I finally got tired of having my trunk lid not opening without help (thus could not use the arm-rest button!), and then not staying up. The lid would occasionally come down on my head or shoulders when I was reaching inside for items - due to failing trunk struts (the second set ... first was replaced under warranty).
Some time back, I had ordered and received my replacements from here: http://www.spdhardware.com/catalog/GSNI ... s%20Spring. I got the GSNI-5150-80 ... price is $15.84 each, but this is way less than even the OEM ones, with discounted prices, of over $100 each from http://www.everythinginfiniti.com. And the dealer wanted $243 labor to replace the ones I brought in!
This above strut was the right dimension (15" extended, 9" compressed, 6" stroke, 80 lbs) for the trunk struts for a Y34 chassis (i.e., 2003 and 2004 M45).
So, for $45.73 (including tax and shipping) and 30 minutes of work, my son and I replaced the struts yesterday - and avoided spending the $450 or so that the dealer wanted for parts and labor!
It was a pretty straightforward job, and I will step-by-step my method here - in overkill detail perhaps!
Tools needed:
- A narrow flat-blade screwdriver.
- A small 10mm wrench or socket/driver.
1. Prop up the trunk lid safely - you do not want it coming down on your head or hands when reaching inside.
I used a "ceiling light fixture replacement rod", but a broom would have worked equally well. Also, whenever I reached into the trunk, I asked my son to hold on to the lid and be ready to prevent it from coming down onto me or my hands.2. Move both front seats forward as far as possible, and tilt the front seat backs forward too, to give additional room to work.
3. Below the center of each rear seating position (i.e., two locations), there is a small black plastic ring below the seat edge. While pulling on this ring (mind your fingers!) towards the front of the car, gently pull up on the seat at that location. This free's up a small U-shaped metal bracket on the rear seat, from the latch on the car.
4. Remove the rear seat - pull forward a bit and then it should slide out sideways. For all further work, be careful of all the sharp metal edges that are now exposed!
5. If your car is like mine was, you will now want to vacuum up all the old debris that made its way down there.
My son (when infant) dropped everything from coins to french-fries 
, pencils, etc.6. Unscrew two black bolts and washers that hold the seat back to the car - these are located in the lower left corner and lower right corner of the seat back. These are 10mm hex head bolts - they may not be too tight in the first place, by the way. Set bolts and washers aside - don't lose them! Power tools would have been faster than the small 10mm closed-end wrench I used - since I could not find my metric socket set.
7. Pull down the center arm-rest.
8. Reach into the upper side of the panel board behind the arm-rest, insert your fingers into the top of the board and pull it forward - this is held in place with velcro, by the way.
9. Unscrew the two nuts behind the board - these attach a metal plate/bar on the seat back to the rear of the car. Set these nuts aside - don't lose them!
10. Behind the panel board, you will also notice a round metal rod attached to the seat back that fits into a U-channel on the rear of the car.
11. Two people: Slide each side of the seat back upwards till the round rod clears the U-channel - this is not a weight issue, but without pulling up on both sides of the seat back at the same time, it flexes too much and it is not easy to lift the seat up cleanly. Two people make it easy.
Then pull the seat back a bit forward to release it from the car.12. Slide the seat back out of the car - being careful with the seat belts, of course. This is not a tough process at all, by the way - the belts will move enough to allow this to be done with relative ease.
13. In the upper corner behind the seat back (near the window), there is a small opening (under a flap of insulation perhaps). Look inside and you will see the strut end.
14. Using a flat-bladed screwdriver: insert the blade into the indentation on the strut, into the metal clip that engages the strut mount, twist a bit, and pull the clip outwards (do not remove entirely). This should cause the strut to easily become free of the round strut mount, so pull the strut off the mount. (You can practice this process of sliding the blade of the screwdriver into the clip on the new struts before you start, by the way, to see how it works!) Repeat for the other strut.
15. Check to make sure that the trunk lid is still braced and ask your helper to get ready to catch it if it falls on you when you reach inside the trunk!
16. Look inside the trunk on the side of the trunk lid hinge ... you should see the other end of the strut. Using the flat-bladed screwdriver, disengage the metal clip on this end of the strut (same procedure as from the other end). This releases the strut entirely ... remove the old strut. Repeat for the other strut.
17. Using the flat-bladed screwdriver, lift the metal clip on a new strut to get it ready for installation. Get back inside the car, slide the new strut into the opening (keep the rod end inside the car - the gas-filled piston end towards the rear of the car), place the connector onto the strut mount, and press the clip in. This will now swivel relatively freely, so don't worry about that, but do be sure that the strut is secure on the mount. Repeat for the other strut.
18. Look inside the trunk and attach the new strut connector to the strut mount on the hinge. Exactly the same process of lifting the clip, putting the strut on the mount, and then pressing the clip in. Repeat for the other strut.
19. Remove the lid brace and check for proper operation of the trunk lid opening, etc. This will be the moment when you grin in satisfaction.
22. Two people: replace the seat back inside the car. Remember to start a bit high to make sure to engage the round metal rod inside the U channel. Also remember to keep the seat belts in the correct position in front of the seat back (slide the back in behind the belts).
23. Install the two 10mm nuts in the center behind the arm-rest board on the metal plate, and the two bolts and washers in the lower corners of the seat back. Tighten, but be careful not to shear the bolts on the corners - they seem to be a bit more fragile than I would like (particularly the washers - I bent mine).
24. Replace the rear seat bottom. Start by setting the seat a bit forward and then sliding it backwards while lifting the front edge at the center of the seating positions. The U-shaped metal brackets should be lowered into the latches (while pulling out on the black plastic rings a bit to avoid breaking the plastic of the latches). Remember to make sure that the seat belt connectors are above the rear seat, of course - position them in the slotted channels of the seat bottom if you want!
You are now done!!
Some other observations:
1. If I had had a very long narrow flat-bladed screwdriver or similar tool, and a bright light (perhaps on a goose-neck?) I might not have had to remove the back-seat. Because I might have been able to reach the connector on the front end of the strut. Look inside your car with a bright light to see what I am talking about.
2. Do not follow the instructions that tell you to remove the trunk liners, or the rear deck, etc., by removing various clips. This is not necessary at all - you can generally reach both ends of the strut pretty easily ... particularly if the rear seat is removed.
3. If you do get the Nissan Infiniti struts (more expensive!) made by Stabilus, they come in Left and Right versions (marked on the struts), because their mount connectors do not rotate! So make sure to order left and right versions and use them as necessary to keep the rod end of the strut inside the car and the piston/chamber end near the trunk. This is not an issue for the replacement struts I bought because the strut connectors will rotate easily enough (not the piston rod, of course!)
4. I forgot to clean and re-grease the moving parts and hinges on the lid - will do this at some point later to make sure that the hinges operate smoothly.
Final comments:
In cold weather (was about 42 F yesterday), the two new 80-lb struts will lift the lid all the way up when the trunk is released.
In time, this may change, but this is way more than the OEM originals did when new - which was just to pop the lid open and up about 6 to 12 inches.And pushing the lid down to close it takes more downward force too.
So, I would definitely NOT use 90-lb struts as was mentioned in another post - the 80-lb is plenty good enough and even when it degrades over time (like all struts do), this will not be bad at all! The extra pressure of a 90-lb (or more) strut may make it difficult for some people to push the trunk lid closed, and may put more of a stress on the lid locking mechanism than is really necessary.
On the old struts that I removed, I noted that only one was pretty bad. When pushed in manually (still quite a bit of pressure), it released very slowly with some raspiness and roughness, but the other was still smooth, although I did not test to see what forces they still had left. Clearly, one old strut is not enough to hold the lid up, let alone raise it.
Z
They are priced differently on the EverythingInfiniti.com web site too ... the Right (thinner one) is $114.62 and the Left (thicker one) is $104.20. Again, not sure why!
My final straw was when I reached inside the trunk (when I had the old struts) and the lid came down on my head ... quite painful!
