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Discussion Starter · #1 · (Edited)
I guess just a brief intro. My name is Jason and this is my Wife's '04 Denali. We're the 2nd owners and we've owned it for roughly 4 years. It mainly gets the kids back and forth to school and the BMX track. I currently work at a Hot Rod Suspension company with access to some pretty cool tools, software & engineers.

The truck has mostly been neglected, other than receiving routine maintenance. It's been a great truck other than the common dash issue. When we bought it, it had some ugly a$$ 24" wheels on it. Those were ditched in favor of some 17" MB wheels with Nitto 285/70 Tires. I cranked the stock torsions roughly 2", made some jounce spacers and had it aligned.

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I've added a Spectre Intake, Magnaflow muffler, and '05 Electric fans. My buddies at Gio's Performance tuned it for me as well.

Recently, the truck started swaying in turns and scaring the wife. It was getting so bad that She refused to drive it on the freeway. So I crawled underneath and glanced at the stock rear bags. Both bags had holes in them and the shocks appeared to be leaking. After a little searching I realized that stock replacement bags were more expensive than a good aftermarket set of shocks(Bilstein or maybe Fox's).

This is where things took a turn for the..........expensive. After measuring the stock shock pickup points I realized that I could fit a longer shock in place. Then the light bulb went on when looking at some aftermarket lift kits. It appeared that the stock 4-link would allow for a lot more droop than the stock shocks/bags could offer. So I put the back of the truck on jack stands and removed the stock shocks/bags. Inch by inch I let the rear axle down taking measurements and noting where any issues arose.

The stock shocks allowed for roughly 3" of droop from ride height.(keep in mind the bags weren't functioning so would likely be less with them working)

Here is what I found once the stock shocks were removed at one inch increments.
4" droop(shock centers 23.750") = ABS sensor on the frame needs to be turned 90 degrees
5" droop(shock centers 24.750" = Panhard bar is getting to a pretty extreme angle(need to go back and get a pic)
6" droop(shock centers 25.750") = The brake line bracket on top of the axle needs to be bent up roughly 15-20 degrees. The anti-sway bar contacts the diff cover.

6.25" droop(shock centers 26") = 18" Strap limits travel(*NOTE* The panhard bar has pulled the axle over 1" from center)

Here are a few more measurements with the 18" strap removed.
7" droop(shock centers 26.75") = The stock springs become unseated. Ride height sensors come undone, the lower link bar hits the positive stop on the axle bracket
8" droop(shock centers 27.875) = ABS sensor needs to be relocated and diff vent needs to be longer, need longer brake lines(20" or more)


While I was in there I went ahead and removed the springs and went the other direction. There is roughly 4" of compression from ride height(again bags not functioning). The shock centers were 17" with full weight sitting on the bump stop.

After a little research I found a shock that would be perfect in a 6" droop/4" compression scenario(from current ride height).

2" FOA 10" Coilovers are 16.5" closed and 26.5" open - Technically these are about the same price as factory replacement bags. I added in 18" straps as they are also the perfect length in this scenario.
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Now, you may be thinking "Wait, those are coilovers". I plan on eventually swapping these to the front and replacing the rears with something even longer but smooth body.

Doing a little mock up. Just a hair over 10.25" of total travel using 9" of the available 10" shock travel.
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18" strap mounted to the anti-sway bar bracket and lower shock hole, fits perfect.
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I bent the brake line bracket up a little using the handle of the jack.
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ABS Sensor turned 90 degrees.
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There is some empty area above the spare tire mount for the reservoirs.
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A typical reservoir mount was too tall so I made some low profile ones. Basically just some 1"x.125" bar bent into submission. I cut a slit in it to allow the clamp and then welded the hole shut.

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I will likely mount the reservoirs directly to the shock body once these are replaced by smooth body shocks.
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This is why a typical roll cage type reservoir mount is too high. There is just barely enough room above the factory fuel tank fill line for the reservoir line. Anything taller than a tight up against the floor mount will hit the lines.
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The driver's side reservoir fits in place with no issues. The reservoir fits right in between the body and the front of the shock mount.
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The Passenger side needs some slight trimming of the body and inner panel to clear the reservoir line. Because of the rear A/C lines the reservoir has to be installed behind the shock mount and then the line needs to be lifted over to the front of the shock mount.
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Unfortunately, the FOA provided misalignment spacers are for 1/2" bolts so I ditched them and made my own for the stock 14mm bolts. The shock needs to be offset .25" in the upper mount(to the outside) so the shock body doesn't hit the shock mount.

The anti-sway bar link modification was fairly easy. I just cut the stock links in half and threaded them 1/2"-20 L/H & R/H and then just made a corresponding L/H-R/H sleeve. I'm sure the CJ links would be sufficient too but I wanted to have some adjustment for future height changes.
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This has made an incredible improvement in performance. I look forward to addressing the front suspension to even up the score. The back handles so damn good now that the front is terrible in comparison.
 

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Discussion Starter · #2 ·
Here are some teasers of things to come.
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That's some bad ass work on the rear end. I wonder if the shock mounts could take the vehicle load and remove the stock coil spring for a full coilover rear setup?
 

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Discussion Starter · #5 ·
That's some bad ass work on the rear end. I wonder if the shock mounts could take the vehicle load and remove the stock coil spring for a full coilover rear setup?
The stock mounts could be braced pretty well. There is a little room under the floor to make a cross brace to tie them both together. That was my original plan until I found that skyjacker makes springs that theoretically are perfect in rate and height for what I want(2.5" lift - 20" long). The other issue that will arise is the tire may contact a coilover spring at full droop on the driver's side without panhard bar correction.

I plan on making new upper mounts for longer shocks. There is roughly 2" to gain(vertically) at the top mount.
 

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The stock mounts could be braced pretty well. There is a little room under the floor to make a cross brace to tie them both together. That was my original plan until I found that skyjacker makes springs that theoretically are perfect in rate and height for what I want(2.5" lift - 20" long). The other issue that will arise is the tire may contact a coilover spring at full droop on the driver's side without panhard bar correction.

I plan on making new upper mounts for longer shocks. There is roughly 2" to gain(vertically) at the top mount.
You could always get an adjustable spohn panhard which has a little room to be extended but most guys get it for lowering. I thought about dumping my denali autoride/spring for a rear coilover but wasn't sure how shock mounts would hold up.
 

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Discussion Starter · #7 ·
You could always get an adjustable spohn panhard which has a little room to be extended but most guys get it for lowering. I thought about dumping my denali autoride/spring for a rear coilover but wasn't sure how shock mounts would hold up.
Without having seen a NNBS factory mount, I would assume with some basic reinforcement it would handle the load of a lowered truck(Offroad would be a different story). You'll have the added bonus of increasing roll stiffness as well. Assuming the shock is mounted outboard of the factory springs.

The angle is fubar with the suspension dropped out. So even an adjustable bar will treat the symptom but not cure the disease.
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There are kits out there that drop the frame bracket to help with lifted trucks. I am not too confident in their strength though. I've got some ideas on how to make it better. I also plan on moving the axle mount(up and out) to make the panhard bar longer and raise the roll center.
 

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This is all overwhelming. We are still debating the merits of the Glowtie and cannot comprehend actual modification. :hack:
 
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Without having seen a NNBS factory mount, I would assume with some basic reinforcement it would handle the load of a lowered truck(Offroad would be a different story). You'll have the added bonus of increasing roll stiffness as well. Assuming the shock is mounted outboard of the factory springs.

The angle is fubar with the suspension dropped out. So even an adjustable bar will treat the symptom but not cure the disease.
20170306_173518_zps4yr6691m.jpg


There are kits out there that drop the frame bracket to help with lifted trucks. I am not too confident in their strength though. I've got some ideas on how to make it better. I also plan on moving the axle mount(up and out) to make the panhard bar longer and raise the roll center.

The rears are completely the same from 00-14. Not sure about 15+ but pretty sure the same also. Yes my lift I went with long arm custom kit with fabtech and zone parts. Tubular arms so no drop brackets. My lift has a panhard bracket to keep axle centered when up but still will swing to passenger side when unloaded. I have plenty of tire clearance to shock with my offset and spacers.
 

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Discussion Starter · #11 · (Edited)
The rears are completely the same from 00-14. Not sure about 15+ but pretty sure the same also. Yes my lift I went with long arm custom kit with fabtech and zone parts. Tubular arms so no drop brackets. My lift has a panhard bracket to keep axle centered when up but still will swing to passenger side when unloaded. I have plenty of tire clearance to shock with my offset and spacers.
That's pretty interesting that the rear is the same. I plan on making longer links for mine with custom frame brackets. The upper link could be extended roughly 4-5" before interference with the body mount but I want it longer than that. When I have some time I am going to remove the running boards and get a better look at it. Pinion movement is pretty substantial(roughly 10 degrees change thru 10" of travel). Not to mention that anti-squat values double in the first two inches of droop(from stock height). I've yet to check how much driveshaft plunge there is but I am fairly certain that it will become an issue once I install the 12" shocks.

I read through your big thread and didn't see any pics of your current rear set-up.
 

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Discussion Starter · #12 ·
Used my connection with Parts Authority to get some upgrades.

NNBS brakes with Centric(StopTech) slotted rotors

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& the one component that pretty much started the whole landslide of bad ideas with this project.

NNBS axles

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That's pretty interesting that the rear is the same. I plan on making longer links for mine with custom frame brackets. The upper link could be extended roughly 4-5" before interference with the body mount but I want it longer than that. When I have some time I am going to remove the running boards and get a better look at it. Or maybe just check out a Tahoe instead. Pinion movement is pretty substantial(roughly 10 degrees change thru 10" of travel). Not to mention that anti-squat values double in the first two inches of droop(from stock height). I've yet to check how much driveshaft plunge there is but I am fairly certain that it will become an issue once I install the 12" shocks.

I read through your big thread and didn't see any pics of your current rear set-up.
Yeah I've been through a whole nightmare on setting up mine. I haven't gotten any recent pics of the rear since I changed to the Zone adjustable uppers and a dual cardan shaft. I was able to completely eliminate any vibrations out the rear with the dual cardan. The front two piece just got replaced and now have to put it back in then test it. I will try to get some pics this week of the parts.
 

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Im donald trump and I approve of this build.

Which is an actual build.

Not just some fgty light bars and color matching done.
 

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Im donald trump and I approve of this build.

Which is an actual build.

Not just some fgty light bars and color matching done.
Not a grippy pepboys chevy logo steering wheel cover in sight.


OP, I like it, keep it up, or i'll stab you.
 
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Discussion Starter · #16 ·
More parts are arriving daily. 1.75" & 1.50" x .120w Chro-Moly tubing for the link bars. I had to buy 20' sticks so I will likely make a rear bumper out of the extra 1.75". I had to tag them or else our manual machine guys will use them unknowingly.

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I have a 4'x6' .180 chro-moly sheet allegedly arriving today as well. This material will be for the front control arms. I'm still undecided how much wider over stock I am going to build them. The NNBS axles are 1 7/8" wider than NBS but of course I want it wider than that. Trying to decide between running CV spacers, biting the bullet and ordering the Mazzulla 3" over NNBS axle shafts(4 7/8" over total ), or really dive in the deep end and have my buddies at Currie make me some 2 1/8" over(4" over total). At least the Currie route would allow me to make custom sizes in the future if I am so inclined.

I also need to formulate a plan on putting all this crap together. Spring break is coming up so I have opportunity while the wife won't need the truck as much, or at all.
 

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Discussion Starter · #17 ·
I hadn't planned on doing the NNBS brake swap until later but I needed the core moneys for other things. So I got home from work last night and went to town on it. The swap was pretty straight forward but I couldn't get the brakes to bleed at all. I used a vacuum pump, I tried gravity feed and finally just gave up and went old school. No matter what I did the pedal just wouldn't come up. I had tried everything and I was about to lose my mind. Around midnight, after many F-bombs, I finally just gave up and went to bed not knowing how I was going to get to work.

I got up early this morning and went back at it. Put the truck back up on jack stands and just sat back and ran thru in my head everything I had done. Finally, the light bulb turned on. I had the damn calipers on the wrong sides so the bleeder was down instead of up. A thousand F-bombs later I got it bled properly and took it for a spin around the block to bed in the pads. What a huge difference it has made. I am so glad that I did this. The truck is bound to get heavier with larger wheels/tires and boxed arms very soon so the extra braking power is going to come in handy.

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I know on mine I had to have the truck running to get the brakes bled properly too
 

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Discussion Starter · #20 ·
Spring break has begun so I am already taking advantage of the wife not needing the truck.





I removed the hitch and rear bumper in preparation for custom pieces. I actually have an idea utilizing a roll pan but the wife is 50/50 on that idea. If she doesn't come around then I'll just fab a prerunner deal and call it a day.



I also yanked the drivers side running board. Having access to the frame rail helped with making link bar bracket templates.



Here is the lower link template. I didn't make a template for the upper bracket because they will be pretty straight forward. There has been a bit of guess work on anti-squat since I don't have actual ride height yet. I have been using 2.5" over current ride height to at least get it close.


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The Skyjacker C25R springs showed up today. I am going to test the rate of these against the stockers at work next week. I had my little helper wanting to put them in.



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I haven't even began building the front end yet and I have an idea to gain some droop/travel. It helped having the truck up on stands during the day to really get a good look at everything.
 
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