MTFCA Forum

I have here pictures from left and right of a 1909 front axle. As you can see there is no caster to the
front axle. I have a friend who also has this problem on his 1912 Model T.
Is this common on the earlier cars? Is it due to the wishbone being bent or on the upper side?
Should I just find a way to bend it and add a second wishbone?
Do I need new perches?

Thank you.

Dave , turn your axel around .\
Toon

Dave,
I think Toon is right.
The Spring ax and the wishbone ax are even.
The angle to the front is on the lower side of perch.
I think you perch on the left side should be on the right and your right perch should be on the left.

Andre
Belgium

Dave, the first picture looks like there is some positive caster, just not very much. This would require twisting the axle (top of axle rearward) to bend the wishbone to the Ford spec of 5.5 degrees.

Am I correct that the early axles, with the shallow yokes, have a notch to clear the spindle arms? I know the NRS axles are like that. If so, it's clear what is the front side of the axle and it is not possible to "turn the axle around" as those clearance notches would be mislocated. Again, I'm going from NRS experience.

It may be that the wishbone is upside down? I have seen this a few times on brass era Ts, There may be a bit of angle built in, a slight tweak up where the front pin fits into the perch. Other than that, the early wishbone has no obvious up or down. I have seen several cases where flipping the wishbone over fixed the problem.

Definitely the perches are 180 degrees out. Just Sayin as Toon stated.

There is some sort of issue with the geometry of the front end of that car.
It is supposed to be a straight line from the frame, through the spring, through the perches, and through the axle.
That car has a very jagged line and this will produce a binding suspension and a bad handling car, possibly the death wobble.
I suspect the spring perches are backwards but can not tell for sure.
That needs to be fixed first and the geometry needs to be rechecked again.

Other things of note:
As the wishbone ball and seat wears it moves up and reduces caster.
If it is too worn it will not help this.

Looking @ the pictures there might be caster in the car, or maybe my eyes are fooling me.
Check the caster @ the kingpin, that is the only place that really matters.
Most axles are bent in some way unless they have been straightened somewhere in the recent past.

If the wishbone to perch nuts were left loose it will wear the back of the perch and wishbone ends.
If there is some wear here a small spacer can be installed to replace the metal.
Only do this last if all other things are correct and not first as a quick band-aid

A good quality in depth inspection (and look for cracks or other damage) is needed to find out exactly where the issue it.
Mike

My eyes are telling me that as sitting, the spring perches are both aimed "down" toward the front and if the wishbone was removed from the pan, the springs would unwind and the perches would allow the axle to cant backwards giving more or less correct caster. From the pictures I do not suspect they are in backwards.

A quick check would be to pull 1 nut off of the wishbone - if the machined face on the perch (under the nut) is flat, it's in correctly, if there is a big radius on the hole, it's in backwards as that radius is meant to snug up against a machined radius on the wishbone, at the root of the part that sticks through the perch. If perchance the wishbone and perch were in pristine shape, and the perches were in fact put in backwards, it would be impossible to draw the wishbone up tight to the perch and a small gap would exist where the wishbone radius crashed into the square perch ID.

I don't own a print on the early wishbones but folks who I respect all state that the wishbone is made straight and then bent after assembly to get the correct caster. I do know that every "used" early wishbone I've seen is in fact bent, and if that "as bent" wishbone is installed upside down, it would result in exactly what we're seeing on these pictures.

I had the same problem on mine, flipping the wishbone over cured it.

Definitely worth a try.

If you haven't already done so, the first thing to do is place a carpenter's square against the lower spindle bushings as described and shown in the service manual to verify if there is positive, zero or negative caster.

If there is zero or negative caster, then flip the wishbone over as others have described and that alone may cure the problem.

Someone who is familiar with the early front suspension needs to take a look at that. Improper assembly, incorrect parts, loose, bent, or worn parts, damage to the frame, cross member or oil pan need to be ruled out or corrected. The condition of the front spring affects caster. Engine mounts need to be as-designed. The steering system and springs need to be properly lubricated to work as they are supposed to.

The perches are in correct position per my eye.
With the axle positioned vertically (and therefore the perch pins thru the axle being vertical), then the spring and wishbone mounts would be canted forward as is seen in the pic. With the spring & wishbone mounts horizontal, the perch axle pin and top axle mating face would be canted back to provide caster.
The perches, and axle, are fine.

I have never been able to find any early wishbone specs detailing whether the rods were straight, or if they had a bend, and if so, how much. Regardless, in my search for an early wishbone with a good ball, of the 4 I have in my hands, ALL have a slight curve in the last 6 inches, some greater, some less, but all there. I would therefore agree with others suggestions to try reversing your wishbone first before you do anything with the axle. Other things to check would be the condition of the ball (worn undersize), as well as if the ball socket is seriously/deeply worn and may require repair or shimmed, both of which would also force the axle out of alignment canting forward neutralizing caster.

His axle: Reflecting the perch in current position:
Perches mounted as is, but properly canted back: My axle for comparison (both his & my perches in correct position):

It looks to me from the comparison pictures that the 09 axle perch has a slight back twist to it. It’s not much but it is turned to right just a bit to much. Look close and compare the last pics that were posted. It’s canted backward but it’s turned back.

Caster is set by the spring perches, which are angled so that the top of the axle beam is canted to the rear. The caster is maintained by the radius rod. The threaded ends of the forgings at the spring end are set at an angle to the Y of the yoke. If you set those threaded ends on the level, the arms on the yoke will rise considerably.
The geometry can be stuffed up by fitting the perches at the wrong ends of the beam. On later axles without the relief in the end yoke, you simply have to turn the axle around. if the radius rod is fitted upside down, that too will upset the geometry, as will "straightening" the threaded ends of the radius rod.

Allan from down under.

From the looks of the 09 it doesn’t look like it’s driven much and the car has nice paint. If there is really a concern about the way it drives and handles it may be be best to pull the front end assembly, using another 09 as a guide, maybe turn the axle around as suggested, check the wishbone and spring perches. Put it back together and drive it. If you’re careful you shouldn’t have to repaint any areas around the axle. Then again it all depends how much it’s driven.