Is anyone interested in the science and engineering of steering?

[ShadowsPapa]

I have pulled out my college books that address steering, suspension angles, the effect each has on the other, the effects of improper toe, how caster and camber impact toe, how toe can cause shimmy (not loose, but shimmy) and how and why changing tires and wheels can change {wandering") - this is all from SAE (likely no one has heard of those folks) and another American Engineer group.
I thought about a write up using examples from the books, some of their diagrams and such and keeps it to the level that would be handy for those changing wheels and tires or having very specific problems.
It wouldn't be any sort of "DON'T DO IT!" thing but would be more for -"if you decide to to this, here is what you may run into and here's how to resolve it". (all I care about is successes)
It will take some time to put together as I'd be pulling from books as well as other resources I have - factory manuals, professional journals and all and I'd try to trim it to useful stuff, not stuff no one would ever use or need.
If there's interest, I'll write it up as I had considered doing this for another forum - I operate and administer a large car forum and write up electrical how-to's quite a bit and have done a little in steering and suspension but most of that is aimed at people LOWERING vehicles drastically.

For example, I have info on some of the causes of shimmy (that's not been addressed elsewhere as far as I know) as well as why taller tires can cause wandering - and how wheel offset can solve wandering,.
I can also explain why it's generally not possible to change the "caster spread" on a solid axle...... and what it takes to change caster and how caster and camber impact the NEED for toe - each in opposite ways, and which one causes the wheels to turn in and which causes them to turn out.

If there is no interest, fine - tell me to go to hell no one cares - I may save some hours, or I may do it anyway for the forum I operate. I'll back up everything via pictures, diagrams, and engineering information.,
You'll see a small fraction of what I had to know to get my degrees and certifications.

Sponsored

 

[ZTMAN]

Have at it

 

[Rollcast]

I'm interested. Maybe you could just do a brief intro paragraph of each the various topics and then flesh them out one at a time so it doesn't turn into a doctoral dissertation dumped on us all at once.

 

[ShadowsPapa]

I'm interested. Maybe you could just do a brief intro paragraph of each the various topics and then flesh them out one at a time so it doesn't turn into a doctoral dissertation dumped on us all at once.

Good idea........

 

[WanderingTrail]

I'm in. Love learning new things from an engineering point of view.

Ron

 

[PyrPatriot]

I am. Learning about cars/mechanics as I can through videos and forums

 

[ShadowsPapa]

People snarkily (if that's even a word) asked how anyone can diagnose anything from a distance. Well, not only does training help, knowing the engineering and reasoning behind things, but using logic helps. If you can understand how and why things work as they do, why were they designed as they were, then when it's not working as it should, you can sometimes figure it out without even touching it.
Of course modern electronics, stability control, traction control, ABS, and the self-parking features all complicate purely mechanical systems, but I found this tidbit in one of my books and it's soooo true.
I don't care for throwing things at the wall and seeing if one of them sticks. Sometimes it works, maybe you get lucky but it can be expensive in time, money and frustration.
And the bit of all xxx vehicles should have the same setting for this or that is also bogus - because other factors enter into it as I will show with logic and fact. You'll almost certainly see why it's wrong.

So I'll start working on things and try hard to follow Rollcast's thoughts.

Frankly, it was and is a good refresher for me as well as some of these things I had not used in a while.

 

[Desert Outlaw]

I'm interested in learning more about this essential science. Please also include the sources in order that I can maybe purchase a copy for my library.

 

[ShadowsPapa]

I'm interested in learning more about this essential science. Please also include the sources in order that I can maybe purchase a copy for my library.

Some of the sources may be pretty hard to find - I got my degree in 77 - so some of the stuff is likely out of print but I do have some later stuff.
I can say that the authors and sources include a former product service coordinator for GM, a former coordinator of automotive training Henry Ford community college and other authoritative sources.

Going over some more things now - again, in part to ensure that I'm not mis-stating things, to brush up on areas where I could be rusty, to ensure I'm correct, etc.

Here's a tidbit - an areas I double-checked myself - toe-in.

Toe is related to only two factors - tire wear and toe that is incorrect can cause shimmy. Not loose steering, not wander, but a high speed shimmy.
When toe is off while driving, the tires don't track straight and are dragged or pushed a little bit sideways causing the feathered wear, sort of a saw-tooth pattern.
If things are a bit loose, wear, or toe is too far off, what can happen is one tire tries to track perfectly straight - parallel to the path the vehicle is taking forcing the other to track further out. Once that one reaches its limit it tries to straighten up, pulling the other out of parallel with the vehicle movement. You get a fast shimmy effect as the tires try to go back and forth quickly.
NOT a wander. A SHIMMY and that's not correctable by moving the steering wheel and won't cause the steering to be or appear loose.
It will feel like a wheel out of balance laterally.
That will be covered later - and toe effects will be covered better - and the forces that work against each other, one trying to force toe-in while others try to force toe-out.
Toe needs to vary somewhat to deal with those forces because those forces themselves vary.
Caster is one of the forces that tries to force the tires to toe-in, camber and SAI work to force toe-out - but to a greater degree than positive caster works to toe-in.
You are also driving the front tires from inner side of the tires. Imagine you have a wheel on the end of a shaft or rod. You are holding the rod so the wheel is to your left and you are walking moving the wheel along. Since it's out to your left, you have to exert force to keep the rod from falling back on your left. That wheel on the end tends to pull back and away, it's resisting you.
Thus, you set toe-in.

Front wheel drive vehicles are the opposite - you are pulling the car with the front wheels and the front wheels are pulling on the chassis to their inside, so front drive cars want to toe-IN, so some have the toe spec as a toe-out.

Why the variety of toe specs? Why not set all to the same toe-in specs?
Because of the varying degree that the caster, camber and SAI work to pull the tires out/back.
And the point of intersection, where the SAI (KPI) and tire center meet will vary depending on wheel offset and tire size. So - toe may need to vary if you change wheels and tires. Bigger tires, different needs, wheel offset different? Need different specs to compensate for the differing forces now.

More later, didn't intend to get into anything that deep yet. Will have pictures/diagrams and better info, but I wanted to make a quick point that one size does not fit all - one spec or measurement isn't good for all. You may get by - it "may work" and "may be fine" - but it's not ideal. My truck should not have the same toe settings as a Rubicon with 37" tires and wheels that are set out further than mine.
And the guy who has 31" tires setting toe to x/y" then goes to 35" tires now has a totally different toe measurement by the tape - but the toe ANGLE will be the same. But the forces will now vary......... so toe would likely need to be changed.

 

[RH 67]

Jeeps have a toe in of 1/8" standing once underway they toe out that 1/8" to have the tires going straight this is true regardless of tire size. Caster on a Jeep is simply the axle moving forward or backwards and in effect changes the pinion angle. A stock Jeep should never have an issue with caster unless parts are worn, those adding a lift will have the front axle moving backwards, this produces a harsh ride and quicker steering this can all be corrected with adjustable control arms bringing everything back to factory specs. with correct castor.

Jeeps are extremely simple once you get to know them, it`s not like the old Ford I Beam.

 

[ShadowsPapa]

Jeeps have a toe in of 1/8" standing once underway they toe out that 1/8" to have the tires going straight this is true regardless of tire size. Caster on a Jeep is simply the axle moving forward or backwards and in effect changes the pinion angle. A stock Jeep should never have an issue with caster unless parts are worn, those adding a lift will have the front axle moving backwards, this produces a harsh ride and quicker steering this can all be corrected with adjustable control arms bringing everything back to factory specs. with correct castor.

Jeeps are extremely simple once you get to know them, it`s not like the old Ford I Beam.

I'm trying to convey college level information, some from the engineers that designed this stuff and we get this?
Come on - this is NOT a discussion. Jeeps are not unique. Other vehicles have used the same or similar designs over the years.

There was a comment about software and how if there was a software issue everyone would have it. WRONG. More on that later......

So many here act like I need caster and toe explained - I actually HAVE taught the concepts. My high school instructor and a college professor both relied on me to help others in the classes. There are some Jeep specifics I am getting familiar with - the specific lay of the control arms or links on the front axle, their angles at curb height, what's welded where and so on, but the general principals apply to ALL 4 wheel vehicles, no exceptions.

My credentials -
IQ tested north of 130 - I banter with Mensa members now and then. (thus my lack of social skills - )
Started doing power equipment and cars at age 14-15. I had my own shop (and business cards) at 16 and I still have a copy of the newspaper article about that.
I did not have to take the first two automotive courses in HS because I had my own shop and "passed out of the courses" by explaining how a C6 transmission hydraulic circuits operated and the power flow in every gear as well as all of the circuits in a Holley 4bbl carb. I also won a bet with the teacher and he had to pay by buying the steel and welding me up a test bench - I still have it.
State champion Plymouth Troubleshooting contest - aced the test (perfect score) fasted time to judging in the practical, hands-on part with only one deduction. That record was never broken, they ended the contest a few years later due to MOPAR and money issues.
I completed HS requirements in 3 years instead of 4 - but stuck around to graduate with the class by joining VICA (and working in a former AMC shop afternoons) and taking advanced math classes (I didn't have to take the college math then)

College degree in automotive. Made the dean's list with a 4.0 GPA.
I came from a blue-collar family - my father was the wage earner, UAW, in a factory. (He became a UAW local president for a while) so there wasn't money to pay for my college - so I worked after classes doing - yeah, FRONT END ALIGNMENTS and brakes and tires and so on.
I got to use my training hands-on and dealt almost every day for hours with caster, toe, camber, included angle, SAI, point of intersection, scrub radius, etc. (guys, I know what caster is, how it's set, toe, how it works, etc.)

Out of college I applied for a job - the service manager was working on a car and having trouble getting rid of a weird miss. We chatted, he said if I could resolve the miss - I had a job. I read the scope, checked a few other things and came up with the solution in about 10 minutes. I was hired.
Manager of the biggest Jeep dealership in Iowa heard of my reputation by then and called me (at work, on my lunch break) and offered me the job of service manager. I turned it down. My boss then was excellent and I loved the work - I was more hands-on than paper and management. By then people were bringing in cars, trucks, Jeeps, yes, Jeeps, even small tractors and requesting that I be the tech to work on them.
Life changes - boss sold the shop, the corporation was stripping benefits and people left in droves.
I moved on - ran my own shop up on the farm I moved to and operated. Skid loaders, straight trucks, 4x4s and vehicles of all sorts. I got into computers during slow times.
I went on to Principal Financial Group where I resolved major endpoint security issues, did troubleshooting of network and endpoints and was eventually put in charge of several servers and desktop security software. I found an obscure bug in a corporate security software and worked with the developers at Symantec to duplicate and resolve the issue. Only a few companies in the world saw the issue - we were among them. They changed the code and I alpha tested it. They named the modification after me.
I was called in on a conference call with the US Navy, GM and others when a major viral threat was found and helped develop protections.
I moved on to Compressor Controls Corp where I designed the computers that were the interfaces for their then new Series IV turbo-compressor controllers. I also developed the environmental test battery, the image for the computers and worked with Young Micro Systems where the system boards for the computers came from. My first review my boss asked me what I though I should get as a raise - I said how about 10%. I got it.
I also resolved an obscure network issue involving log-ins to the Netware servers. I worked with Novell engineers and found the solution. I went up to upper management with my solution because my then boss refused to accept my ideas. Upper management gave me the green light and I restructured the network over a weekend - they said I could have anyone in the company help me. Monday morning everything was fine, all issues, including other weird issues, were gone. Weeks before they had paid big money to hire professionals to come in with sniffers to try to resolve the issue and could never find it. I used my methods and resolved it.
CCC was bought out by Roper, so I moved on - to government. I was promoted faster than anyone had been at that time.
I jumped past two levels up to ITS4 and was given charge of network security and become a network admin. After the network admin retired, I was then in charge of the entire state - 34 offices, 24 servers, 350 computers, LAN, WAN, mobile devices and more.
My wife and I sold a business and I used some of the money to build my shop and started automotive work again.
I retired from government and now do restorations and auto electric in my shop, including nickel and zinc plating, wiring harness design, diagnostics, etc.

Not new to computers, software or anything automotive having worked in the field for over 45 years.

Someone commented that if there was a software/firmware issues - well that just cannot be or all people would experience the same. No, that's not how software and computers work. You CAN have software that acts badly under specific circumstances and on specific electronics. At CCC, there were times when they had to specific NO SUBSTITUTIONS on certain components because, say they spec'd a Motorola IC but couldn't get it, so they went TI - same specs, they were direct replacements. They found no, the software behaved slightly differently and that the very slight differences in the way the TI worked under certain conditions caused trouble. I also found similar in the computers I came up with for their interfaces - if you put the video card in the slot next to the power supply, then the com ports, then ethernet and so on, it was fine, but swap the video and com ports and it would fail at certain times. TIMING. The electronic circuits appeared to act like water lines - and if one got a signal an extremely small fraction before the other -crash.
Watch Microsoft updates and patches - do ALL people have the same results?
Why would an Apple iOS update work fine on this iPhone but crash at a certain spot on another of the same model?
Jane's phone crashed at this screen after the update, John's did not. Same phone, same update. So yes, there can be software/firmware "bugs" that impact one but not another. (and an update may be specific to a rev of hardware)
That's why these companies want as much testing on as many different platforms under as many different conditions as possible.
I am not saying this IS software or not - just saying you cannot say it's not possible.
But I started this thread to share and convey facts, not shade-tree stuff read out on the web repeated enough times that it became true - because hundreds of people are saying it. That doesn't make it true.

It looks like I should give up trying to get valid real info out there because there will always be someone who knows better and will dispute it. I'd bet some even argue with doctors and electronic engineers.

 

[Renegade]

I'm trying to convey college level information, some from the engineers that designed this stuff and we get this?
Come on - this is NOT a discussion. Jeeps are not unique. Other vehicles have used the same or similar designs over the years.

There was a comment about software and how if there was a software issue everyone would have it. WRONG. More on that later......

So many here act like I need caster and toe explained - I actually HAVE taught the concepts. My high school instructor and a college professor both relied on me to help others in the classes. There are some Jeep specifics I am getting familiar with - the specific lay of the control arms or links on the front axle, their angles at curb height, what's welded where and so on, but the general principals apply to ALL 4 wheel vehicles, no exceptions.

My credentials -
IQ tested north of 130 - I banter with Mensa members now and then. (thus my lack of social skills - )
Started doing power equipment and cars at age 14-15. I had my own shop (and business cards) at 16 and I still have a copy of the newspaper article about that.
I did not have to take the first two automotive courses in HS because I had my own shop and "passed out of the courses" by explaining how a C6 transmission hydraulic circuits operated and the power flow in every gear as well as all of the circuits in a Holley 4bbl carb. I also won a bet with the teacher and he had to pay by buying the steel and welding me up a test bench - I still have it.
State champion Plymouth Troubleshooting contest - aced the test (perfect score) fasted time to judging in the practical, hands-on part with only one deduction. That record was never broken, they ended the contest a few years later due to MOPAR and money issues.
I completed HS requirements in 3 years instead of 4 - but stuck around to graduate with the class by joining VICA (and working in a former AMC shop afternoons) and taking advanced math classes (I didn't have to take the college math then)

College degree in automotive. Made the dean's list with a 4.0 GPA.
I came from a blue-collar family - my father was the wage earner, UAW, in a factory. (He became a UAW local president for a while) so there wasn't money to pay for my college - so I worked after classes doing - yeah, FRONT END ALIGNMENTS and brakes and tires and so on.
I got to use my training hands-on and dealt almost every day for hours with caster, toe, camber, included angle, SAI, point of intersection, scrub radius, etc. (guys, I know what caster is, how it's set, toe, how it works, etc.)

Out of college I applied for a job - the service manager was working on a car and having trouble getting rid of a weird miss. We chatted, he said if I could resolve the miss - I had a job. I read the scope, checked a few other things and came up with the solution in about 10 minutes. I was hired.
Manager of the biggest Jeep dealership in Iowa heard of my reputation by then and called me (at work, on my lunch break) and offered me the job of service manager. I turned it down. My boss then was excellent and I loved the work - I was more hands-on than paper and management. By then people were bringing in cars, trucks, Jeeps, yes, Jeeps, even small tractors and requesting that I be the tech to work on them.
Life changes - boss sold the shop, the corporation was stripping benefits and people left in droves.
I moved on - ran my own shop up on the farm I moved to and operated. Skid loaders, straight trucks, 4x4s and vehicles of all sorts. I got into computers during slow times.
I went on to Principal Financial Group where I resolved major endpoint security issues, did troubleshooting of network and endpoints and was eventually put in charge of several servers and desktop security software. I found an obscure bug in a corporate security software and worked with the developers at Symantec to duplicate and resolve the issue. Only a few companies in the world saw the issue - we were among them. They changed the code and I alpha tested it. They named the modification after me.
I was called in on a conference call with the US Navy, GM and others when a major viral threat was found and helped develop protections.
I moved on to Compressor Controls Corp where I designed the computers that were the interfaces for their then new Series IV turbo-compressor controllers. I also developed the environmental test battery, the image for the computers and worked with Young Micro Systems where the system boards for the computers came from. My first review my boss asked me what I though I should get as a raise - I said how about 10%. I got it.
I also resolved an obscure network issue involving log-ins to the Netware servers. I worked with Novell engineers and found the solution. I went up to upper management with my solution because my then boss refused to accept my ideas. Upper management gave me the green light and I restructured the network over a weekend - they said I could have anyone in the company help me. Monday morning everything was fine, all issues, including other weird issues, were gone. Weeks before they had paid big money to hire professionals to come in with sniffers to try to resolve the issue and could never find it. I used my methods and resolved it.
CCC was bought out by Roper, so I moved on - to government. I was promoted faster than anyone had been at that time.
I jumped past two levels up to ITS4 and was given charge of network security and become a network admin. After the network admin retired, I was then in charge of the entire state - 34 offices, 24 servers, 350 computers, LAN, WAN, mobile devices and more.
My wife and I sold a business and I used some of the money to build my shop and started automotive work again.
I retired from government and now do restorations and auto electric in my shop, including nickel and zinc plating, wiring harness design, diagnostics, etc.

Not new to computers, software or anything automotive having worked in the field for over 45 years.

Someone commented that if there was a software/firmware issues - well that just cannot be or all people would experience the same. No, that's not how software and computers work. You CAN have software that acts badly under specific circumstances and on specific electronics. At CCC, there were times when they had to specific NO SUBSTITUTIONS on certain components because, say they spec'd a Motorola IC but couldn't get it, so they went TI - same specs, they were direct replacements. They found no, the software behaved slightly differently and that the very slight differences in the way the TI worked under certain conditions caused trouble. I also found similar in the computers I came up with for their interfaces - if you put the video card in the slot next to the power supply, then the com ports, then ethernet and so on, it was fine, but swap the video and com ports and it would fail at certain times. TIMING. The electronic circuits appeared to act like water lines - and if one got a signal an extremely small fraction before the other -crash.
Watch Microsoft updates and patches - do ALL people have the same results?
Why would an Apple iOS update work fine on this iPhone but crash at a certain spot on another of the same model?
Jane's phone crashed at this screen after the update, John's did not. Same phone, same update. So yes, there can be software/firmware "bugs" that impact one but not another. (and an update may be specific to a rev of hardware)
That's why these companies want as much testing on as many different platforms under as many different conditions as possible.
I am not saying this IS software or not - just saying you cannot say it's not possible.
But I started this thread to share and convey facts, not shade-tree stuff read out on the web repeated enough times that it became true - because hundreds of people are saying it. That doesn't make it true.

It looks like I should give up trying to get valid real info out there because there will always be someone who knows better and will dispute it. I'd bet some even argue with doctors and electronic engineers.

Well hey, I stayed at a Holiday Inn Express last night so....
Actually, I’ve enjoyed reading what you have posted to this point, but some of it is above our heads, and difficult to apply practically. Don’t stop, but please don’t get caught up in the back and forth. It will just piss you off. Contribute, and people who want it will take it. Ignore anyone who doesn’t. It shouldn’t get personal or it won’t be fun. Best wishes.

 

[ShadowsPapa]

Well hey, I stayed at a Holiday Inn Express last night so....
Actually, I’ve enjoyed reading what you have posted to this point, but some of it is above our heads, and difficult to apply practically. Don’t stop, but please don’t get caught up in the back and forth. It will just piss you off. Contribute, and people who want it will take it. Ignore anyone who doesn’t. It shouldn’t get personal or it won’t be fun. Best wishes.

Thanks for the constructive critique - appreciate it. Yeah, I tend to get caught up............
And hints are always looked at and appreciated.
My son has hinted I'm the Sheldon Cooper of cars - I suspect he means that two ways........
I hope your Holiday Inn experience was better than mine in Collinsville this past summer. The event was a blast in any case.

 

[MarineHawk]

It looks like I should give up trying to get valid real info out there because there will always be someone who knows better and will dispute it. I'd bet some even argue with doctors and electronic engineers.

Take this for what it’s worth, but it seems to me you are too caught up in this forum, including, for example, the length of your post above, mentioning, inter alia, your IQ testing. You are averaging 21 posts per day since you joined two months ago, and it seems to be increasing exponentially.

People are going to disagree with you in any environment whether you are right or wrong—and nobody’s always correct.

As far as “some even argue with doctors and electronic engineers,” I assume you mean “electrical engineers.”

My father has a Ph.D in Electrical Engineering from the early ‘70s. He’s evolved over the decades more into a Physicist, and is the leading expert globally on certain aspect of laser beam shaping.

Yet, I have corrected him on a few items relating to physics during deep discussions about the same.

My almost-16-yr-old son was 3 years old in 2007, and had congestion. His doctor prescribed pseudoephedrine for his condition. I explained to the doc that same medicine tended to give me, an adult with half of his genes, tachycardia when under physical stress. She insisted that it was the only prudent course. I refused. Less than a year later, the U.S. regulators correctly banned prescribing pseudoephedrine to children for the reasons about which I was concerned. I was right, and my doctor was wrong.

Take this for what it’s worth, but you seem to have tied too much your self-perceived value on this forum with your value as a human being. There is so much more to that than your hoped-for irrefutable expertise on this forum.

Your information here is valuable, but not invaluable, including to your own sense of self-worth.

I was really involved in a forum about a different, no-longer-produced, vehicle a while back, and that forum no longer exists. Forums are useful to some degree, but they are not life.

You don’t need to be the unrefuted expert on this forum on everything to be a good and happy person.

If you have useful information to post, great. But don't expect everyone to agree with it, especially beforehand.

 

[jebiruph]

I'm interested. Maybe you could just do a brief intro paragraph of each the various topics and then flesh them out one at a time so it doesn't turn into a doctoral dissertation dumped on us all at once.

This, but keep each topic on it's own thread to keep the discussion focused. Then maybe have a master thread to keep track of the individual threads.

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