To shackel or not? Rear quarter ellipticals?

The promised photos. Top Photo is the front view of the front brackets and also shows the shackle brackets I make that weld to the rear end with a small gusset and the shackle angle I like to start with so under load the shackles hang straight, photo 2 is the rear side that of the front brackets that weld to the boxed frame rails, Photos 3 simply shows the lower shock mounts I make that weld to the ladder bar axle brackets. Photo 4 shows the 1/2 inch spacers welded on that need to be added to the frame side to clear the front bolt nut & weld to the rails. Confusing?

 

This is mine on my new 29 woodie project.

 

Here's the ones I made out of samurai springs. Re-arch them then built my own sandwich plate to support the center bolt area and built my own brackets etc.

 

Great stuff, several good ideas. Lot's of different ways to skin the cat.

 

That last picture looks like it would bind as it went up and down, as the spring and lower link go through different arch's.

 

Nope, no problems at all. With the shackle on the housing the spring is free to move however it wants.

With the triangulated 4 link the springs only job is holding up the car.

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@BJR you might be seeing it wrong. The link bar mount is behind the shackle. I know when I first looked at it I thought the link was attached to the bottom of the spring eye or something and was confused.

My set up is really similar to @krylon32 other than some minor details. I was going to mount my shocks like that also but ran into some packaging issues with my exact situation.

 

Mine, short Pete and Jake's shackles.

 

^^^^Dang, that’s pretty!

 

That is exactly how I saw it, I thought the lower link was attached to the same mount as the spring. Now it makes sense. Thanks.

 

@BJR sorry for the confusion, here's a better pic.

 

Now that makes perfect sense. I wouldn't have even posted if I saw this picture first.

 

Lostone: What do you have planned for the shocks? I always put mine in front of the rearend pointing forward. That way nothing shows from the back. Your installation is similar to one I did for customer where the spring was the bottom bar and I triangulated the upper bar like yours, No shackles. Again the shocks in front of the rear end.

 

Dang Krylon32's post # 27 should be archived for the explanation of with or without shackles.
A pox on the clown who dug up a 20 something year dead thread to show us that he thinks he is an expert on something though. I still say that threads should lock after being dead for a certain amount of time and only the original poster can reopen them.

 

@krylon32 here you go, first Pic is shock just hanging and you can see lower shock mount made onto the lower bar bracket.

2nd Pic is shock bolted to the mount so you can see the angle of the shock in position.

 

My original goal back in 84 was hang the rear so no suspension showed behind the axle. I continued that theme with yellow giveaway car pictured on the first page and several after it. Doing it again with the new highboy 3 window.

 

I had considered hanging the shocks on the front but space there is at a premium. Even considered mounting the bottom of the shock to the back part of the lower link bar but thought if I did then I'd only basically have the upper bars to adjust pinion angle with.

Most of my rearend will be hidden if I get the rear height where I want it and still considering running 32' style gas tank.

I figure most will see the lower shock body and think it's a coilover. That's one thing I do like about quarter elliptical springs, they're easy to tuck up tight and hide...

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That is an example of the proper application of shackles, because while the natural rotation of the diff under power would cause the diff to flag, that is counteracted by the upper triangulated tracking/panhard bar. Really nice engineering and execution. Other methods allow the diff to rotate a bit clockwise/counterclockwise freely in travel without shackles. Both methods work well as long as the engineering is thought out.
As to the pox, kinda reminds me of when I was in high school in the 70's. Somebody had written on a locker with a felt pen. "I am a child of God". The next person wrote under it, "You are a vandal". The next person wrote, "You are a hypocrite". The next person wrote, "So are you". Glad we have the internet now. Saves on marker pens and all of that janitorial cleanup.

 

To hell with that. There is so much great information that comes out of old threads being brought back up .If you see an old thread that offends you ,Just move on. This site is based on old history, with much to learn. Have a great day.

 

The biggest challenge of being a clown is putting up with the tantrums of the children.

 

My engineering brain says to me shackles are necessary, but when I look at all the pre-war speedsters with 1/4 ellipticals, I don’t recall seeing any. As such, I designed my front 1/4 elliptical setup without shackles. The springs along with the friction shocks act as a 4-link type setup. Mine will be similar to this.

 

Looks like hockey pucks for bumpers. Good use

 

Shackles or no shackles, I always look at the rotational forces that I expect to see on the axle. Up front, (like Ziggster) the axle will tend to put a low mounted spring in compression under its most extreme condition - panic braking. A common leaf spring with little arch should be able to control the axle since the load pushes the spring rearward into its mount. The amount of load is also mitigated by the small contact patch of most hot rod front tires. No shackles are needed although they could be used if there was a separate pair of lower control arms. It’s much cleaner as it is.
Having seen the carnage inflicted by drivers happily dumping the clutch, I don’t like to use 1/4 elliptics with no shackles as lower control arms on a rear axle. Again the rotation of the housing under acceleration puts the spring under compression but the forces can be much greater causing the spring to arch and the housing to rotate. Using shackles, the spring just bares the weight of the back of the car while 4 link bars or ladder bars maintain the position of the rear axle.
You could make a case for using 1/4 elliptic springs effectively as a lower control arm on a very light, low powered cruiser but I don’t usually build stuff like that.
Or you could take a chance and opt for no attachment at all….

 

This makes more sense to me now that you mention the potential torque the rear axle would apply to the spring. I’ll have to look into using shackles for my rear 1/4 elliptical setup. With my mild flathead, it might make around 200 ft-lbs of torque, but I also have a T5 out of a Mustang, and the rear diff ratio is 4.11:1. This might make for some higher than “normal” forces on a hard launch.

 

I really love this pic. Not sure how she could see what was in front of her. Can't tell if it's shackled. Also curious if it's a torsion setup. I've really enjoyed the contributions here. Really appreciate when someone has done something and has had success (or failure) that they can share.

 

I prefer using quarter elliptical springs on the rear in a weight bearing capacity only.

Reasons are being so short and the fact that springs are made up of thin pieces of steel and as mentioned above dumping clutches/hard use can be really hard on them, I've actually seen on set bent right behind the small eye on the main leaf.

Another reason is I like using "solid" style suspension, 4-bar, ladder bar, hairpin etc. I prefer the actual torque load transferred to something solid and that doesn't always mean "bulletproof" either.

Thru the years I've fixed plenty of race/street car rear suspensions that thru abuse were failing. Actually had one car rip the ladder bar axle mount completely off of the rear axle tube and turn sideways under the car at a traffic light launch and end up sideways in the intersection. I've ripped the spring perch completely off of a rearend on my own car and dropped the body down on the rear tire.

I'm not telling people not to do it or they're wrong I'm just conveying the reasons I prefer not using quarter elliptical springs as a mounting point on rear suspension....


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The car that I'm going to use quarter ellipticals on is a '35 3 window, chopped and lowered with skirts. I have an Olds 303 and a '65 Buick diff. There's no crazy horsepower. Since I'm not using an early ford drivetrain, I opted away from split bones and the original spring. Splitting the rear bones messes up the whole concept built into the closed driveline system and really starts to twist things. Those bones weren't built for that. Quarter ellipticals have the advantage of allowing you freedom to set ride height. I kinda settled on lower QE's with upper tracking bars at 30 degrees, no shackles. I'm just curious what the tangible difference would be between a 4 bar setup with 30 degree angled uppers and coilovers. In that setup, there's no shackle to be found. You have bars, springs, and a fixed path of travel. The reason that I'm clinging to this idea is that I am trying to keep this build as traditional as I can, using vintage parts as much as possible.

 

Does anyone happen to remember a build thread on a Model A Roadster from several years ago that was built by a gentleman, I believe from Iowa, who used basically a triangulated four-bar setup but was using unshackled quarter elliptics as the the bottom two bars? If I remember correctly, he did some drag racing with it and I don't recall him commenting on any adverse effects of having unshackled quarter elliptics serving as the lower bars as well as the springs. If my memory serves correctly, the car was a dark blue when completed.

Lynn