Caster?

[Ricosan]

Hey Guys,

I’m having trouble with my steering. When I make a turn, the steering wheel has to be manually returned to the straight forward position.

I made up a crude instrument to measure the caster in the front wheels. I got measurements of 2.5 degrees on the left side and 0 degrees on the right.

Are these acceptable figures?

Richard

[Mart]

Can you explain exactly where and what you are measuring?

[Ricosan]

Hey Mart,

I used the instrument pictured below. I know it’s crude and the accuracy could be questionable but I just wanted to get an idea of what may be contributing to the flat steering.

I carefully placed the two legs on the a straight mahogany stick with screws. I placed the two legs against the rim and measured the angle.

I took the measurements vertically.
Richard

[Krylon32]

On all the customer straight axle chassis I've built over the last 40+ years I have recommended 5-7 degrees of caster. I have recommended 1/8th of toe in for radials and 3/16th for bias tires. Seems to have worked good all these years.

[Kube]

Originally Posted by Ricosan

Hey Guys,

I’m having trouble with my steering. When I make a turn, the steering wheel has to be manually returned to the straight forward position.

I made up a crude instrument to measure the caster in the front wheels. I got measurements of 2.5 degrees on the left side and 0 degrees on the right.

Are these acceptable figures?

Richard

From your description of the issue you are experiencing, it sounds as if the toe-in is not correct. Not enough toe-in will hinder the front wheels from returning to forward position.
Positive caster will make it difficult to steer.

[Ricosan]

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Hey Mart,

I used the instrument pictured below. I know it’s crude and the accuracy could be questionable but I just wanted to get an idea of what may be contributing to the flat steering.

I carefully placed the two legs on the a straight mahogany stick and attached them with screws. This allowed me to bypass the hub cap and maintain a straight line from one rim side to the other. I placed the two legs against the rim and measured the angle.

I took the measurement vertically.

Richard

[kartrae7]

Not saying its accurate or not but if measured on side of wheel you measured camber not caster.

[alchemy]

Stick your small magnetic protractor to the flattest spot of the front of the axle. Maybe span over the web. That will show you caster. I don't know what Henry built them to, but as Gary said 5 to 7 degrees will give you a nice steering effort. But it's rather involved (requires butchery like cutting and welding) to adjust caster on a Ford wishbone.

[cadillac512]

Originally Posted by kartrae7

Not saying its accurate or not but if measured on side of wheel you measured camber not caster.

Correct. Camber is the relationship between the top and bottom of the wheel. Positive camber means top of tire/wheel is tipped outward compared to the bottom.

Caster is the angle of the kingpin in the front axle. Positive caster will have the top of the kingpin rearward compared to the bottom.

[alchemy]

Maybe your problem is related to other components. How's the steering box and tie rod ends condition? If they are not smooth, I can see how it won't want to return to center.

[Bored&Stroked]

You're measuring CAMBER, not CASTER.

Caster would be your king-pin inclination angle (how many degrees "tilted" to the rear). A simple crude way is to take your angle gauge and put it on the back of your I-beam axle (against the two i-beam ribs - middle of the axle).

This should give you the angle of the axle itself - which should be the same as the king-pin inclination angle.

[drolston]

Ford documents stated 4.5 to 9.0 degrees positive camber. The rule of thumb was to shoot for 7 degrees, roughly the halfway point.

You can actually calculate caster from the camber angle rig you made up. The math is complicated, so the process I will describe is to simply determine if caster is positive or negative, and if left and right caster are approximately equal (they should be, unless the axle is twisted.)
1) Roll down the driver side window.

2) Put a jack under the center of the axle and raise it so that both front wheels are just barely off the garage floor by an equal amount. Adjust the jack location left and right as needed to accomplish equal tire clearance from the ground.

3) With the wheels straight ahead, use your gadget to measure and record the camber of the left wheel.

4) Without disturbing the car, turn the steering wheel all the way to the left turn and measure the angle again, and record. If caster is positive the angle you record will be larger than the straight-ahead camber. If camber is negative, the angle you measure will decrease. Not good.

5) Turn the wheel full right turn and measure the angle. If you have positive caster, it should decrease from the straight-ahead camber.

6) Subtract the full left number from the full right number. Your caster is bigger than that number, but at least you know whether it is positive or negative. Guestimation? - your caster is three times the difference calculation.

7) Repeat for the right front wheel. Hope that the results between left and right are similar.



Because the change of angles is small, you need to accurately determine small changes in angles. If your gauge can not be read accurately to a tenth of a degree, you will need to purchase a digital inclinometer.



Okay, I have never actually done this, but it should work.

[69a]

Cadillac512 is on the money!
Post #9
Why make things complicated when they are not!

[Brian]

1934 Ford right? take this how you please...whilst I have no first hand experience with 34's, I have considerable experience with 35 Fords. 35-36 fords, by the design of their steering boxes, need to be steered in and OUT of a turn. I'd imagine 34's are the same. Fitting a 37 or later model steering box into a 35-36 is like fitting power steering, and the car steering will self centre coming out of a turn. 37 and later steering boxes are worm and roller, earlier steering boxes are worm and sector. Much more friction with worm and sector. I think you'd need to fit say, an F1 steering box [worm and roller] to achieve the same effect.

[Tinker]

Originally Posted by Kube

From your description of the issue you are experiencing, it sounds as if the toe-in is not correct. Not enough toe-in will hinder the front wheels from returning to forward position.
Positive caster will make it difficult to steer.

I could be really wrong here but you want a slight toe out of 1/4". A toe out will give you drag to right wheels were a toe in won't.



With the drag link behind the axle gives it the self righting properties. A property of inertia.

[ford38v8]

This just in:
Tinker admits he’s really wrong!

[Tinker]

wouldn't be the first time Alan. but then again i don't have to return my steering to go straight.

[Bored&Stroked]

Another Important Fact - Just In:

Tinker Goes Straight!

[Ricosan]

I’m back.
Thanks for all your helpful comments about my steering problem. Apparently it’s a camber I am trying to measure.

I measured the degree and here is what I got. Left front wheel right turn -6.5 degrees, left turn +1 degrees. Right front wheel right turn -9 degrees, left turn - 1/2 degrees. I tried to find a digital inclinometer but the were over $50.

While doing taking these measurements I noticed that the whole steering setup is very loose. I grabbed the front tire at the 90 and 180 degrees and shook them. They moved easily an inch either way! Up and down was tight. I was planning on resetting the toe in this afternoon but with the steering this loose I don’t think there is a chance of setting it accurately.

My brother is coming by this afternoon to turn the steering wheel while I look from underneath.

Richard

[Bored&Stroked]

Sounds like the most important thing is to figure out where the looseness is coming from. Either parts are worn or things are not adjusted correctly . . . or a combination of both.

You may have issues in your tie-rod ends and/or pitman/steering arm ends. These steel balls, cups and springs do get worn and/or may not be correctly tightened. Also, your steering worm and sector can be worn and the play is coming from the steering box.

On these old Fords, it is usually a combination of multiple things - and outside of the steering box itself, not terribly difficult to replace parts and get things back to spec.

Best of luck, keep the questions coming!
B&S

[Ricosan]

B & S, it’s the steering box. I put the front end up on jack stands and vigorously shook the front wheels. The pitman arm would readily move back and forth an inch or so without movement of the steering wheel. I’ve had a lot of slop in the steering wheel since I got the car in January but I didn’t think that was the reason my steering would not self center after a turn. The car has recently been restored and all of the other steering components appear to be new. It has an f100 steering box that has been adjusted all the out (in). I have the kit to rebuild the box but haven’t yet found the courage to tackle a big job like that. I have a friend who has offered to help - still waiting.
Since all of the rest of the steering is tight, do you think I could get an accurate toe in measurement?

[glennpm]

When you get to rebuilding that F100 box, I just found this for you.

https://www.classicperform.com/tech_...teeringBox.pdf

[cas3]

The steering box by itself has nothing to do with toe in settings. That would rely on good king pins and good tie rod ends to get an accurate setting

[ford38v8]

Ricosan, since the toe-in is independent of the steering box, I see no reason why that adjustment could not be made accurately, and your box rebuild be postponed in the meantime.

[Ricosan]

Thanks Glenn, that is perfect! I’ve printed it out so I can take it up to my garage. That is the rebuild kit that I have.
Richard

[1948F-1Pickup]

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Originally Posted by Kube

From your description of the issue you are experiencing, it sounds as if the toe-in is not correct. Not enough toe-in will hinder the front wheels from returning to forward position.
Positive caster will make it difficult to steer.

Nope. Doesn’t work like that.
Toe in settings are always minimized. They compensate for “road drag”….. that force created by driving down the road and the tendency to force the front tires apart toward being toed out while you’re driving down the road.
Not having crazy Toe out or Toe in is critical to combating what you sometimes hear referred to as “death shake/wobble.” (That and worn out or mis-adjusted steering boxes and steering components)
Positive caster is the setting that centers steering after a turn.
Your comment about positive caster making it difficult to steer is true, particularly if you crank it up to high numbers like 7 degrees.
My ‘48 truck is set at around 4…… that’s plenty.

I worked in the suspension industry for a number of years…..

[Tinker]

If you haven't installed new kingpins and all new joints. It probably doesn't matter toe in or out. Toe in is correct. But like everything here... Death wobble is usually caused by bad angles. Like drop axles without drop arms and loose joints. Toe in or toe out shouldn't make you fear driving.

[Randy in ca]

Originally Posted by 1948F-1Pickup

........................ .......................... ......................... ..................

Positive caster is the setting that centers steering after a turn.

Your comment about positive caster making it difficult to steer is true, particularly if you crank it up to high numbers like 7 degrees.

My ‘48 truck is set at around 4…… that’s plenty.

I worked in the suspension industry for a number of years…..

__________________________________________________ __________

Many vehicles (even without power steering) drive very well with caster of about 7 degrees.

If anyone is having trouble visualizing the effects that the caster setting can have on handling and stability, visualize riding a bicycle (or motorcycle) with neutral or negative caster:

-

[Ricosan]

Hey Guys,
I pulled a muscle in my lower back a couple of weeks ago and it’s gotten to the point that I am forced to back off from my work on my car for a week or two for some healing.

In the mean time here is a picture of my toe gauge that I made with one 2X4 lodgepole pine stud and a few scraps of wood. There is a screw on the right side that would go against the front of the rim about 9” up above the floor. The left end has a rule clamped to it.

It’s looks kind of crude but I believe I can get an accurate measurement with it.

Richard

[V8COOPMAN]

Originally Posted by Ricosan

Hey Guys,
I pulled a muscle in my lower back a couple of weeks ago and it’s gotten to the point that I am forced to back off from my work on my car for a week or two for some healing.

In the mean time here is a picture of my toe gauge that I made with one 2X4 lodgepole pine stud and a few scraps of wood.

Richard

Richard.....You do some nice wood work there, but lifting that rig off of the work bench is probably what cranked your back out of whack! Besides, you're making this TOO complicated. May I re-suggest a very simple method shown in your OTHER thread on the same subject, which will likely give you a measurement of greater accuracy than your wooden back-buster can.


A good old fashioned plumb bob works. patiently and accurately hang it from the center of a tire TREAD in front of tire and mark the floor. Hang again from center of tire TREAD in back of that same tire and mark the floor. Make TINY DOTS using a sharp "SHARPIE".

REPEAT this same procedure on the opposite tire.

Now, you should have four dots on the floor. After moving the car rearward for easy access, measure the distance between the two FRONT dots.

Now, measure the distance between the two REAR dots.

COMPARE the two distances with each other. For example, you SHOULD have a FORWARD DOT measurement one eighth inch (1/8") LESS between the FORWARD DOTS than the REARWARD DOTS. This is what you are striving for IF you have a standard 1/8" TOE-IN. In other words, the front is TOWED-IN 1/8" as compared to the rear dimension.

If your measured dimensions do not equal 1/8" toe-in, adjust your TIE ROD until your measurements show 1/8" less between dots in FRONT, than between REAR dots.

Make any necessary adjustments to tie rod in small, careful increments.

Coop

.

[frnkeore]

Caster and king pin inclination are different but, work in the same way.

Both center the wheels by adding weight to the wheel, by lifting the chassis. The wheel will move back, because the weight pushes it back. In addition to that, KPI sets the center of the turning radius near the center of the tire contact patch.

You can use your tool for measuring caster, set the tires straight ahead, then mark 20° on the floor, to the front of both tires, turn the wheel, until it parallels that mark. Measure the camber, then turn the wheel the other way and again measure the camber. Add those two measurements together and that is your CASTER.

That's why alignment shops use turntables but, you can get very close with the above way.

[Ricosan]

Thanks Coop, I like it. I’m going to use your method as well as my tool and hopefully We will get the same measurement.

My back still has me out of service. Therapy this afternoon.

Thanks Frank, as soon as I can get back to my garage, I am going to use your method and compare to the figures I got the first time I measured it without scribing the 20 degree mark.

Richard

[alchemy]

Not sure if was mentioned, I'll admit I didn't read every word of the replies. When you are measuring the center of the tires, front and back, you need to make sure you are actually using the centerline. Don't trust the tread grooves. Jack the wheel up and spin it, and tightly hold a fine sharpie marker to the tire as it goes around. Make sure you can brace your hand against the bumper so you don't waver. Then use your good line to measure from.

[cas3]

Totally agree with alchemy ^^^, I like to wrap the tire with masking tape so the marker pen doesn't bump around on the tire treads, and makes an easy to see fine line. If you move or goof up the line, tear it off and do again. easy-peasy