379 Low Air Leaf Height

How long has it been set at 6.5 before you changed it?

 

there is a low air and a low low air leaf the low low sets at 6.75 from center of axle to bottom of frame in front of rear axle. not axle housing, the axle it's self. measured from center of axle at the end to the ground and add 6.75.

 

There is no visual difference. We have several car haulers with low low air leaf and the hangers still just say low air leaf and nothing looks any different than other trucks with low air leaf. I think it really just depends on what height they set the drive line angles.

It is possible that someone lowered the truck at some point and reset the drive axles to match. If you have low air leaf and want it at the correct spec, you'll have to set it at 8.5" and check drive line angles. To fix it, you'll be changing the shims on the rears.

 

Low low air leafs main bracket is the same as low air leaf BUT it is drilled higher up on the frame so it makes the truck sit lower.

 

I've been battling the same deal with a 2000 379 with supposedly low air leaf.
With the ride height set at; empty, bobtail, brakes released, and measured out to 8.75 from the bottom of frame rail at a point in front of the rear drive to the center of the axle. Center axle height was derived by measuring from the top of the tire on the rear axle to the ground and then divide by two. Add suspension spec, which is 8.75 ", to that measurement and as said earlier, from in front of the rear drive axle, measure from the bottom of the frame rail to the ground. That gives you the 8.75" measurement to the center of the axle.
With this measurement applied to my suspension the truck is really riding rough and feels so stiff it feels as if it is kicking from side to side on some rough spots in the road. It has a new transmission, and both differentials are new but, it feels as if it has a vibration coming from somewhere when under a moderate to hard throttle.
Just to see what would happen with the ride and vibration, I went to the low low air spec of 6.75 inches and the ride is significantly better and seems to have no vibration now.
I've been told that this truck has low air leaf but, I am not so sure now. I don't want to have problems show up somewhere down the line due to bad angles if I keep running it at low low specs.
I suppose the angles need to be checked.

 

I thought that there is a difference in the two suspensions besides the ride height. It has to be some way to tell just by looking.
Is there anyone out there that really knows?

 

While we're on the topic, the '86 in my sig has the air leaf suspension (not low air leaf or low low air leaf just plain air leaf). Does anyone have the ride height numbers for it?