Air bag ride height help

[jmlcolorado]

Hey guys!
I'm getting to the point in my build that i need my bags rigged up.
My setup is completely out of the norm for most of the builders on this site as i don't have drop spindles, rather a 6" Z in the frame under the cab.

I would like to use the factory spring mount location in the rear to mount the bags, with some bracing/plates of course. And ill use the typical plate at the front spring perch up front.

I have seen a few folks that use the factory location in the rear for their bags and their getting around 11" of lift. I really only want 6"
Same for the front. I only want about 6" of lift.
I am planning on using a bag cup of some sort up front.
As it sits now, the lower control arms come within 1" of contacting the upper spring mount in the front, and in the rear, i lay frame with a 2" pipe notch.

SO, do you guys have a idea of how much you get in the front using a RE7 bag or something similar?
I'm really looking for advice as to how to accomplish getting only 6 inches of lift all around.

Bags are new to me so a few more questions.
At what point do manufactures suggest the ride height be at? I assume if a bags max hight inflated is 11" and fully compressed is, say, 4", they don't want you riding at 10" all the time. Is it in the middle of max and min height of the bag? for example, 7.5" ride height?
How is that limited so not to overextend the bags? Do the shocks take care of that? If so, how do you find the right shock? Measure shock mounts at ride height then again at compressed height then find a shock that fits those measurements? As i type that out, it seems you wouldn't want the shock to be at max height either so you'd need it above ride height. This leads me to believe that strictly air pressure sets this. If so, what is a normal pressure in front and rear? When you fill your bags, you just have to be sure you stop at that particular pressure right?
So many points to cover, sorry guys.



I know ill get a few punches for having scrub line issues with having the z in the frame and i completely understand where your coming from. I assure you i am taking my time on this project and doing as much research as i can before i execute anything.

Obviously, this z would pose alot of problems using the C10 body, which I'm not so heres the project. Thanks in advance for your input.

[gcburdic]

ttt

[67c10rustbuket]

typically the front susp travel is resticted by a bump stop on the top of the frame behind the upper a arm to keep the upper control arm from whacking the spring pocket, ive had 2 bagged trucks and neither had an overtravel issue in the front. they were 97s10 and 95 silverado, as far as the rear the s10 was restricted by shock length and the silverado was not restricted ive heard of some people using a steel cable to limit suspension travel on a bagged truck but i never did. never had a problem just lift the rear of the truck by jacking the rear end. never jack the frame and leave the axle hanging unless you want to rip a bag.

[67c10rustbuket]

on the 67-72 the front bump stop to limit upward travel is in the underside of the upper a arm. just looked at mine (no its not bagged.....yet)

[jmlcolorado]

So when i go to bag my truck, do i look for a bag that rides right in the middle of its articulation then? I don't have bump stops on the a arms so i will obviously cup the lower arms to prevent smashing the bags.

[67c10rustbuket]

generally everyone uses a (firestone) 2600# bags front and rear on a full size chevy, and firestone 2500# on front of an s10 or other mini w/ 2600# on the rear . some use 2500# all the way around on a mini so they can carry 1 extra bag instead of 2 different ones.
as for your truck i would use a 2600# firestone (re7 equivalent i think) for front and rear. on the front you want a bag that will put the suspension at full lift without stretching the bag. if you use a bag that only gives you 6" of lift without locking the front suspension up you will stretch the outboard side of the bag. example if you use a 2500# bag on the front of a full size truck you will get less lift but it will require higher pressure and the outboard side of the bag will be stretched and eventually rip or blow. if you think about it the inner side of the bag does not lift as far as the outer because its closer to the pivot point. and if you get a smaller bag that only lifts the front to 6" it will ride like your sitting on a brick at 6". you have to have a little extra up/down travel from your desired height to make a comfortable ride.
a smaller bag requires more pressure to lift than a larger bag. more volume uses less pressure, . in a full size truck your pressure to achieve desired ride height should be around 90-100 psi front and 40-50 psi rear depending on weight . assuming thats a small block, a big block would require more like 120+ psi to lift the front. also at full drop the bags should be fully compressed (3" i think between mounts cups whatever) if the bags are not fully compressed this will cause you to use excess pressure to lift the truck.
weight , bag volume, lift angle/position, all change the general psi of lift.
if you only want 6ish" in the rear it would be best to use over the axle mounts rather than in the stock spring location and the bags will last longer due to them being worked in a more direct up/down motion. in the stock spring location the will be inflated on an arch where the rear side of the bag will be lifting higher than the front.
I have used upper and lower "cups" but i prefer plates on the bottom that bolt to the control arm because the recess in the control arm does not have a consistent depth due to the shape of the coil spring. there will be a lower spot where the end of the coil must be clocked into so the recess is not flat in the bottom so the cups can wabble around. not to mention that when deflated the bag will squish out the sides (like a flat tire) so its nice to have a flat surface for it to squish on instead of a sharp edge of a cup (depending on the diameter of the cup).
another thing to think about most first timers mess up is the air bag may fit into the spring pocket just fine when its new and un-inflated but when you inflate it it will not only inflate up it will stretch outward so make sure you have close to 1/2 inch clearance around the bag to spring pocket. this is a huge problem on s10s.
I think most retailers websites list the specs of the bags they are selling i know i used to check them out as far as compressed height, full lift height, suggested ride height, bag material ply, weight lifting capacity, max psi, etc..
the truck looks awesome and theres nothing wrong with a big fat Z as long as its all aligned and welded properly. nice project !

[67c10rustbuket]

usually people get a truck bagged and play with the suspension to figure where they like the ride height . then go get it aligned . so say you like it (however many inches off the ground) look at the gauges and remember what the psi is. say the front is at 110 psi and the rear is 45 psi, do most of you driving at that psi and your tires will like you. if you dont have it aligned and you drive it 3" lower than your last alignment you tires will hate you.

[jmlcolorado]

Originally Posted by 67c10rustbuket

usually people get a truck bagged and play with the suspension to figure where they like the ride height . then go get it aligned . so say you like it (however many inches off the ground) look at the gauges and remember what the psi is. say the front is at 110 psi and the rear is 45 psi, do most of you driving at that psi and your tires will like you. if you dont have it aligned and you drive it 3" lower than your last alignment you tires will hate you.

That was some excellent information! There are defiantly a few things in there I did not think about.
I'm hoping to have about 4" height on the lowest part of the frame so I will be cutting my lower control arms and welding in cups to achieve that height. I guess my biggest worry was over extending the front bags while driving. Colorado isn't known for their smoothest roads
I will definatly be keeping as much clearance around the bags so they don't have any chance if contact in their range if motion.
I certainly didn't think if the arc of the pivot points effecting one side of the bag more then the other. But as I lOok at the truck in the proposed ride height, the spring perch and a arm seem pretty parallel. The only time that will change is parked in decompressed stage.

You mention at the beginning that you want the bag to lift the truck till the suspension is locked. What do you mean by that?
Excuse me if I'm asking rookie questions
thanks a bunch for your advice!

Posted via Mobile Device

[67c10rustbuket]

when i say locking up the front suspension i mean at full upward travel. like when you jack the truck up with the jack under the engine cross member it will lift so far before the wheels come off the ground. once the wheels come off the ground the front suspenson is "locked up" in my vocabulary i think i got that phrase from reading too many lowrider magazines back in high school. ill try to load a pic of the 95 silverado front later this evening to show how i cut the spring pocket out and so you can see the arch of the suspension. it looks like the 67-72 frame has enough room in the spring pocket to put my head in so i dont think thats an issue on these trucks. later

[jmlcolorado]

Originally Posted by 67c10rustbuket

when i say locking up the front suspension i mean at full upward travel. like when you jack the truck up with the jack under the engine cross member it will lift so far before the wheels come off the ground. once the wheels come off the ground the front suspension is "locked up" in my vocabulary i think i got that phrase from reading too many lowrider magazines back in high school. ill try to load a pic of the 95 silverado front later this evening to show how i cut the spring pocket out and so you can see the arch of the suspension. it looks like the 67-72 frame has enough room in the spring pocket to put my head in so i dont think thats an issue on these trucks. later

Gotcha.
Wouldn't you want a small bit of travel left after the bag reaches "ride height"?

Obviously, you dont want to setup so the bag over extends when the suspension is locked up, but i figured you'd want some slop room there so you dont......um.....bottom out, or the opposite of bottom out when traveling over a bump, like a large speed bump.

[67c10rustbuket]

Exactly , you want the bag to have a slightly longer range of travel than the suspension so you dont stretch the bag or shoot it right out of the frame when you go dukes of hazard over a hill. some "cups" dont bolt in, some do, i like everything bolted in.

i attempted to upload a pic lets see if it worked .....

[67c10rustbuket]

That pic is my first bagged truck/first install sometime around 2000 it is a 97 S10 the front brackets are a cup upper mount with a bolt that goes into the old shock hole and the bottom is a plate that bolts into the control arm. these brackets were designed to make the bag at an upright angle at ride height instead of the lopsided accordian look that cups will give you. i liked those brackets alot ..
Now for my next magic trick i will attempt to resize and upload a pic from a digital camera .....

[67c10rustbuket]

ok in the following pics you can definately see the lopsided accordian look at full lift on a 95 silverado. this is full lift not a ride height, there will be less of an arc at ride height. also you can see where the spring pocket had to be cut out quite a bit to keep the bag from rubbing at lift as well as at full compressed drop. The janky looking notch in front of the bag is to give clearance for the tie rod when laid out. I did not do this install but i did cut out the spring pockets more than the PO because they were rubbing and replaced the bags. i dont think cutting the spring pocket is necessary on our 67-72 frames but its a huge issue on 88-98 and 94-0? s10 .
and to clarify this is a firestone 2600# bag(bigger). the pic above in the s10 is a 2500# bag(smaller)

[67c10rustbuket]

And for the record im pretty sure here in oklahoma we have worse roads with bigger pot holes than you. i found out the hard way on my S10 when i had some 215/35/zr18 tires on 18x8.5 wheels they lasted 3 weeks. i blew a tire and bent a rim when i hit a crack ? bump, where the concrete cracked and sunk about an inch on an interstate on ramp. i thought i ran over something big . lesson learned i went and bought some 245/40 tires

[67c10rustbuket]

Hey bro, I was just looking at another build and I realized when you talked about cupping the front lca your talking about recessing a huge chunk of 8"? Pipe through the c arm . Not the old school 5" pipe cup sitting in the spring pocket of the c arm that I was thinking of.(like the 95 pic w green cups). That will work great I'm going to have to do that on mine too.
Posted via Mobile Device

[jmlcolorado]

Originally Posted by 67c10rustbuket

Hey bro, I was just looking at another build and I realized when you talked about cupping the front lca your talking about recessing a huge chunk of 8"? Pipe through the c arm . Not the old school 5" pipe cup sitting in the spring pocket of the c arm that I was thinking of.(like the 95 pic w green cups). That will work great I'm going to have to do that on mine too.
Posted via Mobile Device

Thats right. By using that large pipe, I'll be able to set the suspension to be able to lay frame without ever having the chance of crushing the bags.
Posted via Mobile Device