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Old 06-22-2012, 09:01 PM   #1
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73' cadillac elderodo convertible

I've got a 73, 31' center bath AS that's been totally restored. New axles, tires , A/C, stove, refrig, floor, couch, etc, etc....... I was thinking a cool tow vehicle might be a 73 cadillac elderodo covertable, but have some questions/concerns about the equipment needed for it to work. Most of these cars have a HUGE engine that I feel sure can do the job, but what about the shocks in the rear? It sits fairly low in the back to begin with, Also the transmission would I need to beef that up, or install a transmission coolant? and I've read that these cars are front wheel drive? would that make a difference? Go figure..... I didn't know they made front wheel drive cars back then. Any insite to my dream towing vehicle would be greatly appreciated
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Old 06-22-2012, 09:23 PM   #2
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Cords and Citroens were front-wheel drive before WWII. The Eldo went FWD in 1967, with the gorgeous "Knife-edge" styling, following the intro of the wild '66 FWD Toronado. Not only is the Caddy FWD, but it's CHAIN drive... and quite the chain too! An enclosed chain connects the engine to the transmission for better packaging.

I'm not going to venture to guess what the towing dynamics would be like, but if you even want to consider trying you'll definitely want a good transmission cooler, a "desert cooling" radiator or better, etc. You'd want all new rubber bits in the suspension (see recent excellent post from Rednax on the general topic.)
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Old 06-24-2012, 10:49 AM   #3
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THere is a prominent member here who uses a '75. Do a search on "eldorado" and you'll find his different posts about that car, how he has modified it, used it, and several assessments of its' ability.

My folks used a '76 Sedan De Ville for 12-years to tow their 8k/lb Silver Streak. A RWD car has a few advantages for towing that should be considered.
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Old 06-24-2012, 10:59 AM   #4
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Talk to Kevin "overlander64". He has the good info about Caddy's and towing.
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Old 06-24-2012, 12:58 PM   #5
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73' cadillac elderodo convertible

Greetings Neal!

Quote:
Originally Posted by neal View Post
I've got a 73, 31' center bath AS that's been totally restored. New axles, tires , A/C, stove, refrig, floor, couch, etc, etc....... I was thinking a cool tow vehicle might be a 73 cadillac elderodo covertable, but have some questions/concerns about the equipment needed for it to work.
The early Eldorado convertibles (1971-1976) do make attractive tow vehicles, but there are many compromises involved and the expense of preparing one can quickly become cost prohibitive.

Quote:
Originally Posted by neal View Post
Most of these cars have a HUGE engine that I feel sure can do the job, but what about the shocks in the rear? It sits fairly low in the back to begin with, Also the transmission would I need to beef that up, or install a transmission coolant?
The engine is an 8.2 Liter for the 1971 and newer Eldorados (through 1978). Generally, if well maintained, the motor should not be a huge concern as it is my understanding that all of these motors had the flame hardened valve seats so unleaded fuel is not a concern that would be with the earlier 472 cubic inch V8s.

The suspension is one of the areas that will require work on virtually any of these Vintage Eldorados prior to use for towing. The front has torsion bars, and be prepared to have them inspected prior to purchase to be sure that the ones on the car that you are considering are not worn out as these are no longer available from any source so far as I have been able to determine. I was fortunate with my Eldorado as it was a one-owner, low mileage example that had very good original torsion bars that just needed to be adjusted to their highest height setting. I searched around for the very best available front gas charged shocks that I could find . . . finally had a competent auto parts house measure my originals and found a compatible set that weren't listed as an interchange for the Eldorado (I think they were for the GMC motorhome that was contemporary to the Eldorado).

The rear suspension poses a few more issues. Most of these Eldorados had rear level-ride as standard equipment. So long as you follow the correct hitching procedure this does not pose a problem, but it can take some searching to find the heavy duty air shocks that need to be added to the system to allow towing without blowing out the shock's air chamber. I ended up going with heavy-duty Gabriel air shocks with manual adjustment (I inflate to the minimum pressure specified by the manufacturer when towing and allow my Reese hitch take care of leveling). I also added new Cargo Coil progressive rate rear coil springs to replace the original springs that were sagging badly (unless the springs on the Eldorado that you are considering have been replaced in the last 36-months, you can be virtually certain to need new progressive rate rear springs before considering towing your Airstream). Since i also run Boyd Coddington custom wheels on the Eldorado when I am not towing, I installed air bags in the rear coils . . . again, for towing, they are inflated to the minimum air pressure specified by the manufacturer prior to towing so that the Reese hitch can do its job.

The suspension rebuilding is one of the keys to successful towing with a Vintage Eldorado. In addition, you are virtually certain to find that the front end will need upper and lower ball joints (again, do not scrimp on quality replacement parts . . . I went with heavy-duty Moog components when the front end was rebuilt prior to towing, and have had no problems since . . . going into ninth season this year). The lash in the steering gear will likely need adjustment, but a good front end alignment shop should do this as part of the front end alignment.

The transmission is a Turbohydramatic 425 (a Turbohydramatic 400 specifically designed for the 501 Cadillac and 455 Oldsmobile front wheel drive cars as well as the GMC Motorhome). This transmission is among the heaviest-duty of the turbohydramatics of that era. You will need the 16,000 pound auxilliary transmission cooler as a minimum towing a Sovereign. I would suggest having an experienced Cadillac mechanic service the transmission. My local Cadillac dealer has a mechanic with more than 35 years experience with Cadillacs and he went through my transmission with a comprehensive service and tune . . . have never experienced any transmission issues requiring nothing more than fluid and filter changes every fourth season. My Eldorado now has approximately 135,000 miles on its odometer and the drivetrain is all original with nothing other than regular service being required.

The two largest downfalls of the 1970-1978 Eldorados as tow vehicles that I have encountered are related to cooling. The radiator is just barely adequate for the car by itself. One of my first big expenses prior to towing with my Eldorado was having a custom radiator built. The shop that built my new radiate reused my original tanks, but custom built the core. Factory core was a three row, but my building insisted upon building to "ambulance" standard which was a four-row core utilizing "large-bore" copper tubes and fins. With the custom radiator, I have never had issues with excess temperature . . . but I had periodic problems with the OEM radiator just driving in hot summer weather without imposing the additional stress of towing.

The second problematic area has been the Exhaust Heat Riser Valve. This problem rears its head nearly every season. The valve likes to "freeze" in a partially closed position. Driving the car solo doesn't usually reveal this problem, but hitch up the Airstream and it becomes apparent within 30 miles of towing. When this valve sticks in the partially closed position, heat quickly build immediately adjacent to the car's firewall . . . this heat quickly becomes so extreme that it can cause the brake fluid to boil in the master cylinder resulting in no brakes on the car. I now carry a cut-off broom handle that I use to check the operation of the Exhaust Heat Riser Valve prior to departing with either the Argosy or Airstream . . . if the valve doesn't move freely, the car/trailer combination does not leave its parking place until the valve is freed-up or replaced (I carry a new replacement in my emergency parts bin at all times).

Quote:
Originally Posted by neal View Post
I've read that these cars are front wheel drive? would that make a difference? Go figure..... I didn't know they made front wheel drive cars back then. Any insite to my dream towing vehicle would be greatly appreciated
The Eldorado was equipped with front wheel drive beginning in 1967. From the 1967 model year through the 1973 model year, the standard final drive ratio was 3.07. Beginning in 1974 through 1978, the final drive ratio was 2.70. The 3.07 final drive is highly preferable to the 2.70 final drive ratio when it comes to towing. The 3.07 was the base for the GMC Motorhomes. With the 2.70 fnal drive, the factory trailer tow rating was 6,000 pounds on the Eldorado. While I would have loved to upgrade my Eldorado to the 3.07 final drive, the cost would have been over $3,750 as it would have required replacing the vast majority of the transmission/drive axle assembly. I wouldn't want to tow a Sovereign with the 2.70 final drive as my Overlander is a load for the 2.70 final drive . . . I have avoided the Rocky Mountains when towing the Overlander as I have grave misgivings about whether it could handle steep grades even in first gear. The Eldorado did wonderfully evehwyere that I towed the Minuet . . . over 8,000 miles in 2008 touring the Rocky Mountain region . . . Yellowstone, Glacier National Park, and Rocky Mountain National Park.

The biggest difference that you will notice from the front wheel drive is the "launching" characteristics if you are on loose gravel and starting from a stop with any kind of grade. With this setup, if your weight distributing hitch is not properly adjusted, the front wheels will just spin for lack of traction. One of the first lessons that I learned was to drop one additional link on my chains (link 5 rather than link 6) to force a little additional weight forward to reduce the chance of loosing traction . . . my first trip was typified by spinning front wheels every time that I exited the Interstate as it seemed that each exit ramp had just enough grade with recent oil and chip surfaces that the Eldorado's front wheels would just spin.

I owned my Eldorado before the Airstream, so I decided to make do with the vehicle that I owned rather than searching for something that would have been easier to modify. Had I been starting with a blank slate, my choice would have been a 1970 Cadillac Coupe DeVille Convertible. While the 472 cubic inch V8 would have required the heads to be machined for the installation of flame hardened valve seats, that cost would have been minor in comparison to the costs of preparing an Eldorado. The DeVille's rear differential gearing can be changed with modest effort and expense . . . 3.73 or even 4.10 gears were available the last time that I checked. The radiator is also of a design that is more common, and a full custom radiator likely wouldn't be required.

The 1970 DeVille Convertible also has a top mechanism that poses far fewer problems. The Eldorad convertibles through the 1976 model year had the "grasshopper" or "scissors" top mechanism that includes a number of wear parts that were irreplaceable until recently. While you can now replace the hinged bows with brand new replacement, it is still quite costly and continues to be a source of headaches. The top latches on the Edlorado convertibles are also of a design that is more failure prone than the 1970s DeVille's latches.

Good luck with your investigation!

Kevin

P.S.: The wheels on the Eldorado are also a Very Weak Point . . . I had to search for a number of years before I finally located a shop that could straighten and true these wheels. These wheels of an offset that is nearly unheard of today, and custom wheel builders do not routinely make wheels with the proper specifications nor are there any modern wheels that are interchangeable. Even with the carefully rebuilt wheels, it is still difficult to get the the wheel/tire combinations properly balanced and keep them balanced . . . the problem is intensified by the OEM wheel covers that seem to have a heavy spot in the same position as the wheel's heavy spot.

The photos below are of my Eldorado with its trailer partners:



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Old 06-24-2012, 04:35 PM   #6
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Now that is an informative post!
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Old 06-24-2012, 06:01 PM   #7
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73' cadillac elderodo convertible

In re-reading my post, I realized that I neglected to mention the fuel consumption with the Eldorado. Solo, in perfect tune, the car averages 11.5 to 12 MPG. Towing the 3,100 pound Minuet 6.0 results in an average, flat-land, fuel economy of 8.5 to 9.5 MPG . . . in the Rocky Mountains, my average was between 6.5 and 7.2 MPG. The fuel tank holds 25 gallons so the car does become intimately familiar with gas stations along its route. With the Overlander, I have never towed further West than Kansas nor further East than Western Kentucky/Southern Ohio. On what can best be described as flat land or gently rolling hills, the Eldorado averages between 8.2 and 9.0 MPG with the Overlander.

Kevin

P.S. Friends who tow an Ambassador (1963) with a 1970 Cadillac Coupe DeVille (not a Convertible) average about 2 MPG better solo and close to 3 MPG better when towing their Ambassador (they have 3.73 differential gearing with the 472 Cubic Inch V8). The 1970 Coupe DeVille is close to 1,600 pounds lighter than my 1975 Eldorado Convertible while a 1970 Coupe DeVille Convertible would be about 1,200 pounds lighter than my Eldorado.
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Old 06-24-2012, 08:10 PM   #8
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My folks averaged 7-8 mpg, nation-wide, with their '76 Sedan.

Was fun to watch the fuel gauge drop in climbing Rocky Mountain passes (I didn't pay the fuel bill).

.
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