Front End Alignment Changes -- Toe-In

H

H. L. Chauvin

Well-known member
FWIW:

Maybe something to consider as to why Model A's may wander "occasionally" when driving on different or the same highways:

1. According to the Model A Ford Service Bulletins Book, & current recommendations, it is advisable today to follow Ford's revised toe-in measurements from that of the earlier 3/16" to 1/4", to the later prescribed toe-in of 1/16", + 1/32"; & naturally, remembering that this 1/32" is only about a very tiny dimension of 0.031".

2. Next, many agree that Model A wheels are quite serviceable if they only "wobble-in" or "wobble-out" approximately 1/8" from the center of rotation, or something close to this recommendation. (Some may wobble more, some may wobble less, some may wobble as much "in" as "out" of the axle's center. LOL).

3. Then upon providing just one (1) single very accurate alignment, while setting toe-in at exactly 1/16" toe-in while using Ford's toe-in tool, curtain rods, wood jigs, etc., with measured & tested "acceptable" wobbling tires/wheels, one may expect to experience:

A. A "toe-in" of approximately 5/16" if both front tires are in a "wobble-in" position of 1/8" from axle center, i.e., (-1/8") + (-1/8") +(-1/16") = (-5/16"); &,

B. A "toe-out" of approximately 5/16" if both front tires are in a "wobble-out" position of 1/8" from axle center; i.e., 1/8" + 1/8" +1/16" = 5/16"; &,

C. Then after driving around curves & corners, with one front wheel rotating faster than the other, one could theoretically experience different dimensions of maybe approximately 5/8" measured between the fronts of the two (2) front tires. Interesting?

D. If one subsequently verifies one's Model A toe-in, several times, each time a few days later, after driving around several miles, one may think his tie rod may be turning slightly & or his toe-in moved & needs to be re-adjusted.

E. May be a good idea to carefully look more closely at one's adjusting of one's front end alignment to decide which dimensions works best for which of his 80+ year old "wobbling" tires/wheels.
 
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I'm not sure it that is "over thinking" or the opposite. When the original Duby gauge is used (properly), wheel wobble is completely removed from the equation. That makes all other premises irrelevant.
 
"
C. Then after driving around curves & corners, with one front wheel rotating faster than the other, one could theoretically experience different dimensions of maybe approximately 5/8" measured between the fronts of the two (2) front tires. Interesting?
"

So, are you saying "wobble" or "Ackerman", or both? It depends on the radius,
I would think. Ford also changed the ackerman in the front end in late 28 or 29.
 
Russell in Tulsa said:
Food for thought eh?
Click to expand...
WAAAAY too much "food":p
Just run straight wheels, set the toe in properly & forget about the Ackerman Angle!
ALL cars wander, just observe the small corrections your hands make when you drive, to keep you in your lane. Also, consider the 4 small tire footprints that keep you "stuck" to the pavement---NOW, THAT'S SCARY!!!!
Bill W.
 
Spin the tires to check the 'wobble', then set the wheels in a position to split the difference.
Set the toe and go.

Most wheels on most vehicles are 'warped' and this should be taken into account when doing an alignment.

Once you look at the front end parts you'll notice that the wheels are not pointed in the same direction during a turn, supposed to be like that. This is an over simplistic answer, but....
 
Comments above are correct.

No doubt straight wheels can contribute to better overall steering where the distance between the "front" of both front tires remain constant.

However, the main problem with Model A "wobbling" wheels appears to be that in theory, all vehicle front wheels want to go where they are pointed; hence, with one or two "wobbling" Model A front wheels, & each or both wheels maybe pointed in different directions, they are sort of like (2) "wobbling" drunks walking down a sidewalk unsynchronized ..... & definitely not pointed in the exact same direction.

Bill, I just know you can explain this Model A front wheel intoxication better than I can.
 
H. L. Chauvin said:
Comments above are correct.

No doubt straight wheels can contribute to better overall steering where the distance between the "front" of both front tires remain constant.

However, the main problem with Model A "wobbling" wheels appears to be that in theory, all vehicle front wheels want to go where they are pointed; hence, with one or two "wobbling" Model A front wheels, & each or both wheels maybe pointed in different directions, they are sort of like (2) "wobbling" drunks walking down a sidewalk unsynchronized ..... & definitely not pointed in the exact same direction.

Bill, I just know you can explain this Model A front wheel intoxication better than I can.
Click to expand...

Ok, I get where you are going. However the wobble in the wheels can impact balance but that's about it unless the wobble is huge such in inches. Otherwise the wobble does not impact direction. Direction is determined by the axis. The axis will remain true unless the wheel bearings are loose!

As an example, Jack up one wheel slightly and spin the wheel and draw a chalk line as close to the center of the tire tread as possible. If the chalk is held in a fixed position as the wheel is spun then any wobble would show as slightly more tire tread on one side of the line at one point and more on the other side of the line at a different point. The line however is where the wheel will 'aim' or track, not the edges of the tread.
 
If one or both front wheels are bent inward at one spot, & bent outwards at another 180 degree opposite spot, one could park the vehicle where at one time the front wheels could be slightly pointing inward & the next time the front wheels could be slightly point outwards ....... or both pointing either left or right.

The axis will remain true, but these wheels would appear to act like they have loose wheel bearings ....... just like the shopping cart always parked by the front door at a Wal-Mart.
 
BILL WILLIAMSON said:
WAAAAY too much "food":p
Just run straight wheels, set the toe in properly & forget about the Ackerman Angle!
ALL cars wander, just observe the small corrections your hands make when you drive, to keep you in your lane. Also, consider the 4 small tire footprints that keep you "stuck" to the pavement---NOW, THAT'S SCARY!!!!
Bill W.
Click to expand...

yes my size 13 boots are widered than my A's tire s
 
I once prepared 15 wheels for repainting. I checked each one for wobble by spinning it with a block against it. The best one, no cracks ,no pits, perfect finish, and round, had a 1/8" wobble.
 
What Marco describes is correct in that front end alignment is really adjusting the two front spindles such that the front wheel nuts move very slightly forward to provide toe-in.

Then for said spindle adjustment, toe-in settings for the front spindles are measured on the tires at the same points after moving & rolling tires approximately 36" forward.

If one has perfect or near perfect wheels/tires, one can rotate or change out perfect or near perfect wheels/tires every month & almost never have to readjust front end alignment of the spindles.

From an experiment this past weekend, I had near perfect tires out front with close to 1/32" toe-in.

Then I rotated tires with non-perfect tires & immediately noticed perceptive wandering ..... plus each time I rode out & returned, I noticed the front tires pointing in different direction, similar to that in reply no. 9.

I re-adjusted toe-in from 1/32" & increased it to 3/16" & the wandering stopped on the wobbling tires.

Then I removed the wobbling tires & substituted the front tires with the almost perfect ones & re-set alignment back to 1/32" & had no problem.

I guess the bottom line is:

If one only has "wobbling" Model A tires, & one gets discourage because one's Model A wandering when driving, changing the toe-in slightly can make a big difference.

That is what I was trying to point out in post no. 1, in the last paragraph E.

Have to go back to work.

Just hope it can help someone some day.
 
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H. L. Chauvin said:
What Marco describes is correct in that front end alignment is really adjusting the two front spindles such that the front wheel nuts move very slightly forward to provide toe-in.

Then for said spindle adjustment, toe-in settings for the front spindles are measured on the tires at the same points after moving & rolling tires approximately 36" forward.

If one has perfect or near perfect wheels/tires, one can rotate or change out perfect or near perfect wheels/tires every month & almost never have to readjust front end alignment of the spindles.

From an experiment this past weekend, I had near perfect tires out front with close to 1/32" toe-in.

Then I rotated tires with non-perfect tires & immediately noticed perceptive wandering ..... plus each time I rode out & returned, I noticed the front tires pointing in different direction, similar to that in reply no. 9.

I re-adjusted toe-in from 1/32" & increased it to 3/16" & the wandering stopped on the wobbling tires.

Then I removed the wobbling tires & substituted the front tires with the almost perfect ones & re-set alignment back to 1/32" & had no problem.

I guess the bottom line is:

If one only has "wobbling" Model A tires, & one gets discourage because one's Model A wandering when driving, changing the toe-in slightly can make a big difference.

That is what I was trying to point out in post no. 1, in the last paragraph E.

Have to go back to work.

Just hope it can help someone some day.
Click to expand...

Get the proper tool and that will not occur. They still make them.
 
Ok, It's clear that folks don't understand how the proper tool works. When used properly it fully compensates for bent/wobbly wheels. That means it always sets the spindles to the proper relative angles. You can set your toe in with one (any) pair of wheels and then change the wheels and check it again. You will receive the same reading with no adjustment necessary.

By contrast, if you use ANYTHING that requires removing from one location on the tires and measure another location, I'd guess the odds of accuracy is something above 10,000:1

Check my link: http://abarnyard.com/workshop/align.htm
 
Marco has it right. The Model A Ford king pin inclination creates the need for toe in. The tire assembly creates a cone of the tire and wheel and when rolling a cone on the ground the cone wants to toe out, hence the need to toe in the wheels. The Ackerman principle is to get the left tire assembly to toe out more because it will roll on a smaller radius than the right tire/wheel on a left turn.The right or outside tire on a left turn will need to roll on a larger radius. If rear axle is in proper position (not shifted or bent) its center line is the radius established for the center turning radius of the car. King pin inclination is what gets the king pins centerline to intersect the road at the center of the tire/wheel assembly. This then allows all the steering effort to be exerted on the bearing around the king pin. Tire scuffing is caused when toe in is incorrect. The toe in requirement (measurement) is actually established by camber and king pin inclination. When these measurements change the cone size and shape change requiring a different toe in requirement. Make some different paper shaped cones with two different angles and roll them on a table, turn the cones to the point where you can roll them in a straight line and you will notice you have to turn one cone more than the other.
 
"When these measurements change ... the cone size and shape change ..... requiring a different toe in requirement."

This is what I was often told by vintage professional mechanics, especially when working on vintage vehicles like Model A's in the 1930's & 1940's.

Many Model A's had bent axles either caused by crossing high railroad tracks, curbs, countless pot holes, or having the front axles improperly jerked by someone pulling someone out of a mud hole with a chain.

Many small shops had no axle bending ability; hence, alignment toe-in dimensions were sometimes tried, varied slightly, & were set by trial & error as opposed to strict manufacturer's recommended measurements.

When I bought my 1930 Town Sedan, it was odd to find the front wheels set at 1-5/8" toed out ..... the former 20 year owner said he bought it like that & never checked it or tried to adjust it.
 
BILL WILLIAMSON said:
WAAAAY too much "food":p
Just run straight wheels, set the toe in properly & forget about the Ackerman Angle!
ALL cars wander, just observe the small corrections your hands make when you drive, to keep you in your lane. Also, consider the 4 small tire footprints that keep you "stuck" to the pavement---NOW, THAT'S SCARY!!!!
Bill W.
Click to expand...

Not SCARY
all things being equal our small footprint give as much or more grip,
to grip the road you need
1 hard V soft
2 texture
3 contact area
4 pressure lbs per square inch
doubling the contact area halves the lbs per inch
 
I believe the best and most accurate way to set toe is with "toe plates" bolted to the spindle. The plates can be as simple as a length of steel bar matching the tire diameter with a center hole or can get more complex with pointers and indicators. Very easy to fabricate and use. Anyone who's done circle track racing will be very familiar with this approach.
 
Seems always a good idea to begin with a properly adjusted axle.

No doubt Ford's original axles met Ford engineer specifications for which they recommended a specific toe-in for their design.

It would appear interesting to hear from gentlemen who have actually straightened a few used Model A front axles ..... and to report how many were found to meet Ford's original specifications ..... and how much & where did most dimensions differ.

Every axle I ever saw was bent forward from the center & appeared to be bent from towing or pulling out of mud holes with chains.
 
To further confuse----in 1936 Ford came up with a newalignment machine for dealers to buy, it worked in degrees, and toe was to be set at 1/10 of the total camber---the example given--if camber is 1 degree total toe would be1/10 of 2 degrees, or 12 minutes ---and it goes on saying for cars with less than 2-1/2 degrees caster a slightly higher toe is required
there is a chart that includes A, and shows toe as 3/32"*, with * refering to the 10-1 ratio
 
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