Quarter Elliptical Mount Idea

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fwak1234

Active member
Joined
Jan 13, 2009
Messages
26
Location
Central Utah
Need some Ideas on how I can mount a 1/4 elliptical on my 2A I am building. I have a buddy with a cutting table so I can fab up pretty much any mount I'd like.

1. Has anyone thought of a way to mount it like more of traditional leaf mount but with the spring cut in half. IE: the cut side of the spring gets u-bolted to the front axle with a normal leaf perch, then run the shackle like you would see in the rear of say a toyota pickup at a 30-45* seated angle. Would be running the springs at a 0* angle and then run a set of HEIM joint control arms at an inward 45* so it is almost identical to a coilover 4 link but in this the spring would be the lower arm and spring in one.

I have see people run it reversed like the way the speedway or posie kit comes, just wondering if I could run it backwards. Worried about the spring not even holding any of the weight and the frame just slamming down onto the ground.

2. Does anyone have experience with running a no shackle 1/4 elliptical? IE sandwich plate off the side of the frame with spring a 0* with the spring bolted straight into the axle with no shackle. would still like the run the inward 45* control arm uppers. With this setup I am just worried about spring bind when attempting to compress and the control arms limiting the axle from moving as it needs to.

I could always run the traditional style of 1/4 but seeing if anyone has put any thought into another way or even put it into use. Trying to do something a little different but can't find much information on 1/4 aside from offroad builds.

Also what is the best place to mount the shackle if I run the traditional style? Top forward side if the axle, rear lower, top back, lower forward? SOOOOO many options.
 
Attached a picture of the first idea I was talking about.
 

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I replied in your build thread.
Best thing to do is just post the questions and pics in your build thread. Everyone will follow along there, give the advice you're lookin for and not have to jump around :)
 
Need some Ideas on how I can mount a 1/4 elliptical on my 2A I am building. I have a buddy with a cutting table so I can fab up pretty much any mount I'd like.

1. Has anyone thought of a way to mount it like more of traditional leaf mount but with the spring cut in half. IE: the cut side of the spring gets u-bolted to the front axle with a normal leaf perch, then run the shackle like you would see in the rear of say a toyota pickup at a 30-45* seated angle. Would be running the springs at a 0* angle and then run a set of HEIM joint control arms at an inward 45* so it is almost identical to a coilover 4 link but in this the spring would be the lower arm and spring in one.

I have see people run it reversed like the way the speedway or posie kit comes, just wondering if I could run it backwards. Worried about the spring not even holding any of the weight and the frame just slamming down onto the ground.

2. Does anyone have experience with running a no shackle 1/4 elliptical? IE sandwich plate off the side of the frame with spring a 0* with the spring bolted straight into the axle with no shackle. would still like the run the inward 45* control arm uppers. With this setup I am just worried about spring bind when attempting to compress and the control arms limiting the axle from moving as it needs to.

I could always run the traditional style of 1/4 but seeing if anyone has put any thought into another way or even put it into use. Trying to do something a little different but can't find much information on 1/4 aside from offroad builds.

Also what is the best place to mount the shackle if I run the traditional style? Top forward side if the axle, rear lower, top back, lower forward? SOOOOO many options.

If I am reading your question correctly, it looks like you want the half spring to be your bottom axle locator and then have a separate control arm on top. Sort of like a 4 bar, but the spring will be the bottom bar.


Years ago, I owned an Austin Healy Sprite, and that is the way they did it. There was a spring on the bottom and a locator bar on top of the axle. It worked fine there, but that car only weighed like 1300 pounds or something. There was no shackle at all, a bolt went directly through the eye in the spring and into a mount on the axle.

I have seen cars that people have built with that setup on the front axle, and the only concern I would have there is that as the axle moves up and down the caster would change, as the spring stretched out.
 
I built a '27 T roadster with the spring on top and the locator bar on the bottom. No shackle. Worked fine. Make sure the effective length of the spring and bar are the same.
 
Thanks for the responses Don/Bob. Yeah I drew my diagram with the spring on the wrong side. Was just curious if it would be advantages to run a shackle on the frame side to help with the caster issue and with ease on the uppers. May even mock it up when i build the frame to have the control arms under the frame/axle and the springs up top. IE springs mounts/control arm mounts at the edge of the frame and with the control arms at 45 so it's a | \ / | style
 
I'm thinking the 1/4 elliptical can work good without the shackle. I believe the shackle on a leaf spring only gives the spring a place to go. On a full leaf spring, when the spring is under pressure, the length increases. The shackle allows that to happen. If you're using a half spring, you only need your up and down movement. You can deal with caster off your control bars...
I'm tuned in. My first vehicle was a 42.
 
Yeah, I think the caster change, as the axle goes up and down, would be negligible , probably no worse than radius rods.

There are a ton of quarter elliptic setups in use, so I think you will be ok.
 
I think if you use a shackle you also need a real lower arm or theres nothing to control the caster. Axle will want to pivot on the upper mount. Seems like weird thing might happen under braking when the axle wants to wind up. Here’s what I did. Mounted the whole spring inside the frame rail. Lower arm is just at a slightly different angle from the spring. Caster is set at about 4* at normal load and approaches 0* when compressed. Drives fine.
 

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