Leaf spring dimensions

[j-c-c-62]

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.

This discussion has become pointless, a waste of my time and B body bandwidth.

For more "pure BS", review this link, especially approx 3/4 down where it refers directly to leaf spring camber.

Leaf Spring Design and Engineering Strength of Materials

"The amount of bend given to a spring from a central line passing through the eyes, is known as camber. The camber is provided so that even at maximum load the deflected spring should not touch the machine member to which it is attached. The camber shown in the picture is known as positive camber."

I'm done.

 

[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.

This discussion has become pointless, a waste of my time and B body bandwidth.

For more "pure BS", review this link, especially approx 3/4 down where it refers directly to leaf spring camber.

Leaf Spring Design and Engineering Strength of Materials

I'm done.

I would quit too if I was you. Your author doesn't know the english language and if you think using that word to describe an arc in a spring in the context of discussion of automotive suspension, well, you guys are a good fit. And if you can't figure out what the flattening of the spring does to it's effective length, you're the last guy that should be telling other members to do their homework.

 

[70bigblockdodge]

The rear springs do steer the car on a Chrysler product. A Nova or Mustang not so much. It is because of the short and long segments.
If you let the rear hang on our cars it moves forward, the slip yoke will be in toward a transmission seal. When the spring is flat at designed ride height it is as far back as it gets, yoke is pulled out the furthest.
As the outside wheel loads beyond flat the movement.is very limited for and aft, part of the long and short segment spring design the rear segment moves the shackle in extreme loading to prevent a oversteer.
The inside wheel moves forward.as it moves from flat to arched as it is unloaded. There is no Ackerman angles on a solid axle it can only pivot around the center between the mounting points. Rear steer is opposite, if you pivot to the right (right rear being flat spring and in compression,left rear being in rebound moving forward)the front of the vehicle will move left helping the front steer left which is correct.
I don't think it is wrong to call it camber, simply because it does move in a arc which is what a front wheel does, it is just viewed from a different point of view.

 

[Steve Garner]

The rear springs do steer the car on a Chrysler product. A Nova or Mustang not so much. It is because of the short and long segments.
If you let the rear hang on our cars it moves forward, the slip yoke will be in toward a transmission seal. When the spring is flat at designed ride height it is as far back as it gets, yoke is pulled out the furthest.
As the outside wheel loads beyond flat the movement.is very limited for and aft, part of the long and short segment spring design the rear segment moves the shackle in extreme loading to prevent a oversteer.
The inside wheel moves forward.as it moves from flat to arched as it is unloaded. There is no Ackerman angles on a solid axle it can only pivot around the center between the mounting points. Rear steer is opposite, if you pivot to the right (right rear being flat spring and in compression,left rear being in rebound moving forward)the front of the vehicle will move left helping the front steer left which is correct.
I would not call the arc that the axle moves through incorrectly called camber, simply because it does move in a arc which is what a front wheel does, it is just viewed from a different point of view.

I would disagree with the use of the term camber in this situation. Camber is a measurement of the wheel off perpendicular to the ground, by definition. Doesn't apply here and not what the dictionary definition refers to. Simply serves to confuse in this discussion and is inconsistent with the dictionary definitiion.

When we think about the arc the axle moves in as the spring moves, there are other factors to consider. One is that when any arm travels in an arc,how the axle moves depends on where it is in it's travel. If, at rest, the arm(front spring portion) is below horizontal, movement upward of the arm (downward of the car) will move the axle back as it approaches horizontal. However, downward movement of the arm will move the axle forward. If at rest the arm is horizontal the axle is now furthest from it's pivot, it doesn't matter which direction the arm moves, up or down, the axle will always move foreward. So that is one thing you need to determine in a discussion like this.

The relevance to that is what's happening on the other side. In a lean one side is down, the other up. If the design is of the latter type where at rest the straight line from centering pin in the spring to the eye is horizontal, the side that's low is moving the axle forward, but the other side, that's lifting, is also moving the axle forward. Result, no change in relation to the front to back centreline of the car.

Not so much on these cars because at rest the main leaf is nearly straight, is that the spring arc needs to be considered. How much the axle moves forward is a function of two things, the amount of up or down travel, and the length of the radius. In the context of this discussionsions, whether it's GM, Ford, Mopar, the length of the spring behind the axle is unimportant. It's the distance from the fixed eye(in this case the front, but that's not always the case) to the axle centering bolt. The back half is along for the ride. As the arc in the spring changes through deflection the effective length of the radius changes. If it goes from an arc to a straight line, the distance increases. If it goes from a straight line to a curve, like these cars are at, the distance decreases. That does two things. Shortening the radius moves the axle forward, but it also tightens the arc that the axle travels in. Which means for the same amount of travel the axle will move forward more.

In short, this is far more complex than the oversimplified, applies to all, explanation given here. We haven't gotten into spring wrap under aceleration and it's affect on the geometry. Are you into the throttle or braking. But to put this into perspective, this is hardly a topic that applies to 99.99% of the membership here, and certainly not one that a member should take attitude with another over their lack of knowledge on the subject.

BTW, the axles on most cars with leaf springs or front to back trailing arms (c2/c3 Corvette) will move forward when hanging.

 

[Steve Garner]

The rear springs do steer the car on a Chrysler product. A Nova or Mustang not so much. It is because of the short and long segments.
If you let the rear hang on our cars it moves forward, the slip yoke will be in toward a transmission seal. When the spring is flat at designed ride height it is as far back as it gets, yoke is pulled out the furthest.
As the outside wheel loads beyond flat the movement.is very limited for and aft, part of the long and short segment spring design the rear segment moves the shackle in extreme loading to prevent a oversteer.
The inside wheel moves forward.as it moves from flat to arched as it is unloaded. There is no Ackerman angles on a solid axle it can only pivot around the center between the mounting points. Rear steer is opposite, if you pivot to the right (right rear being flat spring and in compression,left rear being in rebound moving forward)the front of the vehicle will move left helping the front steer left which is correct.
I don't think it is wrong to call it camber, simply because it does move in a arc which is what a front wheel does, it is just viewed from a different point of view.

A picture to augment my thousand words. The arrows show which way the axle would move through their arcs in the different designs.

 

[Longknife]

Who obviously still hasn't as suggested done his homework.


Enough of the games.

From #9 here:
"Over arched leaf springs often promotes roll oversteer."

When an arched spring compresses from additional load on the outside wheel during a turn, the axle moves rearward in its upward arc, when the inside spring loses load in the same turn, it extends and it's arc moves that side of the axle forward.
Voila, we have roll oversteer.
That must have been left out of Chrysler mechanics training in the seventies, I guess.

Yes, building race cars was left out of Chrysler training in the 70's and I really doubt they that have added it since. All the references you have posted here would be great, IF you are building a 200 MPH Oval trac race car,,,Geeeze, give me a break!

 

[Longknife]

Steve, did you ever get the measurement you were looking?

 

[j-c-c-62]

A picture to augment my thousand words. The arrows show which way the axle would move through their arcs in the different designs.


View attachment 1591125

Your sketch above indicates very well what an over arched leaf promotes.
And the only thing you have contributed to this discussion that has any true bearing to my claim made on #9 here.
For those undecided, the top sketch promotes understeer, the bottom "overarched?" sketch promotes oversteer.
EVERY reference book you can find will state the exact same thing.
You might want to go back and edit your replies, but then I did copy most to cement your unsupported claims. You are welcome.

 

[j-c-c-62]

Yes, building race cars was left out of Chrysler training in the 70's and I really doubt they that have added it since. All the references you have posted here would be great, IF you are building a 200 MPH Oval trac race car,,,Geeeze, give me a break!

I am not giving you a break. Nobody is giving me any break and quite the opposite it seems, but no matter.
All the suspension geometry in this discussion applies at ANY speed to any RWD dual leaf spring solid axle car.
I suspect it was left out of the 70's training manuals as they felt it would not be within the understanding of their trainees. I might be wrong.
However, I think the point that it is now 50 years later it is still highly misunderstood and contentious proves that point somewhat.

 

[j-c-c-62]

I would disagree with the use of the term camber in this situation. Camber is a measurement of the wheel off perpendicular to the ground, by definition. Doesn't apply here and not what the dictionary definition refers to. Simply serves to confuse in this discussion and is inconsistent with the dictionary definitiion.

When we think about the arc the axle moves in as the spring moves, there are other factors to consider. One is that when any arm travels in an arc,how the axle moves depends on where it is in it's travel. If, at rest, the arm(front spring portion) is below horizontal, movement upward of the arm (downward of the car) will move the axle back as it approaches horizontal. However, downward movement of the arm will move the axle forward. If at rest the arm is horizontal the axle is now furthest from it's pivot, it doesn't matter which direction the arm moves, up or down, the axle will always move foreward. So that is one thing you need to determine in a discussion like this.

The relevance to that is what's happening on the other side. In a lean one side is down, the other up. If the design is of the latter type where at rest the straight line from centering pin in the spring to the eye is horizontal, the side that's low is moving the axle forward, but the other side, that's lifting, is also moving the axle forward. Result, no change in relation to the front to back centreline of the car.

Not so much on these cars because at rest the main leaf is nearly straight, is that the spring arc needs to be considered. How much the axle moves forward is a function of two things, the amount of up or down travel, and the length of the radius. In the context of this discussionsions, whether it's GM, Ford, Mopar, the length of the spring behind the axle is unimportant. It's the distance from the fixed eye(in this case the front, but that's not always the case) to the axle centering bolt. The back half is along for the ride. As the arc in the spring changes through deflection the effective length of the radius changes. If it goes from an arc to a straight line, the distance increases. If it goes from a straight line to a curve, like these cars are at, the distance decreases. That does two things. Shortening the radius moves the axle forward, but it also tightens the arc that the axle travels in. Which means for the same amount of travel the axle will move forward more.

In short, this is far more complex than the oversimplified, applies to all, explanation given here. We haven't gotten into spring wrap under aceleration and it's affect on the geometry. Are you into the throttle or braking. But to put this into perspective, this is hardly a topic that applies to 99.99% of the membership here, and certainly not one that a member should take attitude with another over their lack of knowledge on the subject.

BTW, the axles on most cars with leaf springs or front to back trailing arms (c2/c3 Corvette) will move forward when hanging.

And BTW, your opening diatribe on C2 aftermarket rear LCA appears to be flawed, but I refuse to engage in another total keyboard circle jerk exercise.

 

[j-c-c-62]

I would quit too if I was you. Your author doesn't know the english language and if you think using that word to describe an arc in a spring in the context of discussion of automotive suspension, well, you guys are a good fit. And if you can't figure out what the flattening of the spring does to it's effective length, you're the last guy that should be telling other members to do their homework.

BTW, humor us with a quote you find so lacking in the knowledge of proper English in the attached link regarding Leaf spring design.
Should be a piece of cake for a grammar nazi, right?

 

[j-c-c-62]

Long rear hangers did the same back in my day, and IMO, with a lot less drama.
Over arched leaf springs often promotes roll oversteer.

Back to square one or #9 it seems.

 

[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.

 

[RemCharger]

Thanks fellas. What I am trying to accomplish is getting as close to the exact factory ride height with the factory installed springs.

Back to square one or #9 it seems.

The first quote was square one. Then morphed into " over arched leaf springs " often" " promote" roll oversteer.

My question is, the main reasoning of the argument, is based on the idea that the rear axle is pivoting in the car, changing the thrust angle?

 

[j-c-c-62]

The first quote was square one. Then morphed into " over arched leaf springs " often" " promote" roll oversteer.

My question is, the main reasoning of the argument, is based on the idea that the rear axle is pivoting in the car, changing the thrust angle?

Bingo!

 

[RemCharger]

Could it even add up to 1 whole degree.

 

[j-c-c-62]

Could it even add up to 1 whole degree.

The amount is IMO not the important part here, it's the widely held effect that results that is, and with the outside tire having the greatest load and therefore grip, it drives the rear of the car.
Longer front leaf segments reduce the effect, meaning short segment SS leaf's promote it, whether is under or over steer. What matters is we have roll oversteer, and what promotes it.
Might want to add, the longer only 2d located rear leaf segment here other than its contribution in ride height and leaf stiffness, plays little part in under/over steer effects.

 

[70bigblockdodge]

A picture to augment my thousand words. The arrows show which way the axle would move through their arcs in the different designs.


View attachment 1591125

Yes to some extent. However the stiff front segment in Chrysler application once it goes flat it stays flat the only movement of the axle is distance to pivot. On rebound since you don't like the word camber, the spring curves and it rotates around the front pivot moving it much further forward, steering the axle.
So in conclusion it does matter. Yes you are right on paper as you nicely drew with a compass which is not changing in distance. The spring doesn't work like that.
This is all pointless. The system works better than on a symmetrical leaf spring period, for what ever reasons you choose and whatever you want to call it

 

[Fury Fan]

FWIW, the word 'camber' is used to describe one of the characteristics of a fan blade - the arc.
I've not heard it used to describe a leaf spring, but it certainly could.

My big question is - if we're doing a nut & bolt resto on a car, why are we re-arching springs?
A leaf spring gets flatter due to fatigue, and to put it back to its original shape you have to yield it.
A good restoration of a car should include new springs unless the original leaves are in exemplary low-mileage condition?