By Glenn Goodspeed (April, 1997)
I'm so glad they invented gas shocks. Now I don't have to replace the sagging springs on my P1800. Instead, I replaced the stock hydraulic shock absorbers with the new gas-charged type. Since gas shocks exert a constant pressure of about 100 pounds each (judging from the force required to compress them for installation), my car looks like it has had a 400-pound weight lifted from it.
Shock absorbers. Think about them. Have you ever held one in your hands? They are really tubular on the surface, comprised of two long cylinders, one of which fits inside the other. Grab both ends and try to compress it. Not easy, even with a hydraulic shock. But when you let go, the hydraulic shock stays exactly where you left it. On the car, the springs would have to force it back to its uncompressed length.
Shock absorbers are also called dampers, which is a more descriptive term, since the spring really does most of the work. The shock absorber helps absorb the road wheel's impact, but its main purpose is to make sure the spring doesn't bounce too much. It damps the action of the spring. If you've ever driven a car with a bad shock absorber, you know what I mean. Bounce, bounce, bounce. Three blocks and you're seasick.
Gas shocks look identical to hydraulics, but when you compress them and let go, they quickly return to their maximum length. On the car, gas shocks do the required damping with ease and add a constant force to the springs, keeping them from sagging.
I found the front shocks for about $30 apiece (KYB brand) at the local imported car parts specialist, but they did not have the rears, and could not even order them. I called IPD, and was happy to find that they had the rear shocks, although I was alarmed at the price of $100 each. Oh, but they're Bilsteins. Bilstein, Shmilstein, says I, but faced with the prospect of a lowrider P1800 dragging its butt all over town, I decided to buy them. If I didn't like them, IPD would take them back.
Well, the $30 front shocks really have done better than the $100 Bilsteins. Not in the damping department -- there, they're about even. The difference is in the fit. The Bilsteins have a 7/16" diameter stem on the top, compared with 3/8" stock (the stem being the bolt-like part sticking out the end). This gives too little clearance between the stem and the hole where it goes through the body of the car, and on my car, it made an annoying squeak when the stem rubbed against the hole.
It took me months to find where the squeaking was coming from, culminating in an evening with my wife driving down bumpy roads while I, crammed into the back seat, tried to locate the fiendish clamor. When I finally figured it out, I put the old hydraulic shocks back on the car and threw the Bilsteins into a box. I know I could have sent them back to IPD, and they would have given me a refund, but I wasn't sure I could find gas shocks to replace them. Besides, I was too angry to look at the silly things long enough to pack them up and take them to UPS to be shipped.
A year and a half later, the car was beginning to look like the aforementioned lowrider, so I got interested in the Bilsteins again. In my less-rabid state, I formulated a plan. The stem is 7/16", I reasoned, and that is too big. Why not make the stem skinnier? Oh, that would require a lathe. OK, time to make a lathe. So I put my electric drill in the bench vise, put the threaded part of the stem in the chuck and put the other end of the Bilstein into a holding fixture made with a few blocks of wood.
Running the drill at a moderate speed, I used a big round file to remove a sixteenth of an inch from the diameter of the stem where the squeak mark was. Polished it with sandpaper, and then did the other one. The shocks have been back in the car for two days now, and so far no squeaks. I'll let you know if they return.
(June, 1999)
Actually, it's been some time since I finally removed the gas shocks. I never could get them to stop squeaking, and here's my theory as to why not. The rear shocks are mounted at an angle. Since they exert a constant upward pressure, the top stem is always being forced toward the uppermost edge of the mounting hole. Even though I tried different kinds of rubber bushings and greasing the stems, the pressure always forced the stems to contact the holes sooner or later.
My solution was to replace the shocks with stock hydraulic units and to replace the coil springs with IPD's overload coils. I would not recommend these springs for performance driving, because the rear sits a little higher than normal. It is o.k. for me, because I sometimes haul heavy items in the trunk. Anyway, the squeaks have been gone since I re-installed the hydraulic shocks, and it has been more than a year now. I haven't been able to sell the shocks to anyone else, so I'll send them back to IPD and see if they'll give me a refund five years later.
I'm still using the KYBs on the front, and they seem to work fine.