quarter eliptic setup...my way anyway.

Here's a few pics of a suspension setup I am doing on a buddy's 27 coupe....we used springs from my scrap pile and my pal cut all the gussets and hangers and brackets on his plasma cutter. I did a similar setup a few years ago but with 2 upper triangulated bars....we decided to try something a little different this time with just the one upper bar. I think the springs will be able to control any lateral movement (not like it's a road racer) Still have to add the shock mounts.

 

Springs shouldn't be used to control lateral movement. You should add a panhard bar or watt's linkage. Other than that, it looks pretty solid to me.

 

I think a lateral locater (panhard or Watts link) will be required.

Edit: It appears that pinstripebob types faster than me.

 

on a parallel leaf setup don't springs control lateral movement?

 

Brewsir, how bad is the Pinion angle change? I mocked up a torque arm like that and scrapped it due to crazy changes in angle (mine was a shorter arm however)

 

They normally have a panhard bar if it's a factory set up, I believe.

 

Bullshit.

How many parallel leaf spring suspension cars and trucks
have been produced without a Panhard bar ?

Millions ?

 

The only OEM parallel leaf rear suspension to use
a Panhard bar was a Chrysler minivan.

 

Actually ya, you might be right. I know my Cad has one, but I helped my friend lower his truck and I think it only had an anti-roll bar.

 

Leaf springs that are anchored at both ends don't need a Panhard bar. The fact that leaf springs won't bend sideways keeps the rearend located under the center of the chassis. With semi-eliptics---well---I just don't know.

 

correct

 

Since the upper bar and the leafs are essentially the same length there is really no change in pinion angle at all....much like a 4 bar setup.

 

Well...the leafs still won't bend sideways and are anchored very well at the frame end....and the brackets on the axle are 1/4" plate with a nice box so I don't think that end will go anywhere either.....and...it is going on a 27 T so maybe a 2500 lb car. I really think it will be no problem.

 

I agree that parrallel leafs will stop lateral movement, but that's only when they are anchored at both ends. Your setup will work on top with two points anchored on the frame and the one point on top of the rear end. Everything else looks good but I wouldn't trust it with just the one bar on top.
Del

 

If you triangulate the center linkage on top of your pig it will solve your lateral movement issue. Easy fix too, just add another arm from the frame to the pig center point or re-engineer your current arm. Although you are correct about parallel leaf suspensions I would still add this loactor for better handling. My old Jeep Cj had no locators besides the springs but it was awful around the corners.

I would also caution about welding the spring retaining bolts like you have. Even if you started with grade 8 bolts, the heat from welding them could have brought their temper back down to grade 2 level. I can't presume to know why you did this but I would grind them off and restart using grade 8 bolts with locking nuts below.

Welds look good and I like the stiffeners you put in the Z'ed section, they look like they're out of an ocean liner. Nice work.

 

Look under a solid-rear-axle Alfa Romeo from about 1974.
In place of your upper rod, they used an A-arm, so as to provide lateral location, incorporating a ball joint instead of a heim joint for compliance.

They also had a Panhard rod. One of the best-handling solid axle cars.

 

I would say go for it and if it becomes a problem add the panhard. I would be more concerned on the single bar designed to keep rear end roll from happening. Heim ends don't seem that strong if a 2500 lb car grabs traction or under wheel hop conditions. Never seen a rodder yet that hasn't got on it sometime.

 

I had originally started with an A arm type upper bar but our racecar neighbor thought it would bind (and convinced us of the same) under articulation...the top center of the pumpkin rolls about an inch from side to side as the suspension works. I think rubber bushings in the eyes og the arm would parobably allow enough flex to work but changed to this anyway.

As for welding the grade 8 bolts...it seemed like a good idea at the time but you make a good point. think I'll fix that.

 

Thats kinda where I'm headed...it's easy to add if needed. The heims are 3/4 x3/4 from a stock car racer....I'm sure they are not going anywhere.

 

How many QUARTER ELLIPTIC rear leaf spring suspension cars and trucks have been produced??

I'd add an A-shaped bar to the top instead of that simple link. You'll get the same travel, but that'll keep the rear end from shifting from side-to-side. Never underestimate the forces at work. You'd be surprised how much crap moves around when you're driving. The springs MIGHT hold it in place as it is, but then you're putting a LOT of sideways force on your mounts. With some other locator the springs and mounts can hold the rear end up and not have to worry about sideways forces. Why induce bind if you don't have to?

 

Yeah, it looked long enough but I tought I would ask!

 

That was my original design(with an upper A arm setup) but I got talked out of it by a guy that really understands suspension design (he builds racecar chassis for a living) he had a good point and I went with it. We will probably add a panhard bar before it's done.

 

what rear end is that? i thought it might have been a toyota but all the toyota rear ends that i've ever seen have a flanged input and not a yoke. my guess is it's something japanese.

also what size heims are you using?

***edit*** saw your post about the heims. thanks.

 

3/4 heims I think it's an 8 inch ford rear

 

8" ford is more oval than round. plus most had a pair of dimples in them.

 

Guess I don't know either then...it came with the car.

 

I'm glad to here you say you'll put a panhard bar on before you're done because a few of the replys here are right, parallel leaves are attached at both ends, quarter eliptic, not so much, it may not give you trouble right away but it will one day. Does'nt take that much to be sure everything stays where it should.

Oldschool66

 

My modified (avatar) has 1/4 elliptics similar to your setup.....no shackles. The rear is located by a slightly triangulated 4-link using flex bushings at all of the ends. There is no side-sway that I can feel and it drives just fine.

 

Or not. The Bugatti, one of the world's most evil handling cars; the Type 35 alone having one of the worst records in racing; used quarter elliptics on nearly every car he ever built. Even the Royales.

Ettore NEVER used a panhard rod (he never even worked for them, t'was Deutz where he started).

I would, however, build a box around the leaves, for better lateral location.

Your friends is very correct about the A arm upper - a simple diagram will reveal just how much it would bind.

One more thing to consider: a panhard bar, no matter how long, WILL move the rear from side to side. This WILL cause the leaves to also move sideways, which they are not designed to do. I usually cite the example of the early fifties Olds', which will half change lanes given a good enough bump to both wheels at once. It uses a factory panhard bar, a long one. You still feel the effects...

Cosmo