Setting up Quarter Elliptical Springs

[PeteT]

Still at the mock it up and see if it will work stage.

Got myself a Posie quarter elliptical spring kit from Speedway and I think it may work but I'm not sure on how to set the ride height and shackle angle.

What should the shackle angle be with no load and at ride height? I've seen pictures with the shackle vertical but this doesn't seem quite right to me.

Also I'm not sure how much they will compress once I get some weight on the front. I'm trying to avoid using the big adjuster bolts that come with the spring kit and mount them under the chassis rails. I've got the chassis at 8" above the ground so haven't got a lot of room to play with.

The only way I can see is make the chassis, fit the engine and then clamp the springs on and try it, but then I'm totally committed if it doesn't sit low enough I've got some major cutting to do!

Has anyone used one of these kits that can give me any clues on setting up.

Thanks in advance. Pete

 

[Youngster]

i haven't used them up on the front but used them on the rear before. i had the same problem, too much ground clearance. that was with the spring on the bottom of the rail. i ended up mounting them on the inside of the rail with the spring on top of the mount and in the final assem. had to use a spacer to adjust the heigth.

i just thinking here, so don't take this as gospel. the thing to remember in setting up any front end is the arcs the pieces move in during articulation. the shorter part will have a smaller arc than the longer ones. if you keep the small arcs inside the larger arcs, you eliminate binding and thus have a smooth working suspension.

now with that in mind, at rest, the components should be in the center of their arc. the shackles function is to compensate for the differences in the arcs. the part of the arc that will be used the most is on the downward or bottom half of it.

this is how i would go about setting this up. i would take the spring apart and use the main leaf with a spacer to make up the missing stack heigth. i would then set the shackle as you show it.

as i said, i have not attempted this set up yet so this is just my thought process. if GAB or someone else has, please correct any errors.

Ron

 

[joecool]

I built a Modified type car with 1/4 elliptics and they worked out great.
But I used 57 Chevy springs and cut them in half,using the stiffer shorter front half for the front and the longer in the rear. I drilled holes in them and bolted them to a reinforced lower frame rail. I then put tabs on the axle ( not shackles) and used those as the method for raising and lowering the ride height to suit me.
By not using shackels I was able to use the spring as the bottom link in what is like a four bar ar four link. I then used a upper link to locate the top of the axle.
Now to get back to your question,I think making a new longer shackel or shortening it will be your only method of changing ride height. The better way may be ,as suggested, mount on the inside of the frame rails so the adj. bolt would be hidden.
I will try to send pic's of my car but no guarentees if I can get it to work.

 

[PeteT]

Thanks Ron, I see what your saying, I'll keep that in mind.

Joecool, I like that idea... looks nice and clean a bit like ThunderRoad

Does the caster angle change as the suspension goes up and down ie the length of the spring/bottom link changing? I can't get my head round this one and not sure if it matters or not.

Are you running cross steering or side steering? If side steer are you going to have problems with bump steer because of the difference in length between the steering arm and tie rod. Or is this like Ron said, a smaller arc inside a larger arc so it doesn't matter.

 

[Youngster]

the upper bar on that setup is so close to the same length as the spring that i wouldn't think it matters. the thing i would wonder about here is the angled bracket on the axle. seems to me that would cause binding.

Ron

 

[joecool]

Pete ,that is a NICE setup in your post, to answer your question I don't believe the Bump steer applys because the axle tends to move straight up and down instead of an arc with a cross spring,radius rod axle. I do know it drives great ,we took it on Power Tour this year and other tahn sunburn it was flawless.

 

[oldtman]

Jeep wedges, the guys that jack up their 4 x 4,s use wedges to adjust pinion angle , goes between spriing and axle . google leaf spring wedges and you will find several.