Imperial Home Page -> Repair -> Frame, Spring and Shocks -> Gas Shocks
Question from Roy:
Can anyone explain to me what the big deal is about gas shocks? Seems you can't even find regular old hydraulic shocks anymore! I just don't get it, shocks are supposed to dampen a spring, i.e., stop it from bouncing, up OR down, so what happens with a gas shock? You hit a bump, the spring gets compressed and then the "gas" shock, spooiingg, pushes it to the other extreme! Not to mention the gas is under pressure, just waiting to leak out! Combine that with the added headaches of installation, I just don't see any advantages except to those that manufacture and sell them. I'll stick with good old hydraulic shocks, if I ever find any again.
Most gas shocks do not add significant spring force to the suspension -- that's not what the gas is there for. The gas is added to maintain pressure on the hydraulic fluid (oil) in the shock. This reduces foaming, the big enemy of a hydraulic shock absorber. During foaming, air bubbles spread out through the oil, get into the working chamber, and pass through the orifice. When this happens the shock absorbers effectiveness is greatly reduced and bouncing/heat generation increases. It thent takes a while for all the air bubble to dissipate. Some manufacturers simply charge up the shock with some kind of gas that remains above the oil. Others use a durable bag or "cell" to contain the gas. Oil foaming has been a problem since hydraulic shocks were invented. Various approaches have been tried to eliminate it. Remember GM's spiral tube shocks from the 60sor 70s? Oil running down the ramps inside the shock body was supposed to help dissipate any bubbles.
This is a very small point in actual driving, I suppose, but may be important for race cars or any car with very low unsprung weight. The gas is essentially part of the spring suspension for the car, but unique in that it has essentially zero mass. Because of this there is no lag and no oscillation (vibration) between application of the compression force and the resultant reaction from the shock. Therefore it does a marginally better job of keeping high frequency road disturbances from getting to the unsprung weight. I think the claims are more marketing hype than actual benefit you can feel in a normal road car.
In the steady state, as on a smooth road, all the gas does is help hold the car up, and not very much of that, either. For a while when the gas shocks first came out, they were pushed at the sports car crowd, and developed a reputation (deserved?) of being higher quality shocks.
I've read several times that the English term "dampers" describes best what a shock absorber does - to keep your springs from "spronging" too many times when you hit a bump. Also the shocks are still hydraulic, there's just a different gas, supposedly better than "air", taking up the space where the hydraulic fluid ain't!
I have been using gas shocks since 1986, when I bought my Dad's 76 Supreme from him. I put on Monroe gas-matics,and immediately felt an improvement. This car was very front heavy and for years handled poorly, but when I had them installed, stopped it from bottoming and gave it much better control in cornering and on the highway.The rest of the handling issues were resolved with the addition of front and rear stabilizer bars off a 442 and urethane bushings
I gave my '78 Ferd Denson-mobile the same treatment, with gas shocks and urethane bushings, and it has helped as well.
So now I have my 1970 Chrysler, and I'm Imperializing it: I installed Gabriels I got on sale, but they're still not up to the job...my friends car has the Gas-matics, and I think theyre better, but even THAT may not be enough to help my tired torsion bars. A friend with a '68 Plymouth Fury wagon has KYB's, but I don't think I want to go that far.
Gas shocks are far better than the old oil shocks, especially for our big heavy cars. They do not increase the spring rate, which has already been pointed out, they are just stiffer dampeners, and can really help out a tired suspension, especially since torsion bars for Imperials are not available new.
Even if I could buy new torsion bars, at OEM spec, for my Chrysler, I would still use Gas shocks, and urethane bushings for the better control and handling. Imperials weigh between 4700lbs and 5000lbs, so you wont feel a "harsh" ride. It will stiffen the ride somewhat, but the results are worth it, plus the rest of your suspension doesn't have to take the pounding.
I have a 65 LeBaron and about 3 months ago I installed a new set of KYB shocks, of course they are gas. It improved the ride 100%. Car is not as clumsy and handles much better! The ride is much improved without being harsh. The car has 25,000 original miles and is completely original with a suspension that reflects very little wear. The rear leaf springs still have the leather strips on them....I think they were some sort of silencers, right? Anyway, the KYB shocks will be my choice from now on with any older domestic cars I own. I think it's important that the rest of your car's suspension is in proper condition before spending the money on new shocks. Quality shocks alone can't work a miracle, but when installed on a car with a good suspension they can make a BIG difference. Good luck finding them. I even had a hard time getting them when I called the company direct. You have to be persistent, their sales department is not very aggressive.
The gas in the shocks is Nitrogen. Nitrogen is used because it will hold very little water, which inhibits rust, and non-flammable. The Air Force and Airlines have been using this gas in its aircraft landing gear struts since.....well, since aircraft had retractable landing gear. The gas is used to precharge the strut cylinders and dampen rebound. It also serves to greatly reduce aeration (foaming).
Question from Roger:
When the original shocks are replaced in 1974 Imperial with kyb gas shocks do you leave on the coil springs that are on original shocks ?
If there are "coil-over" shocks on the car, it usually means the springs are tired. Before you replace these, check by removing them and seeing how bad the rear sags. You will probably have to re-arc the springs if you use non-coil-over springs such as the KYB that you are contemplating.
Follow-up from Roger:
Well I just put a set of kyb shocks on the front of my car makes quite a difference left rear shocks on , I was told that the 74 was supposed to have air leveler shock system none was there no compressor or lines, just a set of shocks with coil springs. This is the third car I have heard of without the air shock system. Does any body have a 74 IMp with the air shock system?
Reply from Terry:
The 75 IMPERIALS had the leveler shocks as standard, I think they where optional in 74.
Tip from Flint:
I put gas shocks on my 68 (non-adjust) and I am very pleased.
Question from Chris:
What brand? Where did you buy them, and do you know the part number? I can never seem to get the fronts for my '67 and it needs them!
Gabriel Pro Ryder (heavy duty gas shocks). Sorry looked and looked but couldn't find receipt with part numbers. Pretty sure I got them at Pep Boys. Wallow around corners no more.
I just installed Gabriel Pro Riders from Pep Boys. I could not install the shock with the washer and new rubber grommet on the end. I had to install the shock in the opening, compress it then slip the grommet and washer (super glued together) in above the shock before letting the the shock decompress. This was not the hard part, the shock was a little fatter than the old one that I had to wiggle and pry to get it out past the lower control arm. The fact that the darn thing wouldn't stay decompressed was not the big issue. I waxed the shocks when I took them out of the box, but ended up scraping and denting the one side slightly putting them in. The main reason I replaced the shocks was because the old rubber grommets was all but gone...the shocks weren't to bad considering I think they were the original shocks.
Question from Jack:
Boy, did I have a good time last Sunday putting front Gas Shocks on my 68. Did GM design the lower control arms or what...they didn't put holes in the bottom of them to get the shock in or out! Does anyone have a trick without taking the ball-joint apart. I just beat mine in with a hammer! The front suspension is nothing like the "C" body little sister cars.
Reply from Zeke:
I, too, had this problem on my 67. THe way I got around it was to use a zip tie to hold the shock in its collapsed form, which allows you to get around the lower A-arms. Then, when the shock is around the arm, you cut the zip tie, and guide the shock into the upper hole. This usually takes one really strong zip tie, or two lesser strength ones. It will take a couple tries. Hope this helps.
This page last updated September 13, 2001. Send us your feedback, and come join the Imperial Mailing List - Online Car Club