Gear sidebar (July/August 1957), and “Patent Cures – Toe-in” (July/August 1995).

Although toe-in is the only adjustment that can be easily done in the home workshop, caster (5 degrees backward tilt) can be adjusted – as pointed out in Valot's article – by “…raising or lowering the position of the radius ball (with shims) in the ball socket beneath the flywheel housing…”

Lastly, although hopefully never needed, the above article by Steve Smith discuses how camber can be changed – as is done with solid front axles on commercial vehicles – by having a professional alignment shop re-arch the axle (that ought to take your breath away).

Of course all these adjustments are only effective after ensuring the correct tire pressure, straight (as possible) wheels, properly operating spring shackles, correctly adjusted front bearings, king pins/thrust bearings/bushings, etc.

[Lembomw]

Brent/Skip, thank you for your responses.

With about 3/8 inch between points a and b I am guessing that the degrees of caster is maybe 1.5. I do not have any experience with suspensions, but the way I read your post, with 0 degrees caster it would be easier to steer but it will be more difficult for the car to want to track straight? I am very reluctant to even try to let go of the steering wheel as it does want to dart all over the place and I need to “muscle” the steering wheel to keep it going straight. Perhaps since the toe in needs adjusting and the tie rod is not straight are adding to the steering difficulties since when I stand back from the front of the car and look at the front end it looks like the fronts of the tires are pointing out instead of in. That is not good. When I do the toe in measuring process it looks like in order to get the 1/16 inch wider measurement in the back I need to adjust them out at least ¼ inch……after I get a new tie rod.

The Tudor cam with the '35 wheels. I don’t remember the size of the tires, but they are the largest I could put on the rims so that they would be the same diameter as a stock Model A tire. I have no idea how the bigger tires affect the steering.

The front spring is new so that would decrease the camber from what you indicate. The spindle arm on the passenger side is new, the other side looked OK, short pitman arm is new, all new guts in the tie rod ends and drag link (put the Teflon cup kit in for easy steering).

So from what I have been reading, if I want the car to track straight down the road I need to increase the degrees of camber. Any suggestions on how I can do that? Seems like this is where one of the old time front end shops as Skip has indicated would need to bend the beam so that the top is out farther than it is now in order to get the 5 degrees?

Mark

[Bluebell]

Caster is the tilt of the king pin. (forward and backwards) usually forward at the bottom.
This means that the king pin points at the ground just foward of where the tyre touches the ground. In a conventional leaf spring vehicle it is usually achieved by the fitting of wedges between the springs and the axle mounting face.
In your ford it is as previously posted. If you had too much caster then it would be harder to turn than if you had less of it. As previously indicated, caster is there to make the steering "self center" or in other words it helps the vehicle to return to the straight ahead position.
There are five basic settings to wheel alignment;

Caster, as above.
Camber
King pin inclination (KPI)
Toe in
Toe out on turns

All need to be correct, but once again, as already covered, everything else needs to in good condition as well.

Hope this all helps.

[Tom Wesenberg]

Sponsored Links (Register now to hide all advertisements)

Tie rods can easily be bent straight, so you may not need a new tie rod. Original tie rods are hollow.

[Patrick L.]

First things first. Lets get the tie-rod fixed and the toe set correctly. Toe should be 'in' 1/16" . A vehicle will be a real 'hand full' if the toe is off very far, especially if it is toed out. And if you can see it, its really off.

[Lembomw]

Bluebell, thanks for staying up late and responding. Tom & Patrick, boy you guys get up early to help others here.

Bluebell, your response indicates that “in a conventional leaf spring vehicle it is usually achieved by the fitting of wedges between the springs and the axle mounting face”. The Model A has the transverse springs. I do not know what is considered to be a conventional leaf spring vehicle. Does the Model A fit into that category. If so I do not see where to put wedges except up in the cross member where it mounts.

Tom, am going to try to straighten it today, if I don’t like what I see I will get a new one from Snyders.

Patrick, yes it is a handful with both front tires pointing more out than in. When I finally saw that I realized that the front end was trying to go in opposite directions at the same time. The tie rod and toe in adjustment are the first things I will do. Should help a lot.

Thank you gentlemen.

Mark

[1931 flamingo]

Continue as you plan, get the toe in correct and then try driving it. Is there lube in the strg box?? What's the tire pressure??
Paul in CT

[Patrick L.]

Once the toe is set correctly, a little extra + caster can be had by adding a 'warped' fender washer on the top side of the radius ball.

[Napa Skip]

Lembomw - see pm sent earlier today.

[Lembomw]

Gentlemen, thank you for all your responses. Things look better today. Went out early and took a close look at the tie rod. Too many bends in different places and on different sides of the bar. You can’t notice that it is not straight until turning it to adjust the toe-in. Ordered a new one from Snyder’s this morning. Since I am bringing it to the interior shop tomorrow so he can take a look at the interior of the car before the LeBaron Bonney interior arrives in a couple of days, I need to be able to drive it so I did the toe-in alignment with the not straight tie rod. Took a little while (have not done this before) but I finally got rid of the toe-out on both wheels and now have toe-in. Should be able to do a better job when the new tie rod comes.

I also ordered a couple of radius ball washers. I will put as many as I can under the radius ball cap. Maybe I can pick up a degree of caster.

This morning I talked to Randy Gross (F-100 Steering Box) to get directions on how to “fine tune the new steering box as it seemed that I had some play in it. Turns out that after removing the drag link from the pitman arm and following his instructions to center the steering box…….no play. However, not moving the pitman arm, when I reconnected the drop link both front wheels were pointed a little to the left instead of straight ahead. Hmmmm. Talked to Randy again and he gave me directions on how to adjust the steering box with the wheels pointed forward so there would be no play since the box was not at center anymore.

Took it for a ride. Wow, what a difference. Nothing like having some toe-in and no play in the steering box to take the terror out of driving the car. I can let go of the steering wheel now and it goes straight ahead. It no longer darts all over the road in unpredictable directions (most of the time looking for a ditch to go in) and I don’t have to have a death grip the steering wheel and fight the car down the road. Should be even better once I get a straight tie rod installed.

Thank you all for your advice and guidance.

Mark

[glenn in camino]

It could be a bent wishbone.

[Lembomw]

Thanks Glenn. I will check that out tomorrow.

Mark

[quickchange]

Mark, How do you ajust, centre a F1 box as there are no ajustments like a two tooth A box, Derek from a snowy freezing NZ

[Tom Wesenberg]

Too much toe out from a bent tie rod you say?

[dr.j]

I noticed a few days ago that the car seemed to be a wee bit more active with tar snakes and uneven road surfaces. Once home I checked the tie rods and drag link for tightness. Gave each (4) caps an extra turn or two and the "darting" cleared up. For what it's worth

[Lembomw]

Quickchange, the following is what I was told to do in order to fine tune the steering box. Normally no adjustment is needed though. When I went through the process my box had no movement at all when it was at dead center and I tried to move the pitman arm:

ADJUSTING F-100 STEERING BOX

Disconnect pitman arm from drag link.

Turn steering wheel all the way to one side.

Turn back EXACTLY 2 5/8 turns.
This will put the steering box worm gear in the dead center spot.

Grab the pitman arm and see if the sector shaft will move.

It there is movement loosen the nut on the side of the steering box while holding the bolt in place with a screwdriver.

Tighten the bolt with the screwdriver only about 1/8 turn then check again.

Do not overtighten.




On my car when I connected the drag link up to the pitman arm the wheels were pointing to the left and not straight ahead. So I moved the steering wheel to straighten the wheels out, then tightened the bolt on the side of the box again. It didnt take much to snug it down. I have a brand new box so I dont know if this will

do anything to it but the car went down the road straight and didn't seem to have any wheel wobble.

If you have an F-100 steering box and you think you are having problems, I would call Mel/Randy Gross and tell them what it is doing. They can give you the best advice if there is a problem.


Dr. J, when I put the new tie rod in I am going to tighten them a little more than normal so they are really tight.


Thank, Mark

[Kurt in NJ]

[

Dr. J, when I put the new tie rod in I am going to tighten them a little more than normal so they are really tight.

When you adjust the tie rod ends and the balls are not round make the adjustment with the wheels turned full lock where the balls are largest, if you tighten too much in the straight ahead position they will bind on the larger diameter of the ball when turned.

[KR500]

One of the items overlooked may be the switch to "35 wheels and tires meant for the later years. Camber and KPI play a part ensuring that following the king pin center down to the ground should end up at the point where the centerline of the tire makes contact with the road. Wheel offset different tire widths change the specs. The reason for toe in is that with the spindles KPI (if correct) makes a cone of the front tire assembly. What happens when you roll a cone? it does not roll straight ahead. In order to accomplish a cone to roll straight ahead, you must turn the cone inward at the front. Camber changes although not critical change the toe in requirement to keep tires from scuffing. Camber is to place the front wheel weight against the larger inner wheel bearing and King Pin inclination is to place the spindle weight against the king pin bearing directly and have the king pin center intersect with where the tire meets the road.