shackle help needed

[bigbadchev84]

ok well i wanted my truck huge, but i didnt want a really stiff ride, so i got the crazy idea in my head that i would just lower the front shacles down and use my 8inch springs and zero rates, well i didnt think about lengthining the rear shackles, i thought that it would help out with my front driveline, well i got to drive it today and the thing will not drive in a straight line anything over 10mph so i am gonna have to build longer shackles for the rear, here are some pics of what i am dealing with, how long do i need to make my new ones? and what thickness of metal should i use??

 

[bigbadchev84]

ok the stock measurements are 2inch on the front hanger and 3-3/4 center to center on the rear shackle......so since i am now 8inchs on the front hanger so would that mean i need to go for every 2inches 3-3/4" of shackle, so would i be right in thinking i need to go with a 15" shackle to return this thing back to stock specs???? if this is right, what if i went with a 12" shackle, would this still mess up my camber really bad? this thing already looks goofy i dont want huge ass shackles on the back, too.

 

[Greg72]

Just to clarify, you are not messing with camber when you change shackle angles......you are changing "CASTER". Caster is the imaginary line drawn between the upper kingpin and lower bearing in the front axle. You want the upper bearing to be slightly "layed back" from the lower which is probably what you're getting at. Longer shackles WILL mess up the caster.

Also, it's sort of implied but caster is only for a steering axle. There is no such thing as caster in a rear (non-steering) axle. Crazy shackle lengths WILL mess with your pinion angles no matter what, so you may end up with some vibes once you get the shackle lengths corrected.


As for the length of the shackles, it might be somewhat trial-and-error. For that front, it looks like you'll need to be at least 3" longer to keep the spring eye from hitting the frame as the spring flattens out. If you have any 3/8" thick flat steel that would be a good thickness to use. If the final design ends up being really long, you might consider welding a cross-brace between the inner and outer shackle plates to keep them from bending under side loads.

 

[BigCountryx]

To get your caster back to stock specs, you would have to extend your shackle the same amount you lowered your front hanger. So you lowered you front hanger 6", That means your shackle eye to eye should be 9 3/4" to be equal. You probably will gain around 3" more in lift also.

Lets see pics of the whole truck.

 

[bigbadchev84]

there are pics of it in my other thread "poser wheeling"