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Newby's basic questions about quarter elliptic suspensions


New Member
I was about to hijack another post into a direction unintended by the original author. So I decided to start a new post here instead. Here's the relevant portion of the quote.

joecool said:
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.


I'm interested in your use of quarter elliptic springs at both ends of the car because I'm considering doing something similar. These are not criticisms (as in, "Why didn't you do it the right way, like me?"), I'm just trying to learn, (as in, "I've never built anything. How does that work?").

Does the lower spring do a good job of holding the axle from moving from side to side - either from hard cornering or from little bumps as you're driving straight? How about on the rear? Did you find you needed a panhard bar on either end of the car? Why did you put the spring on the bottom instead of the top?

Could you have put two lighter springs at each end of the axle - one on top and one on the bottom?

Could you have eliminated the top mount altogether by mounting the spring solidly to the axle, exactly like you mounted it to the frame?

Inquiring minds want to know...

Here's the original post in context.
great questions. i would also like to hear joe's answers.

We are using a Posies quarter eliptic spring setup on the rear of my Son's 30 RPU. They said we could use the spring as the bottom locating bar, but we decided to go with a four bar setup in addition to the spring. He is running a pretty built 455 Olds through a Moser 9 inch rear end setup, and we figured it would be better to be safe than sorry.

We are using a panhard bar on the rear setup, and you can see it in some of these pictures.


These are just temporary four bars in the picture, we are using them as mockups so we don't scratch the stainless ones.


nicely done Don. the panhard bar isn't a necessity but with that torquey Olds, it's probably a real good idea. i really like the work you and your sons do.

Ok a little background here first,I mostly build drag cars with a oddball combo sometimes for excitment. I am no expert with my stronger asset the abilty to not realize that I can't do it. I think in almost anything we do there is dozens of ways to fix a problem.
The car was built on a bet,you know a half dozen people around the garage crying about prices and costs to put a street car together.I bet I could have a safe ,drivable street rod for $2500.No doubt looks would suffer but that part could be improved in time.
Now for the car,The axle is a late 30's mopar tube axle,it would normally have two parrell springs on it. we did not have any of that hardware to use.We thought about a suspension setup that would work correctly and be budget friendly.A friend was adding a Continental kit on a 57 Chevy and found he needed heavier springs.We calculated that his car's rear weight was about 1600 lbs and that was about the weight of our total car .Therefore if we used the springs half in the front and the other half in the rear we may be close. We could always take out leafs or add if we were wrong.
The front of the leafs are shorter and therefore stiffer,so they went on the front ,the heavier half of the car.We cut the springs with a chop saw and drill holes with a plasma cutter. Because of the load being on the lower front part of the frame we put a reinforcement piece inside the rail, welded it and welded nuts on it so we could remove the spring after we boxed the frame.
Now for one of your questions,the reason we mounted it on the bottom was just because we thought it looked better,it would work either way.
You can't solid mount both the front and the back,the axle needs to rotate slightly .On this application the mounts on the axle would not allow sideways movement.
A little more explanation here,when Henry Ford designed the A's and T's the front axle was connected to the frame with a wishbone.this mounted in the middle of the car on a pivot.This allowed the wheels to move up and down freely ,pivoting on this ball . When Hot rodders decided to swap engines and lower their cars , this wishbone and the center mount was in the way. The easy way to fix this was to cut the wishbone and pull the ends out to the frame and mount them there. The problem was the axle was then restricted from movements up and down because it no longer could roll on the center ball.Every straight axle ,cross spring with wishbone type radius rods has this problem. On light weight cars when everything is overbuilt most times there is no problems. But is still isn't a 100% correct situation.
On the panard bar, IT IS MY OPINION that only vehicles with cross type steering nedd a panard bar. In a cross sterring car witha cross spring the axle settles evenly on the shackels at ride height. When a cross streered car is turned it pushes the right hand spindle in or out. This movement transfers to the axle and pushes the axle sideways until the shackels stop it by running out of slack. Cross steered car are frequently sluggish in turning,and sometimes even overturn when the shackels correct them selves.Now there are 50,000 T bucket owners will tell you their car doesn;t do this. Ask any reputable builder. Now my car was a Mustang box and the streering ran alongside the frame. When it was turned it would then push forward or back on the axle,and we had it mounted not allowing those movements.
Now on the rear,it's somewhat different . The power of the car and other forces will try to push the rear around. Poor handling and tire rubbing will be the result. What I did in the rear was the topside struts running from the frame to the rear end housing are angled in. This is not much different than the auto manufacturers have done in their three and four link rears.
I will try to incude some more pic's. Let me know if I can help any more. The best thing I can ever tell anyone is never modify or assemble your car until you understand what the result will be. Just stare at it long enough it will come to you.
Don, Please can I ask about shackle angles? In your photo is it at ride height? I've seen pictures with the shackles vertical at correct ride height, what do you think about this? Would it be the same for the front?

Joecool, thanks for the explanation ,it's good to hear from someone with practical experience.
Thank you Ron.

Pete, I think as we add more stuff like the bed, gas tank, etc it will settle down a little and flatten out the arc on the perches a little. We have some adjustability with two more holes in the plate where the perch goes *one over and one under the one now in place) plus the spring is adjustable with those two bolts on the frame end. We can crank them tighter to raise the car or loosen them to lower it. We can also crank the ends on the four bars to move the axle fore and aft to give us more arc on the perches or less, so we will have to dial it in when the car is all together. I think you would want some angle to the shackles so there is room to travel on bumps.

These quarter eliptic setups are pretty neat and from all reports ride well. I had a bugeye Sprite years ago that had them on the rear and they worked well there too, even after I shoehorned a 289 Ford into the car with about 5 times the original HP. :D


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