I will start with some disclaimers:
1. It is a very difficult job to do mentally, not physically, it takes about a day and a half (my first time doing it).
2. You will require two people at certain parts of the build, mostly to lift things up without damaging anything.
3. I believe that mechanically inclined people can do it as I will give you guys the information I gathered while doing the job. You just need patience, a LOT of patience.
4. I am completely sure you guys will have other, more creative, ways of doing some stuff that I did, so feel free to share your ideas.
5. I am paranoid about my car, I believe a simple needle can and will destroy it. So everything I did to fix the hydraulics was done as gentle as possible.
6. No, you can't do it out in the open, or you can do it if you believe that you are really quick or that your neighbours won't steal stuff or damage your car. You need a garage.
7. I did this post because I've seen no tutorials on how to do such a thing and there is little to no information about how to do this.
I will describe the steps, please keep in mind I will not tackle all the parts of the hydraulic lines replacement, but only the ones that I found to be annoying. If you have any questions, just ask in the topic and I will try to help us much as I can.
Step 1 - Ordering the required parts
Parts you will definitely need (car production year does not matter):
1x 54377311084 [Hydraulic Lines] ~ 800 USD (the usual price is around 1000 EUR, but I found them cheaper on ebay, they were "created" on 05.2019, so I guess that 800 USD is a steal for this part)
1x 54377220536 [Mounting kit for the rear roof shell] ~ 40-50 USD (if you preffer on being 50$ cheap on a 900$ job you can skip this part and reuse the old screws, BUT I DO NOT RECOMMEND THIS)
1x 54377223332 [Mounting kit for the hydraulic lines] ~ 40 - 50 USD
1x ~500ml ZH-M Oil (you can buy BMW brand / FEBI / Mercedes) ~ 10 - 80 USD (depending on brand)
Parts you will need if your car is produced before 07/2014:
Note: For example, if your car was produced in 2011 you will have two different sensors that cannot be plugged
into the new wiring harness. So you either go the hard way and remove the plug from the old wiring harness,
cut the new wiring harness and mount the old plug in OR you buy the items below.
1x 54377228585 [kinematics box sensor] ~ 20 USD
1x 54377228586 [kinematics box sensor] ~ 20 USD
4x HDD Screws ~ 1 USD
Tools you will probably need if your car has a NON-operating or partially-operating roof:
1x 83300496598 ~ 20 USD
1x 83300496597 ~ 30 USD
Step 2 - Initial Preparation Steps
Note: I will have multiple "small" steps here, to make it easier to explain.
1. Remove the trim pieces from the trunk. Strip it completely, I mean it. Picture below.
![Image](https://i.imgur.com/VTCMBRe.jpg)
You can find information about how to do this here. Follow all the preliminary tasks before, then continue with the other side. Please note that you can remove almost all (the only part that you cannot remove is the thing behind the left and right rear lights) the trim from the trunk without opening the convertible roof.
2. Since we will be working on the roof, lets use what germinator, a Z4 owner from the german forum, taught us. We will make the car think the trunk is locked so we can have more access to the trunk when we will start to work on the car.
Please reffer to this video and do the same to your car.
3. ATTENTION: If your vehicle has a NON-OPERATING roof, please follow this step.
i. Release the hydraulic pressure on your hydraulic pump turning it only 0.5 turns (or a little bit more if you believe it's really hard to manually move the roof later on). Reffer to the image below taken from the newtis manual in order to find the right "screw" on the pump. Only do 0.5 turns, about a year ago somebody did 1.5 turns on my pump and I got left with a leaky pump and had to do another sh*t ton of stuff in order to fix it.
![Image](https://i.imgur.com/w3OeoDX.png)
ii. Continue by reading this link (please keep in mind not all steps need to be followed, below you can see which steps NOT to do) while bringing the roof in the position you can see my car in below.
FROM THE LINK ABOVE DO NOT FOLLOW THESE TWO STEPS, YOU DO NOT NEED TO DO THAT:
![Image](https://i.imgur.com/DgYCvSQ.png)
Bring the roof in this position (imagine the rear shell is still attached to the arms please), please note the broom that you NEED to add:
![Image](https://i.imgur.com/M3EvKJV.jpg)
3. ATTENTION: If your vehicle has an OPERATING roof, please follow this step.
i. Bring the roof in this position (imagine the rear shell is still attached to the arms please):
![Image](https://i.imgur.com/M3EvKJV.jpg)
ii. Release the hydraulic pressure on your hydraulic pump turning it only 0.5 turns (or a little bit more if you believe it's really hard to manually move the roof later on). Reffer to the image below taken from the newtis manual in order to find the right "screw" on the pump. Only do 0.5 turns, about a year ago somebody did 1.5 turns on my pump and I got left with a leaky pump and had to do another sh*t ton of stuff in order to fix it.
![Image](https://i.imgur.com/w3OeoDX.png)
4. Remove rear shell by removing the 3 bolts (on each side) that hold it to the car. Please mark it somehow so you will find it easier to put it back on the car. Also, keep in mind there are some spacers between the bolt and the roof that MEAN A LOT. Please put them in separate bags in order to easily find them after. Reffer to this link from the repair manual.
5. Remove front shell seal. Reffer to this link from the repair manual.
6. Remove the rear trunk partition shell (the thing you use to allow your roof to be stowed away in the trunk), it's fastened by 4 screws on each side.
Step 3 - Changing the lines
Note: This chapter will give small guides on each section so you can know how to replace the hydraulic lines on that part of the car.
Note 2: Put the new hydraulic lines in the car "following the contour" of the car.
Note 3: Start on the left side of the car as it's a little bit easier and it helps boost your part replacer ego.
General Tips
1. Since the hydraulic lines were probably fitted manually in the factory by somebody, the hydraulic lines that go in the pump and the ones that go in the hydraulic cylinders are NUMBERED so even a dummy like me can fit them where they belong. And yes, if you are wondering the numbering did not change over the years because the hydraulic lines number (amount) is the same.
2. You are probably wondering how we'll do it now, well, the algorithm in which we do the job is pretty simple and straightforward, you do pictures, you remove the old lines, you plug in the new lines. Rinse and repeat until mental breakdown or back aches, I am actually not joking.
3. Put the zip ties IN THE SAME POSITION THAT THEY WERE BEFORE, there is NO REASON to be creative with your car. The zip ties that were placed from the factory have a specific meaning. This being said, if you feel as an artist, you can try to put the zip ties everywhere you'd like on the trunk floor as it doesn't matter that much.
4. Do not zip fully the zip ties until you found the best position for the wiring. Please keep in mind that the zip ties from the 50$ kit you bought are different from normal, super market ones by having a smaller clamp at the zip end.
5. If you take out a zip tie from somewhere, think twice as it might make your life easier to just leave it there and remove it later. Also, before removing a zip tie, make a picture.
How do I remove a hydraulic line from a cylinder?
As you might have seen in the hydraulic lines kit you received new safety "pins" for the hydraulic lines, so, refer to the picture below that shows you how to remove a hydraulic lines from a cylinder and remember that you need to replace the safety pin on it after.
![Image](https://i.imgur.com/IPCSKrC.png)
It's also nice to remember that hydraulic lines contain hydraulic fluid which is pretty much oil that will leak in your car if you do not use a cloth to tape the ends down from the hydraluc lines that you disconnected.
How do I put a hydraulic line back in a cylinder?
First of all, you have a new set of O-rings in the kit that came with the new hydraulic lines, that means we will need to put an O-ring on the new hydraulic line that goes in the cylinder. First, you check inside the cylinder for an old o-ring (those m-f*ckers always get lost in there) then put the new hydraulic lines (that has an O-ring on it) in the cylinder and clamp it down with the new safety pin that you have received.
Steps for the top part of the roof - Roof Arm
1. Do pictures with the roof wiring as I did below in multiple positions of the rear shell arm (below are some pictures from me or found from other peopls on the internet) so you can know how to put the new lines back on the car (pretty much how the new lines should look after you finished the job).
![Image](https://i.imgur.com/Bf0jYOV.jpg)
![Image](https://i.imgur.com/NSkXf2u.jpg)
It might help if you also take a picture with the hydraulic lines when the roof is in the closed position.
2. Start by removing all the zip ties on the arm and below it (under the front shell) then proceed with removing the wiring (you should get all the wiring out that goes towards the top part of the roof). Remember when I asked you to remove the front shell seal? Now it will help a lot when fitting in the new lines, you can squish in the new lines in the same position easily now.
3. Start putting the new wiring in while looking all the goddamn time at the pictures so you won't f**k up. It's as easy as doing legos after you do it for a while.
Steps for the kinematics box (left side of the car)
Note: Please note that on the right side there is an additional sensor that goes in the cylinder that you need to be sure you get back in the right position (or you pay an additional 300$ to replace it).
1. I recommend removing the kinematics boxes and working on them near the car since you can sit down (probably) and actually work easier. Refer to image below for instructions in how to remove it (also, roughly note the position of the kinematics box as it has to be aligned later on).
![Image](https://i.imgur.com/v328gZp.png)
2. OPTIONAL STEP: If you have the old sensors as I said at the top part of this post, it's time to change them *sigh*. You will need to drill out the old two screws that are keeping the old sensor in as they have loctite on them (thanks BMW for making our cars future proof again). For the screws that you have drilled out you can do as I did, use two screws from an old HDD (I prefer Western Digital HDDs, only the best for my car). Put the new zip ties in as in the picture below. THIS IS VERY IMPORTANT, if you get creative and put them in a different way a leprechaun will come out from underneath your car and bite your new sensor's wires. Also, if you can get a little bit creative if you understand how gravity works and how the kinematic box goes back in the trunk.
![Image](https://i.imgur.com/BuedowW.jpg)
3. Put back the kinematics box, and use pictures (or w/e you used) to remember the alignment (you don't need to get it perfect as we will align the entire roof in section 4)
Steps for the M*ther f**ker cylinder
Note: This one is in a tight spot and made me loose two "fastening" clamps. I can also say that I wasn't really creative when I was taking it out from the said spot.
Note 2: Please note that on the right side there is an additional sensor that goes in the cylinder that you need to be sure you get back in the right position (or you pay an additional 300$ to replace it).
These two cylinders are located here (red rectangle):
![Image](https://i.imgur.com/SyPFnQ6.jpg)
1. Remove the wiring that is in that area in order to avoid damaging it
2. Remove the studs that are holding it inside (they have a clamp on the opposite side, similar to the one that you found at the kinematics). Studs are represented with green "dots" in the image above. In order to remove the stud at the bottom I became creative and used a grinder to cut a little bit of the yellow side (it doesn't come out in another way). YES, I KNOW it's part of the hard top structure, YES I KNOW it's my f* up, but I grinded so little of it that it doesn't even matter. Other way of removing said cylinder is up to you guys to find, please let me know as I will probably do this job again.
3. When taking out the cylinder, hold the hydraulic lines on the cylinder with your hands so you can see how they were before. Picture below as example. Then, mark the number of the hydraulic line that goes into each hole on the side of the cylinder, so you can know which line goes where. (since you will be taking the cylinder out of the trunk and working on it outside and you won't know which thing goes where)
![Image](https://i.imgur.com/X3twdVz.jpg)
4. Put the cylinder back in, put the studs and clamps back in. (Carefull with the clamps, those tend to run away when working with them in impossible to reach areas).
Hydraulic Pump
Note: I have no pictures here since it was a struggle to do it (my trunk wasn't staying open as germinator's video and I had to keep it open with my back, YES, it still hurts to this day).
1. Take pictures of the zip ties in the trunk area around the pump, marked with the red rectangle in the picture below.
![Image](https://i.imgur.com/hyMTEN8.jpg)
2. Take out the zip ties that are holding the pump in place. Put a thick cloth on top of the battery then place the pump on the battery.
3. Remove the 3 (or 4 on > 2012 cars) microswitches from the pump, the "main plug".
4. Unscrew the screws next to the hydraulic lines, detach the hydraulic lines from the pump, then put back in the new hydraulic lines (check the goddamn numbers on it before doing it). Screw the new hydraulic lines in with the new provided screws.
Other stuff
1. CTM - Convertible top module - There is literally no point in talking about this as it's straightforward, remove two connectors, put back two connectors while routing the wiring the same way.
2. There is a microswitch on the right side (trunk partition area), do not forget to plug that back in.
Step 4 - Final Steps
1. Remove the ends from the zip ties, check twice before cutting them as you don't want to damage the new wires.
2. Check! Check! Check! Check everything, play with the roof arm, compare every wire routing with pictures that you've taken before. Check for possible leaks before running the pump!!! It's not as hard as it sounds, but you need to be sure everything is done well before playing with the roof.
3. Put the pump back into it's place and remember to fasten the screw that released the hydraulic pressure. Put the trunk partition panel back. Put some hydraulic oil into the pump (if you see it's below MAX). Go inside the car, start "opening" or "closing" the roof. You will hear the pump hissing, it's taking out the air from your hydraulic system. After it does that for like 4-5 seconds, go back in the trunk and check the hydraulic oil level, then add more if needed.
4. It should work now but it might make an awkward noise when it closes / opens the "trunk" part of the roof. That wasn't such a big challenge after all, wasn't it? Now, time to start aligning everything.
Step 5 - Alignment and putting everything back
1. While you are working on the alignment of the roof and the kinematics box I recommend taking your headliner from the front and rear shell and bringing it to a specialized car wash for a full treatment. (might cost 15-20$, but it's worth it).
2. Put back the front seal that you have taken out. Link on how to put it back together is here.
3. Align the kinematics box using the information provided in the image below. It's really easy, just check it out.
![Image](https://i.imgur.com/hZg1cXx.png)
4. Remove the hydraulic pressure (you already know how). Put back the rear roof shell using the new screws and align it. There should be a 4.0mm gap between the front and the rear shell. In order to achieve this. Fasten the first two bolts on both sides from the top part of the rear roof shell, then let the roof go down on it's own, I used an 4mm drill head to achieve the "desired gap". Then fasten the bolts from inside the car. After that, fasten the screw from the hydraulic pressure, then get the rear roof shell into "working position", fasten the last 2 bolts (one on each side). Then let the roof go down on it's own (by removing the key from the key fob) and check for alignment, if it's ok, then you are done.
5. Put back the roof headliner.
6. Put back the entire trunk trim.
Congratulations, you have new hydraulic lines and a mental breakdown.