Heavy Duty 3800 5K bags need cupped. How deep do they need to be? Car hauler C30

[jarrodblake]

I have a 1970 C30 with 1975 C30 front suspension. The truck is a car hauler. 31 tires. I'm not planning on slamming it but like to be able to lower it when I need clear the dovetail in low spots and to raise it to help with loading and I would like to be able to air it up when I have a heavy load on it to keep it for riding on the bump stops.

I ordered the bags from Chassis Tech. They are the 3800 bags rated at 5,000 LBS Each. The compressed height is 4.5 Inches, Normal Height is 9 Inches and max extended is 12.5 Inches with a diameter of 9 inches compressed.

I have already cut one of the control arms to be cupped. I don't know how deep I should cup it? From most the the threads I have read it looks like most people do a 2 or 2.5 inch cup as most bags are 2.5 compressed. However my bags are 4.5 inches compressed. So should I cup mine 3.5-4 inches?


Pics of the bags.

IMAG1652 by jarrod vanwinkle, on Flickr
IMAG1671 by jarrod vanwinkle, on Flickr

I don't have fittings yet I just have a valve stem wedged in there leaking air max is 12.5 but its not to it in the pic, but you get the idea.

IMAG1654 by jarrod vanwinkle, on Flickr

unmodified control arm.

IMAG1650 by jarrod vanwinkle, on Flickr

IMAG1651 by jarrod vanwinkle, on Flickr
IMAG1655 by jarrod vanwinkle, on Flickr

compressed this would be about a 2 inch cup

IMAG1657 by jarrod vanwinkle, on Flickr

IMAG1658 by jarrod vanwinkle, on Flickr
IMAG1659 by jarrod vanwinkle, on Flickr


Should the cup be angled like factory?

IMAG1664 by jarrod vanwinkle, on Flickr

or should it be a even all the way around?

IMAG1666 by jarrod vanwinkle, on Flickr




heavy load



stock height maybe a bit of sagg.


IMAG1663 by jarrod vanwinkle, on Flickr

[jarrodblake]

Well I went ahead and started on cupping my lower control arm. I went with a three inch cup as the bags only compress to about 4 inches and most bags used on c10 compress to about 2.5 inches and it looks like most of them use a 2 cup. I'm not planning on slamming it or any thing. I'm just trying to get the bag to operate efficiently. I assume when the bag is at rest or slightly compressed is where the bag is most effective? granted I know very little about air ride. I have measured my current ride height on the truck from the top of the lowering control arm to the bottom of the spring mount to be 6 inches. The bags at rest are 9 inches and with the 3 inch cups it will be at the stock ride height of 6 inches. The bags max height is 12.5 inches so I can lift the truck 3.5 inches and lower it about 5 inches.

IMAG1651 by jarrod vanwinkle, on Flickr
IMAG1655 by jarrod vanwinkle, on Flickr
IMAG1656 by jarrod vanwinkle, on Flickr
IMAG1657 by jarrod vanwinkle, on Flickr
IMAG1658 by jarrod vanwinkle, on Flickr
IMAG1661 by jarrod vanwinkle, on Flickr
IMAG1660 by jarrod vanwinkle, on Flickr
IMAG1663 by jarrod vanwinkle, on Flickr
IMAG1666 by jarrod vanwinkle, on Flickr
IMAG1695 by jarrod vanwinkle, on Flickr
IMAG1696 by jarrod vanwinkle, on Flickr
IMAG1697 by jarrod vanwinkle, on Flickr
IMAG1698 by jarrod vanwinkle, on Flickr
IMAG1699 by jarrod vanwinkle, on Flickr

The mounting points are wider than normal bags that and the mounting points needed to be moved over so I milled some new slots and moved the hole over.

IMAG1701 by jarrod vanwinkle, on Flickr
IMAG1702 by jarrod vanwinkle, on Flickr
IMAG1703 by jarrod vanwinkle, on Flickr

This is it at 6 inches.

IMAG1704 by jarrod vanwinkle, on Flickr

[tinydb84]

I'm a bit late to the post but I wouldn't have the cup sit any lower than the arm. It is already the lowest hanging part on the front end and having it sit an inch or two lower seems a bit worrisome.

Chassis Tech is also known to put out some less than quality products. I assume the bags are DOT approved but I would spend some extra time really looking them over to make sure they don't have any defects.

[Bentbolt]

what tinydb84 said less then quality products. my buy bought a set of bags and I filled them and stuck in 5g bucket with water and they all leaked at the seam. so we bought bags from switch suspension (their economy line) and they was great to work with and bags didn't leak. they also have larger bags.