Are shocks used according to vehicle weight?

I was just wondering if you don't have a make on a car, one off or very modified, what do you use to determine what shocks to use? I ***umed weight.

 

More important is that they have the correct compressed and extended lengths and that the shock mounts on top and bottom are correct. If you look through shock manufacturer cross-references and application charts, you realize that they use the same shocks on vehicles that vary a lot in weight. Like some shocks with the same number might fit a mini pickup or they might fit a 3/4 ton van which weighs 2000 pounds more.

If you just want a shock that will do the job, anything that fits with the correct compressed and extended height will work as a shock. The differences between different brands of normal p***enger car or light truck shocks are pretty subtle unless you start getting into racing shocks or adjustable shocks.

 

yep...sprung weight is the determining factor

 

Unsprung weight and leverage.
Look at an early Duo-Glide. Notice the shocks are positioned halfway down the length of the swingarm.
Now look at a late Sportster. Shocks are mounted at the axle.
This radical difference in location dictates a very different shock (Also different springs, but not what you asked).
The Duo-Glide's wheel will move the same (per similar bump) as the Sporty's wheel, but the shock will move roughly half as much, meaning that, to provide the same level of wheel control, it will need to be much stiffer in both compression and rebound damping.

Unsprung weight will affect damping by the increase in weight that the shock is asked to control. More unsprung weight needs more control.

Just FYI, shocks advertised as drag shocks with a 90-10 ratio (or some such) bias 90% of the shocks damping towards rebound, allowing the shock to rise quickly, and fall much more slowly. These will NOT work well on the street.

Gas-Charged shocks use nitrogen (or other inert gas) to keep the fluid from bubbling. Bubbled fluid dampens very poorly.

Worn out shocks can be cut apart and the outer can used to tunnel antenna. This is thought to be very traditional.

Cosmo

 

Might help you when the vehicle is about finished,water in engine and calculate 10 lbs per gal. for each gallon of gas add weight of fuel tank as full. two persons and have it weighed at a Public Weighbridge.
This will help to work out range of shox you need.
If its a costly special then use a shocker which is adjustable to improve ride and handling. Hope this helps Chris

 

Out side of compressed and extended length, spring rate is the most important factor. The shock controls the oscolations of the spring under compression and rebond.
Carroll Smith has books covering spring rate and shocks. The books are for race cars but the information is appropate for street cars.

 

Weight should be a consideration as well as intended purpose of the vehicle lowered or lifted etc.

but more often than not the primary concern is the length of the shock, ectended and compressed being real important.

 

Are we talking shocks or coilovers? Spring rate is important, but he was just asking about shocks. There isn't actually a whole lot of difference between different normal tube shocks unless you step up to fancy Billsteins or something that have the damping rate custom tuned to a particular car. If you look through the Monroe catalog, they list compressed height, extended height, and shock mounts for top and bottom. They don't tell you anything about the damping rate. You can find several different shock part numbers that have the right ends with the right compressed and extended lengths. Then you can see what vehicles those are applicable to and try to figure out if they'd be applicable to yours too. Whether the cars they're applicable to have the same type of suspension will help you decide too, like if that car has a-arms, solid axle, etc. But once you start cross referencing the shocks, it's obvious that they're not exactly custom tuned to particular cars when you see that say the same shock is applicable to a variety of cars or light trucks.

If you're just putting together an old hot rod, if you get a shock that fits and has the right ends and the right compressed and extended lengths that match the suspension travel you need then a shock is a shock. It just dampens the suspension so that it doesn't resonate and boing up and down all day. If you take a shock out completely, the car still sits at the same ride height, but if you hit a bump, the suspension bottoms out and then the whole car floats up and down and goes boing boing boing up and down like waves in the ocean at whatever the resonant frequency of the springs is. So any shock is going to dampen those resonant frequencies and keep the car from floating up and down. If you get a shock from a 3/4 ton truck, it's going to dampen it more than a shock from a Datsun B210. But if you look at a pile of standard old shock absorbers, there's not a lot of difference between them in how they're constructed. They mostly have the same size piston. If you want to really tailor the ride to be perfect, you should look for some adjustable shocks. They don't sell adjustable shocks in every end style and compressed and extended length known to man though. Most of the adjustable ones I see are for coilovers or for particular applications only.

A lot of lower priced coilover kits come with one standard shock that they use for all applications and you swap springs in and out to change the spring rate. Unless you pay big bucks for adjustable shocks or for racing shocks, you get the one standard shock no matter how heavy the car is.

There are some special heavy duty standard car shocks made for special purposes, like shocks on cop cars sometimes have a small coil spring added to them and a larger piston to make the suspension stiffer. From a company like Monroe, I think there's only a handful of basic shock designs -- normal, gas filled, off-road, etc., and they make those cover a huge variety of cars and trucks by just making them different lengths and with different ends on them. Shocks for rear wheels will usually have a dust cover can on them, and shocks for use with a-arms up front might not have the dust covers on them.

 

Thank you

 

I realize we are talking about shocks but springs did come up and just hought I'd add something. Cars with factory air have different spring rates between the front sides to compensate for the heavier AC ****. If you got a car that handles like **** and you don't have AC **** you want to see if it came from factory with AC.