Question: GM IFS suspension set-up

[duramaxzak]

I'm building my 02' GMC into a 2.6 truck from a W/S puller. I would really like to remove the OEM torsion bars and replace with a coil over or air shock. Or could I just run a shock and set my ride height with my bump stops.

Has anyone ran a Air shock like this?

View attachment 35706


Any info or suggestion's would be greatly appreciated!

Thanks Zak

 

[56taskforce]

So that shock from King is a complete suspension in one unit? If that is the case, depending on available weight capacities that could be the way to go. Could be like coilover setup that is fully adjustable from the driver's seat.

 

[bubba2400]

If you can get it to come up off the stops then there is no need for a spring. But it has to come off the front stops. Would save some weight with no springs and less expensive. Typically you will need some sort of spring on the front to push the front off of the stops.

 

[Chevy1925]

no air shock will hold these trucks up and last . not even 2 on each corner. unless you feel like cutting out the old frame mount shock mount to make a coilover work well on a stock height truck, buy a nice shock you can properly valve to your liking

 

[duramaxzak]

Yes they act as a shock and spring. The 2.5's have a 1000lbs load carrying capacity each. They are charged with nitrogen, so you would need a nitrogen charging set-up to change psi in the shocks. The shocks really don't have to carry the weight of the front of the truck, they just need to put upward pressure to lift off the bump stops.

 

[Chevy1925]

Yes they act as a shock and spring. The 2.5's have a 1000lbs load carrying capacity each. They are charged with nitrogen, so you would need a nitrogen charging set-up to change psi in the shocks. The shocks really don't have to carry the weight of the front of the truck, they just need to put upward pressure to lift off the bump stops.

let off the throttle at the end of a pull and within just a couple you will blow the seals out and nitrogen. 1000lbs load carry is not anywhere the same as spring rate. you have 4k on the front just as a dmax truck sits, then what ever else you put on the front for weights.

you can try it but i already know whats going to happen. ive been around air shocks long enough to know where and what they can do.

 

[duramaxzak]

Thanks for the info James, that's why I'm asking because I have zero experience or knowledge of air shocks.

Truck does have a 4" lift. I guess I will probably be looking at a coil over set-up than.

 

[Chevy1925]

Thanks for the info James, that's why I'm asking because I have zero experience or knowledge of air shocks.

Truck does have a 4" lift. I guess I will probably be looking at a coil over set-up than.

the air shocks are just weak. guys that run them on sand rails or even rock buggys have to constantly rebuild them if they actually put them through any kind of abuse. internally the seals to keep nitrogen where it belongs fails, this bleeds oil into the nitrogen and vise versa, no good. and if you slam them hard enough, you can blow the bottom seal out of the shock and have oil go everywhere. on a light duty application, they work ok. they seem to be best suited for rock crawlers. even sand cars have a hard time with them due to shock fade and seasonal rebuilds.

a 4" lift should let you get away with a 2.0 coilover. just watch the coil next to the cv axle. it will be tight there. if you want to place the coil above the axle like my setup or like a toyota tacoma and most other factory coilover truck with 4wd, you will need to cut the frame mount off and fab a shock tower for it to use the shock correctly and not have it limit you from dropping the front all the way down

 

[duramaxzak]

James I saw your coil over thread on DF, do you think 800lbs spring rate is enough? Or would you go more like 1000lbs?. Also thinking about F.O.A shocks.

 

[Chevy1925]

James I saw your coil over thread on DF, do you think 800lbs spring rate is enough? Or would you go more like 1000lbs?. Also thinking about F.O.A shocks.

i have one on DF?? i dont remember putting one there.

there is a lot to consider and spring rate is only one part. you need to figure out where you want ride height, then measure how much suspension travel you want or can live with. being you pull, full suspension compression will something you need to look at as well or where you want the front end to be when full of weights up front (what i mean by this is not how much travel you want left when weighed down, but where you mount the upper shock mount will determind how low the front end will be when full bottomed out). you will also need to find a shock length that will work and more than likely beef up the LCA mount as the weight on the front is really gunna want to break those two little bolts and bend the bracket when you let off at the end of the pull and the front slams down. a bumpstop would be a good idea stoping the shock 1/4"-1/2" from full compression.

i would NOT run FOA. the seals just dont last in them. if you dont mind fixing them, might be a good choice. personally, id find a set of fox, sway-a-way, or kings. a 1000lbs spring might be a bit stiff on the street but may give you a little more adjustment room when weighed down compared to the 800lbs spring. i would start with that spring and go from there. you stuck with a 2.0 shock for any over 800lbs springs though. just make sure you take block height into account when setting everything up. allowing spring bind to happen is a good way to kill a spring in short order.

 

[x MadMAX DIESEL]

Sub

 

[moparkxracer]

I'm running 800lb ones on mine.

 

[duramaxzak]

i have one on DF?? i dont remember putting one there..

http://www.duramaxforum.com/forum/suspension-steering/166059-coilover-setup.html

Lol! Thanks! QA1/Viking performance is local to me, I might see what they set me up with. They sell a double adjustable coil over that might work for me and can come with a stud top mount.

 

[moparkxracer]

Some have had issues with the top stud mount pushing through the bushings.

 

[duramaxzak]

Some have had issues with the top stud mount pushing through the bushings.

Hmm.....might be better to use the stud mount conversion bracket than!

 

[moparkxracer]

That's what we did on mine.

 

[Chevy1925]

http://www.duramaxforum.com/forum/suspension-steering/166059-coilover-setup.html



Lol! Thanks! QA1/Viking performance is local to me, I might see what they set me up with. They sell a double adjustable coil over that might work for me and can come with a stud top mount.

Huh, completely forgot I had one there lol.

Your issue will become ride height. Your not going to be able to hit stock height and if you do, your issue will be shock length meaning the shock will be fully extended before any bump stop is hit on any bumps you hit in the road. Very bad on the shock.

If you like a lowered truck look, it will work better but I know some have had issues with the spherical balls going out in them and the shocks just not lasting in dd cases. Not sure if you dd that truck

 

[duramaxzak]

Truck is not DD anymore, strictly track only.

You think these would be too short? My truck at ride height sitting on bump stops is appr. 18" from bottom shock bolt to the top of shock bucket. Than subtract 1.5" for coil over shock mount bracket would put me at about 16.5" shock length at ride height. I really only want the front to raise off the bump stops about 1" when pulling.

http://m.summitracing.com/parts/hal-dd701

http://m.summitracing.com/parts/hal-dd901

 

[Chevy1925]

Truck is not DD anymore, strictly track only.

You think these would be too short? My truck at ride height sitting on bump stops is appr. 18" from bottom shock bolt to the top of shock bucket. Than subtract 1.5" for coil over shock mount bracket would put me at about 16.5" shock length at ride height. I really only want the front to raise off the bump stops about 1" when pulling.

http://m.summitracing.com/parts/hal-dd701

http://m.summitracing.com/parts/hal-dd901

The adapter is only 1" more.

What is the ride height you like when setup ready to pull?

That shock might work pretty well in place of the stock shock. That with a 1000lbs spring may work out well for ya. Due to the leverage on the shock point, it will take 4-5" of shock compression for the spring to support the truck with 0 preload. You then have about 2" of preload available to put into the spring before spring bind can happen. Knowing spring block height will help you stay away from that point and just how much preload you can put into the spring.

 

[duramaxzak]

The ride height with the shock mount adapter would be 16.5-17". Truck sit's on the bump stops that I made to hold CV shafts level with weight on it.

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