Front suspension planning, 1/4 Ellipticals

[Dirtyrat]

Just doing some rough planning on the front axle, and suspension.

The plan is the speedway 1/4 elliptical springs.

Now for the question, using the stock ford beam axle from 49, with steering behind the axle, it appears as though it would be easier to make things work with the spring as the top arm of the 4 link, and a single lower link on each side triangulating the front axle. (green circle is where the steering link is 1"Ø)

Obviously this will create a change in caster on suspension travel, reducing caster. Does anyone see this being a problem? Or should I continue on sorting out how to put the spring as the bottom link? Suspension travel is an issue I'm worried about the spring hitting the steering link (obviously I would design it so it will not, but that creates an issue with how low the spring eye needs to be under the front axle).

Thoughts?

 

[gold03]

Hey DR, I really like this type of suspension. Most I have seen were spring on top. You could form lower control arm around steering a little if needed. Somewhere I saw a really good write up using the speedway stuff. I'll look around to see if I saved it anywhere.

Gold03

 

[Dirtyrat]

Its weird cause most I have seen that make it like a 4 link with no shackles have the spring on the bottom... just having issues with that, and the steering being behind the axle...

 

[gonegonzo]

I'm at the same stage you are DR . I like that set up as well but am getting overwhelmed with the geo's and such . I've even been tossing around rack and pinion steering but it's early yet .

I'll follow along and see what happens here .

gonzo

 

[Dirtyrat]

I'm going to draw up some more ideas tonight and see what I can come up with, my main issue is having the lower spring mount be the lowest part on the suspension/frame. I have to get new tires for the front, I may opt to go a bit taller and get the height of the axle higher so I am happier with the lower spring mount having enough ground clearance.

 

[Ricks Garage]

This setup works great on mine.
I used Cougar thrust rods to act as shocks and to triangulate
the axle. I used stiff springs so there is little caster change .

weld on......[

 

[donsrods]

I don't see a problem. If the front end of a hot rod moved up and down a lot it would affect caster angle, but typically a front will only bounce an inch or two at most, unless you have some very weak springs.

Don

 

[Dirtyrat]

My calculations put the speedway springs around 200-230lb/in rate....
Mounting effects the rate too.

Anyhow, I'm estimating about 1100-1200 lbs up front so less than 3" of deflection at static load.
The speedway springs are, if I remember correctly, 5.5" before they are completely flat from loading.

 

[gonegonzo]

I'm sorry for the lack of knowledge on this set up . I understand the physics but not what material to use .

Is it my understanding with what's said in this thread , that I will need a specialty spring to accomplish the 1/4 eliptic sustem ?

Is there more to it than cutting a leaf spring and using the longer half for the suspension ?

I'm at this critical phase in my chassis planning . I'm stuck until I understand what to buy . I'm not trying to hijack your thread DR .

Thx ,
Gonzo

 

[Dirtyrat]

I'm sorry for the lack of knowledge on this set up . I understand the physics but not what material to use .

Is it my understanding with what's said in this thread , that I will need a specialty spring to accomplish the 1/4 eliptic sustem ?

Is there more to it than cutting a leaf spring and using the longer half for the suspension ?

I'm at this critical phase in my chassis planning . I'm stuck until I understand what to buy . I'm not trying to hijack your thread DR .

Thx ,
Gonzo

I don't see why using 1/2 of a leaf spring would not work.
I ended up with speedway's 1/4 elliptical springs, if they are not enough I'll have some made up I guess.

I also ended up going with the spring above the axle, so that the spring eye comes right over the original spring mount area on the axle. When i get the frame home I'll probably start fabbing up the brackets for the spring and arms.

 

[bob w]

Here's the setup on my son's '27 roadster. Datsun B210 springs cut 2" past the center bolt hole. Had to add a long leaf to support the weight. This arrangement uses no shackle as the spring and the bar and the same length. I have also done this on a rear suspension.

 

[gonegonzo]

DR ,

I was looking at Speedways springs . Which one did you go with .

I want to make everything I can to keep this project affordable . However , I want the suspension right .

Bob W.

Can you give me a more detailed picture front and rear ? I'm trying to visualize your front set up .

Thx
Gonzo

 

[Dirtyrat]

Right now all I have is sketches. Until I get the frame home, I wont have much to look at.

I can try to post up some cad drawings of what I was planning on if you like?

I bought the speedway springs, not the posies ones.

 

[bob w]

This is the only other pic I have. The roadster is at my son's house buried under household items.
In the first pic on the left side you see a square nylon block. It is at the front corner of the frame. he springs are pretty long and run down the side of the frame. That provides more wheel travel. I put the nylon "rubbing" blocks on to perform the function of a Panhard bar. There is 1//8" clearance between the side of the spring and the block. Actually, the spring never moves to the side enough to touch the block.

In the second pic you can see there is no shackle. The roadster has about 10,000 miles on it. The suspension is softer than an early Ford style cross leaf spring. While it rides better I find it a little less stable over 60 mph. I have repositioned the shocks to dampen the spring action but a little more dampening would be good.

 

[gonegonzo]

D R ,

I'd like to see the cad drawings . An idea here and one there might bring this project closer to completion .

Bob ,

I like your set up but I'm thinking a hair pin instead of a single bar . The nylon blocks are a super idea .

Thx ,
gonzo

 

[Dirtyrat]

I'll see if I cant get something posted up late tonight, I'll be drawing up some things I need to make.

I was planning on having the springs on the axle like above, but the 2nd link above that coming in at 20 degrees rather than below. I'm not a fan of anything suspension related below the axle line if I can help it.

 

[gonegonzo]

Where are we with this post . Anything new ?

Gonzo

 

[Dirtyrat]

I forgot to post pics, I'll get to it eventually =)