Adding castor to the axle

Is the axle straight?

I made up a set of rods and checked the few axles I have. I found they were all bent at the perch point outward. Some had twist.

The 2 'good' axles I have came back into alignment when I corrected the bend rearward. That is the twist came out at the same time.
Based on some of the axles I have seen posted on the boards mine were pretty lightly bent.

It is interesting to note that an axles heated at the perch point bent VERY easy. I would do like 8 pumps of my press, get a big bend in the axle and it would spring back with like 1/16" of change. An axle that was heated was very soft the same 10 pumps did like 1/2" of correction.
My conclusion is a heated axle is not something to be used on a car that you will drive.

Before anyone speaks. Yes I know a lot of people have a dropped axle and they all say they are fine. It is interesting no one has driving an axle hard and check to see if it actually was still inline. I like evidence.
 
Is the axle straight?

I made up a set of rods and checked the few axles I have. I found they were all bent at the perch point outward. Some had twist.

The 2 'good' axles I have came back into alignment when I corrected the bend rearward. That is the twist came out at the same time.
Based on some of the axles I have seen posted on the boards mine were pretty lightly bent.

It is interesting to note that an axles heated at the perch point bent VERY easy. I would do like 8 pumps of my press, get a big bend in the axle and it would spring back with like 1/16" of change. An axle that was heated was very soft the same 10 pumps did like 1/2" of correction.
My conclusion is a heated axle is not something to be used on a car that you will drive.

Before anyone speaks. Yes I know a lot of people have a dropped axle and they all say they are fine. It is interesting no one has driving an axle hard and check to see if it actually was still inline. I like evidence.
 
all ford forgings should be straightened cold..hot axle drops have been done for years,doesn't mean they are safe,just one more in the list of reasons 'why hotrodders die'..
 
Proper precautions have to be taken to not heat the forgings too hot and they should not be pulled like taffy to make up for the drop. A heavy I-beam forging like the Ford straight axles were, still have plenty of ductility if properly dropped. It also has a tendency to stress relieve and old fatigued forging if properly done. They will be as safe as they were from the factory.

Ed & Bob Stewart dropped a lot of axles in their two generations long careers. Here is a good history on them from the HAMB. https://www.jalopyjournal.com/?p=3972

A well dropped Ford axle is stronger than a lot of the aftermarket crap that has been available over the years.

To do a small amount of correction, cold bending is a lot safer for those that have no metallurgic knowledge but for a really bent one, heating is a good idea if not for the stress relief alone but it makes it a lot easier to straighten one back out too.
 
Seeing as Bill Williamson isn't on here right now I'm going to say neuter it and it won't
wander so much...
 
MWkKiS7.jpg


I guess Ford had no metallurgical knowledge..but those that do know heating ford forgings hardens them and will lead to failure..
 
Ford's illustration as to the ruggedness of their axles:
 

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I've not heard too many tales about broken Ford front I-beam axles on ones that were dropped unless they hit a bridge rail or something like that. I've not heard of one breaking in the modern era. These things were so overbuilt that it would be a rare thing to happen outside of an accident that causes a front wheel to strike something. Folks are still dropping them to this day. Now the guys that drill big lightning holes through the web are definitely weakening them. Anyone that drills them outboard of the perch mount needs their head examined.

Now rear axle shafts are a different story. I've seen a lot of them break.
 
The chassis on our speedster was assembled by a hot rodding business and without my asking they cut and re-welded the radius arms to give 6-7degrees castor. This enables the car to be driven at 60mph down a motorway, tracking perfectly and needing only a very light touch on the steering wheel. However on very tight corners, it does appear to load up more than might be expected? I have noticed in the past, a very heavy load in the rear of a standard Model A can alter the castor and result in the car wandering more than normal
 
Some rodders cut a narrow pie section from the wishbone arms on each side then bend the arm to close the gap and reweld. Others split them with rod ends added and adjust the castor by where they weld the brackets to the frame. The last poster noticed how hard they can get to turn off center. Shimming to to where it works best overall is usually the best bet since it can be changed further till a happy medium is felt. A person can lock it in after that but what if they change to different type tires or wheels?
 
I bought a pos aftermarket front spring about twenty years ago. It was way thicker and the curvature was higher. My car drove horribly. I barely drove around the block before I pulled it out.
 
Just researching how to add 2 to 3 degrees caster on a car where all the spring, axle and other components are to specs, including mounts, u bolts and engine slope. It seems that the angle when measured as close as possible to the spindles indicates a twist from the perches to the spindles. This is same exact condition on both sides indicating no damage to the axle or frame. Any way to add a couple of degrees without disturbing the set up? No wandering is noticeable so perhaps the concern is unfounded?
 
A few comments:


The wishbone for the later AA trucks was a different part than the old one and was done to reduce caster to make the trucks easier to steer.

I saw a Craigslist ad for a modified car, I think it was some sort of speedster, that had the wishbone bent to increase caster. They had a very noticeable bend in the center.

I fixed the caster on my Model T, on one side so the axle was twisted, by using a 6 foot pipe wrench and a floor jack. I wrapped 1/4-inch thick aluminum around the axle to protect it. The front end of the car actually lifted off the ground so there was a lot of torque on the axle. Now, a Model T axle is more easily bent than a Model A axle so it may take a 12 foot pipe wrench for a Model A. I have seen adjusters for the Model T that are cut out of thick steel and fit over the axle.

An iPhone with an angle application can be used to measure the caster.

Fix and tighten everything before you start changing the caster. And adjust the toe-in afterwords.
 
So how would one hold the perch areas and just twist the king pin holes without removing and clamping the axle in a large vise? I suppose one could remove the axle with the perches and spindles intact and try that?
 
Have you checked the toe-in? I have found that wander can be caused by insufficient toe-in. Toe-out leads to wander, Too much toe-in makes the steering twitchy.
 
nkaminar said:
The wishbone for the later AA trucks was a different part than the old one and was done to reduce caster to make the trucks easier to steer.
Click to expand...

Neil, that is interesting as I had not seen that on my prints. If anything when you compare the perch end of the 'wishbone' it appears it even has more caster than what the 1928/29 'wishbone' had. I will make a note to look at that the next time I go back to the archives and see if it is mentioned in the Engineering Information notes.

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duke36 said:
Just researching how to add 2 to 3 degrees caster on a car where all the spring, axle and other components are to specs, including mounts, u bolts and engine slope. It seems that the angle when measured as close as possible to the spindles indicates a twist from the perches to the spindles. This is same exact condition on both sides indicating no damage to the axle or frame. Any way to add a couple of degrees without disturbing the set up? No wandering is noticeable so perhaps the concern is unfounded?
Click to expand...

If both sides are the same angle, the car drives and handles w/no issues, the tires don't wear abnormally just drive it as is. "If it ain't broke, don't fix it"
 
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