Leaf springs front suspension.

I've been looking at a few straight axle set ups and am wondering why they, the parallel springs, are installed with shackles in front and the fix mount in the rear very much like a CJ Jeep's suspension. Why? I would have thought the fixed mount would be up front so that the axle would want to come back under compression rather that trying to push itself forward. . Alan

 

this was covered some time ago but I'm to lazy to look for it. I can tell you that I mounted mine with the shackle in the rear and fix ount to the front. There was two sides to this if I remember correctly.

 

I put my shackles in the rear and fixed up front. Straight as an arrow at 134mph.

I think a lot of the Jeep guys use a reverse shackle kit which switches the shackles from front to rear. It's supposed to make a huge improvement.

Most guys that are building g***er style cars are probably just looking at the old magazines and doing it the way they used to.

 

I wonder if it has anything to do with stability while braking? Like maybe it kind of forces the tires against the pavement more when you hit bumps while braking?

Otherwise, it seems like it'd be more stable with the shackles in the rear. Who knows though.

 

My '31 Plymouth originally had parallel springs up front and the fixed mounts were in front and the shackles behind the axle. They had really ****py roads back then, so I'm guessing the engineers knew what they were doing back then. It does seem weird to put the shackles in front of the axle.

 

Thanks for the input. Seems like all the project I've seen lately are running the traditional setup and what confused me was they were getting new springs from Speedway??? I always preferred the fixed eye upfront set up in trucks. Was going to do my 55 Pathfinder but after seeing a 50 Chev G***er may do my 51 Pontiac coupe instead especially since it's still a field car.

 

I always thought that the solid mount was on the same side of axle as the sterring box

 

I've always wondered this, too.

I put the solid end on a Plymouth Coupe 'g***er' on the rear, too, because that is what I saw the old timers doin'.

My stock '57 Chevy truck has the solid mounts at the rear, and the steering box is behind the axle, too.

 

...Chevy pickups from the 30-50's all have steering box behind the axle and shackles on the front.

 

Guys it is to do with push pull steering geometry and under and over steer characteristic of the shackles being either at the front or rear.
It is easier to get right if they are the front but there is no hard and fast rules.

 

Here's another possibility:

As the front rises under acceleration, the front axle moves back slightly, and as the nose settles on the top end, the axle will tend to come forward a touch - might be good for a millionth of a second... or might help to keep from red-lighting by a thousanth. Okay - probably not a good reason.

The only serious reason I can see is that caster will improve under braking with the shackles up front, making the car less squirrely in the shut-down area.

 

Jeep box in front of axle, shackle up front. 79 ford 3/4t box in front of axle, fixed up front. I know from 4x4ing fixed up front better, less broken or bent springs.

 

From the little I know about leaf springs...I have this to offer.

The part of the spring that is fixed is more like a locating bar (like a trailing arm on rear coils) while the part with the shackle takes more of the spring function.

If a frontend has coils or transverse leaf, the locating bars (split wishbones, radius rods, etc...) never seem to go towards the front, so wouldn't it be natural to do the same with parallel leafs?

 

we installed a shackle reverse kit on my 94 jeep wrangler it stopped the bump steer problem i had after lifting it 5 inches