Shackle question???? Need info!

[FleXXedOUT88]

Ok I have a shackle question. I am doin a shackle reversal with 54in chevy springs. and I will be countsinking the shackle into the frame rail. Much like this pic that was posted in anoher tread.
http://i74.photobucket.com/albums/i277/onesun06/stuff030.jpg
now my question is what angle should my shackle be at? Should it be strait up and down? Should it be more like what is in the pic? What about lenght? I always thought the shorter the shackle the better. Bt I should have to make the shackle pretty long if it is goin thru the frame rail. Just wanna do it the right way the first time. Thanks.

[gotmike]

the longer the shackle the more flex you can get... to a point... eventually too long a shackle becomes a weak link... but yes... a slight rearward pitch to the shackle when at rest is desired... that way you can't "fall off" your shackles... or invert the shackle...

[Hard Knocks]

I have always used boomerang shackles,and set them at 45* with the weight of the vehicle on the springs

[FleXXedOUT88]

Ok so at what point does the length of the shackle become unsafe? And when u say rearward pitch do u mean where the shackle attaches to spring or where it attaches to frame? And how much is slight? Is 45 degrees to much??? I'm kinda lost here?

[gotmike]

in the pic... if you compress the spring then it pushes the shackle back but that shackle can only move about 15 degrees max before it contacts that body mount... so to me that would seem to be a bit too much rearward deflection... i would go about 30 degrees past vertical from the frame mount to the spring eye... as for how long is too long... that depends on gusseting... if you stick to about 6-8 inches and reinforce the sides like in the pic then you should be okay with individual link shackles... but any longer than that and you'll need an H shackle... with a gusset in the middle... which will hurt flex a bit...

essentially if the shackle goes back... away from the axle... it can't reach a "breakover" point because the spring itself is in the way... the spring will hit the frame... but if the frame anchor is too far away and the shackle looks like this ( \ ) then the shackle can actually invert itself on extreme flex and force the spring eye end higher then the frame mount end which will arch your spring all the way out locking it in position... one way of combating this is to put limiting straps on the axle... i've even seen bump stops retro-fitted onto the shackle to keep it from inverting... each rig is a bit different...

[FleXXedOUT88]

thank you very much very informative... now i was planning on ordering the h style shackles... but u meantioned the link type is that somethign i could build myself??? what is the acceptable way to bulld something like that?:confused:

[gotmike]

my shackles are simply 2 pieces of 1 1/2" x 1/2" steel bar with a hole at either end measured out and centered... one for either side of the leaf spring... mine are only about 7" long... so i don't have a gusset inbetween them...

[FleXXedOUT88]

oh ok cool that i can handle. also since i cant correct caster on the axle tube by rewelding the perches due to the d44 having the perch cast into the housing. and i am goin to be running a good amount of lift.. could i adjust my pinon angle with the angle of the leaf spring? i know that will have an affect on my caster and such. or should i make the leaf spring perfectly flat?

[gotmike]

they do sell shims to correct caster angle... or you can use the shackle to a point...

[FleXXedOUT88]

thank you very much for the info.