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Guys, please allow me to give you a brief lesson on hydraulics to explain why a cup seal instead of a O ring.
If you see the picture below, in the left of the rod is a cup seal, in the right an O ring. When pressure is applied inside the cylinder, in the V seal the pressure pushes the
lips of the seal against the cylinder wall and the rod wall, therefore creating a strong seal. In the O ring, the pressure pushes the liquid against the pressure the O ring exerts over the cylinder and rod surface, so it is dependent on the stiffness of the O ring and under very high pressures it will leak. Bottom line O rings are only use on static seals at relatively low pressure........V rings high pressure hydraulics..!
Thanks for that -
I don't quite understand the function of this ram - isnt it double acting - that is - doesnt it pull and push? So in that case how does the same figure apply?
Oh - I just found a schematic - I understand your thinking now.....
See post here - might also be helpful to OP for instructions.
I think the lack of failures with the o-ring solution over at the R170/SLK230 forum is possibly due to the low lifetime cycling of the cylinder - possibly 1/day or per week as opposed to many times per day or per hour.
Last edited by Billy22Bob; 05-28-2022 at 10:07 PM.
I have a question about the roof and trunk staying open during front cylinder replacement:
I plan on sending my cylinder to Cabriolet Hydraulics for re-build. However I have a short garage, and my car won't fit in my garage unless the trunk lid is closed (its really tight). I'm hoping to keep the car in the garage while I replace the cylinder.
So, my question is when I partially open the pano roof (and the trunk lid raises and sticks out the back of the car), once I have the cylinder out, can I remove the roof brace and let the roof lower AND, more importantly, can I lower the trunk lid (so I can shut my garage door) while waiting on the re-built cylinder????? Hopefully this makes sense? Are there any other issues to consider? Sorry if this is a dumb question, and I did search and read some posts about moving the roof/trunk manually, but they seem pretty confusing to me, and my hydraulic system will be "open" during this time since the lines to the front cylinder will be cut, which I think might cause other issues???? Or with the key off and system depressurized, can I move things manually without issue????
Any thoughts or suggestions would be appreciated. Hoping to tackle the cylinder removal this weekend.
It's been awhile since I've done one, but I think the only reason you need to open the roof is to remove the headliner. I would open the roof, remove the headliner, then close the roof and see if you have access to the cylinder mounting bolts.
I don't think they sell shaft collars that small. Use a nut, re-drill to the size of the shaft end, tap a threaded hole on the side, grid it as necessary! But, that is my system, you may find alternate solutions!
If you are removing the whole cylinder and the hydraulic lines, you would have to open the trunk for access to the pump connections. So when that is all done, I see not reason for not closing the roof temporarily with the trunk closed.
The procedure is already around, and all you need to move the roof is create space to remove the screws holding the liner at the front. A short driver will do..so need about 4". After the liner is off you have access to the cylinder and pressure lines. You may have some unglued clips, but that can be fixed with a good plastic glue when re-installing.
I would think that you could remove the cylinder guts and if you have no means how to repair it, send the piston/rod/seal assembly to your preferred shop and tell them to install the seal. Putting it back is a lot simpler than dealing with all these hydraulic lines! I even think that the rod end could be welded to the shaft while maintaining the rest of the assembly under water to avoid heat damage.
I agree if you are not going to use the connectors that can be purchased from cabriolet hydraulic. If you are removing all the factory lines and sending the cylinder in with them attached, the trunk needs to be accessed. I used an aftermarket o ring which is much less disassembly required
Just sharing my experience in addition to what has been shared above..
My front top roof cylinder started leaking. I covered the interior with a painters plastic drop cloth from Lowes. I made my "Vario Roof Brace Tool" out of 1x4 wood about 17 inches long with notches cut in both ends and covered the notches with microfiber towels. It was a little tricky getting the roof to a mid point where I could insert the roof brace as the roof de-pressurized and dropped, and at the same time hold a rag in the corner of the roof where fluid was dripping. Once the system was depressurized, I was surprised at how easily the roof moved (albeit heavy).
I removed the headliner as others have stated above (rear clips were dethatched making removal easier). Once the headliner was removed, I let the car lower the roof and fully close the trunk before removing the cylinder (as others stated, if you aren't removing the lines all they way back to the trunk, you really only need the roof open to remove the headliner).
On the headliner, I scraped the majority of the old glue on the rear clips (I left the glue on the side clips as reference points), I re-glued using JB weld Plasti bond.
I decided to go the re-build route for the cylinder using Cabriolet Hydraulics. I removed the cylinder (careful with the e-clips), and then cut the lines on my cylinder per the instructions from Cabriolet Hydraulics, and sent it off for rebuild. They called after they had received it to collect payment. I was very pleased with their work, it took about a week from when I shipped it to when I received it back. It was about $170 including shipping and the couplers. This was probably a little expensive, but well worth not having to remove the lines all the way back to the trunk in my opinion. They weren't the best at communicating, but I'm happy with their work!
The couplers from Cabriolet Hydraulics add some length to the lines (maybe 1/2 inch). I wish I had cut about 1/4 inch out of lines, because once everything was installed, the lines were a little cramped (seemed a little too long for the space), and the extra curves may put a little stress on the lines (probably insignificant, but would have made for a cleaner install). Regardless, after everything was installed, I wrapped the line couplers in very thin foam, and zip tied the ends of the foam to hold in place. I'm hoping this will prevent the aluminum couplers from hitting the metal on the roof, etc.
Overall, this was easier than I expected. It took a while waiting on the re-built cylinder, but otherwise pretty easy.
I raised and lowered the roof a few times, all seems good! I'll put the headliner in tonight.
The rubber/velvet window trim on the passenger side is slightly deformed (fluid and stretching while removing headliner). Depending on how wrinkled it is, I may try cutting a wedge in it as others have suggested.
Lee, good summary..! I wonder what type of couplers they sent to you.>! Thread in couplers?
Of course, if you don't have the "required tools" that is the easy way out..! I removed the guts of my cylinder leaving the lines attached...and the only thing needed to do that is drill the small hole over the body to push the retaining ring out of its track.
Thinking it all over, I dislodged the clevis to be able of slide the new seal in, but if I have to do it again I would grind the shaft coining holding the piston, and push the piston out. Once the seal is in, will make a chamfer at the end of the piston, drill a small and shallow hole on the shaft and flare it over the piston...That will be cleaner solution instead of dealing with the clevis collar.!
Nice writeup, I just completed the same job on my SL550. I had done a O-Ring repair on my R171 a few years back and it was still holding up well when the car was totaled 3 years later but went this route this time using Cabriolet Hydraulics Quick method. Service and price was excellent .
I did not want to remove all the parts necessary to remove the lines all the way back on a 15 year old car since this could cause new issues. The connectors are threaded and include easy to follow detailed instructions.
As most have noted all the headliner mounts had separated and were reattached using Gorilla Super Glue Gel but as a bonus it stopped all the roof noise when the top is up!
I've got no issues with cab. hyd., just had a trunk lift cylinder rebuilt by them. However, I don't like adding splices to a line when they are not necessary. I know it is less work, but you also add 4 potential leak points.
As far as your noise, that sounds more like brake drag or something along those lines. Does it change when you apply brakes?
If I may ask, what do they charge to rebuild the cylinders?
Lynn, the procedure is so easy that could be written on a line 6 inches wise using Arial font 14..!
The plastic reservoir is connected to an aluminum block. That block has a couple of bolts with allen heads. Remove the one closer to the reservoir. Find you a large syringe (those used to inject seasoning in turkeys will do). Fill it with Pentosin, place the tip of the needle into the hole once occupied by the aforementioned bolt. And slowly start injecting fluid! Fill the reservoir to the indicating line!
I did not see/notice this green disk (and I'm assuming mine has never been apart before).
Does anyone have a part # or at least what "material" it might be made of?
Mine felt snug (I was going to say tight BUT...), so unless I missed something (and dropped it without seeing it, its not in the car that I can find), I'm not sure I have room to add it anyway?
What does it do (take up slop?, stop rattling?)?
Thanks,
Tom
It is there to prevent metal to metal contact on the pivot. If you can find something to replace it, fine, otherwise I wouldn't lose sleep putting it back together without it. Mercedes lists the pins and e-rings, but not that thrust washer.
It is there to prevent metal to metal contact on the pivot. If you can find something to replace it, fine, otherwise I wouldn't lose sleep putting it back together without it. Mercedes lists the pins and e-rings, but not that thrust washer.
Curious that there is not one between the bottom contact surfaces?
There are a few threads about this cylinder so I though I would respond to a few of them with my biggest lesson learned that had not seemed to be covered in previous instructions.
1st Picture
The center bracket has a manual over-ride (light blue arrow) that allows you to manually move the cylinder/locks with a ratchet in order to help reveal the mounting hole (to remove the pin) and re-align the holes during reinstallation.
Since the mounting bolts (red arrows) for the center bracket are "captured" (they do not fall out when unscrewed), and I did not see that there was some "adjustability" (a slight elongation of the holes) to allow adjustment/centering. So, next time I would put a scribe mark on the roof for initial alignment). I spent about an hour trying to figure out why one side of the top was releasing and the other was not (and the roof would start to torque (BAD!) as well as why one of the lock micro-switches was clicking and the other was not. :-(
2nd Picture
So I started the engine and barely started the open-cycle and found that the left side gap (red arrow) and right side gaps were not the same (almost 3/4" different). I finally discovered that by slightly loosening the three mounting bolts (see above red arrows) and tapping lightly on the center bracket I could move it ever so slightly (probably a 1/4") which would change the gaps enough to make them equal and (all of a sudden) the micro-switches started to work and everything worked as advertised. :-)
Took around an hour. Took my time. Was much easier with the pictures on this post.Thanks! FYI, there is a slight adjustment in the locking assembly. My top was binding a bit when opening and the micro switch on the drivers side was releasing after closing so the dash was saying it wasn't closed. I loosened the screws and moved the assembly slightly to the passenger side and it cleared right up.
TIA
I wish I had not missed this post...would have saved a ton of time.
:-)
05-28-2022, 03:57 AM
