How-to Plans On Drop Shackles Nnbs

spikesputnik · July 24, 2009

HELP!? So I think I'm gonna do this myself, probably with help from a buddy, but it will be a first for either of us. Any pointers, suggestions or input would be much appreciated! THIS IS NNBS and 2WD Silverado EC. The local hitch place a tire store said about $200, but they have no actual experience with this exact procedure on this NNBS, so they would be doing it for the first time themselves, albeit with better equipment and much more undercarriage experience than me. But they might be less inclined to take the time and consideration to do a GOOD JOB like I will, so here goes. Some of this is original thought, so is pirated and accumulated from various posts. I'm doing the "no bed seam cutting or bending" method. ALSO THIS IS NNBS, NOT OLDER!! Comments about the procedure in general again are very welcome, but how it was done on other makes or year models are irrelevant...

Plan:

1)round up all of the appropriate wrenchs, sockets,extensions, ratchets, impact, compressor etc. Two 3 ton floor jacks capable of 18-20" lift, 2-3 ton stands capable of 16-18" (bottom of back end of frame is 13" above floor); I was thinking about getting them from a rental yard.

1.5) place chocks infront and behind front wheels and rocked in tight.

2)while still on ground, remove the 8 bolts/nuts holding the OEM hitch on(3 on each frame rail, 2 back by the bumper)

3)remove the rear 4 frame to bed body bolts, loosen the front 4 bolts

4)from each side simultaneously jack up near rear of frame(where usually is on lift) untill rear wheels just leave the ground and place jack stands, lower onto jack stands, remove jacks.

5) places jacks under axle or shock mount on each side of axle

6)jack up axle until it is unweighted and unsuspended-neutral and no tension on the shackles

7)remove lower shackle bolts, loosen upper shackle bolt nuts

8)jack up axle until spring eye contacts seam in bed, then continue to jack up lifting bed off of frame until there is enough clearance to slide upper shackle bolt under the bed and over the frame. Probably do this near simultaneously as to not twist the bed up on one side much more than the other.

9)remove upper shackle bolt, remove OEM shackle and replace with Belltech 2"drop shackle

10)lower axle to where lower shackle bolt can be installed. Torque both upper and lower shackle bolts to 37 ft-lbs

11)jack up frame from both sides at simultaneously, removing stands and lower to ground

12) torque bed bolts to 63 ft-lbs, reinstall hitch and torque to 75 bolts-83 nuts

13)ride 2" lower

OK. I'm a noob here as far as under body and on-jacks work goes. I'm plenty mechanically handy and mentally capable and of a balding vintage, but just do not have any experience with this type of job. So any advice, additions, suggestions, warnings etc are greatly appreciated!!! And yes, I can handle constructive criticism too. I know this would be a whole lot easier with a whole vehicle lift, but I'm actually looking forward to this little project in the garage!

Thanks in advance!!

Spurshot · July 24, 2009

You might want to look into correcting the pinion angle after it's lowered. Chances are that it'll be too steep (angled up) once it's lowered.

spikesputnik · July 24, 2009

Yes, I've been pondering that too. There seems to be a range of opinions on the necessity of this and depending on the amount of drop. Sounds like a good poll idea?

Zembonez · July 24, 2009

Yes, I've been pondering that too. There seems to be a range of opinions on the necessity of this and depending on the amount of drop. Sounds like a good poll idea?

One company I am involved with has installed hundreds of sets of lowering shackles over the years and never needed a shim. Lowering two inches will not result in incorrect pinion angle. Lifting or extreme lowering will... but 2 inch shackles are not a problem. I've run them on my current truck since new and have had them on many other trucks without issue.

Sounds like he has the plan all figured out!

Matt_ · July 24, 2009

If you take off the bump stop and put your OEM bottle jack between the axle and the frame you can remove the shackle without loosening the bed. I dont think I had to take my hitch off either..... Just jack the bottle jack so that there's no more pressure on the springs, remove the lower shackle bolt, lower the bottle jack until the upper shackle bolt can be removed. Then re-install with new shackle.

Edit: just took a look at my GMT900... looks like the hitch still needs to come off... but the bed doesnt.

spikesputnik · July 24, 2009

Zembonez- I'm glad you chimed in! You know I've been kicking this around for a while; thanks for the input. Care to comment on the bed loosening necessity, again? I beleive you did in the past confirm this, contrary to sk1er18's experience...

But the bottle jack idea to take weight off of the springs I like.

I may be making too much work out of this, just trying to not get in a pickle on a saturday afternoon.....

Zembonez · July 24, 2009

Zembonez- I'm glad you chimed in! You know I've been kicking this around for a while; thanks for the input. Care to comment on the bed loosening necessity, again? I beleive you did in the past confirm this, contrary to sk1er18's experience...

But the bottle jack idea to take weight off of the springs I like.

I may be making too much work out of this, just trying to not get in a pickle on a saturday afternoon.....

You can remove the old shackle without loosening the bed but a 2 inch drop shackle will hit the bed pinch weld and you can't get the bolt through it without lifting the bed or bending the metal on a GMT900 truck. I used jack stands under the frame and my floor jack under the pumpkin to install mine. All I did was remove the bed bolts (leaving the front two tight to keep the bed alignment) and put a small piece of 2x4 block under the rear mount. That gave me plenty of room to swap them. Took all of about 30 minutes for the whole job.

Good luck!

spikesputnik · July 24, 2009

Zembonez- I'm glad you chimed in! You know I've been kicking this around for a while; thanks for the input. Care to comment on the bed loosening necessity, again? I beleive you did in the past confirm this, contrary to sk1er18's experience...

But the bottle jack idea to take weight off of the springs I like.

I may be making too much work out of this, just trying to not get in a pickle on a saturday afternoon.....

You can remove the old shackle without loosening the bed but a 2 inch drop shackle will hit the bed pinch weld and you can't get the bolt through it without lifting the bed or bending the metal on a GMT900 truck. I used jack stands under the frame and my floor jack under the pumpkin to install mine. All I did was remove the bed bolts (leaving the front two tight to keep the bed alignment) and put a small piece of 2x4 block under the rear mount. That gave me plenty of room to swap them. Took all of about 30 minutes for the whole job.

Good luck!

Bed alignment! Theres a thought-thanks! You lost me just a bit though on the old shackle/new shackle clearance though. It is the spring eye that will come up and hit the seam, not the shackle itself, right? So I don't understand how there is a difference between either ( OEM or Belltech) shackles upper bolt to clear the frame/bed either coming off or going on??? Lastly, you put the 2X4 peice under the bed near where the bolt was removed to hold it up, right?

Thanks again.

Zembonez · July 24, 2009

Zembonez- I'm glad you chimed in! You know I've been kicking this around for a while; thanks for the input. Care to comment on the bed loosening necessity, again? I beleive you did in the past confirm this, contrary to sk1er18's experience...

But the bottle jack idea to take weight off of the springs I like.

I may be making too much work out of this, just trying to not get in a pickle on a saturday afternoon.....

You can remove the old shackle without loosening the bed but a 2 inch drop shackle will hit the bed pinch weld and you can't get the bolt through it without lifting the bed or bending the metal on a GMT900 truck. I used jack stands under the frame and my floor jack under the pumpkin to install mine. All I did was remove the bed bolts (leaving the front two tight to keep the bed alignment) and put a small piece of 2x4 block under the rear mount. That gave me plenty of room to swap them. Took all of about 30 minutes for the whole job.

Good luck!

Bed alignment! Theres a thought-thanks! You lost me just a bit though on the old shackle/new shackle clearance though. It is the spring eye that will come up and hit the seam, not the shackle itself, right? So I don't understand how there is a difference between either ( OEM or Belltech) shackles upper bolt to clear the frame/bed either coming off or going on??? Lastly, you put the 2X4 peice under the bed near where the bolt was removed to hold it up, right?

Thanks again.

Basically the difference is that the new shackle is quite a bit longer than the old one (hence the 2 inch drop). If you look up under there, you'll see that the shackle mounts upside down so the added length puts the top of it very close to the bed itself where the old one was inches away.

2x4 goes between the bed and mount to keep it up high enough to get the upper shackle bolt back in.

You're on the right track!

Befo and after PICS when done!

Matt_ · July 24, 2009

Les... too bad you're in FL. I would love to give you a hand getting the new shackles in. I see what Jim is saying with the longer shackle... but id love to try to get one installed without messing with the bed

Zembonez · July 24, 2009

Les... too bad you're in FL. I would love to give you a hand getting the new shackles in. I see what Jim is saying with the longer shackle... but id love to try to get one installed without messing with the bed

I have a theory that you COULD try installing the top bolt first and then wrangle the shackle into position at the bottom. It didn't seem feasible when I did mine but I guess it's possible. There is minimal room to do the job because the upper bolt is obstructed by the frame unless it is all the way to the top (which hits the bed). Problem with installing the top bolt first is trying to get it through the eye of the spring. It's a job that looks amazingly simple until you actually try it with the fram and bed in the way.

Matt_ · July 24, 2009

when i put new shackles on my truck i installed the top bolt first and then used the bottle jack to separate the axle from the frame until the bottom hole lined up with the shackle mount... very very easy to do as long as you are utilizing the bottle jack in between the axle and frame to control the height.

spikesputnik · July 25, 2009

Well I just got off of the ground looking at things some more, ruler and micrometer in hand, and I still can not see how the top bolt could go in first, at least on mine. In order for the spring eye to go up high enough to allow the bolt to come in, over the frame, shackle or none( it's not the shackle flanges that will hit the bed but the spring eye), the ridge in the bed must be moved up about 1/2-3/4". I'm not sure even the "cut and fold" methods described elsewhere would do enough, but some say it does...

My theory, Matt, is that there is something different in your Denali back there- no ridge, spacers between frame and bed, different spring eye diameter? Heck there might even be a different frame dimension?

One way or another, it's gonna happen, dammit! Pics and how to thread coming!

spikesputnik · July 25, 2009

One last dumb question- Is the differential an adequate single lifting point for the whole rear of the truck to put up on stands? I never thought about wether they designed it for that much stress in that direction, but it does look sorta beefy.....

Jeeze I'm clueless on this stuff

Zembonez · July 25, 2009

One last dumb question- Is the differential an adequate single lifting point for the whole rear of the truck to put up on stands? I never thought about wether they designed it for that much stress in that direction, but it does look sorta beefy.....
Jeeze I'm clueless on this stuff

Plenty strong. I've used the center to lift my trucks for years.