changing rear springs on 74 deville...go original or cargo load

Started by lentel, April 25, 2016, 08:04:39 PM

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lentel

i am changing rear coil springs on my 74 deville... will the stock  replacements or the cargo load give it the most lift back to factory
thanks very much for any info

chrisntam

I put springs in my '70, I used cargo coils, my understanding is that they are variable rate, in that normal height when there is no load in the trunk (or back seat) but when loaded, the springs get progressively more firm to retain the original ride height.

I assume factory replacement springs will sag (slightly) when loaded as compared to cargo coils.

Keep in mind, this advice is free, worth what you paid for it.  I had cargo coils in my '75 olds 88 vert for 24 years and they were great!

chris.
1970 Deville Convertible 
Dallas, Texas


Scot Minesinger

I would use standard springs.  Actually, just replaced the rear springs on a 74 DeVille with standard and it came out great, nice and level. 

BTW use spring compressors, do not drop the axel and control arms plus disconnect brake lines as suggested in manual.  This is the only time, I ignored shop manual, way easier and faster.

Seems the original factory springs always drop on this year and model.
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

lentel

thanks scott... since you did your 74 deville recently.. let me ask you this... i bought the coil insulators and was able to find ones for the bottoms of the springs but where i got them (summit) claims the bottoms and top insulators are the same and to me  they dont appear to be... the bottom wouldnt work for the top insulator it needs to be larger...I cant find a top insulator that is listed as correct for my deville.. all companies are showing the same for a 74 deville.
Were you able to find the correct upper insulators....thanks for your help

Scot Minesinger

The top rubber insulators are not at all the same as the bottom.  The springs I replaced included the upper isolators.  Have done this job on three 1970 Cadillacs and the upper spring isolator was not included with them (same spring as a 1970, hence I switched vendors), and just re-used existing.

The upper isolator was just a section of rubber hose with ID about equal to spring coil wire OD about 6" long.  You can slip the isolator over the first 6" of the spring coil.

Of note the position of where the coil stops in the upper section of the frame is critical.  Make sure it goes back in same position as original.  Mark with silver sharpie and note indentation where coil end is supposed to stop.  If don't do this the coil will make the back not level side to side.  I had to correct a 1976 Cadillac with wrong spring location.  It is actually more work to rotate the springs to the right position (if you get it wrong) than it is to install them when using compressors because had to compress, rotate, release, and repeat several times for both sides.
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

lentel


64\/54Cadillacking

I actually recently replaced the rear springs on my 94 Fleetwood which is almost like a 70's Caddy in design and layout.

I knew something wasn't right about the ride for years that I've owned the car as the rear suspension was overly stiff and the ride was harsh. So after looking up rear springs for the car, I saw that I could only get cargo coils for the Caddy.

The original owner looked like he used to tow things because I have old receipts of a tow hitch being installed one point in time back in the 90's, so I am assuming for added stability, he added cargo coils.

Anyways, I did some research and found that I could get constant rate rear springs from a 94 Roadmaster which has a lower spring rate than the Caddy rated cargo's, plus the constant spring rate springs are better for a softer ride quality that I was aiming for.

The constant rate springs that are in there now really helped improve the ride and actually made the car more level and stable over the road vs the cargos which were way too stiff and bouncy that it made the car ride like crap including making the Caddy jitter and wobble side to side over uneven pavement. Plus less road shock is entered into the cabin compared to before. And the cars ASS isn't sticking up in the air anymore either because the cargo coils have a higher height rating and barely compresses.

Overall if you are looking to retain that Cadillac ride and low stock look, I would definitely get the constant rate springs, but if you want better load carry ability, and the rear end being a little higher off the ground than normal, then get the cargo's.
1964 Sedan Deville (Own)
1987 Brougham D’Elegance (Sold)
1954 Cadillac Fleetwood 60 Special
1994 Fleetwood Bro (Sold)
1972 Sedan Deville (Sold)
1968 Coupe Deville (Sold)
1978 Lincoln Continental (Own)
1979 Lincoln Mark V Cartier (Own)

chrisntam

This has cargo coils in it .  Ride height is the same as it was prior to the replacement springs being installed.
1970 Deville Convertible 
Dallas, Texas