Coil over converted lbz with cognito uca

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
21,761
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Phoenix Az
You did a nice job chase. Really the only thing I’d have concern about now is tower flex from hard off roading but that’s nothing an engine brace wouldn’t take care of. I would run much more than 150psi in resi pressure with shock fully extended as well.
 
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04chase

Member
Mar 28, 2008
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ill update now ive logged miles. The springs settled and ended up 1.5" pre load on the 800 lb springs at ride height. im sitting right at 42.5" to fender in the front with 295/60/20 tires (~34.5"). Just got the truck back from alignment and i am nearly maxed out on the adjusters and all the way tight with rare parts tie rods. tracks straight now , has a bit more front end body roll than with the torsions but is much softer. I ended up throwing some green on the duramax truck now also. added a radiance light bar with green back light that i have on with the ignition on circuit and edge cts2 screen for light bar control.

now im considering linking the rear but not sure ill pull the trigger. It will probably be when i find a steal on a set of 2.5x10" coil overs. Ive done some drawing and it looks like it would be pretty easy to do actually. Just expensive in material no matter which way you go. Id like to use 4130 over d.o.m. but its 2x the cost. Just in rod end/bushings from ballistic it will cost 400 to 4 link with a pan hard . plus adding brackets for bags to still be able to tow.




 
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04chase

Member
Mar 28, 2008
222
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Ill add some, with some added time on this truck. The front is settled and seems happy but i have had noted that arm bushing dont stand a chance. Both the oem and cognito bushings are wearing quickly from the torsional loads being applied . I am making all new arm bushings from delrin. Thats not to bad but id like the rear to be able to travel the same amount or more with the ability to DD like a caddy and even tow when needed. Not very easy to have something that will do this without some changes being made everytime to the truck. So i had considered a link setup ,but then once costs and work involved was factored. The purpose of this truck was to be able to offroad better , and still be a 3/4 Ton diesel.

I finally got these components.
-deaver f87 1/2 ton 4" springs
-rough stuff HD anti wrap kit
-air bags with pinned mounts for quick install
-fox 2.5 bypass shocks
.25 wheel spacers

With a 5" exhaust and stock fuel tank ,there isnt much room to fit new shock mounts and the big 2" dom arm that will be just off the pumpkin on the passenger side. The axle tubes have been welded already. Ive already seen some contact from the driveshaft to the k3la so it will be moved.

Im still determining the shock setup, not sure which legnth and valving will be used.

I did also add a fox steering stabilizer. It is slightly longer than stock but on my truck the most compressed mine has been is the length the new fox stabilizer was compressed. So a tapered bolt is needed to bolt the eye of the new stabilizer to the centerlink.

I also have added a hd hood and will be getting some paint done and shown what sulastic shackles look like after 15k miles on the highway.
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04chase

Member
Mar 28, 2008
222
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Looks mean as F! Nice job Chase. Are you field service?


yes sir, started my own thing about 2 years ago and been working every day since. hard work, long hours, just enough to get by. but i do make my own scheduele and work on what i want. I honestly expected it to be a little easier, but in time it will. One truck will be two this time next year.
I do most class 5-8 trucks , primarily car haulers and telecom. my experience is telecom and boom/lift trucks , seems to be the best pay being specialty so trying to stay where the best income and least resistance is. Ill change oil until i die if it pays the bills. I did build a very nice service truck for my self though. not a Dmax but a 12 5500 Ram with lots of upgrades(kelderman 4 link and front air ride with accuair elevel control, custom stereo i did with a fiberglass center console for sub . fridge in cab, EFI bobcat 250, 3 cylinder eaton compressor, 420DD Gates crimper, Autocrane 3202 with outriggers i built into the cabinet structure in the rear. To many custom touched to recall now. Ill never do it again unless i buy new.

To the Duramax, i installed new leafs yesterday, travel with no shock in the rear is at 12" with the Deavers from ride height to full droop plus the 4-6" inches up travel. will be using some 32" long fox shocks with 14" travel . will be moving the passenger shock to the rear of the axle for room for the trac bar arm.

Made a few new bushings for front arms from delrin. Rubber dont last on this truck.
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Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
21,761
5,933
113
Phoenix Az
oooohhh that leaf separation! :eek: dont dont dont let them do that. that will snap a main leaf quickly.

you need to pull the leaf pack down to the main leaf only, stick a block of wood the same thickness as the leafs you pulled under the main leaf between the axle and cycle the suspension. 2 reasons for this, one you dont want the leafs going inverted arch before full bump (will kill the arch and then the leafs) or no more than 1" into the negative arch and two, you need to see where the shackle is cycling. the stock shackle is short and is stopping your down travel and may hinder your up travel or bind the spring.

that axle probably needs to be strapped up 2-3" so the shackle is not hitting its own mount and causing the leaf separation.
 

04chase

Member
Mar 28, 2008
222
1
18
Strapped the rear since the shocks were limiting the rear . They will never see full droop unless rolled off a cliff. The front is no where near what rear can do. The addition of the anti axle wrap bar has dramatically increased stability . Feels like i added a sway bar almost. Though it will now sit slightly low on the driver side from the added weight and low spring rate.

This isnt a long travel truck by any means. It can haul ass on dirt roads and hit minor bumps at speed while maintaining control. Exactly what i was after. Now to get this hood painted and add the bags.

I ended up strapping the rear end just before max shock extension which is about 5-6" before max droop.
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Milehighduramax

New member
May 14, 2020
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California
I am wanting to do the swap like Chevy1925 did but I’m confused how to measure my current ride height on my lifted Duramax to crossover to what size coilover to buy. I’m on about 13” of lift so do I just buy a 12-13” coilover? So many questions. Hope you guys will see this old thread.