Technical quarter eliptical question

Hi I am new here and have a question.. I am doing a q e spring setup on a chevy I beam axle up front. I set it up and from the front solid mount (bottom of spring) to the pad where the spring bolts down is a quarter of a bubble up from being level. My question is does the spring need to be level with the ground? or will it be ok as long as the bottom bar is level? almost forgot the spring is on top Thank you

 

Picture,,,??,,need more info

 

You building a four link with a radius rod on the bottom and the spring on top?....we need pictures!

 

I cant take a good pic but this was my inspiration

 

With both links (the spring and the lower bar) being different lengths, the angles of the mounting are totally out the window. You will need to make some sample mock ups and test things. Need to make sure the axle's caster stays where it needs to be throughout the axle's travel. Shouldn't be too much travel, so you can probably get it within spec for your application, but there's no way for us to guess with your little sketch.

 

These are some pics from the mock up. Hope this helps

 

That is the best way to do it , if the spring is used as a link.

The spring wont curl under when there is brake torque applied through the axle.
Also having a shorter spring [or longer lower link] will increase + caster during dive ,so you have inherently got anti-dive when the brake torque tries to induce - caster

Ideally the spring eye to spring pad "line" should intersect at a point with the lower link "line" making a theoretical "instant center" .
Even though it is parallel when static, the difference in upper and lower lengths will shorten the instant center during compression [again ***isting anti-dive]

Anti-dive is when the brake torque tries to lift the front , while weight transfer tries to lower the front.
This causes the tyres to plant into the pavement more.

The opposite on the rear is anti-squat

 

Thanks for your help it sounds like it should be ok.

 

Finally had some time to work on this. Now I have another question, the springs are at 13 degrees should the bottom bar be as pictured, at 13 deg, or something else?

 

This system needs a panhard bar to keep centered. This is a very poor design because the upper and lower bars need to be the same length. When hitting a bump with one wheel, one side will increase caster while the other side will decrease caster making vehicle vary unstable. There will also be a twisting action on the lower leaf spring as the vehicle goes up and down.
U tube video explaining twisting action using a rear setup which is similar to front.
https://www.youtube.com/embed/okBrx2RTUAQ

 

A panhard or a watts is preferable [recommended] but you can also get away with having the springs or links triangulated [looking down] Chrysler did this on semi-elliptic spring rears.

Upper and lower bars do not have to be the same length , in fact having a shorter radius on the uppers is recommended.
The best way is to have the links horizontal at normal ride height. When the suspension compresses the upper link moves up in a shorter arc inducing positive caster. And when the suspension droops the upper link moves down in a shorter arc inducing positive caster.
During body roll weight transfer causes the car to rotate around the roll centre causing one side to compress and the other side to droop inducing positive caster on both sides.

Brake torque induces negative caster , so you have engineered anti-dive into the front end by having shorter uppers.

 

Using a leaf spring in a triangulated manner as Chrysler did allows the spring to work as it was designed. In the above project, the spring is being used more of a torsion bar setup where the spring will twist as it goes up and down. In a parallel 4 bar, the caster remains the same were as in a hair pin or split wishbone there is some caster change. This is reduced by having the length of the hairpin or split bones fairly long as to reduce the caster change. A short upper and long lower link accelerates the caster change when hitting a bump. When using a short upper, it is usually 80% of the lower and in the above project the upper appears 50% of the lower link. The above project appears to be some sort of rat rod car as I've never seen a traditional hot rod with this type of suspension or any car for that manner.

 

No it is not a rat rod...it is a custom no front fenders on a 46 flatbed truck. 261 L 6 5 speed headers and dual 1 barrel carbs I was asking about the angle on the bottom bar. Since it is triangulated should the bottom bar be inward the same deg or straight with the frame or angled outward?

 

you can run it parallel with the frame or angle it outward toward the wheel but you will still need a panhard bar.

 

Thanks everyone for your replies I will use your advice and use a pannard