Air Spring Options for Softly Sprung Tow Vehicle?

[overlander64]

I hope that I am dealing with the final issue on my “towcar in-training”. After three weeks of struggling to find a set of wheels that are straight enough to roll down the road without vibrating the vehicle apart, I finally found a dealer with five NOS American Racing mag wheels with a weight rating of 3,600 pounds each with the proper off-set for the Cadillac. The problem with the new wheels is that tire clearance is reduced to less than 2” in the rear, and with the soft suspension (the car has heavy duty Cargo Coil springs that were new last year) my tire dealer is afraid that a pothole might cause the lip of the fender to contact the sidewall of the tire (deflection would have to be about 2.25”).

The solution that is being considered is to install either AirLift 1000 air bags inside the rear coil springs (a kit is available from AirLift for this application), Firestone Ride-Rite air springs (a kit is not available so a weld-up custom install would be necessary), or ShockWave 9000 (Shock combined with Firestone Air Spring) <this would require cross-referencing the car’s original shocks to the new units and comparing manufacturer’s specifications to available clearances>. Does anyone on the list have experience with any of these products?

I am satisfied with the towing performance of the car with the current heavy duty Cargo Coils and heavy duty air shocks with my Reese Dual Cam hitch setup. The goal of this modification is to maintain the ride height at the most consistent level possible to avoid having contact between the rear tire sidewalls and the inner lip of the fender.

Any input will be welcome!

Thanks!

Kevin

[john hd]

kevin

sounds like the air lift kit would be the way to go. inside coil air bags.

that way you make no mods to the shocks.

let the springs be springs and the shocks be shocks.

then you could adjust it for either of your trailers.

btw, did you look into new coil springs?

you might try madison spring inc. here in wisconsin. i can get the number for you if you like.

john

[jcanavera]

Kevin,
I guess I would be concerned about clearance. Even if you beef up the springs via airbags or whatever, short of making it physically impossible to compress the springs, you still have the possiblility of hitting those tires.

I remember I used some spacers that fit between the coils on the front coils on an old '65 Buick Wildcat. The springs had sagged from age. While that did raise up the front end, the local auto club diagnostic center noted that the use of these spacers would reduce the travel of the coil springs thus transmitting more shock to the frame and body of the car. Sort of the equivalent of bottoming out the suspension.

Jack

[Chas]

Wouldn't a properly setup WD hitch keep the Caddy on the level? I hate to say it but I think InlandAndy said something about coil-overs, air shocks, air springs and ther like contributing to instability and loss of control? I know my old man used to run air shocks on all his Cadillacs but he never pulled a travel trailer with it. I also remember that even with the skirts off the rear tires ran pretty tight inside the fenderwells, snow chains were impossible to use. If I remember correctly Chevy trucks use the same bolt pattern as the old Cadillacs, not sure on the offset but I do remember the old man running the Chevy truck wheels occasionally, he would pull the mud grips off the pickup and run them as needed.

Chas

[uwe]

Kevin,
I would load the trunk until the suspension goes way down, and take a close look with a flashlight. A drive on lift, like those ones the muffler shops use, would be very handy for this.
When you say deflection, do you mean side to side? Your Caddy is fwd, no? I could not see why the rear tire would go this far from side to side inside the fender well? Since it has coil springs, then there must be a substantial axle control system. You might investigate bushing condition etc at the same time, and do necessary repairs, to minimize side to side movement of the rear. It will make for a tighter tow.
2" is a lot of clearance, in my opinion. My wagon has about 1/4" inside the rear fenderwell, from lip to outside of tire, and about 1/2 in the front.Never scraped, ever. But that's independent suspension. If the Caddy has a solid rear axle tube, then the wheels will go straight up inside the Fender. If it's independent, then the wheels will most likely tuck in towards the top when loaded, which provides additional clearance from tire to fender bead lip.
I suggest to investigate and observe the suspension movement first, then decide how much room you need.

[overlander64]

This Cadillac has been a real challenge to prepare for towing, and I wouldn't have attempted had it not been for the fact that I purchased nearly a year before I purchased the Airstream. On the surface it looks like a great tow vehicle:

500 cubic inch V8, 190 Horsepower (net), 360 ft. lbs. torque
Turbo Hydramatic 425 Trans Axle with 2.73 (approx.) final drive
Shipping weight of 5, 120 pounds, wheelbase 126.3", overall length of 224.1", treadwidth front 54.1" & rear 54.5"

The wheel and tire issue is actually the last thing that must be addressed before I feel that the car will be truly roadworthy. It has already had (in the last 2,000 miles):

New, custom 4-row core radiator.
New, 12,000 pound rated auxilliary transmission oil cooler.
New Cargo Coil coil springs (30% stiffer than standard)
New Monroe Air Shocks (recommended replacement by my regular Cadillac mechanic).
New Monroe gas filled front shocks (recommended replacement by my regular Cadillac mechanic).
New heavy duty water pump.
New heavy duty fuel pump.
Front End rebuilt in 1998 (4,000 miles added since)
New bushings in rear suspension

The issue has been with the original style wheels that seem to self-destruct if they hit potholes or are curbbed too often - - the rim itself remains true, but the inner "spider" gets knocked out of alignment with the wheel and vibrations and wobble results causing ride and handling quality issues. It has been a problem with the original wheels since day one, and there are 12 pages in the factory service manual dealing with diagnosis of problems with these wheels.

When checked after new tires were purchased and installed on my car it was found that three of the four wheels were bent enough to cause the a pronounced shake at speeds in excess of 50 MPH. The first route was to try to get new wheels from GM or another OEM source - - the wheels on this car were only used from 1968 to 1978 and were shared only with the Oldsmobile Tornado of the same vintages - - no new wheels were available from GM or other OEM sources. The second route was trying salvage yard wheels - - after eight with only one more good one, I wasn't anxious to continue to make multiple trips to yards more than 100 miles from home only to find the wheels to be worse that what I had. The third route was to try aftermarket wheel manufacturers -- trying to find a 15" wheel with 5 bolts on 5" center, with a 6" rim width, an offset of 3.31 and a load rating of at least 2,600 pounds" immediately narrowed the possibilities to three at one store and none at two others.

I chose to go with the wheel that came the closest to the factory specifications - - the only place where it was slightly off was in offset - - it was 3.4 rather than 3.31, and it had a 3,600 pound load rating. The net result is that the wheel is slightly repositioned within the wheelwell which places the tire such that the sidewall will contact the lip of the wheelwell if the springs compress or deflect more than 1.3" with trailer or 2.3" without trailer. Fortunately, Cadillac switched to open wheelwells in either '73 or '74 so I don't have to worry about fender skirts or this wheel would not have worked.

The AirLifts/Firestone Air Springs or ShockWave 9000 are to help insure a stable ride height when towing more than anything - - I don't think that there will be a particular problem when solo. We have tried all of the measurements using the already installed air shocks, and while they may be sufficient I like the idea of having a little additional insurance and feel that the combination of an air bladder device in addition to the shocks will result in a less objectionable change in ride quality - - kind of like the quad shock setup currently utilized on some of the GM sport utilities.

So far, I have had the most positive response from the AirLift dealer. He has inspected the car and has advised me that the system will work as it is currently equipped. He was of the opinion that the best ride/towing situation would be to run the air shocks at the same inflation that I do for regular daily driving and then use the AirLifts to compensate for attaching the trailer.

His suggestion was to get the hitch setup just the way that I want it prior adding the AirLifts. Then (as per manufacturer's recommendation) inflate the AirLifts to maximum pressure (this step is necessary to be sure that the air bladders properly inflate and don't get pinched in the springs) and hitch the trailer using the spring bar adjustment determined in the first step. With the trailer hitched and car loaded for the trip; decrease the AirLift inflation until the car is level. The system of hitchig up is basically the same as that recommended for the level-ride system that I had in a previous tow vehicle.

The one last option that my tire/wheel dealer is looking into is whether there is a 60 series tire that would have the same load carrying ability as the 75 series tires that I had initially purchased - - this would increase the available clearance by more than an inch - - but load rating will be the determining factor and the dealer wasn't too optimistic when I last spoke to him.

I am seriously considering going with the AirLifts as they are only about 1/3 the cost of the other two options - - and I wouldn't have to find a fabricator willing to customize the installation kits. If this doesn't work, I may end up selling the Eldorado and looking for a '70 DeVille Convertible with the more traditional rear wheel drive.

Kevin

[Chas]

Oh no,

Sorry but I missed the fact that it is an Eldorado. They do have a very unusual wheel design. I could see where the extreme offset would make them prone to damage. As far as the tires touching the wheelwells most of us ex-teenage hotrodders are familiar with rolling the wheelwell edges flat, helped me get those 50's on the rear of my old Torino. Maybe the Caddy could use a little help in this area as well?

What do these custom wheels you have located look like? You might need to get a set of Vogue Tyres to go with them but watch out, your Eldo might end up looking like a pimp-mobile.

Chas

[overlander64]

Greetings Chas!

The wheel opening lip modification is on my list of next steps if the AirLifts don't achieve the desired results. My qualm with this modification is that it would also require modifying the wheel opening molding as well - - a part that would be nearly impossible to replace - - or removing the moldings from both rear wheel openings - - I think that if this is the approach, I will likely have the moldings removed and store them as I don't think that they would be missed by most.

What do these custom wheels you have located look like? You might need to get a set of Vogue Tyres to go with them but watch out, your Eldo might end up looking like a pimp-mobile.

That was my first thought when the whole issue of aftermarket wheels came up. The wheels are either five or seven spoke with a very highly polished finish - - and the tires as they stand now are 1" whitewalls. Tomorrow it is off to the tire dealer for a final analysis before making the final decision to forge ahead.

The technician who has been working with me is a former student so he has been enjoying a few chuckles over my "hot rodding project" as they are calling it in the shop.

Kevin

[TricoastalJoey]

I saw the questions on GM Eldo/Toro. I have had Quite a few of these models and towed a lot of miles with them. Cargo-Coils and airsprings are the only way to go/with the air suspension inflating the airsprings.You can modify the valving to inflate the airspring individually to keep the side to side sway under control. A good quality Extra HD set(4)shock is a must. You also need to replace the factory steering shock with a Ex.HD unit. I used the aluminum spoke wheels on my cars(hard to find today) and had no problems with either alignment/balance. A 235 70R 15 XLR Radial T/A fit well and had the handling to keep it all under control. My trailer was over #9000,and LONG! It was a joy on the road,After I found the combination that worked. Good Luck. JOEY

[uwe]

Joey,

Welcome to the forum!!

[Action]

During compression (pot hole) the tire side wall will be flexed out, and could make contact with the wheel well. In addition the body of the car is traveling down around the tire. So the solutions you are looking at are to stiffen the suspension to limit the travel of the body of the car. (And it's worse with a trailer hanging off the rear end) Are there tires with stiffer side walls? Seems like going backwards, but isn't that what bias plys were all about?

Radials were created cause their rolling resistance was a lot less. Hense better fuel economy. They also became stronger with steel belts. however they do squat .... way more than bias ply tires. The other down side to radials is they do not hold air as well as bias ply tires.

I may be way off base. Just my musings.

>>>>>>>>>>>Action

[overlander64]

The wheel/tire saga that never seemed to end may have finally concluded. The long awaited custom wheels from the vendor in California arrived in late September and have now been installed on the car along with a set of Yokohama 255 - 50 - R - 17 (100V series) tires. Through the process, it was discovered that the passenger side torsion bar height adjustment mechanism was stripped out and the one on the driver's side was frozen - - those parts have now been replaced and it looks like all is set for the first outing next spring with the Minuet/Cadillac combination. The picture below is of the Cadillac with its new wheels and tires. The batteries on my camera were evidently very low as the picture is one of the poorest that I have taken with this camera.

Kevin

[59toaster]

Sharp! Those Boyd's?

[overlander64]

Greetings 59Toaster!

Yes, the wheels are 17" x 7" Boyds. The degree of polish is amazing, but it didn't show up in my photo - - I took five and the one that I posted was the best of the group. My tire dealer was impressed with the quality, but that was a given with Boyds according to what I was able to learn before ordering. The set of four wheels with tires actually cost more than what I paid for the car when I purchased it an estate sale nearly nine years ago.

Kevin