2" lift shackles WILL lift your van 2"s - leave it to the ex

[Bread Van]

The new leaf springs corrected the pinon angle and got rid of the vibes.
I was also previously using the Hellwig 815 helper springs with the shackles, (to compensate for the saggy leafs) and noticed that the vibration with the shackles alone was not that bad...but when I added the helper springs it became very noticeable.

So let me see if I can get this straight.
2" shackles caused a slight vibration
adding helper springs w/ shackles made vibration worse
but removing all the above and using re-arced springs for a 3" lift caused no vibration

Is this common? Do different springs somehow keep the pinion angle correct when shackles do not? I always thought it was simply the lift that caused problems with the angle

btw: I may be interested in those lightly used shackles

[Shad0wXCalibur]

I'm a little confused on that too, Bread Van. Lumpy said he had a slight vibration after he did his 2" lift which consisted of 2" body spacers for the front and shackles for the rear. I went up twice that using only new springs but have no vibration at all. I'm guessing the shackles do something funny.

[vangogo]

You read correctly Bread Van, those are the symptoms I had with each lift component. Shackles change the pinion angle, (which can be corrected with shims). Im guessing the Hellwig helper springs made the pinion angle worse because they stiffen the rear half of the leaf, it seems this would take the flex out of the leaf between the shackle and rearend, where a soft (saggy) spring would have flex that would have some 'give' and somehow reduce the changing of the pinion angle by flexing. (hard to explain, probably lost everyone there XD). You are also correct about the new springs keep the pinion at the correct angle, so no vibes =).

[Bread Van]

Well, the shackles only move the rear of the spring which would probably have a different effect on the angle of the rear axle compared to moving both the front and rear. I starting to wonder if somehow the act of unbolting the axle from the spring allows the axle to return to a more "neutral" position. I'm guessing most people do not unbolt the axle from the spring when installing shackles...but clearly must do so when installing new springs. I wouldn't think this would be very pronounced...hence my confusion. I'd have to look at everything much more closely to see how things might move, in reality, and how movements of different pieces are propagated through the driveline. I've never lifted a vehicle before so trying to "visualize" this is only getting me so far.

Off to the vet, my best old dog is sick again.