Hydraulic shocks

[Paul K.]

Would Hydraulic shocks help the corvette feel more solid? I changed mine from gas to a set of Hydraulic shocks. The car seams more solid or is just my imagination

Paul Klemetson

[David M.]

All shocks are hydraulic "oil filled"(for the sake of standard automotive applications).
Some have a gas charge over the oil volume. These are referred to as "gas" shocks. The gas charge provides a cushion and better road manners when combined with radial tires. The gas pushes back on the oil to better react to the up & down motion and it dampens the little flutters from a never 100% flat road surface.

Shock performance is directly related to the compression rebound valving. Or resistance up & down. That dictates the shocks overall performance and reaction to road conditions and handling characteristics.

Poorly spec'ed or worn out gas shocks may appear to provide a crappy-er ride compared to high quality standard shocks(not gas charged).

IMO you cant beat fresh suspension, radial tires, and high quality properly sped'ed gas shock.

[Duke W.]

All shocks are essentially "hydraulic" because they use a viscous liquid (oil) forced through small restrictions to provide a resistive force (damping) as they are stroked.

If conventional hydraulic shocks are stroked very rapidly the fluid can cavitate, reducing the shock's effectiveness.

In the 1950s a European (Dutch, I think) by the name of deCarbon invented the high pressure gas shock. By keeping the viscous liquid under under high pressure from an insert gas these shocks were much more resistant to cavitation and became very popular with off roaders. They have also been OE on many European cars. Most people know them as "Bilsteins", but other manufacturers, like KYB now offer high pressure gas shocks because the original DeCarbon patents have expired.

Back in the seventies or eighties so-called low pressure gas shocks showed up, but I'm not sure how they differ from normal non-pressurized shocks... maybe it's just marketing hype.

One nice thing about deCarbon type shocks is that they usually maintain their original damping characteristics until they fail completely, which can usually be recognized by the car's behavior and a major oil leak in the proximity of the failed shock, but they can last for many years and 100K miles or more. Conventional non-pressurized shocks (sometimes referred to as "twin-tube" shocks) deteriorate slowly over time.

The problem with most shocks is how the damping rates are selected. Typical OE shocks, especially back in the day on American cars were pretty limp to give a smooth ride on smooth roads, but these cars typically became "floaty" when driven aggressively especially on other than billiard table smooth roads.

I recall reading a quote from well known race car designer Bob Riley years ago that "90 percent of setting up a race car is shock rates", and I can say the same for road cars, especially if you want to optimize the ride/handling compromise for your driving style and road conditions.

If you're interested in dialing in a vintage Corvette for maximum handling and driving fun the first thing you need is decent set of soft compound speed rated tires, not the typical "van tires" than most guys run - repro bias ply or low speed rated radials that lack the safety of a spiral wound nylon cap belt.

The next thing is shocks that are "tuned" for your driving style and quality of the roads you drive on. Race cars usually have "double-adjustable" shocks, which allow quick adjusting of both jounce and rebound damping rates with the shock on the car.

I don't think "double-adjustables" are necessary for most aggressively driven road cars, but I definitely recommend REBOUND adjustable shocks like Spax or QA-1, that you can tune to your driving style and conditions.

So it's difficult to generalize, however, in general high pressure gas shocks are higher quality. They last longer and are typically more expensive than twin-tube shocks, but that doesn't mean their damping rates are best for your driving style and road conditions. It all comes down to how you drive your car, how well you want it to ride/handle, and how much you're willing to spend, and adjustable shocks provide the best flexibility to dial your car in.

If you don't drive your Corvette in a "sporting manner", but just enjoy moderately cruising around, going to shows, or doing NCRS judging, I believe that most such users find that Delco OE replacement shocks okay, and they judge the best. My understanding is that they are essentially the same as "Monroe" OE replacement shocks that were formerly manufactured by Federal Mogul, which was taken private by Carl Icahn, fixed up and sold to Tenneco.

Duke

[Paul K.]

Thank you for that very well written information

Paul

[Patrick H.]

If you don't drive your Corvette in a "sporting manner", but just enjoy moderately cruising around, going to shows, or doing NCRS judging, I believe that most such users find that Delco OE replacement shocks okay, and they judge the best. My understanding is that they are essentially the same as "Monroe" OE replacement shocks that were formerly manufactured by Federal Mogul, which was taken private by Carl Icahn, fixed up and sold to Tenneco.

Duke

Current shocks sold under the ACDelco name are made by Gabriel.
They "bulge" in the middle, so are easy to identify.

[Duke W.]

A quick internet search showed that the Gabriel brand is now owned by Mat Holdings, a privately held company with manufacturing locations in North America, Europe, and Asia.

Automotive brand ownership and manufacturing locations are a constantly changing landscape.

https://gabriel.com/History

https://www.matholdingsinc.com/about.php

Duke