Make sure you have enough clearance around the coilovers, the air cups are 120mm in diameter, the fitting is 17mm. (110mm air cups available on request)
The air cups can only be installed on linear springs, it will not fit on ''shaped'' springs as shown in the figure. In some situations shaped springs can be changed to linear springs.
Measure the thickest part of the shaft, we strongly recommend to measure with a caliper.
Air cups are available for coilover shaft diameters: 12,5mm, 14mm, 15mm, 16mm, 18mm, 20mm, 22mm, 40mm* and 45mm*
Maximum outer diameter: 99mm.
Minimum inner diameter: 61mm. (57mm on request)
Maximum outer diameter for 110mm air cups: 89mm.
In most cases the air cup will take between 20 and 30mm of height. The air cup itself is 20mm thick and with most coilovers the top hat comes on top of the air cup, this will take around 10mm. If there is enough thread left on the coilovers to lower the springs, it won't be a problem. If not, you will need to install shorter springs.
The lift from the air cups comes from the droop / rebound of the coilovers. If you don't have enough droop, the air cups simply can't lift the full 50mm. If you're using the standard spring rates that came with your coilovers, it should be fine. If you're using higher spring rates we recommend to use helper springs to get the full lift.
Droop, also called rebound, is basically the amount of travel you have between ride height and full extension. Too much preload will decrease droop, we recommend to set a minimal preload. If you're using extreme high spring rates, higher than the original rates that came with your coilovers, the weight of the car won't compress the springs enough to create enough droop. This problem can be solved by installing helper springs, these will create enough droop for the air cups to lift.
Custom rear cups are available for cars with a separate rear spring and shock. So far only applicable on the BMW E9x series and 350z platform (350z, 370z, g35, g37, genesis coupe).
The custom rear cup will take 30mm of height, If there is enough thread left spring perch to lower the springs, it won't be a problem. If not, you will need to install shorter springs. For the 350z platform, keep in mind that if you don't have a linear spring adapter yet, this also will take 30mm of height.
Recommended spring lenghts:
- BMW E90 series: 180mm
- 350z platform: 160mm
- Linear springs needed. For the 350z platform you can use a linear spring adapter to install linear springs
- Minimal spring lenght before installing the rear air cups: 210mm
- Spring perch thread diameter: max 50mm (Suitable spring perche)
- Minimum spring inner diameter: 61mm
- Maximum spring outer diameter: 105mm
- Diameter: 130mm
- Height: 75mm
- Air cup stroke: 25mm (results in 40-50mm actual lift)
- Air cup thickness: 30mm