Front Front shackles 1959

[dennislbrooks]

It seems to me that the last year of the front front shackles was 1959. Then after, anything with front leaf springs had the shackles on the Front rear - 4wds like my 67.

I fought a darting problem on my conversion 1959 GMC Fleet 4wd - 85 running gears. My 1959 front leaf springs have all new bushings and pins front and rear. Also a new steering box, new ball joints, all new joints in steering. It has had the toe set to zero.

The only thing I had left was front front shackles unlike my 67 with front rear shackles.

Changing my 59 to be like the 67 is very involved but I have improved the steering with a 3/4 ton 4wd sway bar.

I wonder how the pre 1960 Napcos drove with the front front shackles.

[leegreen]

is this picture at ride height?



That drag link angle looks like it would make it turn left on bumps, it needs to be closer to level. Can you get a pitman arm with less drop or steering arms for the knuckles that sit lower?
Or raise the steering box.
Or convert to cross steer.

[dennislbrooks]

My bad, that pic above is with a 2" rise steering arm. I have since put the stock one back on and the steering link below is near level like my 67.

[leegreen]

Not sure I have anything valuable to add.
in both pictures the front ball joint on drag link looks like it is twisted, an issue with that?


The original TF steering box location behind the axle also had a pretty short drag link, putting the drag link pivot in front of the rear spring pivot. As the spring flattens the axle will move away from the fixed shackle and the drag link will force in a bit of right steer. Same things happens with your setup. Based on looking at some pictures the factory built in some downwards angle to the drag link so that as the axled moved up in it's travel the drag link arc of travel would add some left steer to counteract. With the box in front you'd need to angle the draglink up like in the first photo.

so IF you get darting to the right on braking try going back to the steering arm in first picture and see if it reduces the right dart or changes it to left dart.

If it darts either way randomly or following road camber, check alignment, maybe add some caster with a shim. You have power steering now so can deal with more caster.

[dennislbrooks]

Leegreen, thanks for the input. It was not so much on braking as a very slight turn left or right. It seemed to dart so that it needed corrected the other direction. Again, the sway bar has stopped pretty much all movement left and right on the front shackles which makes me think it is the front shackles giving to a point. One carriage bolt holds them together. As you said, steering box in front may have contributed to the problem with front shackles.

It is very drivable but this winter I may switch the rear and front mounts - about 8 rivets each side. I checked and the leaf center bolt is in the middle of the eyes so I will be able to turn them around.

I think I can straighten the front ball joint on the drag link for now. I have already added some caster.

[leegreen]

"very slight turn left or right. It seemed to dart so that it needed corrected the other direction"

Maybe a bit more toe or play with front tire pressures a bit?


I'm assuming everything is nice and tight. including rear shackles