My brother just got his Pro Comp shocks for his '90 4runner yesterday. Every new shock we've ever seen, has a piece of plastic holding the shock in the compressed state until mounting. The first thing we noticed was that these were compressed, but nothing is holding them that way. You have to pull the cylinder out of the housing. Shouldn't the normal state be pushed out? In other words, if you push the piston in, it should push back out when you release it?

 

No, it depends on the type of shock. Pressurized shocks will push out. Non-pressurized won't.

 

Thanks for the quick reply Steve! Can you tell me what the differences/advantages/disadvantages are between pressurized and non-pressurized? Thanks.

 

Simple hydraulic shocks: Non-pressurized twin tube design. Cheapest to manufacture, but offer the least consistent dampening in comparison. Twin-tube shocks are much more susceptible to fade, aeration and poor heat dissipation. Typically smooth highway ride. The ol' standard.

Gas Pressurized shocks: Gas shocks can be valved differently to offer a ride just as smooth as a twin tube shock, while still providing far superior shock-damping consistency than any regular shock. Not nearly as vulnerable to the oil aeration as a standard shock absorber. Gas pressurized shock absorbers are built with pressurized nitrogen inside the shock body. There are a number of basic kinds - gas-cell uses a pressurized self contained foam cell of gas to keep the oil under pressure and keep the gas and oil separate, and gas-charged uses gas in the shock body itself. There are low pressure (used in some twin tubes) and high pressure. The pressure can range anywhere from 80 to 350 or more p.s.i. This keeps the oil from aerating because nitrogen does not mix with the shock oil, and forces the oil molecules to stay packed together much more closely, thereby all but preventing the oil from getting any air bubbles within. Gas cell shocks can be ruined if overheated, but otherwise can provide superior performance over gas filled shocks.

Mono-Tube (Single Wall) Shock Absorbers: These shock absorbers types use a single-wall shock tube to enclose the piston, the shock oil and (sometimes) the pressurized gas. These shock absorber types are much more precise at dampening than the standard shock absorber because they are made with considerably more precise standards during the manufacturing process. Additionally, in most cases, the single-wall shock absorber is considerably stronger than the twin-tube shock absorber because they typically use a larger diameter piston. Further, the single-wall absorber is more resilient to shock fade because it can divide the shock’s oil from the air space far better than a twin-tube shock. With this type of construction comes the benefit of better heat dissipation as well. Mostly used for street shocks as they are limited in their travel.

Remote reservour shocks just use the reservoir to hold more oil and to control heat dissipation better. Neccessary for off road racing, not needed for 99% of vehicles - but look cool.

 

Yea, if they arn't gas chrged, they have no return force and therefore need nothing to hold them in compresion.

 

Hey. This is my first post. I had to register first to put my 2 cents in here. I'm Jovis' brother with the ProComp shocks. I'm wondering then after reading the replies, what's to bring the shock back to the uncompressed state after I hit a bump or something? With little to no resistance, is the truck going to be resting all of its weight on the springs and possibly sitting lower? When I bought these I had no idea they weren't charged. I don't recall seeing anything in the description one way or another. Had I known they weren't I most likely would not have got them. Hmmm...

 

Shock absorbers do just that, absorb (or dampen) up and down motion. Springs support the weight of the vehicle. Gravity, inertia and the springs will restore the truck to the original ride height after hitting a bump, the shocks are just along for the ride, damping out the oscillations.

 

Ditto.....even with charged shocks, springs set the ride height, not the shocks.
Shocks are only there to dampen the vibrations.

 

Thanks a lot for the (as always) quick replies. I think my brother is going to put them on, at least till the lift