1972 Cadillac Eldorado - no level control

[Scot Minesinger]

I'm going to be working on a 1972 Cadillac Eldorado that has been substantially unloved most of its life that has now been matched with an owner who plans to invest in restoring the mechanicals to near perfect and very reliable condition.  The air compressor that serves the level control is inoperable/gone and the shocks and springs in rear are original.  If this was a DeVille or Fleetwood, I would just order the regular shocks and springs, leave the inoperable auto-level works in place and have a non-level control car.  I do not want to the do the air shocks with shrader valve-pump it up once a month thing.

Question is what springs and shocks do I buy to change the car over to non-level control, std rear sprung with std shocks vehicle?  Perhaps the Torando did not have level control and by 71 GM had made Olds and Cadillac use same mechanical components and I could buy Toranado rear springs and shocks.  Want a comfortable functional driver with level ride height unless trunk is heavily loaded.

I feel like I cannot just buy DeVille rear springs (or maybe I can) because without the weight of the differential (maybe 100lbs max) and the top/bottom of springs may be a little different and not fit.

Does anyone know if the std DeVille rear springs will work in the Eldorado?

[TJ Hopland]

I have manual fill air shocks on several cars and rarely mess with the air pressure, maybe once per year.   Unless there is a leak they seem to hold pressure just fine.  Since its not a common application anymore you can get em that have been on a shelf for a long time and leak just from shelf rot. 

I don't remember if I read it or researched it myself once but I think the C car vs E springs were significantly different.   I think the C cars were heavier in the back so their springs make the Eldo run really high and stiff.     Toronado is an idea but I think they often had air ride too so not likely a common replacement part.   

[James Landi]

My suggestion:  I've rebuilt several of the vacuum actuated level compressors when I owned 60's Eldorados, and the service life varies, and the rebuilding process can be a major frustration... I would suggest the second generation electric motor compressor and the sending body height components and associated parts. These are relatively trouble free and provide not only level control but some associated improvements in driving dynamics.  James

["Cadillac Kid" Greg Surfas 15364]

Scott,
ALC WAS NOT an option, it was standard.  I have seen Eldos with "replacement" springs and heir owners were not very satisfied.  There is so little weight on the rear springs with just the driver and the difference when adding passengers and luggage is quite remarkable.  As TJ said, replacement of the AlC with manually refilled air shocks is the most common "fix".  If you decide to restore the ACL drop me a PM.  I have all the components off my '72 that I removed when I went to a manual system including a compressor I rebuilt (removed while working) and a full rebuild kit.
Greg Surfas

[Scot Minesinger]

Guys,

Thanks I knew that ALC was standard and no non ALC springs available.  Also understood that rear was light and passengers plus luggage creating a huge variation in rear weight percentage likely made the ALC a standard equipment.  So as I feared, the ALC is an important part of the drive ability of this car.

Let me see what this car is doing on Sunday when it arrives and will report back.  Will either go with rebuild kit to original or maybe the upgrade electric compressor.  Originality is long gone on this car, but it can still be enjoyed.

Thanks,

Scot

["Cadillac Kid" Greg Surfas 15364]

Scott,
Please be more specific.

Eldorado that has been substantially unloved most of its life that has now been matched with an owner who plans to invest in restoring the mechanical s to near perfect and very reliable condition.
Your initial post would indicated (at least to me) that you had not worked on an ALC Eldo, you did not understand the need for the ALC,  and you were asking for experience. It seems you are just announcing commercial projects you are working on.
Greg Surfas

[TJ Hopland]

Has anyone come up with a reliable method of height sensing?   I have yet to see an electronic one that was working.  Have had several cars with those over the years and the sensor always seemed to be the problem.  The original vac compressor has its issues but the level sensor they used seems to have worked alright.   Anyone try putting a pressure switch on the electric compressor so it maintains tank pressure like the vac one did and then leave the original height sensor?     

["Cadillac Kid" Greg Surfas 15364]

TJ,
Noise is the great drawback with an electric air compressor.  They typically ARE pressure controlled.
Greg Surfas

[TJ Hopland]

Really?   None of the GM ones I tangled with 70's-90's was.   The level sensor / module would run the compressor to raise the car or operate the purge valve on the compressor if it needed to lower the car.

I have never really heard a compressor running with a running engine.  I guess if you were listening for it you could hear it but its kinda like fuel pumps for the most part I don't notice them. 

[James Landi]

They are well shock mounted and the elecitric pump models have a time limit module that ensures the compressor is not wasking away on a leaking hose ... the earlier vacuum compressor will pump until it's worn out...yes. the height is controlled at the pump...in the first gen, purge is at the solid  rear axle ....I recall the first time I heard my 67 purge...I was scrambling on all 4's trying to determine which rear tire was leaking! 

[Scot Minesinger]

Greg,

I am taking your advise and going to make sure that an ALC is functional on this 1972 Eldorado as you suggest.  I was hoping that it could abandoned, but yours and other posts were compelling that it could not be.

Your advice is sought.  I always appreciate your technical information.  Thank you.  Yes it is true I have never worked on a 1972 Cadillac Eldorado before hence my post.

I worked on other cars and other issues that did not need an answer on and did not make posts.

People like it when I work on their cars because there is minimal guess work and take my time, researching included.  This forum has been so helpful on my projects. 

Should I have posted this question differently?

[chrisntam]

I see this post (and others) as "sharing" information.  The more information that is posted, the better we all can be at doing repairs.  Keep the posts coming!  The answers too.  For those of us trying to learn, we (I) enjoy reading these posts.  Both questions and answers are appreciated by me and very likely, others too.

So I'll say it, Thank you!

[Bill Young]

I want to say Thank You too!
Sincerely , Bill Young
Gainesville , Georgia

[beastly beauties]

I have restored my ALC valve without any difficulties. It had been sitting around for more than twenty years when I got it and the compressor was inoperable for who knows how long. I removed the control valve and disassembled it and soaked it and gave it a little cleaning. I recall replacing all the O rings with new ones from a universal assortment I purchased at Autozone. I replaced the air compressor with an electric pump I was installing anyway to operate a set of air horns. I had to delicately drill out the brass fittings on the control valve very slightly to accommodate the new size air supply line to the shocks. Everything works just as intended and I am pleased it worked out well. Sometimes a little luck and engineering can make it happen effortlessly.     Good Luck, David   

[Scot Minesinger]

beastly beauties,

The car is in my possession now and I am going thru it.  Probably will use the electric compressor arrangement as you describe, that way once it is all set up electric compressors can be replaced fairly easily if future issues arise.  This car is operated by a person who might have owned it in 1972, and is not mechanically inclined.  I need to make it as enjoyable, reliable and durable as possible.  An original look is desired by owner, but not authentic operation to every last detail.

Thanks,

Scot

[TJ Hopland]

It seems like all that may be needed to fit one of the later electric compressors is a pressure switch.   I have repaired several of the modern 'oil less' air compressors that use a pressure switch that resembles an automotive sensor rather than the large unit with the cover you would see on a typical compressor.   

What does the 'air horn' compressor cost?    I remember before I had a pile of OE electric compressors I looked for a new 12v compressor to use and what I found was either total cheap garbage or stuff that was way to large and expensive.   I wonder if things have changed since I last looked?

[Scot Minesinger]

GM used electric compressors for air shocks starting I think in the late 70's through the mid 90's and so there are lots of them out there intended for this purpose.  I saw some on e-bay, used that work for good prices, so probably will go there.  Was thinking ride height control is how it should be controlled with maybe a high pressure override.  Not sure yet.  The original post was if I could just go with springs like on a DeVille, but the posts advised against it due to light rear weight and substantial variable rear weight that may occur with passengers, luggage, and fuel.  I have the answer, need ALC, now onto finding out more in the next couple months.

[James Landi]

My suggestion:  purchase the entire system from a donor car.  The ride height is controlled electrically, at the rear of the car... so there's a wire harness that runs up to the electric pump and controls the "on/off" of the electric compressor AND the compressed air purge valve  modulates the height if people or weight changes during a driving cycle. Additionally, the air supply tube has an "over load" device that lets out compressed air if your car hits a pot hole.  As part of the power supply to the electric compressor, there is a time cycle off electronic device (module in the car)...that allows the compressor to pump for 90 seconds, and if the pump cycle times beyond that, the device shuts off the compressor to save it from running constantly.  I have put a pressure gauge on mine, and it usually pumps up to between 60 to 80 pounds, but I have seen it register over 100 when there's real weight in the car.  If the height control valve still operates on your 72 as was suggested in a previous post, you could get away with not having to trouble yourself with the height control, and as he stated, it would save a bunch of time... but you really do need that pressure safety relief valve (on my 80's car, it's hidden in the inner liner of the fender, and you should track down the time-out module.

[TJ Hopland]

Did you get a chance to look and see if there is any parts of the system left on the car?

[Bill Young]

On My 1972 Eldorado Convertible that system is not operating at all, but the Car seems to be level and drives satisfactorily. Is it a big problem to leave it dormant?