Shackle flip or new springs?

[Chevyman63]

I currently have 4" lift blocks in the rear and I would like to change this. What do you guys think is the better way to go? I've looked at the DIY4X shackle flip and am thinking about going that way as opposed to buying new rear springs. Lets hear the pros and cons. Thanks.

[AJs72K5]

A DIY4X shackle flip, with 4.5 inch shackles, will net you 4" of lift with stock springs. I just finished mine and added 2" springs for 6" of lift. It made a huge difference in the ride from the 8" springs it had. Check out my build if you want to see the install and how the flip looks.

The only con I can think of is that it moves the axle forward about 1.5" - 2". You'll either need a set of zero rates/ EZ Inch's (which will lift you another inch) or a set of spring perches with multiple offset holes to move it back. And if you do that, either plan on new spring plates, or drilling holes in your existing ones to compensate for the "moved" spring pin. It's a really easy install...the hardest part is knocking off the factory shackle hangers.

[Chevyman63]

Originally Posted by AJs72K5

A DIY4X shackle flip, with 4.5 inch shackles, will net you 4" of lift with stock springs. I just finished mine and added 2" springs for 6" of lift. It made a huge difference in the ride from the 8" springs it had. Check out my build if you want to see the install and how the flip looks.

The only con I can think of is that it moves the axle forward about 1.5" - 2". You'll either need a set of zero rates/ EZ Inch's (which will lift you another inch) or a set of spring perches with multiple offset holes to move it back. And if you do that, either plan on new spring plates, or drilling holes in your existing ones to compensate for the "moved" spring pin. It's a really easy install...the hardest part is knocking off the factory shackle hangers.

Thanks for the input AJ. I was looking at the EZ Inch blocks as well. I was hoping for about 5 inches so I didn't have the dreaded saggy butt. If I use these, it sounds like that would be the easiest way to go.
Thanks again.

[vtblazer]

ORD makes a set as well if you care to compare.

Only thought I've ever had about putting new springs up front and doing a shackle flip in the rear is that you end up with the front and rear of the vehicle having different spring rates, thus different reaction's to bumps and/or driving condition's going down the road.
May not make any difference but I've always thrown it into the 'con' list only due to being an unknown.

Guess I don't see why a flip would move your axle so much either...gotta look into that one more.
Front hanger doesn't change, just the rear gets longer, correct?

Never looked all that deep into it but definitely worth doing now being by spring I might be doing it too.

[Yukon Jack]

Easy to explain in person but difficult to put in words. The rear shackle flip drops the back end of the spring but not the front. This causes the arch is moved downward and a bit forward. To make it easy. Cut out a half circle of paper and put a mark for your center pin. Put the cutout against a flat surface like a ruler and look where the center pin is located. Now, leave the front part of the circle touching the flat surface but move the back off the flat surface a bit and watch how that affects the location of the center pin.

The effect is more pronounced on the 67-72 trucks and first gen K5's since the factory doesn't appear to have centered the axle in the wheelwhell.

[vtblazer]

Originally Posted by Yukon Jack

Easy to explain in person but difficult to put in words. The rear shackle flip drops the back end of the spring but not the front. This causes the arch is moved downward and a bit forward. To make it easy. Cut out a half circle of paper and put a mark for your center pin. Put the cutout against a flat surface like a ruler and look where the center pin is located. Now, leave the front part of the circle touching the flat surface but move the back off the flat surface a bit and watch how that affects the location of the center pin.

The effect is more pronounced on the 67-72 trucks and first gen K5's since the factory doesn't appear to have centered the axle in the wheelwhell.

I can see/understand how it might happen that way but still surprised at how much it moves it, thanks for 'splainin'.

I like zero rates, so if that's the cure no biggie, easy fix.

[Chevyman63]

Originally Posted by vtblazer

I can see/understand how it might happen that way but still surprised at how much it moves it, thanks for 'splainin'.

I like zero rates, so if that's the cure no biggie, easy fix.

That's what I was thinking...just use the zero rates.

That was a good explanation YJ, thanks guys.

[Chevyman63]

Originally Posted by vtblazer

ORD makes a set as well if you care to compare.

Only thought I've ever had about putting new springs up front and doing a shackle flip in the rear is that you end up with the front and rear of the vehicle having different spring rates, thus different reaction's to bumps and/or driving condition's going down the road.
May not make any difference but I've always thrown it into the 'con' list only due to being an unknown.

Guess I don't see why a flip would move your axle so much either...gotta look into that one more.
Front hanger doesn't change, just the rear gets longer, correct?

Never looked all that deep into it but definitely worth doing now being by spring I might be doing it too.

Good things to consider. But I wonder if the spring rates would make a difference because of all the weight of the engine up front as compared to the weight in the back...or was this taken into consideration back in the design stages of our trucks many years ago? Another question that I have, is there a difference between front springs for a truck with a small block and a big block?

It looks like I'm going to go this way, so I'll be the guinea pig. You do realize that this may take a lot of testing time and plenty of beers for the discussion afterwards. Kurt, I expect you to be here for the testing.

[vtblazer]

Originally Posted by Chevyman63

You do realize that this may take a lot of testing time and plenty of beers for the discussion afterwards. Kurt, I expect you to be here for the testing.

oh man, how well do you know me or what?

[ClassicJimmy]

I understand the shackle flip & all & the pros for it & plan on doing one myself on my Jimmy. Shackle flip & zero rate blocks are probably less costly than my idea, but if you wanted to, couldn't you order longer springs to move the axle back & in doing so you'd have a smoother ride in the back? This was my plan, but I've only been dreaming about doin it - haven't got to put into action, yet......