Spring pocket, spring perch.
The Mark 8 does not have a check-valve in the air suspension system. Each air spring has a solenoid valve, which controls fill and vent of the spring. There is a fifth in the suspension compressor itself, which controls venting the system. I discovered that the seat for vent valve was corroded in my compressor, which would then leak when the system was trying to fill. This resulted in the compressor running, but the car lowering. I was able to clean the seat up for a temporary repair, but ultimately replaced the compressor.
One can purchase an air suspension tractor seat directly from manufacturers such as John Deere or Northern Tool, and from department stores such as Sears. One can also purchase an air suspension tractor seat from an online auction site such as eBay and Amazon.
If it's a noname/low-end post it's unlikely that spares will be available, you're probably better off simply getting a new one. If it's a nice brand, like thudbuster, then a visit to the manufacturer's website will tell you which parts are available, how to get to them, and what they're called.
the seat
what metal is it answer a.s.a.p
Its under the passenger seat,undo spring clips at front of seat and flip seat back.
If in a well replace it as it is worn out. If something was stuck in it set the ball on the seat and the spring on the ball to push ball to seat, then the ball retainer. Pressure should push the ball open and the spring should close the ball. (make sure all the spring is there)
If there is weight on the seat, it senses that (probably a spring systme), and if the seat belt isn't in the buckle (there's a sensor there as well), the light flashes or it beeps.
The seats in an old beetle are removed by sliding the seats completely forward while holding the seating moving mechanism in the open position. You may find it useful to have a small rubber mallet to gently tap the seat runners if you find that the seat sticks during removal. Note: There is a spring located under the seat which hooks from the seat to the seat runners which cause the seat to want to move forwards when the seat mechanism is engaged. If your Beetle still has the spring installed, use a small set of pliers to remove the spring before removing the seat.
No , it's not designed to have a 3rd row seat ( starting with the 2002 Ford Explorer ( 4 door ) a third row seat was available with the new design which has an independant rear suspension )
You will need lowering links to shorten the suspension and seat height. They are available from several manufacturers, below is a link for Devol Engineering.
There is no right seat height, its whats comfortable for you. What is important though is the SAG. So set your SAG then see where your at first. You can adjust the height through lowering kits, seat and links for suspension, and tall seat kits if you need more height.