Mercedes-Benz Convertible top hydraulic seals FAQ.

Q. Is it difficult to reseal the hydraulic cylinder?
A. Lock cylinders are the easiest and do not require any special tools besides a small flat screwdriver. A vise helps to hold the cylinder. Actuator cylinders are a little more tricky, but take very little time once you understand what you are doing. See my writeup.

Q. What is included in the kit?
A. A custom made polyurethane seal and a NB70 nitrile rubber o-ring.

Q. Are the seals come from MB?
A. No, they are custom made for me.

Q. Where the seals are made?
A. Expensive euro hurts.

Q. Are the seals made of the same material as Mercedes-Benz original?
A. Hell no! The seals are made of polyurethane. Polyurethane proved itself in high pressure hydraulic systems for decades, has high durabulity and resistance to wear. Fluoroelastomers loke viton can be the alternative choice and used widely for valve stem seals for example. But our choice for the pressure hydraulic system is polyurethane.

Q. Why the original Mercedes-Benz seals degrade?
A. Probably same reason the engine wiring harness on some Mercedes-Benz cars degrades. There are speculations that the OEM seals are made of polycaprolactone which is a biodegradable.

Q. Are the OEM replacement seals avalable?
A. Not that I know of. Call your MB dealer and ask just in case. Replacement cylinders are avalable. I do not have informations if the MB changed the material for the seals or not.

Q. Do I have to machine the cylinder to accept the seal?
A. NO. This is the main reason for making the correct size seals.

Q. Are all seals the same size?
A. No, you have to tell which cylinders you are going to rebuild.

Q. Do seal size vary with model year?
A. Yes, but only for the main actuator and rear and center locks.

Q. How to determine the main cylinder seal size?
A. Look at the main cylinder when the soft top is half open (rear bow is in vertical position). If the main cylinder has a snap ring on top, let me know. If it does not - let me know as well.

Q. How to determine the rear and center locks seal size?
A. Read the part number on the cylinder from ANY of these locks. Tell me if it ends on 2172 or on 0072.

Q. Are all model years have the same cylinders?
A. Most of them are the same, but some cars have different size for rear locks and main actuators. In case you find that you got a wrong size seal, please, let me know right away and the right seal kits will be rushed to you.

Q. Do R129 and W124 cabriolet share the same hydraulic cylinders?
A. Only two lock cylinders and two actuator cylinders are the same. The other 4 cylinders for W124 cabrio are different. W124 convertible has 8 cylinders for the soft top, while R129 has 12 cylinders.

Q. How to take the main cylinders out on W124 cabriolet?
A. You need to take the rear bench out. Backrest and cushion. Than, take the size panels out. You will see a big rubber plug. Remove that and you will have an access to a T-40 bolt. Get it out. Get the other half of the bolt working from inside the quarter panel. Unclip the cylinder on top and pull it out carefully into the soft top compartment. Unclip the hydraulic lines.

Q. How to disassemble the rear bow cylinder?
A. Put it in a vise. Use propane torch to heat up the threaded area of the gland. Heat it up from three sides where no hydraulic lines are comming out. When the threadlock starts to boil out of the thread try to unscrew the gland with a right angle strong snap ring pliers. Cool down and repeat if necessary. Do not rush. The new seal for this cylinder is tighter, so use more lubrication with ZH-M when guiding the new seal in. Use a dulled small flat screwdriver or a similar tool. It helps to put the seal in almost vertically, than kind of rotate into the seat. Once installed, the seal works perfect.

Q. Where is the hydraulic fluid tank?
A. In the trunk. Under the spare wheel for R129 model and on the right side under the trim for E320 or 300CE Cabriolet.

Q. Where to get the hydraulic fluid?
A. Well, dealer cost is about $20/liter. Some online retailers sell Febi brand for $8-14, but you have to add about $10 for shipping. There no reports of problems with Febi that I know of. Some people think it is the same as MB original stuff. I used it with no problems.

Q. How fast can you ship?
A. I am doing it for to benefit the community and preserve these otherwise fantastic cars. It is not in any way my business. I can not promise the same day shipping. But I have a post office just next building from my office, and I usually take a break to walk around couple times a day. So, usually I can drop your box at the post the same day. Few day delay might happen though.

Q. Do I have to replace all seals at the same time?
A. No. You can replace them one by one. The best approach is to rebuild all the cylinders that are accessible together. Say you have a leak in one of the windshield locks. Getting the second cylinder out and rebuilding at the same time will only add about 10-15 min to repair time. For the main actuators you will have to remove the rear side pannels. It is faster to remove them together at once. Very often, when you fix one big leak, other cylinders start to leak due to increased system pressure. Fix your biggest offender first and all the cylinders you can easily get out together with it. See if any other cylinder start to leak and repeat. All original MB cylinders leak eventually, but this approach give you a chance to work as you pleased. Your roof will become operational right away - what a reward! And you won't have pressure to finish all at once.

Q. How to send my payment? How much?
A. $47.95 per any two kits for wto cylinders. $4.95 shipping total. All 12 kits for R129 are $275 + $4.95 shipping. Send a paypal payment to

Q. I do not have paypal. I hate paypal. Any other options?
A. Please, contact us.

Q. I am not in US.
A. No problem. You will have to send a bank check in $US (difficult and expensive sometimes) or paypal. There is no additional charge for USPS first class mail. It usually arrives within one-two weeks. It is possible to do express mail, but it will cost you more. Honestly, it is not very convenient to me ether as I do not have any express mail post next to me except USPS. So, if you want FedEx, please add couple of days before I can ship.

Q. How much is the shipping?
A. $4.95