The Long and Short of Coil Springs …


Okay, wait till I tell you what that damn dummy did this time!

Way back when I had finalized how I wanted to do the front suspension, I had decided to mount the front suspension from the Olds somewhat higher than the stock ’56 Dodge suspension was. By doing this I was able to better position the engine and transmission in the body without having to do any major surgery to the transmission tunnel or fire wall. Also it allowed me to use the stock Durango engine mounts. To offset the additional frame height, I ordered a set of 2″ dropped spindles from McGaughry and figured that I could fine tune the ride height by either cutting coils or playing with spring rates.

Sometime later when I was putting the chassis back together I was hunting around for a set of springs to use in the front since the stock Olds springs had been heated a lot to lower the front end of the car after the engine and tranny were pulled so that it could be crashed in a movie. Well one day I noticed that the stock ’56 Dodge coils were the same diameter as what I had cut from the Olds suspension. I wasn’t sure about the free spring height or spring rates and since they fit without much problem, in they went!

Of course without the engine etc in the control arms were all the way up on the stops and the wagon had a nice ’60s gasser stance that was nice, but not what I wanted. I decided not to worry about it until I had more weight on back on the car so that I could see how it would sit. Fast forward again to earlier this year when I installed all of the new suspension parts before I put the engine and tranny back in… well the dummy that was helping me also installed the front shocks as well, but since there was no weight on the front end, they were evidently installed with a fair amount of bind on their shafts.

A bit later I installed the engine and tranny and noticed that the wagon still looked like a ’60s gasser, I said to myself, hummmm, I guess the engine and tranny must be a lot lighter that the stock ’56 Dodge pieces. I started thinking that I would probably have to cut a coil or two to get everything sitting right.

Okay, fast forward again to last week. After I had done the rear sway bar, I moved all the junk that I had loaded into the back of the wagon onto the top of the engine, I did cover the engine with several folded tarps to pad everything. I was able to get everything but the floor jack balanced on the top of the engine.

Hummmm…. with all that weight the damn thing is still sitting like a gasser!

After a phone conference with friend Paul, where I explained the situation, and he had suggested that something in the suspension could be in bind and I should check it, but if it looked okay, his rule of thumb was to cut one coil to get a 2″ drop in ride height.

Before I could even think about what was going on, the dummy, who had been sure that the springs needed to be cut since I had 1st put the front end back together, was out in the shop removing the shocks, control arms and springs. Again before I could do anything, the dummy had cut a coil and a half off the old ’56 springs. Well what was done was done, so I closed up the shop and headed home for supper.

The next morning I go out to the shop and install the new shorter springs – they had gone from a free height of 14.75″ to 12.75″ with the removal of the coils. Well the shorter spring height made for an easy install … the springs popped right in without needing any preload (about this time the warning bells and red lights were flashing in my brain). Once I had the control arms bolted up and the ball joints attached I let the wagon down on the lift, it went down, and down, and down, and more down until the lift arms were on the floor and the frame was on the arms. It brought a whole new meaning to laying frame….

Well about this time, I got hold of the dummy and escorted him out of the shop, played with the floor jack and some jack stands to where I could finally get the lift arms out from under the car. I then lowered the wagon back down on its wheels and was finally able to get the lower control arms off their stops. The old girl went from a gasser to a low rider with two cuts of a cutoff wheel… and this was with no additional weight on the front end. Clearly I needed a new set of springs…

After removing the shortened springs I attached the lower control arms to their ball joints so that I could move the suspension through it’s full range of motion. Lo and behold the spring pocket measured from 14″ at full droop to 12″ at full rise. So the coils could only be compressed a total of 2″ due to the design of the front suspension. So the original ’56 Dodge springs at 14.75″ prior to cutting them down to 12.75″ only had .75″ of preload in them. I later found a way to calculate coil spring rates from spring measurements and found that the stock springs had a spring rate of 419 #/in which would have been marginal to the weak side. Clearly the shocks had been installed with bind in them which was causing the extreme ride height.

Long story short, I did a couple of google searches on coil spring formulas and thanks to RideTech and Eaton Spring I was able to calculate what I needed in the way of springs. I was then able to find a MOOG spring chart that listed every coil spring made by them so I could sort through it to find what I needed. The Moog 5276 spring for a 1972 Z28 5.7L Camaro looked to be about the best fit, giving an installed spring height of 11.3″ and a spring rate of 303 #/in. These springs are 17″ long unloaded so they needed about 900# of force to compress them enough to get them in the wagon. As luck would have it, the driver side went together without problem. I had a heck of a time getting the spring compressed on the passenger side though. The damn thing flew apart 5 or 6 times with springs and control arms flying all over the shop. Luckily, I was able to duck them and the managed not to destroy any thing else on the car or in the shop.

After I had them installed I lowered the wagon on the lift and it was sitting about where I had hoped it would. I also was able to bounce the front end several times though out its travel without bind.

Next up I reinstalled the shocks, this time I reloaded the springs enough to where the lower control arms were almost parallel to the ground. After the shocks were in, I did another quick check for travel and again all was well. I finally hooked up the sway bar and checked everything again and had full movement!

Without extra weight on the chassis, the front suspension is sitting about where I calculated it should at the lighter weight. I also measured from the frame to floor in both the front and back and the front was about 1 1/4″ lower than the back. I loaded the front of the wagon with around 200# and remeasured and had an about 2″ drop in the front. So given everything it looks like I am in the ball park. When all is said and done, if the front is either too high or too low, I can find a MOOG spring that will fix the problem. BTW: I ordered the new springs from Rock Auto for $46 on Saturday and had them Monday night!

The Long and Short of Coil Springs

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