single action shock absorbers

[William F.]

Is it true that at least C1 and C2 shocks damped in only one direction rather than both ways as current Delco gas shocks do? Does America's Finest Corvettes market single action shocks for the standard C2 suspensions or only for the heavy duty option ones?
Thanks

[Duke W.]

Re: single action shock absorbers

All cars, modern and vintage, going back before the Corvette was born have "double acting" shocks, but the jounce rates are usually much lower than the rebound rates. Shock absorbers are just dampers that provide a resisting force proportional to shaft velocity.

The electrical analog is a resistor.

Duke

[William F.]

Re: single action shock absorbers

America's Finest Corvette's ad says original Corvette shocks (and ones he's now selling) dampened only 10% on compression but 90% on way back to ride height. Further states that modern gas shocks dampen equally both ways. What should we do when replacing shocks for street, not racing, use?

[Duke W.]

Re: single action shock absorbers

Shocks don't "dampen". They DAMP!!! Damper (noun)... damp, damping (verbs).

I wouldn't trust an ad as far as I could wad it up and throw it. Selecting damping rates is very subjective, and it's critical to achieving the optimum ride/handling compromise, which is why I recommend rebound adjustable shocks, so owners can tune the suspension to work best for their driving style and conditions.

A number of owner's report that they are satisfied with current "Delco" replacement shocks in normal moderate road driving. I have no idea who actually manufactures these shocks. All "Delco" parts are manufactured by third party manufacturers. Delco is now just a marketing outfit and has been for about 30 years when GM sold off all their parts divisions back in the early nineties.

Duke

[Joe L.]

Re: single action shock absorbers

Shocks don't "dampen". They DAMP!!! Damper (noun)... damp, damping (verbs).

I wouldn't trust an ad as far as I could wad it up and throw it. Selecting damping rates is very subjective, and it's critical to achieving the optimum ride/handling compromise, which is why I recommend rebound adjustable shocks, so owners can tune the suspension to work best for their driving style and conditions.

A number of owner's report that they are satisfied with current "Delco" replacement shocks in normal moderate road driving. I have no idea who actually manufactures these shocks. All "Delco" parts are manufactured by third party manufacturers. Delco is now just a marketing outfit and has been for about 30 years when GM sold off all their parts divisions back in the early nineties.

Duke

Duke-----


I believe that Federal-Mogul/Monroe currently manufactures the Delco shocks currently available for 1963-82 Corvettes.

[Joseph L.]

Re: single action shock absorbers

About a year ago, I purchased Delco 520-284 and 520-297 for my 1957. The box says they are gas shocks. The springs are stock and the rears have been re-arched and heat treated. The shocks are stiffer than I would have liked. I saw a comment on the TDB to use the lowest cost oil shocks on these suspensions. Maybe not using gas shocks is a consideration for others on C1's?

Joe

[Dan P.]

Re: single action shock absorbers

A 90/10 shock is a drag racing shock. It holds the front of the car up longer keeping the weight transfer to the rear wheels.The 90/10 shock would not handle at all on a street car.Delco made a lot of shocks that were soft on compression.A Gas shock is still a hydraulic that is gas charged . A Pliacell shock has a plastic bag filled with gas inside the shock.The Gas filled shock,gas bag shock and the spiral shock all had the same goal. Keep the oil in the bottom of the shock.So when you hit a lot of bumps the the hydraulic part of the shock does not suck air.It is sad the some suppliers have to put a spin on THERE product to sell them . You are always better of with the GM parts instead of reproduction . I have cut Delco shocks apart with well over 100,000 miles.Some did not look that bad.Take in consideration the reproduction spiral shock for the Camaro and Chevelle not so good. They leak and the front bottom mount breaks off.

[Don S.]

Re: single action shock absorbers

For 27 years I worked for and then retired from The Monroe Auto Equipment. Duke, Joe and Dan all correct with their post re: shock absorbers.

Shocks are dampers valved to control spring action and keep the tires on the pavement. There are thousands of valve combinations designed and tested for specific applications. Low pressure gas shocks are oil filled and the gas charge function, is only to eliminate fluid aeration. The spiral reserve tube design on a OE Delco shock was for the same purpose and gas charging was an improvement of that design. The Pliacell bag was Delcos early, initial answer to gas charging. As Dan pointed out 90/10 shocks were for drag racing only and we had a disclaimer stating not to use on street driven vehicles. A passenger car shock would typically have a control ratio some where in the range of 60/40 to 75/25. The ratio was determined by vehicle weight, spring rate, and desired comfort. The first number was the rebound (extension) rate as you need more control in this direction vs the natural spring resistance in compression.

I personally don't believe it is possible to rebuild a shock and make it function as new. Replacing the seal and changing the fluid may be possible but anything beyond that would be questionable. So what about the other internal wear items, upper bearing/rod guide, rod, piston and pressure tube? The piston and base valves, which determine control and ride characteristics, also wear out and were specific to a given vehicle. These valves contain up to 12 precision stainless steel components machined to the thousandths of an inch.

To dispel another myth, it is physically impossible to determine a shocks condition by hand. You cannot cycle it rapidly or with enough force to activate the valving to determine condition. All your feeling by hand testing is internal friction. However a totally worn out unit will have zero resistance. The old time bounce test is still the best and most viable way to determine condition on C-1, 2 and 3 cars.

[Dan P.]

Re: single action shock absorbers

Don you are right on the money.You can not tell the condition of the shock by moving it in or out.I look at the shaft were it sets is at at ride height and if the shaft is discolored it is worn out .The shaft is very hard and there is a steel or aluminum bushing at the top that will be worn out.Which takes the seal out. .Your are correct in stating there is no rebuilding a shock . So what I do is cut a NOS shock apart and put everything form the NOS Delco shock into the tube that has the numbers and dates on it for that car . So you are getting a NOS shock back in your housing with the ordinal numbers and dates .

[Duke W.]

Re: single action shock absorbers

deCarbon type (high pressure gas) shocks are easy to evaluate. They generally maintain their original damping characteristics, and then suddenly and completely fail, often evidenced by a complete loss of the internal oil.

I bought a set of Bilstein "Sport" shocks for both my Cosworth Vega and SWC back in the late seventies, and they had a lifetime guarantee. About 20 years ago one of the CV shocks failed, so I called Bilstein in San Diego, told them about the failed shock, and they said to ship them down with a copy of the receipt and they would rebuild all four. How's that for service! Being as how I had a trip to San Diego planned I just drove them down, and they shipped them back to me free of charge about a week later.

I was never quite satisfied with the Bilstein damping rates for the CV, and about that time working with Hutton Motor Engineering in Tennesee who specializes in Cosworth engines including Cosworth Vega engines and had a lot of contacts in the UK, we did a group buy through the Cosworth Vega Owners' Assc. of about a dozen sets of Spax rebound adjustable shocks, and I was able to get the rebound damping rates I wanted.

Rebound damping is the most important shock characteristic to get right for your road conditions and driving style. Typical OE shocks lack sufficient rebound damping, and having the correct amount for sporty driving or race track hot lappping usually makes a car a bit stiffer than most people want for normal driving, but I've never been a normal driver.

Duke