Shackle flip

[Thumper]

Next installment in my question series!

The homemade shackle flip that guys are doing by cutting out the bottom of the stock shackle hanger... how much lift does it give? Is it more then the 4"blocks? I know I will have to shim the rear end up a bit, so if the shim goes in as well as the flip, is my rear end going to be 3" taller than normal? I already added 2 leaves to lift the rear just a bit higher than the front so... is it going to sit way high?

Thanks
Mike


<font color=blue>Thumper
85 Fullsize Jimmy

<font color=red>Lets Go Wheelin! </font color=red>

 

[Thumper]

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<font color=blue>Thumper
85 Fullsize Jimmy

<font color=red>Lets Go Wheelin! </font color=red>

 

[Blue85]

The shackle is 4" long (bolt hole to bolt hole). By flipping it over, the back of the spring is 8" lower that it used to be. Since the axle is located very near the center of the spring, the lift to the axle will be half of that. In short, the homemade shackle flip provides about 4" of lift to the rear of the truck. When I did it, it seemed like I had gotten more like 4 1/2, but I didn't measure before and after.

A shim only about 1/8" thick, so don't worry about how it will affect your ride height.

How much shim do you need? Since the spring is about 52" long (maybe an inch or so shorter from eye to eye at normal ride arch) and the back has moved about 8 inches, you are changing your pinion angle by 9 degrees. sin^1(51/4)=4.5. Most lift blocks have a taper of about 4 to 4.5 degrees, which is about what you want with a 4" lift. If you are replacing the blocks with a shackle flip, you need to shim for the difference, which is 9-4.5=4.5 degrees. Since shims are readily available in 4 degree, this is probably the one that you want.

'85 JIMMY
'90 paint/grill/trim 5"susp 33/12.5/16.5
Fresh 350 B&M '87 TH700