Leaf spring dimensions

[j-c-c-62]

I've held a Journeyman's Cert since 1978 and had never heard that either. The explanation fails to take into account the straightening of the spring as it deflects. So while moving up in it's arc pivoting on the front eye brings the axle forward, straightening of the spring arc increases the distance from eye to centre bolt thus moving it rearward.

No it does not. the front eye location is fixed, as the spring moves up, it may lengthen the spring as it straightens towards horizontal, but it mainly moves the axle rearward on that side, and forward on the opposite side., inducing roll oversteer, which in most cases is frowned on.
This is not my revelation. It's well documented and usually misunderstood, like here.
We are assuming here the spring arc is never becoming inverted, and why I first noted the "over arch" aspect concern, but even if the inverted arc presented, in most cases the handling would go from oversteer to understeer quickly making handling likely extremely unpredictable.

 

[Steve Garner]

No it does not. the front eye location is fixed, as the spring moves up, it may lengthen the spring as it straightens towards horizontal, but it mainly moves the axle rearward on that side, and forward on the opposite side., inducing roll oversteer, which in most cases is frowned on.
This is not my revelation. It's well document and usually misunderstood, like here.

Maybe I'm not understanding you, or you understanding me. The front eye is fixed. Correct. Your explanation says that spring pivoting on front eye moves the centre bolt in an arc with the centre bolt moving forward horizontally as it travels in this arc pivoting on the eye. I am adding that while that is indeed correct, when the spring deflects it straightens, which increases the distance from the eye to the centre bolt. So while it moves forward rotating in it's arc, the radius is lenghtened by the flattening of the spring. So the net change is going to be very little, by design.

By well documented, do you mean in the forums you frequent? Because it doesn't appear in the text books or literature I was taught from.

 

[j-c-c-62]

Maybe I'm not understanding you, or you understanding me. The front eye is fixed. Correct. Your explanation says that spring pivoting on front eye moves the centre bolt in an arc with the centre bolt moving forward horizontally as it travels in this arc pivoting on the eye. No, the center bolt moves rearward, If I am implying that tell me how, and I will correct it. I am adding that while that is indeed correct, when the spring deflects it straightens, which increases the distance from the eye to the centre bolt. So while it moves forward rotating in it's arc, the radius is lenghtened by the flattening of the spring. So the net change is going to be very little, by design.

By well documented, do you mean in the forums you frequent? Because it doesn't appear in the text books or literature I was taught from.

It's in many suspension-oriented reference manuals. I'm including a scan here of a Mopar Track modifications 3rd Edition 1997 page 435 many here should be able review and study. It notes "understeer", but the reverse is simply true.

 

[Steve Garner]

No it does not. the front eye location is fixed, as the spring moves up, it may lengthen the spring as it straightens towards horizontal, but it mainly moves the axle rearward on that side, and forward on the opposite side., inducing roll oversteer, which in most cases is frowned on.
This is not my revelation. It's well documented and usually misunderstood, like here.
We are assuming here the spring arc is never becoming inverted, and why I first noted the "over arch" aspect concern, but even if the inverted arc presented, in most cases the handling would go from oversteer to understeer quickly making handling likely extremely unpredictable.

It's in many suspension-oriented reference manuals. I'm including a scan here of a Mopar Track modifications 3rd Edition 1997 page 435 many here should be able review and study. It notes "understeer", but the reverse is simply true.

View attachment 1590883

Sometimes things get repeated so often on the internet they become treated as fact. A lot of misinformation going around because of that.

Most of what I do is with C2 Corvettes. Here's a great example of what I'm referring to as far as internet "documented"

In the two pics below look at the strut rods. You will see in the diagram the strut is a solid bar, non adjustable. It is mounted in a cam on it's inboard end in order to adjust camber. Now look at the pic. It has a threaded rod with heim joints and camber is adjusted by changing the length of the rod. This is sold all over as an "upgrade" to the factory setup.

In fact, they do not do the same thing. The rear suspension uses the same principle as most front ends, long arm/short arm. In this case the upper arm is the half shaft and the lower arm is the strut rod. The diference in the length of the control arms is specifically engineered to kick the bottom of the tire out as both outer pivot points travel through their respective arcs. So when these guys adjust camber by changing the rod length they are unwittingly altering the design and creating tire scuffing and control issues.

But google that adjustable arm. Found in many performance writeups.

 

[Steve Garner]

It's in many suspension-oriented reference manuals. I'm including a scan here of a Mopar Track modifications 3rd Edition 1997 page 435 many here should be able review and study. It notes "understeer", but the reverse is simply true.

View attachment 1590883

The writeup does not appear to have been written by an engineer and does not discuss the straightening of the spring, only the travel through the arc.
Grain of salt with this one. Here's a well written article (of many out there) about the Corvette rear that many would take as documented. Suspension Guide for C2 Corvette Restorations - Photos Included

 

[Steve Garner]

It's in many suspension-oriented reference manuals. I'm including a scan here of a Mopar Track modifications 3rd Edition 1997 page 435 many here should be able review and study. It notes "understeer", but the reverse is simply true.

View attachment 1590883

On re-reading your article, change that from a grain of salt to a huge brick of salt. The writer goes on to talk about camber and reserve camber on jounce. What the hell is this guy talking about? Does he even know what camber is? Definately an arm chair wanne be engineer.

With all due respect, I would say that there is enough uncertainty in what you're postulating here that I certainly wouldn't go around belittleing anyone else for not knowing/propagating it.

 

[j-c-c-62]

On re-reading your article, change that from a grain of salt to a huge brick of salt. The writer goes on to talk about camber and reserve camber on jounce. What the hell is this guy talking about? Does he even know what camber is? Definately an arm chair wanne be engineer.

With all due respect, I would say that there is enough uncertainty in what you're postulating here that I certainly wouldn't go around belittleing anyone else for not knowing/propagating it.

I'm sorry you feel that way.
I will let the authors know the next time I bump into them.

 

[Steve Garner]

I'm sorry you feel that way.
I will let the authors know the next time I bump into them.

View attachment 1590972

Do you actually believe the engineers write this stuff?

 

[Steve Garner]

I'm sorry you feel that way.
I will let the authors know the next time I bump into them.

View attachment 1590972

Ask them to explain camber on the rear spring when you're chatting. Or perhaps you could take a minute now to explain it. As a hard-core disciple I'm sure you must have followed up on that and the spring flattening detail.
No need to feel sorry about how I feel. I don't believe everything I read just because it has a glossy cover. It has to make sense. I like it that way.

 

[j-c-c-62]

Do you actually believe the engineers write this stuff?

Strange isn't it, how books like "Chassis Engineering" 1993 by Herb Adams page 63and "Race Car Engineering" 1992 by Paul Van Valkenburgh page 28 to name a few, are all equally, taken with any amount of salt, clueless? I could dig up some more like by Caroll Smith, etc, but I think my point is made here who I believe..

 

[j-c-c-62]

Ask them to explain camber on the rear spring when you're chatting. Or perhaps you could take a minute now to explain it. As a hard-core disciple I'm sure you must have followed up on that and the spring flattening detail.
No need to feel sorry about how I feel. I don't believe everything I read just because it has a glossy cover. It has to make sense. I like it that way.

Camber in the context of a spring, much like camber of a cross section of a wing, is describing its curve or what on more layman's terms we have been calling "arc" for the leaf spring.
That was less than a minute, you have time left. Any more questions I can make sense of?

 

[Steve Garner]

Camber in the context of a spring, much like camber of a cross section of a wing, is describing its curve or what on more layman's terms we have been calling "arc" for the leaf spring.
That was less than a minute, you have time left. Any more questions I can make sense of?

Camber, when used in the context of suspension, is described by Oxford as the sideways inclination of the the front wheels of an automobile. Also the curvature of a section of an airfoil. Nowhere is it defined as a synonym for the arc a radius travels through. I'll stick with the author not knowing his *** from a hole in the ground.


You haven't shown your calculations for how the straightening of the leaf and lengthening of the radius doesn't offset any of the horizontal forward movement of the spring eye I with the spring traveling through its arc.

 

[j-c-c-62]

Camber, when used in the context of suspension, is described by Oxford as the sideways inclination of the the front wheels of an automobile. Also the curvature of a section of an airfoil. Nowhere is it defined as a synonym for the arc a radius travels through. I'll stick with the author not knowing his *** from a hole in the ground.


You haven't shown your calculations for how the straightening of the leaf and lengthening of the radius doesn't offset any of the horizontal forward movement of the spring eye I with the spring traveling through its arc.

The item being discussed was leaf springs, and camber applies. I again am sorry if that double meaning confuses you.

Didn't know I needed to show any calculations, regardless, I can't, because the spring eye does not move forward, it's fixed.

I'm starting to get tired of being sorry.

 

[Steve Garner]

Camber in the context of a spring, much like camber of a cross section of a wing, is describing its curve or what on more layman's terms we have been calling "arc" for the leaf spring.
That was less than a minute, you have time left. Any more questions I can make sense of?

Sorry, I misread your definition. Using camber to describe the arc of a spring in the context of a discussion about automotive suspension is pure bs, or intended to boggle the I'll informed. Either way, it's evidence of poor writing.

 

[Steve Garner]

Didn't know I needed to, regardless, I can't, because the spring eye does not move forward, its fixed.

You're still not getting it. The eye doesn't move, the spring gets effectively longer when you take the ARC out of it. Why is that not taken into calculation of the movement of the axle as it travels through its very short arc.

 

[Steve Garner]

The item being discussed was leaf springs, and camber applies. I again am sorry if that double meaning confuses you.

Didn't know I needed to show any calculations, regardless, I can't, because the spring eye does not move forward, it's fixed.

I'm starting to get tired of being sorry.

No, that's a leaf spring, not an airfoil. Camber is not universally used for anything with an arc. Specifically says airfoil. Like I said, don't be sorry for me.

 

[Steve Garner]

The item being discussed was leaf springs, and camber applies. I again am sorry if that double meaning confuses you.

Didn't know I needed to show any calculations, regardless, I can't, because the spring eye does not move forward, it's fixed.

I'm starting to get tired of being sorry.

These guys know a thing or two about the english language. You will note how it does not say the curvature of anything with an arc, but rather specifically, airfoil, roadway or horizontal surface.

At least you're picking up a few things here on our adventure.

 

[j-c-c-62]

View attachment 1591054

These guys know a thing or two about the english language. You will note how it does say the curvature of anything with an arc, but rather specifically, airfoil.

At least you're picking up a few things here on our adventure.

"Camber: ARCHED shape of a.......... or other horizontal surface"???????

 

[j-c-c-62]

No, that's a leaf spring, not an airfoil. Camber is not universally used for anything with an arc. Specifically says airfoil. Like I said, don't be sorry for me.

 

[j-c-c-62]

You're still not getting it. The eye doesn't move, the spring gets effectively longer when you take the ARC out of it. Why is that not taken into calculation of the movement of the axle as it travels through its very short arc.