explain this quarter elliptical set up?

Hey there,

I was just wondering if anyone on here would comment on what makes this STOCK quarter elliptical setup "work" and not allow the axle to shift side to side.


I love the clean, simple look, especially if I replicated the idea (not my truck in the pic) without the overload springs on top.

Thoughts? Diagrams? Examples of the same setup on your project? All is welcome.

Thanks!

 

I'm sure the shackles are keeping it centered. Hard to tell from the pic, but there must be something to keep the pinion angle where it needs to stay.

 

I'm thinking the pic doesn't show it but the lower spring is a full spring to which the axle is affixed in the conventional way. The 1/4 elliptics on top are auxilary (overload) springs and have nothing to do with axle housing control.



Ray

 

What Hnstray said in his first 3 lines is what I think is up also.

 

That's just an overload spring. This ch***is is riding on the semi-elipticals below.

 

Hmmm, I hadn't thought that the bottom springs might have been full leaves. That would make sense! I know the top springs are just overloads, scotty, I was referring to what I thought were quarter ellipticals attached to the axle with the arch facing groundwards.

So, allow me to shift the question slightly, then. Would a quarter ellip set up (such as what appears to be presented in the pic) be possible with the addition of a panhard to keep the pinion correct as Wicked 50 said? Look at my attached thumbnail below for an idea of what I'm trying to do.

Would a panhard from the rear pumpkin to a cross member keep the pinion angle right?

 

Attaching the axle to the spring enslaves the pinion angle to the spring wrap or unwrap. While it may be minimal, it's not really a good thing. Can it be done? Sure.
Generally speaking, panhard bars and leaf springs don't get along. If you consider the amount of lateral sway in a typical leaf spring rear, the axle is allowed to move a good deal side to side by the collective slack in 3 bushings and a shackle. If you dangle a shackle below the axle, connect the ends of your Q-E spring to that, and then rigidly mount the front of the spring to the ch***is, you have less slack than a standard semi-E leaf setup. Now all you need to do is control pinion angle. This can be done with a torque arm, single upper link or triangulated twin links.

There are a lot of ways to do this. Search the HAMB a lot for this subject and you'll find magazine articles, home builts and theory out the wazoo. Even better, google some very early Bugattis, and other Euro makes. They used Q-E systems to the highest degree.

 

A panhard wouldn't keep your pinion angle in place...the simplest quarter elliptical setup is a truck arm system with a shackled 1/4 elliptical spring...the angle of the truck arms keep pinion and sway in check and the 1/4 ellipticals only need to do spring duties...

 

Just asking??

What 2-speed rearend is it?

pdq67

 

I don't agree with your statement that truck arms keep the axle in place laterally. In OEM applications they were used with a panhard bar and in all hot rod apps I have seen. There isn't enough rigidity in the truck arm bushings, especially with the length of the truck arms (leverage) to control the sideward movement of the axle housing.

Ray

 

By the time you get done making everything rigid you might be close to a 4 link style setup, by that time the uniqueness of the setup may be lost in the added hardware. Don't you think so?

 

the pics need to show more, can you post them??

 

I agree, a truck arm system does need a panhard bar, but a dual angle truck arm does minimize sway quite a bit, especially with urethane bushings...but using a panhard does help immensely...

 

Best way to explain this it to Google Bugatti rear, something should pop up and show how they used this system from around 1912 to 1948.

 

you are correct. the lower spring has only a through bolt in the eye. If it where quarter elliptic it would pivot on the bolt and the axle would hit the frame.

 

Looks like a axle out of a IHC 6 Speed Special late 20s. Ratios slow and slower 6 to 1 and 12 to 1 . Had one years ago.

 

"and not allow the axle to shift side"
As someone who has three race cars with 1/4 eliphtic springs I would like to know or have someone explain how in the world can the axle move from side to side unless the springs break.When we made the jeep I even tried to get side to side movement shaking it and prying it . Tis not possible. The blue rail has only a single 1/4 eliphtic in the centre. It runs like it is on tracks. See "Sr Dragsters Third Wheelie" on Youtube if you have any doubts. The jeep has a pair of 1/4s as does the longer rail under construction. The spring is fastened solid at one end. More solid then a 1/2 eliphtic (most rear leaf spring cars like 55 chev, 55 Ford, 63 Dodge , 67 Camaro etc) would be as they pivot at both ends. .The other end is in a snug fitting shackle welded to the axle in most cases or a convention underslung shackle if double radius rods are used. It simply cannot move sideways. It is not possible unless something breaks or falls off loose. No panhard bar , zip nada. It works beautiful.
Don

 

Thanks for all the brain medicine, guys.

Sadly, that pic I posted of the old IH is one I pulled of the internet advertising it being a QE set up.

I did look up Bugattis a little bit last night and found some fodder to ponder, so that was a great suggestion and I will research it more before I decide exactly how to actually fab. my rear.

Ruiner: Is there any way you could post a pic or refer me to a post where the setup your talking about (that, at least minimizes sway) is shown?

Dolmetsch: I'd love to see the single quarter set up you have in that dragster! The last pic. you posted is close to what i"m imagining. I'm going to have to shop around for a decent, virus free CAD program so I can draw my thoughts up in 3d space for me and everyone else to see.

Thanks all!

 

Here's 10 pounds of **** in a 5 pound sack.





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that is a great pic of what simple can be. you dont even need the arms if the app is for just a stock motor and no performace.