Differences between our shackle flips and backwards compatibilityUpdated 5 months ago
We make two shackle flips - our regular one that is designed to work on all trucks with stock leaf springs or aftermarket leaf springs that are not progressive, and our progressive-rate shackle flip which is made for trucks with progressive rate leaf packs.
A progressive rate leaf pack is not very common, but they are used in some Carli 2nd gen suspension systems. These spring packs are made by Deaver, however Atlas also makes them to order. The progressive leaf pack is much thicker because it's designed to eliminate the factory blocks. These leaf packs usually have more than 10 individual leaves in each spring pack, to provide the height needed to offset deleting the stock block, and to provide a smoother transition as the spring pack compresses. If you have a progressive rate leaf pack, you probably put it on the truck yourself, but sometimes you'll find a truck for sale that has them. Just count the number of leaves and you'll know if they are progressive or not. The trick here is that you might get confused if someone used an "add a pack," which maintains the factory leaf pack but then replaces the factory block with a mini pack. This is not the same thing as a progressive rate leaf pack, however for the purposes of selecting which shackle flip kit to buy, you can go either way with this setup.
The reason we make a progressive rate shackle flip is because people who have those leaf packs don't want the truck to sit any higher, but they want the advantages that come with a flipped shackle (compression setup). A progressive rate spring pack will usually have multiple center pin holes which allows you to adjust the axle location without the use of zero rates, saving an extra inch of lift height. We relocated the shackle mounting point up as high as we can and offset it to keep the shackle angle where it needs to be for maximum performance. Using the progressive rate shackle flip on a truck with regular leaf packs (OEM or aftermarket, but with only 3-6 leaves per pack) will result in the shackle angle not being correct.
We get some customers who want to minimize the lift height gained from a shackle flip and think that running the progressive rate shackle flip on a truck with regular leaf springs is fine. Just because you can bolt it up, does not make it correct. If you don't care about the shackle angle, it will work. But we don't advise it and that's not what this product was made for. When the shackle angle is too vertical, the truck will get really squirrely. Could we make a 3rd shackle flip that is for guys who want to run the progressive shackle flip on regular leaf packs? Yeah, but the number of people doing this is too small to justify the expense. Just use the shackle flip that we spent a lot of time designing for your specific needs. It's like with the 2nd gen track bars, could we make a bracket so you can use a 3rd gen track bar on your truck? Sure, but why? The 2nd gen track bar we make is a way better product than if you try to retrofit a "newer" track bar just for the sake of bragging online, or whatever the reasoning is. Some of you guys try way too hard to be different, save that stuff for your airbrushed tailgates and clown car wheels, leave the important stuff like suspension and steering alone. 😂
A regular leaf pack has 3 to 6 leaves usually. The design of our regular shackle flip is based around these very commonly used spring packs. 99% of customers should use the regular shackle flip, part number 1007. This will allow you to remove the factory block if you want, get the axle centered, correct the pinion angle on the differential, and reduce axle wrap drastically and increase the unloaded ride quality of the truck very noticeably, while only adding about 1" of lift in the back. If you're running 2" or 3" coils or spacers up front, this shackle flip is a natural complement to your front suspension height. You also gain the ability to correct any truck lean, which almost always comes from the driver side leaf pack (there is a lot more weight on this side of the truck). So why use a shackle flip that isn't designed for your leaf pack? You don't gain anything from it other than a slight difference in suspension height, at the cost of the suspension not working properly.
If you currently have standard leaf packs and are planning to install progressive leaf packs in the near future, then you could run the progressive shackle flip on the standard leaf packs temporarily. Just understand that the rear suspension will have some quirks. The best way to avoid this is to keep the truck loaded with weight to help the shackle angle until you swap the new springs in.
If you have our standard shackle flip and end up putting on progressive rate springs later, this setup will still work without any compromise, except that the lift height will be about 5.75" inches higher than the advertised lift height of the springs. Remember, the standard shackle flip is designed to eliminate the factory block. The progressive leaf pack is also designed to do that. So you'll end up with a pretty big lift in the back, but it will work good if you plan to run 7" coils up front.
Any other questions, send us an email anytime!