Coil over converted lbz with cognito uca

04chase

Member
Mar 28, 2008
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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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Chevy1925

don't know sh!t about IFS
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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.
 

04chase

Member
Mar 28, 2008
221
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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.

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.
 

Chevy1925

don't know sh!t about IFS
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Oct 21, 2009
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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
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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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Budneeds2beers

Aka Mike Honcho....
Aug 25, 2016
497
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Cali
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?

:woott:
 

Chevy1925

don't know sh!t about IFS
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Oct 21, 2009
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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?

:woott:



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 :D.

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 :rofl: leaving the stock mount also always allows me to go back to stock if I ever wanted to but that’s crazy talk
 

TheBac

Why do I keep doing this?
Staff member
Apr 19, 2008
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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.
 

SmokeShow

Well-known member
Nov 30, 2006
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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?
 

Chevy1925

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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?


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.

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 :D
 

Budneeds2beers

Aka Mike Honcho....
Aug 25, 2016
497
2
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Cali
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.
 

kubitza123

New member
Sep 19, 2016
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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?
 

Budneeds2beers

Aka Mike Honcho....
Aug 25, 2016
497
2
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Cali
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.
 

Chevy1925

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Oct 21, 2009
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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.



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.
 

Chevy1925

don't know sh!t about IFS
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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?



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.
 

Budneeds2beers

Aka Mike Honcho....
Aug 25, 2016
497
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Cali
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???
 

Chevy1925

don't know sh!t about IFS
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Oct 21, 2009
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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???

Bud, i dont think you are considering all the variables i posted. Remember, there are two different fox shock oils and one will substantially stand up to temps much better than the other but the shock better have vitron seals to do it. Resi means nothing for cooling, there is very little oil in the resi and it does not cycle through the shock. Longer shock is like adding a deep pan to the Allison, all it does is prolong hot temp from happening as quick as before but it still will happen and take longer too cool down. It is not the length that you should be looking at if you want to keep things working well. if it was, desert racers wouldnt be going with larger and larger piston diameters on shocks. i would have no issue running these shocks for 300 miles in the dirt because i know where the limitations are and its not in the shocks. they will last that amount of time just fine. Ive logged more miles than that in the dirt on 2.0 coilovers on the front end of a dmax that was driven as hard as you can drive one without bending the frame or losing control arms. Those coilovers lasted WAY beyond my expectations and never had one leak nor did it burn the oil up in the testing sessions. there was some very unconventional shock valving going on inside and other tricks done to make them work though. in the end, coil springs were my actual issue, not the shock for a bolt in stock height replacement. Now if you wanted to get that truck to bomb 2-3ft whoops, it wouldnt happen but you wont get that from one of these trucks without alot more wheel travel, way more shock/s, and no drop brackets or very small ones with extreme reinforcement to the frame rails/crossmembers. by that point, all this about 2.5 shocks and what we are discussing is a mute point.

you are concerning yourself with fade WAY too much. Fade isnt even going to be your main combatant by the time you have that much valving in the shock. The shock doesnt care how much weight is up front, it only cares about shock shaft velocity. what i meant by the rear end is not that it WONT fade, its that you will be limited on travel. This means you either trade comfort for speed or vise versa and you will be limited on speed. the rear end will hold you up from going fast enough to use the front end to its full potential. And if its all on a lift kit using drop brackets, that will be the next weak point/hold up before shock fade.

If you are fading shocks under these conditions, its time to look at shock tuning and experimenting or change to something else you feel will work better.

Honestly, in the end, if it works for you, Screw it! in suspension, there are a few ways to skin a cat and if what you do works for you, then it doesnt really matter but i know what works for me and i know where the potential is or isnt. im always trying different stuff whether its dmax related, cummins, sand car, rzr's, tracker or spit balling ideas with other shock tuners. sooooo much to learn in this section its ridiculous. tuning a shock is like tuning an ECM, you can get 2 vehicles to run sections just as fast and as the other but it doesnt mean you both have identical tuning inside. Just from what i posted, it doesnt mean you CAN NOT do what you would like to do. im simply stating the draw backs of what you may think you are gaining from it. if you want to run a 10-12" stroke shock, you certainly can and it will do its job and give you a big shit eating grin off road. You just asked why i say its a waste to go so big so i gave the reasoning behind it.

EDIT: Fabtech got a 4" shock to fit inbetween the UCA with a custom UCA setup. There should be no reason a 3.0 coilover cant fit. Nets you better springs to holding that weight as well. you already are cutting the stock mount out so may as well go that route assuming you truly feel the 2.5 wont do what you want it to.
 
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04chase

Member
Mar 28, 2008
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I never got to finish a reply so I will now that I have a few minutes. I used a 2.5 because I feel the size was good for a primary on road truck that will see some off road use but not daily. Overall goal was a comfy ride on the street with ability to hit dips and ca roads without worry. I did swap springs from a 16" 3.0" 700lb spring too a 18" 3.0" 800 lb spring and it was about perfect for height setting and the amount of preload I had to set 1.25" with internal shaft mounted bump stops. This will limit travel too 10" total which is plenty for this trucks use with a quality ride. Going to play with psi from 150~ psi and see how it goes with a fluted valve setup . The coil bind was calculated but measurements also changed with the lower coil over mount changed from the stock too a custom mount I made that moved the shock toward to ball joint 1" in total. So from what I recall I was at 21" from pivot too center of tire and about 10" from pivot to shock mount. Going from 9" too 10" changed about 200 lbs of spring needed while going from 8* to 10/11*~* angle . It makes the shock length longer to achieve the same height stance but reduces the amount of spring needed to hold the weight up (sacrifices travel). I will be tryi g both to see what is better for daily use and if I will use the added travel on the street or not. I'll be posting more results when accomplished. I have done my homework on suspension angles and how compounding shock angles work. I did pass geometry best in my class if that means anything.
I own and operate a mobile diesel repair business that does custom work as well from ls engines to custom off road utvs. I just finished a 18 can am x3 with everything under the sun including all new radius arms , custom valved stock suspension with new springs and much more .

I have followed chevy1927 for a while. I've learned many things from his posts as well. He is a great asset to this website and general base for many searches I have made on google lead to his posts. I'm glad he chimed in and voiced his opinion on the matter. Kudos to making a bolt in coil over , to me that is a better choice to 90% of the guys who want a bolt in coil over conversion.
I would have done that if I had no lift and I didnt buy a set of 2.5×8" coil overs brand new for 400 cash. That was the key factor in me completing this . After all said and done i have less than 1k into this swap with none of my time compensated.
I'm a believer in overbuilt vs built just enough. These towers are already over built and I added to that. I have many hours behind the mask ,scars and burns , and even certs to prove it. That means nothing when it comes to engineering something to standards of an oem. Which this setup would not be plain and simple. It would involve different shock angle and much more that i wont get into.
The fact I, could reverse this to stock if wanted doesn't mean it would be easy but can be done in a day. I cut everything off in straight cuts and marked and measured accordingly. I could also install this from a stock truck to small cradle left like I have. Being only 4" this is all I'd feel comfortable using to actually go off road and put through some harsher conditions. I will report my conclusion in the coming weeks to pass as it is not my DD . I also have a 5500 ram that use for daily work that weighs 20k lbs dry and has all kelderman/custom suspension due to hd weight. It rides like a real Cadillac and hate to say ,nice as my dmax wishes but without the power. Just a different beast with a different purpose. It's how I made my business name, Chase truck mobile. Back to the topic and I've added a few pics with the new springs before I left home.
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