92-99 1500 Suburban only 4" Shackle Flip

92-99 1500 Suburban only 4" Shackle Flip

Some GMT400 full-size SUVs may use the Truck-style shackle flip, confirm your application by measuring the rivets attaching the shackle hanger to the frame.

As seen in Petersen’s 4WOR, 4X4 Power, Off-Road.com and ColoradoK5.com. Turns the factory rear tension shackle into a compression shackle for 4 inches of lift without using blocks. Bolts to factory holes with Grade 8 hardware for a stronger than stock mounting system. We also carry stock length u-bolts for installations replacing lift blocks. Check the notes below for details on the Ultimate Adventure K10 rear suspension using our 2.5" shackle flip kit.

How many of you want to get rid of your rear blocks? Due to popular demand, we’ve developed this kit to eliminate rear blocks. They're also an inexpensive and effective way to lift the back of your truck.

Our brackets bolt to the frame in the factory spring hanger holes and "flip" your factory tension shackle over to a compression shackle. The kits give four inches of lift (we do have 2-1/2" lift versions for some applications) so they allow you to use stock springs for a 4" lift, 2 inch springs for a six inch lift and so on.

Eliminating lift blocks helps reduce axle wrap and using flatter springs gives better ride quality and suspension flexibility. This kit is extremely durable with fully welded, ¼" gusseted brackets and all grade 8 mounting hardware. We even moved the mounting point forward to give you a better shackle angle. That’s why the brackets don’t look "straight". We now have available a kit to lift your '73-'87 truck or 73-91 K5/Sub 2 1/2".

**We don't recommend using our 4" shackle flip with our 6" Super Shackles, see explanation on that below**

For online installation reviews check out these links:

Shackle flip install by ColoradoK5.com

Shackle flip install by Off-Road.com

Shackle flips move the axle forward by nature, because they're only dropping one side of the spring. With a factory spring, the 4" shackle flip will move the axle forward about 1/2", this effect is amplified if the truck is lifted beyond the shackle flip (for example, an 8" lifted spring in addition to the shackle flip pushes the axle forward more like 1-1/2"). Many people don't do anything to counteract the axle moving forward, but if you want to push it back to the stock location we do have these offset plates that will do just that.

Tech Notes:

For the 73-87 trucks, if you have 8" rear springs you need to use our 2.5" shackle flip and 6" long shackles. This still gives the same 4" lift height and the extra shackle length will keep the shackles from flipping forward or back when the deeper arch spring extends under load.

These DO fit 73-87 (91) trucks with 56" rear leafs. The brackets are the same, and will mount directly in place of your existing shackle hangers.

Installing a shackle flip will move your axle forward. With a stock spring, it's not much, about 1/4" and most people don't notice. If you're using the shackle flip in conjunction with a lifted rear spring or block, that effect is amplified. With 8" rear springs and a shackle flip, the axle can move forward more like an inch, so you may want to account for that by re-drilling your spring perches, adding a set of our zero rate add-a-leaves to move the axle back or using our axle offset plates (if you don't want the extra lift from our zero rates).

Installation of the shackle flip kit requires removing the rivets from the factory frame brackets by air chisel, grinder, or your favorite other method. At that point, the holes are drilled to clear the bolts and the brackets are bolted on. This will most likely require removing the dropping the gas tank down on Blazers and Subs for access to the bolts. We've had good luck just hinging the tank on it's mounts so we don't have to disconnect the wires and hoses.

Pinion angle is a common question with this kit. The quick and easy answer is that there is no quick and easy answer. Proper pinion angle depends on drivetrain length, wheelbase, gears, tires, vehicle speed and more. It usually boils down to what works for your truck. In general, the shackle flip sets the pinion angle about right for most 4" to 6" lift Blazers and shortbeds, especially the later models with the aluminum transfer cases. Longbeds and Suburbans will probably (but not always) need to shim the pinion down a few degrees for best driveshaft alignment. If you have questions about how to set up driveshaft angles, visit www.4xshaft.com. That's Tom Wood's Custom Driveshafts website and has a good tech section with info on setting driveshaft angles.

***You may wonder why we don't have a Shackle Flip kit for more than 4" of lift. The reason is that to gain more lift, the end of the spring has to drop down twice the desired lift amount. In other words to gain 1 extra inch, we would have to drop the rear of the spring a full 2 inches. This drop at the tail of the spring can become a ground clearance problem and promotes roll-oversteer which is a handling problem in which the rear of the truck starts to feel "loose" under hard cornering with body roll. We've chosen the 4" lift height as the limit for these reasons and this is also why we typically don't use our 4" shackle flip with our 6" Super Shackles.

Load carrying ability is also a common question. Basically, if you keep the factory overloads, you won’t have any trouble. We've designed the shackle angle to retain as much load carrying ability as possible with a lifted 4wd. The brackets are much stronger than stock and the compression shackle doesn't compromise towing ability, many late model Dodge trucks are setup that way from the factory.

There is no more lateral lateral motion of the vehicle than with the stock tension shackle bushing setup. It may look as if the axle could move side to side easier, but the only thing that puts more leverage on the bushings is the additional ride height, which you also gain with blocks or lift springs.

76-91 1-ton trucks require a different flip kit than k5's, k10's and k20's. The kit is the same price, we just need to know it's for a 1-ton when you order it. The difference is that the spring center spacing on the 1-ton axle is only 40 1/2", and on the rest of the trucks, it's 42 1/2". The brackets are a different shape to reflect that.

Petersen's Ultimate Adventure K10 used our 2.5" shackle flip with a custom 5" shackle (since we weren't in production on our 6" HD shackles yet) and a '88-98 1/2T truck spring. The front spring hanger was moved forward about 6" and the shackle flip was moved back about 5" to accomodate the extra 12" in length over the original springs. This created a simple, durable and flexible suspension that worked great on the varied terrain of the UA05.