bottom vs. top mounted resi

Can anyone tell me the difference or advantages to placing the resi tube at the bottom of the shock body as opposed to the top like everyone else? Sway a way makes some mounted on the bottom of the shock body.

From Sway-A-Way's site:

Taking the reservoir off the bottom of the cylinder provides that all of the oil must pass through the piston as it travels in the cylinder. This provides for more control and better performance.

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http://www.swayaway.com/ShockAbsorbers_2.php

Mike1331 said:

Can anyone tell me the difference or advantages to placing the resi tube at the bottom of the shock body as opposed to the top like everyone else? Sway a way makes some mounted on the bottom of the shock body.

Click to expand...

In a bottom mounted resi the compression is all hydraulic (once past the resi tube) and all the generated pressure is against a fixed cap. Adjusting the nitrogen pressure will not affect your ride height or change your ride quality.

On a top mounted resi, all the built up pressure is built up against the resi which has nitrogen and a dividing piston.

One advantage of top mounted is being able to adjust things by changing your nitro pressure, but bottom mounted will be more consistent and will theoretically handle more pressure.

-Randy

great thanks guys. Seeing as a bottom mounted resi shock can handle more nitrogen it should in theory provide less fading throughout a race. So it sounds like a bottom mount could be a better design once you've got the proper pressure and valving coordinated.

Mike1331 said:

great thanks guys. Seeing as a bottom mounted resi shock can handle more nitrogen it should in theory provide less fading throughout a race. So it sounds like a bottom mount could be a better design once you've got the proper pressure and valving coordinated.

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Mmm by pressure I meant hydraulic pressure. A good, but maybe NOT so accurate analogy is air in the brake lines. You want to bleed your brakes so that there's no air. If there is air you get that spongy feeling because of the compressing of air and expanding gas as temperatures change.

ok i see so the bottom mount can delete that potential spongy feeling with the gas at the top of the shock.

Bottom resi's are also alot easier to service/rebuild.

Mike1331 said:

ok i see so the bottom mount can delete that potential spongy feeling with the gas at the top of the shock.

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Mmm Almost...

Taking the reservoir off the bottom of the cylinder provides that all of the oil must pass through the piston as it travels in the cylinder. This provides for more control and better performance.

Click to expand...

The above statement is true because the top end of the shocks is a solid cap. There is no other place for the oil to go except through the piston.

Top mounted Reservoirs (like air in a brake line) means that when compression is happening, the oil is pushed partially past the piston and partially pushing against the nitrogen section of the reservoir.

It is not as bad as it sounds and that's why I was saying the analogy is NOT entirely accurate.

A side effect of bottom mounted reservoirs in theory is a hotter shock since more oil is passing through the piston and being transformed into heat.

-Randy

great thanks for the clarifications.