52 inch front springs

[marklein]

Anyone ever tried putting 52 inch rear spring pack on the front? By making a new rear hanger moving the rear hole back 4 inches, 52 inch rear springs could be used in the front. In theory it should make the ride considerably better. Thoughts?

[my5thmopar]

What about the front distance? Same as stock or else stuff isn't going to hook up. If it's the same, I don't see why you can't.

[Conrad]

Anyone ever tried putting 52 inch rear spring pack on the front? By making a new rear hanger moving the rear hole back 4 inches, 52 inch rear springs could be used in the front. In theory it should make the ride considerably better. Thoughts?

I have to admit that I’ve thought about the rear hanger but the frame shape discouraged me from dreaming more about it. One of the drawbacks of de-arching springs is that it pushes the front hanger forward, which reduces the amount of free travel. Moving the rear hanger back would neutralize that effect. Not sure how noticeably better the ride would be. It would be interesting whether moving the location back tilts the axle back to increase caster. You may also have to flip the eye orientation to avoid contact with the frame.

I wonder how much true engineering went into the front suspension. I’m sure there was plenty when the trucks started using parallel front springs. But how much engineering thereafter probably has more to do with load calculations than driving dynamics.

[Wildergarten]

As I recall, the way the current rear hangar on the front springs works, it distributes the load into a bracket also supporting the bell housing. There is enough steel there to spread that load into the frame because (again as I recall) riveted top and bottom. The weight of the engine/transmission presses down on the bracket opposed by the upward forces from the spring hangar, thus reducing everything but compression loads on the frame. Without that support, you are putting a sharper load on the frame without those compensating forces, thus inducing more stress. That spring hangar is also wider than the frame, so the hangar transmits both torsion loads in turns and moment loads from impact into the frame at that "crossmember" bracket. The bracket thus transmits those loads more evenly into the frame and reducing the point stesses. Remember too that without the spring hangar helping to hold up the opposing weight from the enginine/trans pressing torsion loads into the frame, those forces go uncompensated. You would be putting a moment into the frame along its length instead.

Personally, I wouldn't mess with any of that without either serious analysis or bracket fabrication to distribute those loads. There was a LOT of WWII military gray-beard field experience behind that kind of design. I do have a bare '68 W200 frame outside right now and would be happy to take photos of that bracket for you so that you can see the whole thing more easily and I can see if I my recollections are mistaken.

[marklein]

I have looked at this seriously, the rear spring point would only be 1.5 inches to the rear of the existing bracket. I had mine off to fix cracks and they are now bolted on. I would keep the spring the same distance from the frame that it is stock. The 52 inch spring is a 24-28 split so 24 from the front changes nothing. Making the hanger piece is relatively simple, and as long as i get the spring in the correct position, the only thing that should change is the ride. I think I'm going to try it and see if it will work, if not, I have the pieces to make it stock.

[Wildergarten]

Re the image below and if If were me, moving that hangar backward aligns the center of the shear load from the spring with those two bolts holding the left side of the body bracket and the rivet on top all in a nice straight row at the maximum point of shear.

I'd at least form a 3/16 X 4 spreader plate between the hangar and those bolts at the front edge of the transmission support bracket extending to the far side of the body bracket and another "fish plate" (diamond shaped) doubler on the inside face of the channel, especially if that area had a history of cracking. But that's just me.

[earlymopar]

You would also need to verify the distances from the center of the spring set to the front and rear eyes to see where the rear springs are in comparison to the fronts. The mounting location is almost never in the center of the spring pack. Overall length is only part of the equation.

- EM

[marklein]

One of the reasons I'm looking at this is that the 52" spring are 24-28, the same front distance as the original springs.

[earlymopar]

Understood. That is certainly a good discovery and ought to open up some options.

- EM

[marklein]

Have 1 hanger made, not back as far as I thought it might be. I'm using 1/4 wall material, a bit thick than the oe bracket.

[Wildergarten]

I plan to switch out some rear springs and a front crossmember.
Where are you getting your Gr8 frame bolts?

[marklein]

One side mocked up, the front hanger now sits at the same 63 degree angle as it did before. Gained about an inch of clearance between the spring and frame.

The attachment 20181025_231623-567x1008.jpg is no longer available

[marklein]

Originally I added a plate on the top side of the frame just above the spring bracket for strength, as this area had some loose rivets and some small cracks. It can be seen in the from above photo.

[Conrad]

Thanks for the updates. Am looking forward to the completed view and of course how it works when driving.