At some point you just need to throw science and accounting out the window, admit that something doesn't work and find a viable real-world solution! Shame on Nissan for not doing that!mwohlg wrote:I think we started with the 06 model year, and stopped with the 10 MY. The 2011 I bought used last summer has another company's gas springs. I am somewhat glad to see that a few of you have issues like me even with newer vehicles. (Mine sag in the cold temps also). The problem is mostly with the vehicle geometry, and the car company requirements.
I left the gas spring company in 2008 after 12 years. In the 5 years since, I have forgotten most of the details about these particular OEM parts, but can shed some light on how the gas springs work generally.
High pressue nitrogen gas is captured & sealed inside the tube. How much pressure inside initially, is what determines the output force of the spring. But the pressure of the gas drops dramatically as the temperature drops, remember the ideal gas law from chemistry? I don't remember exactly the ratio, but its something like 20N force loss for every 5 degree drop in temperature.
Plus the nitrogen gas permeates through the seal over time, just like your tires lose pressure. So a gas spring that worked OK when new can be nearly useless after a few years. The common minimum design guideline is to have enough pressure remaining to hold the door open after 5 years (not necessarily to open the door by itself).
The biggest problem in the design of the OEM gas spring is the geometry of the vehicle itself. The center of gravity of the Pathfinder liftgate is much lower than on the Xterra - it's longer, has more sound dampening, more steel, etc. Plus the Pathfinder has a flipper glass as opposed to the Xterra's fixed glass, so there is added weight of latch mechanisms, flipper glass gas springs, etc. The space requirements between the gate and the body D pillar affect how long the gas spring can be, and specifically how long the body can be (more volume in the gas spring body (tube) gives more nitrogen and longer life). Finally, the car manufacturers have to make sure that no 4'9" wives are left dangling by the liftgate because they're not strong enough (or heavy enough) to close it - it has to be designed for a 5th percentile woman to be able to close the liftgate in 100 degree weather.
I have a 2011 and I only needed to replace my lift gate struts. Maybe if anyone is having a problem with the window struts on an older model or aftermarket ones, the OEM's from an 11 might do the trick.shaggyT wrote:Am I the only one that hits their head on the glass every time?
I had to drill the ends out on one side of the plastic connector and use JB Weld to hold them in because the threads were different. It works great and the strut would break before it ever would!mc01ta wrote:These aren't fitting or I'm installing wrong. These have one end that can screw off and you can use old fitting from OE strut. But on the end which goes closest to top of roof does not come off and won't slip on the ball end. Has anybody used this replacement part orsjoukd I send back and get something else?