Duramax Diesels Forum Truck of the Week
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Old 07-03-2018, 07:48 AM
04chase 04chase is offline
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Default Coil over converted lbz with cognito uca

I finally got around to ditching the torsion bars and fabbing a coil over setup for the front end. I used some fox 2.5×8" coil over shocks with the extended lower mount and will be using some 18" 800# springs from eibach. I currently have 16" 700# springs and its not enough to get the front sitting where it was with torsions. The new springs will solve this issue. I used some upper shock towers and modded them to fit and braced them with some cold roll flat bar . I also braced the frame between the a arm with 3/16" thick cold roll plate with holes drilled to plug weld and keep the majority welds parallel to the frame. I could keep it lower like it but shorter tires would be needed. Still coming up with reservoir mounting but the truck is holding up its own on them and drives. I have all measurements and have the ability to make these again. I have a few more trucks i plan to do soon but mine was first for trial and error. I attached some pics of the build and steps i took to get this setup done. Ended up about -15* angle from perpendicular to the frame . Have about 3/8" gap between arm and coil when full droop. Will be using eibach ers internal bump stops . I'm not a supporting vendor and not trying to sell anything yet. I doubt many will want to go as far as i did due to the amount of work necessary. Cutting off the stock shock mounts and bump stop mounts is necessary as well as welding it together while not compromising strength. The new towers sit about 8" above the frame luckily the room is there. The driver side is by far the harder side due to all the brake and p/s lines you must avoid while cutting welding.

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04 Silverado SS - 10.7@130 on 22's 440 lsx twin turbo/4l80 AWD (SOLD)
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07 GMC LBZ CCSB LT3- danville 3794 stg 2 ,Magnaflow 3"downpipe, magnaflow 5" turbo back in black,atp efi dsp5, cognito 4" NTBD w Fox ,deaver mini pack, denali hid retro , focal/jl audio tw3's ,bmf's, Mike L Trans , fass 150 titanium sumped , 6 gallon air , viair 450c , k3la ,cts2 w lots of add ons.
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Old 07-03-2018, 09:08 AM
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800 will net you about 1" more front end height (you may get more initially till springs wear in), beyond that you will run into coil bind if you use all the travel. be very mindful of this.
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02 LL7 2500HD CC/LB dmax/alli "The Limo"

BIG THANKS TO: Mike L, Steve, Trent, Guy, Dan, Ruben, Josh H, Scott, Brian and everyone else who has put a hand in to help me.

best time to date: 12.39

motor died/bent rods = 3/11/11
back from the dead 7:04pm 4/9/2012

Limo is back in the garage, now driving a built chevy tracker
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Old 07-03-2018, 04:32 PM
04chase 04chase is offline
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Originally Posted by Chevy1925 View Post
800 will net you about 1" more front end height (you may get more initially till springs wear in), beyond that you will run into coil bind if you use all the travel. be very mindful of this.
a friend has a converted lml with a similar setup but in a 3500 dually . hes much heavier than i am as well. He has 800 lb springs and sits nicely. his lca has his shock mounted near the same spot , i cant go out any further toward the ball joint so im at the mercy of springs. next would be a 1000 lb 18" spring. id like them to be with greater coil spacing but besides foa viper and eibach. not sure who else can do it.

also has anyone done anything to the rear that will allow a better ride and able to tow? what i had in mind. 4 link with panhard and coil overs with long air bags for towing . i used to have an 08 lmm with a carli air setup and i recall the bags being long travel. wish i would have kept that part.

right now the truck has stock leafs , overload removed, deaver mini pack and sulastics shackles that are garbage. 10k miles and the torsion bushing is fubar.
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04 Silverado SS - 10.7@130 on 22's 440 lsx twin turbo/4l80 AWD (SOLD)
09 CTS-V bolt ons and carbon fiber 792 rwhp on e85 XXXX rwhp on the bottle
14 BMW 335i m-sport - jb4/flex fuel (wifes)
07 GMC LBZ CCSB LT3- danville 3794 stg 2 ,Magnaflow 3"downpipe, magnaflow 5" turbo back in black,atp efi dsp5, cognito 4" NTBD w Fox ,deaver mini pack, denali hid retro , focal/jl audio tw3's ,bmf's, Mike L Trans , fass 150 titanium sumped , 6 gallon air , viair 450c , k3la ,cts2 w lots of add ons.
55 Belaire , Hotrod in progress , airbagged, driver with no power!
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Old 07-03-2018, 04:51 PM
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Default Coil over converted lbz with cognito uca

And did he calculate for coil bind to make sure at full compression they are not touching? You can put 5” of preload into even that 700lbs spring but it does no good due to coil bind.

You can get max, 2” of preload in an 800lbs 3.0 Id 16” spring. The 18” May let you gain a hair more. Going to a higher rate means nothing if the coil bind height increase a substantial amount which generally happens above 800lbs

I’ve been running these for over 5 years now


Did you set the shock tower height so that ride height was achieved around 50% shock stroke while getting the desired ride height?

Also, air bags and coilovers are counterintuitive unless you make he bags removable
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Mike L is my role model. I want to be like him when I grow up.
James

02 LL7 2500HD CC/LB dmax/alli "The Limo"

BIG THANKS TO: Mike L, Steve, Trent, Guy, Dan, Ruben, Josh H, Scott, Brian and everyone else who has put a hand in to help me.

best time to date: 12.39

motor died/bent rods = 3/11/11
back from the dead 7:04pm 4/9/2012

Limo is back in the garage, now driving a built chevy tracker
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Last edited by Chevy1925; 07-03-2018 at 05:11 PM.
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Old 07-03-2018, 04:58 PM
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How come you didnt do a hoop? I like the bucket it looks clean. Im wanting to do the same with a hoop so I can add a 2.5X4” bump stop. Now at the top of your bucket (sixth picture) you couldn’t go taller 10”or 12”? Clearance issues due to angles/other components? What diameter shock?

@james I see he has more room on that shock. Dual rate? 800/900? Also I see in your picture your running the stock shock mount. How come with all those sweet fab skills?

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Old 07-03-2018, 05:19 PM
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Default Coil over converted lbz with cognito uca

Quote:
Originally Posted by Budneeds2beers View Post
How come you didnt do a hoop? I like the bucket it looks clean. Im wanting to do the same with a hoop so I can add a 2.5X4” bump stop. Now at the top of your bucket (sixth picture) you couldn’t go taller 10”or 12”? Clearance issues due to angles/other components? What diameter shock?

@james I see he has more room on that shock. Dual rate? 800/900? Also I see in your picture your running the stock shock mount. How come with all those sweet fab skills?



2.5x4” bump will be too long. Stick to a 2” stroke.

That’s an 8” stroke shock, mine is a 6”. No sense going to the longer shock when we are limited to cv angle. You will only get 12-13” off wheel travel before C.V. starts to bind. Going a longer arm would change that.

Dual rate does no good here. Calculate the actual spring rate of a 800 over 900 lbs spring and tell me what it comes out too, it will be way too soft .

Stock mount stayed because years ago, everyone said the stock mount wouldn’t hold the truck in a coilover app nor would the stock lower shock mounts. I proved all that wrong and it was 100% bolt in so why not? Lol. Matter of fact, the grade 8 shock eye bolts will break before anything else. You also increase the leverage on the frame with a taller mount and if you abuse it off road, you will HAVE to have some sort of engine cage to keep the mounts from tearing. The stock mounts are extremely strong where they are. If you knew the shit they have seen on the other test trucks I was doing research on, your back would hurt leaving the stock mount also always allows me to go back to stock if I ever wanted to but that’s crazy talk
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Originally Posted by JoshH View Post
Mike L is my role model. I want to be like him when I grow up.
James

02 LL7 2500HD CC/LB dmax/alli "The Limo"

BIG THANKS TO: Mike L, Steve, Trent, Guy, Dan, Ruben, Josh H, Scott, Brian and everyone else who has put a hand in to help me.

best time to date: 12.39

motor died/bent rods = 3/11/11
back from the dead 7:04pm 4/9/2012

Limo is back in the garage, now driving a built chevy tracker
Tailgate Crew Member #4
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Old 07-04-2018, 05:04 AM
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James, every time you posts pics and info on coilovers it just impresses the hell out of me.

You're the "Ben" of suspension around here, and I mean that in the highest-compliment way.
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Old 07-04-2018, 07:15 AM
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OP, how low of a lift could you get away with?

James, same question for you? Yours has a pretty good lift. Can you get coilovers to work in the stock shock mounts with a stock or slightly lifted position?
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Old 07-04-2018, 01:29 PM
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Quote:
Originally Posted by SmokeShow View Post
OP, how low of a lift could you get away with?

James, same question for you? Yours has a pretty good lift. Can you get coilovers to work in the stock shock mounts with a stock or slightly lifted position?

For a bolt in 2.5” shock, 6” loft would probably be min but no one has gotten me measurements to know for a fact. If you cut the frame mount out, your options GREATLY open up as you can set the shock/mount to match what ever lift or stock height you want. You can also mount a 6-16” shock as well though anything over 8” is wasted money on stock arms.

Quote:
Originally Posted by TheBac View Post
James, every time you posts pics and info on coilovers it just impresses the hell out of me.

You're the "Ben" of suspension around here, and I mean that in the highest-compliment way.

I appreciate that Tom
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Mike L is my role model. I want to be like him when I grow up.
James

02 LL7 2500HD CC/LB dmax/alli "The Limo"

BIG THANKS TO: Mike L, Steve, Trent, Guy, Dan, Ruben, Josh H, Scott, Brian and everyone else who has put a hand in to help me.

best time to date: 12.39

motor died/bent rods = 3/11/11
back from the dead 7:04pm 4/9/2012

Limo is back in the garage, now driving a built chevy tracker
Tailgate Crew Member #4
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Old 07-04-2018, 06:14 PM
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OP what diameter shock 2.5? Looks a little tight with coils any chance on 3.0? Also you might want to look at your mounting bolts. Size is correct but it looks like your sitting flush on the face of the nylock. Might want atleast 2 thread protrusion from face of nut. Just for safety.

@james. I understand that 800/900 is still weak but its sprung progression and it should free up from coil bind. How much idk without having it in front of me. Or maybe a longer 900lbs coil???
Now you said more then 8” is a waste? Maybe if youre on road most of the time with the exception of a few fire roads and dirt lots. With the weight of these trucks (valving) and shock shaft diameter the oil capacity in a 6”-8” stroke is not enough. It will fade fast in a heavier offroad situation(Im planning to chase the baja and do 100-150 mile round trips through our local deserts not to fast but I like to cruise). So its not necessarily a waste. For myself im not looking for monster travle just more dampening through the suspension travle. How come a 4” bump wont fit? Where did you try to mount? Im thinking somewhere on the top control arm.
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Old 07-04-2018, 06:44 PM
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Does the coil over ride that much better? I could see the advantages with swapping to a SFA but was curious why do one when still running IFS?
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Old 07-04-2018, 08:53 PM
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With the diameter of shock piston size and better flowing valves you will have a world of difference ine suspension dampening. Not only that but weight reduction on front end and a more consistent spring rate. Torsional spring weight and coil sprung weight do ride different imo. I noticed a huge difference when I updated my prerunners suspension years ago. So I think its a huge difference.
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Old 07-04-2018, 10:18 PM
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Quote:
Originally Posted by Budneeds2beers View Post
OP what diameter shock 2.5? Looks a little tight with coils any chance on 3.0? Also you might want to look at your mounting bolts. Size is correct but it looks like your sitting flush on the face of the nylock. Might want atleast 2 thread protrusion from face of nut. Just for safety.

@james. I understand that 800/900 is still weak but its sprung progression and it should free up from coil bind. How much idk without having it in front of me. Or maybe a longer 900lbs coil???
Now you said more then 8” is a waste? Maybe if youre on road most of the time with the exception of a few fire roads and dirt lots. With the weight of these trucks (valving) and shock shaft diameter the oil capacity in a 6”-8” stroke is not enough. It will fade fast in a heavier offroad situation(Im planning to chase the baja and do 100-150 mile round trips through our local deserts not to fast but I like to cruise). So its not necessarily a waste. For myself im not looking for monster travle just more dampening through the suspension travle. How come a 4” bump wont fit? Where did you try to mount? Im thinking somewhere on the top control arm.


I was talking about running 800 over 900 in a dual rate as you suggested. It won’t work. A 2” longer stroke shock is not going to do anything for shock fade. A larger piston is the best way to combat it. What some people think is shock fade is also cavitation. It’s all also heavily dependent on valving stack, bleed holes, oil level, oil type and nitrogen pressure on what you will feel. Not sure how you cruise though because everyone’s version is different. If you are still using a stock rear end (deaver leafs and some sort of shocks mounted under the bed), the rear will never keep up to the point that the front 2.5’s will fade to an extreme amount, and that’s assuming you even do get fade. If you are using a true custom deaver pack and 16-18” stroke bypasses in the rear then you should be upgrading a few things up front besides just to coilovers. I’m not saying a 4” won’t fit, im saying it will not let the suspension work to its full potential and will cause fighting when you valve it all.
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Originally Posted by JoshH View Post
Mike L is my role model. I want to be like him when I grow up.
James

02 LL7 2500HD CC/LB dmax/alli "The Limo"

BIG THANKS TO: Mike L, Steve, Trent, Guy, Dan, Ruben, Josh H, Scott, Brian and everyone else who has put a hand in to help me.

best time to date: 12.39

motor died/bent rods = 3/11/11
back from the dead 7:04pm 4/9/2012

Limo is back in the garage, now driving a built chevy tracker
Tailgate Crew Member #4
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Old 07-04-2018, 10:20 PM
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Quote:
Originally Posted by kubitza123 View Post
Does the coil over ride that much better? I could see the advantages with swapping to a SFA but was curious why do one when still running IFS?


Just a well valved 2.5” smooth body shock will make a world of difference in a torsion front end. Adding a coil spring in place of the torsion makes it that much better. Linear coil spring rates are lower vs the torsion bar netting a softer ride while giving the shock more control over the suspension.
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Originally Posted by JoshH View Post
Mike L is my role model. I want to be like him when I grow up.
James

02 LL7 2500HD CC/LB dmax/alli "The Limo"

BIG THANKS TO: Mike L, Steve, Trent, Guy, Dan, Ruben, Josh H, Scott, Brian and everyone else who has put a hand in to help me.

best time to date: 12.39

motor died/bent rods = 3/11/11
back from the dead 7:04pm 4/9/2012

Limo is back in the garage, now driving a built chevy tracker
Tailgate Crew Member #4
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Old 07-05-2018, 09:20 AM
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True you wont gain much oil in two inches but from a 6” to a 10 or 12? Plus the size of the reservoir. Your right about the rear it will never fade compared to the front but the oil(5wt what fox recommends) will get hot and loose to much viscosity over time. I mean if you put 300 miles on a set of 8”x2.5 in any local desert they would be fine? That oil would be smoked in the front.
For a truck that lives 75% of it life on road 6-8” is great probably wouldn’t have to rebuild them for five years. All I’m saying is for what my plans are I dont think its enough. As for the rear no bed cage still need a truck. Just deavers 6” lift pack and a 10” or 12” bypass if it can fit. Im not looking for monster travel just a smooth 10-11” strapped, that is solid for those heavy footed ahh shit moments alot can be accomplished with 10” of smooth,solid..... travel. I plan on using this more these days and retiring the race truck.

James im not trying to get into a pissing match with you but you have this knowledge that im looking for and this is what im into and I don’t get to talk to anybody else about it. Dont get me wrong I really like to go fast and read alot of technical issues but offroad is where its at for me suspension and electrical everything else is a huge bonus.


Hey op. How long did it take you to cut those brackets out and what did you use? (Tool wise) how much did it suck???
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