Rear airbag mount on trailing arms (not stock location)

[DM310]

Just was wondering how some of you guys have the rear bags mounted on the trailing arm, not looking for the stock coil location.

[laid67c10]

mines not bagged yet but my buddy's 71 longbed has em mounted further foward and a bridge built across the frame....

[bagged69c10]

Thats ^ also what I did, gets pretty good lift. I just drilled a couple of holes in the top of the trailing arms to bolt the bags to.

[shortbed70]

I thought about mounting the bags further forward and welding a cross brace on top of the trailing arms so it triangulates the rear without using a panard bar and getting more lift than mounting in stock location.

[smokekiki]

Originally Posted by shortbed70

I thought about mounting the bags further forward and welding a cross brace on top of the trailing arms so it triangulates the rear without using a panard bar and getting more lift than mounting in stock location.

I don't think that would work very well.It would still let the rear move side to side on the bushings.It would not keep the rear centered.

[XXL]

Originally Posted by shortbed70

I thought about mounting the bags further forward and welding a cross brace on top of the trailing arms so it triangulates the rear without using a panard bar and getting more lift than mounting in stock location.

You'd lose the "in" in independent rear suspension by doing that. They each get to move up on their own, which twists the rearend a bit, but without it, every bump on the left side would also affect the right side and/or you'd rip your welds, etc., apart.

[shortbed70]

I dont understand how it's independent suspension when its a solid rear axle. Corvettes and jags are independent rears. Its hard for me to explain how I would do it without drawing a picture. Just want to clarify not trying to start an argument. OK. Thank you Troy. Even if I kept the track bar I think it could be done without problems with driveshaft clearence or just use a mount that goes on the outside of the frame and mounts to the trailing arms. Just a thought.

[XXL]

Originally Posted by shortbed70

I dont understand how it's independent suspension when its a solid rear axle. Corvettes and jags are independent rears.

I was simplifying things a bit... true, a solid axle is not independent in the way that Corvette and Jag IRS units are. However, try this exercise-- slide a floor jack under the left side of the rearend and raise it 12" or so. Note that the right side of the rearend has NOT risen the same 12" (possibly not at all). What you will see is that the rearend is no longer horizontal, however. That's because the two sides have some "location independence" as a result of the independent swingarm movement. If you tie the two swingarms together, you will lost that independence. I recommend a good suspension tutorial to anyone who is planning on experimenting with these kinds of changes. Vehicle suspension is non-trivial, and you don't want to get into a dangerous situation with it.

[1FaastC10]

Originally Posted by XXL

You'd lose the "in" in independent rear suspension by doing that. They each get to move up on their own, which twists the rearend a bit, but without it, every bump on the left side would also affect the right side and/or you'd rip your welds, etc., apart.

the axle bolted to both trailing arms kills the "in" in independent suspension. agreed though, a bridge between the two would cause the suspension to lose travel. would just ride like crap.

[1low1967]

I bagged my 67 in the rear. I built my own mounts and bridge. I also flipped the trailing arm brackets upside down for better pinion angle. I'll post some pics soon but i get About 26 ins of lift with the front down. And it will lay frame on 20s with a 275/45. i'll post some pics as soon as i get home.

[DM310]

Plus the drive shaft would mostlikely come in contact w/ the cross brace

[BK]

i mounted my bags approx. 8-10" ahead from stock spring perch on my 65 panel, gives great lift(about 19" at rear bumper) while cruizin at a low PSI for a nice ride, and is plenty strong. If i could get my damn panel down here i could get you all pics of the bag mounts, rear notch, and watts-link, but i gotta get it down here to oregon.

[DM310]

I finished my mounts over the weekend so I will try to post some pics tonight

[DM310]

I still need to do a little more but heres where I am at right now

[shortbed70]

Are you going to have to notch the frame where the bag sits so it doesn't rub? I like the look and you should get good lift out of it. What bags are you running?

[BK]

Please make sure and gusset and brace the upper bag mounts, if you dont, they will bend way easy.

[DM310]

Thanks....there is a 1" clearance between the bag and frame. I am running some contitech bags from *****************. Yeah I still need to do some more work

[1low1967]

Heres what I did

[Slammed67]

Why are you guys trying to get so much lift out of the rear end? Seems like you are putting a lot more stress on the trailing arms the farther forward you move the bag mounts. Just curious.

[DM310]

I only did it that far forward b/c it sits so low and I still have part of my stock frame back there. I did not want my airbags rubbing on the frame

[BK]

also, mountin your bags further up on the trailing arms allows you to get the same amount of lift with less air pressure meaning a softer smoother ride at the same height

[SCOTI]

Originally Posted by DroppedChoppedPanel

also, mountin your bags further up on the trailing arms allows you to get the same amount of lift with less air pressure meaning a softer smoother ride at the same height

This sounds good in theory but I think alot depends on what manufacturers bags your running. My 68 is not bagged w/the intent of planting the framerails @ shows. It's set up to be low all the time & add air when it's time to pull a trailer. That being said, when I'm just cruizing around town w/no load/trailer, about 30psi of pressure is as low as I want to get because the ride starts getting significantly more bouncy. At 30psi in the dbl. convoluted 224c Firestones, my rear end housing is up inside the space originally occupied by the bottom of the frame rail. 35-40psi seems about optimum w/no weight & when loaded I run about 60-70psi.

What kind of bags are you guys running when relocating them forward? What air pressure?

[ehjorten]

I feel the need to make some comments...say what you will to me, but moving the bag up on the trailing arm does not allow you to run less pressure. In fact you will have to run more pressure because the effective spring rate at the axle is decreased as you move the bag up the arm. Effective spring rate (Reff) is calculated as such: Reff = SP x (L1/L2)²; where SP = your spring rate at the bag, L1 = the distance from the trailing arm pivot to the bag (spring), and L2 = the distance from the pivot to the axle centerline. So...Spring Rate has to increase as you move the bag closer to the pivot.

Why not use air-bag over shocks like the shockwaves and mount them directly off of the back of the trailing arms? This would allow you to run low spring rates and actually give you a slight mechanical advantage over the axle.

[Slammed67]

I feel the need to make some comments...say what you will to me, but moving the bag up on the trailing arm does not allow you to run less pressure.

Thank you.

[SCOTI]

Originally Posted by ehjorten

I feel the need to make some comments...say what you will to me, but moving the bag up on the trailing arm does not allow you to run less pressure. In fact you will have to run more pressure because the effective spring rate at the axle is decreased as you move the bag up the arm. Effective spring rate (Reff) is calculated as such: Reff = SP x (L1/L2)²; where SP = your spring rate at the bag, L1 = the distance from the trailing arm pivot to the bag (spring), and L2 = the distance from the pivot to the axle centerline. So...Spring Rate has to increase as you move the bag closer to the pivot.

Why not use air-bag over shocks like the shockwaves and mount them directly off of the back of the trailing arms? This would allow you to run low spring rates and actually give you a slight mechanical advantage over the axle.

I think most of the guys that are doing mods like this are all about extreme lift & railing. I don't see any reason for moving them if you're just interested in slight height adjustments for driving down the road.