73-87 Detailed Air Suspension Questions!

[seanconnery]

Greetings all. Ok. I have a few questions concerning suspensions for my 1981 GMC Sierra shortbed ½ ton. First off, I am not new to the world of suspension fabrication, as I used to own a 3 ½ inch bodydropped 1989 s10 that I did all the work to. However, this is my first fullsize truck, so I need to ask a few questions.
1. Whilst browsing the boards, I’ve noticed a lot of the 73-87 guys running parallel 4 links with a panhard bar. Is this for a particular reason? I had a 3 link. Will a triangulated 4 link work for me without relocating gas tank(s) or in general make my life miserable during fabrication?
2. Staying on this theme, I am planning to run a suicide doors tri-4 link with the bag- on- bars setup. Again, am I setting myself up for disaster? I’ve noticed many folks with sleeve bags and traditional bag-on-axle setups. That’s how my s10 was and I wished I had more lift.
3. Right now, I don’t have the budget or desire to bodydrop this one, but do I need to be concerned with the trans. crossmember and any driveshaft issues? I’d like it to lay frame, so whatever needs to be done than so be it.
4. What exactly needs to be done to the front suspension to lay it out besides the 3 inch DJM lowering spindles I’m planning on buying and bags? With the s10 I sectioned out the humps on the lower a-arms for clearance to lay the frame. I have heard about the Porterbuilt “dropmember”. Is this basically a setup for the entire front suspension? Again, I don’t have a budget for a $1,500 application.
5. My truck has air conditioning and 250 inline 6. There’s enough room to sneak a family of Mexicans across the border if necessary. What I was planning on was to move over the air equipment closer to the engine block and reconfigure the aluminum hoses that run into the firewall. Will this work, and will I have to modify the heater core and such? I’d rather not. This truck is really nice, and I ended up sacrificing heat, air and all that for the bodydropped s10. I don’t want to do that now.

Thanks for bearing with me on this one. I searched the boards and didn’t really find too much.

[Tony@AirRideTech]

1. Due to the frame rail widths, rear axle type, the parallels are much friendlier. If you run a triangulated you will have to reverse the angle on the bars or use a for 9".... if it were me and the truck is complete, I would just put a parallel on it with a panhard bar.
2. i would still run a Slevved airspring on the axle instead of a leverages set up.
3. No concerns
4.Depends on your definition of lay out. If you want to hammer it then you will need to look at going with a dropped crossmember. With the factory crossmember you will put your pivot bushings on the ground first.
5. I am not sure I really follow you here but if I am reading you right you wouldnt have to no...

[N2TRUX]

seanconnery...... I need to ask a few questions.
1. Will a triangulated 4 link work for me without relocating gas tank(s) or in general make my life miserable during fabrication?
A triangulated 4 link is not the optimal setup, but it will work with the stock tank. You need to maximize the triangulation to minimize sway. It's not the best option.

2. I am planning to run a suicide doors tri-4 link with the bag- on- bars setup. Again, am I setting myself up for disaster? I’ve noticed many folks with sleeve bags and traditional bag-on-axle setups. You need to decide if you prefer a smooth ride, or max lift. From what I have researched your going to have a smoother ride with a sleeved bag. (I'm sure I'll get some grief for that comment)

3.do I need to be concerned with the trans. crossmember and any driveshaft issues? I’d like it to lay frame, so whatever needs to be done than so be it. Trans crossmember isn't an issue. The E-brake cable needs to be re-routed.

4. What exactly needs to be done to the front suspension to lay it out besides the 3 inch DJM lowering spindles I’m planning on buying and bags? If you truly want to "lay frame" this is where your problem area is at. As Tony mentioned above, the first point of contact when dropping the 73-87's is the pivot point where the A-arm meets the crossmember. You can lay the A-arms with spindles and bags, but the frame is still 3" +/- off the ground. You have a few options if you want it lower. A. Section a stock crossmember. This will give an additional 1.5" of drop. It's a lot of cutting and welding for 1.5" but it works. B. Z the stock frame rails, or "front half" with custom front rails. Either way requires slicing and dicing your frame with all the required mods to make everything line up and work again. C. Buy a dropped crossmember and bolt it in. It will require frame mods for a rack, but that's minimal compared to Z-ing.

5. My truck has air conditioning and 250 inline 6. There’s enough room to sneak a family of Mexicans across the border if necessary.It really depends on how tall of a tire you want to run. If you stay under 29" you won't need to move your stock system at all.

[RunninLo]

[QUOTE=N2TRUX;2944532]
2. I am planning to run a suicide doors tri-4 link with the bag- on- bars setup. Again, am I setting myself up for disaster? I’ve noticed many folks with sleeve bags and traditional bag-on-axle setups. You need to decide if you prefer a smooth ride, or max lift. From what I have researched your going to have a smoother ride with a sleeved bag. (I'm sure I'll get some grief for that comment)

QUOTE]

N2 it is my experience that you raise a valid point and I'm willing to stand with you on the superior ride of the sleeve bags. I have been doing bags since the early 90's and have used just about every option (double/triple convaluted in various sizes, rolling sleeve, cans,bag-over-strut) in just about every location (on axle, in front, in back) and in 1:1 and canti-lever set-ups.

For the last few years I've been using the F9000 sleeve bags in more and more installs after using them in a late 30's ford rod with an ART 4 link.

What I have found that causes me to really like them is they feel like they have a higher (read tighter) spring rate and comsume less volume of air than a trad. bag. They also have a few inches of extra lift compared to a 224c bag.

A few years back I had a customer with a 72 longbed that wanted the crazy lift in the rear like a hydraulic equipted low rider. I built it to his specs not mine. Full back half but stock link It was Z'd 3" up front and laid flat. That part was cool. the part I'm sort of ashamed of was it had 29" of lift in the rear and even with stiff shocks was still bouncy as heck. Since then I have refused to do another like it. The customer was happy but I was not.
My philosophy is as long as it gets the same or slightly more (1-2") lift than the front that's all you need. Sleeves do that and deliver the least bouncy ride.

Josh

[71blaze]

The bag over bar setup will work just as well as a sleeve bag but with more lift. The f9000 works great over the axle because it is it is made for a 1 to 1 ratio. Dubble conviluted bags are made for more like a 2 to 1 ratio. The only reason the dubble con. bag gets a bad rep. for rear use is because of expereance with bad setups like over axle , 3 to 1 ,or 4 to 1 ratio. If properly set up the bag over the bar setup will be smooth and have max lift. Your only issue will be with the shocks you will need to find one with the right stroke it is not good to mount them on the bar(THE SHOCKS).

[ShowSS12]

I will say this about sleeves they do ride better than the double C's I swaped out (sleeves) a set in the back of my impala to double C's and its now bounces more ALOT more.. IMO I would use sleeve over axle over a regular bag..

[N2TRUX]

71blaze I feel you have a valid point....but...(you knew that was coming) in most applications the sleeve bag is easier to set up correctly. I won't argue that you "can't" get a good ride and mad lift from a double con bag, I just feel that it might require your rear to be more demanding in design.

In this particular application where the OP is wanting simplicity and economy in his build, I feel that a simple bag over leaf or triangulated four link would serve his needs best.

[seanconnery]

Well, thanks for all the help so far...