Rear Suspension too low

[jm49hill]

My 1996 Fleetwood Brougham's rear suspension lost it's air last week and then promptly came back up. After that happened, the rear suspension is about 2-3 inches lower than is was before, thus making the ride a little harsher. How can I get more air into the rear suspension?

[Katshot]

Don't bother. You need springs.

[The Ape Man]

Consult the service manual for adjustment and testing of the ride height sensor and arm before replacing springs. Replacement of shocks and springs with the wrong parts will ruin the ride of that car. The factory system is worth trying to keep if it isn't too far gone. I have 2 1980 Cadillacs. One has a working level ride and the other has "heavy duty" replacement rear springs. No comparison in ride. 1980 chassis is same as later years.

[Katshot]

If the car is sagging 2-3 inches as he suggested, the springs are in need of replacement. Calling on the ELC system to take up that much load is overloading it and will cause multiple problems. The "proper" fix in this situation is to replace the springs.

[The Ape Man]

"2-3 inches lower than before" makes absolutely no reference to suspension height measurement as outlined in the service manual. Anyone can condemn parts and throw stuff at a problem without due diligence. It's nice when someone else gets the bill.

[Katshot]

I'm assuming that the car was sitting at least fairly level prior to this problem. 2-3 inches is a lot when talking about trim height. So this taken into consideration, along with the fact that he says that it used to ride good but now has a "harsh" ride tells me that the rear end is sagging a good deal. For a '93-'96 Fleetwood to have a bad ride, the rear suspension must either be rather high, or rather low. I'm guessing it's rather low. Obviously, this is all conjecture and I'd certainly rather "see" the car but I think it's probably safe to point out that the ELC system is NOT designed to carry the weight of the car on even a semi-permanent basis so therefore even on the remote possibility that the car is now sitting level, and before, it was sitting rather high, the guy should be looking at replacing the springs rather than using the ELC system to jack the car back up to where it was.
I'm not trying to make the guy throw money away, only trying to point out the "proper" and "safe" way to use the ELC system.

[ralphb]

Has anyone had experience with air lift bags ? I think that's the trade name - they are cylindrical plastic bags that are inserted inside the rear springs, then inflated.

Do they raise the suspension height ?

How do they effect the ride quality ?

[N0DIH]

Weak or blown shocks will make the car sit low. Gas Shocks push the suspension up, if the car was designed WITH gas shocks, the ride height MUST be measured with good shocks, not bad ones. With a car that came with non gas factory, then you can remove the shock to measure the heiight or have bad ones, it doesn't matter.

[Katshot]

Originally Posted by N0DIH

Weak or blown shocks will make the car sit low. Gas Shocks push the suspension up, if the car was designed WITH gas shocks, the ride height MUST be measured with good shocks, not bad ones. With a car that came with non gas factory, then you can remove the shock to measure the heiight or have bad ones, it doesn't matter.

Gas shocks don't have enough pressure to actually "raise" the car. They are only designed that way to help increase the wheel's tracking ability over changes in the road surface.

[96Fleetwood]

Do you hear the air compressor working?

[N0DIH]

But find me any car that has non gas shocks on it, or blown gas shocks, and install new ones and the ride height WILL rise 1-2 inches. (ok, maybe not the lame $10 shocks)

It is common belief that installing new gas shocks should not change the ride height, but in most every case (new gas shocks on my weak rear sprung Suburban now with a 9.5", didn't), they do raise it. Maybe once they settle down after 5-10K, but in my opinion, most cheap shocks are already worn out by then.

Should it be that way? Don't know, as there are so many variables to put together to get an exact, repeatable ride height, I don't we can dial it in without trial and error.

Originally Posted by Katshot

Gas shocks don't have enough pressure to actually "raise" the car. They are only designed that way to help increase the wheel's tracking ability over changes in the road surface.

[Katshot]

Originally Posted by N0DIH

But find me any car that has non gas shocks on it, or blown gas shocks, and install new ones and the ride height WILL rise 1-2 inches. (ok, maybe not the lame $10 shocks)

It is common belief that installing new gas shocks should not change the ride height, but in most every case (new gas shocks on my weak rear sprung Suburban now with a 9.5", didn't), they do raise it. Maybe once they settle down after 5-10K, but in my opinion, most cheap shocks are already worn out by then.

Should it be that way? Don't know, as there are so many variables to put together to get an exact, repeatable ride height, I don't we can dial it in without trial and error.

I don't know what gas-shocks you're using but all the ones I've installed over the years don't have that much pressure. I mean hell, I can compress them by hand! How is a shock that's compressable manually going to raise the rear of a 5000 pound Suburban? This is a first for me. I've never heard anyone make this claim.

[Zorb750]

If I were you, I would just throw it in the garbage and buy new shocks and springs for the back, because you have a self compounding problem from the sound of it. The spring holds part of the weight of the car, well, most of it. The compressed air shock holds up part of it as well, so as to trim the ride for levelness. If your springs are going bad and starting to sag, your air shocks have to work much harder than they are designed or intended to. This means they will wear out faster (especially the seals for having to tolerate abnormally high pressures).

So... the lack of spring support makes the shocks work too hard, which makes the compressor work too hard. The shocks start to wear, causing the springs to still have to carry more weight. It's a circle. The only way out is to replace. Now, the rear shocks can be changed in your driveway honestly. It's not difficult. Your rear suspension is very simple, as I recall it actually uses leaf springs. You could even do those with a little more work in your driveway.

[Katshot]

No, actually he has coil springs but they ARE very easy and cheap to change.
As for the theory on what happens when the shocks are carrying too much load, you're only hitting the tip of the iceburg here. When the shocks are used to carry too much load on a permanent basis due to worn coil springs:

In addition to the obvious reduction in service life of all the components of the ELC system:

1. You no longer have a usable spring-rate from the rear suspension so the overall handling of the car is adversely affected.
2. The rear shock mounts are NOT designed to support the loads you are placing on them and they WILL fatique and fail. This will cause the upper shock mount to seperate from the frame assembly. Fixing this will require (at the very least) replacement of the upper shock mounts via custom fabrication and a good deal of welding. I know this because I've personally fixed a few Cadillacs that experienced this.

Do yourself a favor and go get a pair of coil springs ( I suggest "progressive-rate" springs) and spend a half hour installing them. It's VERY easy, will vastly improve the ride quality of the car and shouldn't cost more than $150 as I recall.

[Zorb750]

Interesting. I saw an older Caprice with leaf springs. I figured the Cadillac would be the same. You're right though in terms of the handling, I figure that one goes without saying though. I would think the shock would fail and collapse totally before the mount does however.