[FLuke1]

Hello,

I recently purchased a 1984 Rabbit Convertible. It is in need of a new top and while looking for a canvas top and headliner I saw that the later Cabriolet models had a power top option. How are the power tops generally regarded here? More trouble than they are worth or a helpful convenience?

Would it be possible for me to convert my manual top to a power top? If so, do I just need to find the proper pump, struts, and hydraulic lines or would I need to switch the entire top frame?

I found the diagrams linked below. If these are correct the two frames look very similar:

top frame with mechanical operation
top frame with hydraulic operation
hydraulic system for actuating convertible roof

If anyone has details on the Cabriolet power top regarding its functioning or how it differs mechanically from the manual top they would be greatly appreciated. If you happen to own a power top and can post photos or video that would also be very helpful.

Thanks!

 

[primosupremo]

I haven’t used the power top but there’s no way it’s worth it. The manual is so easy to use and will never have any electrical or hydraulic issues.

 

[Butcher]

I have a power top.

The gas struts are replaced with hydraulic actuators. The actuators are attached to the body and the other end to a linkage that is riveted to the main linkage. It would take a bit of butchery to figure out how to either make that linkage and get it attached to the main frame assembly.

The top control module is pretty basic and the top only works when the key is installed. Once the key is turned, the pump will not operate. The front latches work the same. There are no switches so the top works only when the button is pressed. If you understand how relays work, you could figure out how to 'make' a control unit and have the factory switch operate them.

Top Hydraulics Top Hydraulics | Rebuilt and Upgraded Convertible Top Cylinders, Pumps, Hydraulic Lines is a great company to work with. I use them all the time when I have clients with hydraulic leaks in other makes. When I restored the 91 Cabriolet, I sent the actuators out for a rebuild by Klaus. Did they need rebuilding? No, but when a 30 year old car needs to be fixed, it's best to rebuild everything you touch. I did not install new lines. I did disassemble the pump and found the pump was in excellent shape.

Not everything you read is correct on the internet. If you run across this bit of information http://www.cabby-info.com/Files/RepairingPowerTopPump.pdf about repairing a pump, just keep going. It does not apply to a Mk1. Never has. The Mk1 pump is made with old school German engineering. Extremely well made and the only plastic I found in mine was the plastic reservoir.

Good luck finding all the parts. I suggest eBay.de or eBay.uk

As for usage, once you have one, you will not want to go back. You do not have to get out of the car. If you bypass the safety feature, you can operate it while the car is at idle [great at a long stop light], if you have any common sense, you can use it while driving [city speeds of course]. I would love to see a manual top be opened while driving or even at a stop light. You can take my advice from an actual owner and known to be a butcher or others with none.

As for reliability, you never hear people complain it does not work, it's a 30 year old car and it's really hard to think it's a reliability issue if it has worked that long. It lasts longer and is more reliable, than a vinyl top.

I guess the only downfall is that you will use the top much more often and the top surely will wear out faster. Since most of these Cabriolet's will not last another 30 years, that really is not a downfall.

 

[FLuke1]

I haven’t used the power top but there’s no way it’s worth it. The manual is so easy to use and will never have any electrical or hydraulic issues.

Thanks for the reply! I do like the manual top so far and also worry that adding more complexity to the system will add more potential points of failure. There seem to be a few posts here about the hydraulic system leaking or the pump needing to be rebuilt. Are these common problems?

 

[FLuke1]

As for usage, once you have one, you will not want to go back. You do not have to get out of the car. If you bypass the safety feature, you can operate it while the car is at idle [great at a long stop light],

Thanks for the reply! My last convertible didn't have a hydraulic top but it was small enough that it could be opened and closed without leaving the driver's seat. I really liked that convenience so I think I will continue the search for Cabriolet power top components. Also good to hear that the Mk1 tops are fairly reliable. It sounds like the power top frame is a bit different from the manual so I will look for that in addition to the hydraulic components and control module. I'm sure they are rare but maybe I will get lucky and find one that is within budget.

If you happen to have any photos of the power top components or even a video of it operating it would be helpful to see them. Thanks for all of the info!

 

[briano1234]

With a well installed manual top, and the hinge points well cleaned and oiled, I can easily go from top to topless in 5 seconds at a stop light without having to move from my drivers seat.

The manual verses a electric top frame are different. Do they break, well new components maybe not old components you betcha.

 

[Butcher]

But can you close it when it starts to rain? From the drivers seat?

No matter what anyone's opinion is, once you have had a power top, you will change your opinion. A lot like power windows/seats/locking/etc. Sure you do not need them, but it's certainly convenient and it's foolish to think that it's not easier. It's great to have a power seat that remembers my location and all I need is to press one button to get everything back to where I like it. I could adjust it myself, but one finger operation is always better.

I would agree that maybe a bit more to maintain, but many times things that are easier to use, get used more often. When it's used more often, things have a tendency to wear out sooner.

As for pictures, I changed my trunk a bit so the side panels are bolted up. The right side panel has a subwoofer and that can be removed, but not for me to take pictures.
Trunk picture. The part on top is the amp

http://imgur.com/pJNRRxG

http://imgur.com/Zy9kv2j

 

[FLuke1]

With a well installed manual top, and the hinge points well cleaned and oiled, I can easily go from top to topless in 5 seconds at a stop light without having to move from my drivers seat.

Thanks for the reply! Unfortunately, after many years of neglect mine is not this easy to use. It is difficult to open and close even from outside the vehicle. My Bentley manual has not arrived yet. Are there any good online resources describing how to properly clean and oil the hinge points?

The gas struts are replaced with hydraulic actuators. The actuators are attached to the body and the other end to a linkage that is riveted to the main linkage. It would take a bit of butchery to figure out how to either make that linkage and get it attached to the main frame assembly.

Thanks for the photos! I actually managed to find a complete hydraulic top, but because they are so rare the cost exceeds my budget. After doing some more research I'm starting to consider replacing the gas struts with linear actuators or linear servos. I think this route could be cleaner (no fluid leaks) and easier to replace if something breaks.

I've seen it mentioned in a few places that the top frame itself is different on the power top. Does anyone have any photos of the power top frame I could compare to my manual top? Photos of how / where the hydraulic struts are mounted would be particularly useful. I plan to drive the car a bit today. When I raise & lower the top I will try to do so from the points where the struts are attached to see if the linear actuator swap idea could work.

Thanks for all of the feedback everyone! Really enjoying this community so far.

 

[briano1234]

Thanks for the reply! Unfortunately, after many years of neglect mine is not this easy to use. It is difficult to open and close even from outside the vehicle. My Bentley manual has not arrived yet. Are there any good online resources describing how to properly clean and oil the hinge points?

Page 4 pf the FAQ's post 75.
or Cabby-info.com

 

[Butcher]

Anything that pivots is a place to lubricate. The problem is that it's really hard to get the lube in the place that matters. It's easy to spray stuff but that rarely gets to where it needs to be. A lot like penetrating oil. I rarely ever gets into the rusted portion of the threads. It does not hurt.

I would use some type of spray grease. HHS K/HHS 2K/HHS 2000 is a great lube that thickens when the solvents evaporate. Spray the joints, move the frame, spray some more, mover the frame, and when everything is as good as its going to get, wipe the grease off. The good thing is that the stuff does not drip later in life. Wurth USA | Automotive Chemicals | Lubricants

The pivot points are usually riveted so you cannot take them apart to get the lube where it needs to be.

Linear actuators would be ideal if they will work in the space provided. I have no idea what kind of force that is needed to operate the top. The top frames are different because the linkage that the hydraulic ram attaches to are different. I suspect the differences are because they take the full load lifting/retracting the top. I believe the linkage is riveted to the main frame.

There is nothing that can't break down in a car. Anything can happen. Hydraulic leaks is something that has yet to happen to me. I got almost 200k on a 30 year old car. I sent out the rams to get rebuilt, not because there was a problem, its because everything needs a bit of love after that many years. There were no problems before I started or after. Fortunately for me, I like to do things right and can afford pretty much anything I want. I think your worry is misplaced to think electric actuators are better because they do not leak. My hydraulic system has had as many leaks as any electric system.

 

[briano1234]

If you start with a Creeping lube, ie: Kroil, Pb-blaster, then open and close the top frame a few times, then switch to WD-40 followed by the open/close many times, then a heavier wt, like 10w30 and do the open/close you will find that it frees up, and the thicker oil will get into the riveted parts just fine. And don't go overboard as a little spritz goes a long way.

 

[Butcher]

And the oil will seep forever. HHS2000 is a one step operation. Seeps, creeps, and thickens with one application. Does not leak later in life like oils do.

 

[FLuke1]

Learned a lot today. Most importantly: neither of my gas struts are functional, neither are connected to the frame, one strut bracket is broken, and one strut bracket is missing. Looks like this top is going to require a lot more reading and even more elbow grease than I expected. Having said that, she drove very well today and deserves a perfect top so I can't wait to get started!

or Cabby-info.com

This has to be one of the greatest sites ever created. I will be living there for the next few days, probably longer.

Anything that pivots is a place to lubricate. The problem is that it's really hard to get the lube in the place that matters. It's easy to spray stuff but that rarely gets to where it needs to be. A lot like penetrating oil. I rarely ever gets into the rusted portion of the threads. It does not hurt.
I would use some type of spray grease. HHS K/HHS 2K/HHS 2000 is a great lube that thickens when the solvents evaporate. Spray the joints, move the frame, spray some more, mover the frame, and when everything is as good as its going to get, wipe the grease off. The good thing is that the stuff does not drip later in life. Wurth USA | Automotive Chemicals | Lubricants

Thanks for this info. It will be my next step. To focus on the frame I will go ahead and remove what is left of the shredded vinyl top and headliner, then lubricate and adjust until it all moves smoothly. I will also remove the old gas struts since they are going to be replaced, either by like kind, hydraulic, or linear actuator.

The top frames are different because the linkage that the hydraulic ram attaches to are different. I suspect the differences are because they take the full load lifting/retracting the top. I believe the linkage is riveted to the main frame.

Very useful information, thank you. Is the hydraulic ram linkage vs gas strut linkage the only difference between the two frames? I'm guessing the power top does not have the snap catch levers on either side of the passenger seat to lock the top down when open?

I spent a little time tonight comparing the mechanical and power top diagrams from my original post. Below is a graphic I made to highlight their differences. Items unique to the hydraulic frame diagram are in blue, with unique to mechanical in red. Common components are in grey.

What I find most interesting / confusing is that the mechanical top diagram seems to include several pins that are not on the power top diagram (numbers 5, 7, & 9). Are these pins actually missing on the power top or is this a drawing error?

I think your worry is misplaced to think electric actuators are better because they do not leak. My hydraulic system has had as many leaks as any electric system.

This is very reassuring! Good to know that if I end up going hydraulic I can be confident they won't fail.

 

[Butcher]

I do not know what those pins are but I suspect they are the rivets I mentioned above. I also suspect that the same rivets are used for both frames.

30A is the link that locks the top to the body. That part and all the other associated parts are not used on the power system since the top is pretty much locked down by the hydraulic ram. 21 plugs the hole since there is no link.

The hyd ram attaches to the body and the other end attaches to a link which is riveted to the main frame. I'm not certain it's easy to take a picture of that. My VW is at a clients house [I pick up and deliver all my clients cars for repairs]. When I get done with their BMW, I will attempt to get a pictures. Do not hold your breath, I'm busy and forgetful. Tomorrow it's suppose to rain and will probably be at another clients house so I can work on their 2 Mercedes.

I always appreciate someone doing their research before they just throwing parts at stuff, but I really believe you may have to dive in deep and fix the problems you run into. Trying to find a parts car would be ideal. I hope you are handy at making stuff [welders, grinders, lathe, milling machine,etc] because you are going to need it. It's not going to be a bolt on system.

 

[FLuke1]

I really believe you may have to dive in deep and fix the problems you run into. Trying to find a parts car would be ideal. I hope you are handy at making stuff [welders, grinders, lathe, milling machine,etc] because you are going to need it. It's not going to be a bolt on system.

A deep dive is just what I need right now. Between mine and my friends' toolboxes I think I will have everything I need. If not, I'll have an excuse to buy more toys. I haven't welded myself but I have a buddy who welds professionally and he's always happy to lend a hand or at least watch to make sure I don't burn the house down. Should be a fun project! I will be sure to post here as I make progress. If you have a chance to get a photo or two of how the hydraulic rams are mounted that would be amazing. Thanks for all of the help!

 

[FLuke1]

Also, if anyone has photos of where / how the switch for the power top is mounted those would help too.

 

[Butcher]

I can post a picture of the switch. I may be able to post a picture where the ram attaches to the frame. I seriously doubt if I will ever post a picture of where the ram attaches to the body. Too much stuff to remove. I will check to see if I did take some pictures but I highly doubt if I did. DIY posts are not for me so stopping to take pictures is a waste of time.

 

[Butcher]

As promise, the power top switch location.

 

[FLuke1]

As promise, the power top switch location.

Thanks for this! Based on your photo I was actually able to track down one of these buttons and the trim piece. Not sure if I will be able to use it if I go with the linear actuator solution but I will give it a try.

Research updates:

This page lists the dimensions of a hydraulic strut at 2,5 x 41 x 4,5. Presumably this is in cm so that would be 1x16x1.75 inches. If these dimensions are correct, then the side view image below of an extended strut suggests that the stroke is between 10 and 12 inches. If anyone with access to one of these struts can confirm if these dimensions are in the ballpark then that would help he determine what size linear actuators to purcahse.



I found more useful photos (below) in another forum. They give some insight into where & how the struts and pump are mounted. They also give a good view of the guide rods that link the struts to the top frame. I imagine getting the correct mounting angle of the struts is going to be extremely important. This weekend I will be taking measurements in the Rabbit to see what kind of clearance I'm working with.

 

[Butcher]

Note that the hydraulic line at the middle of the strut is where the strut is mounted to the body. The two divots are where pins and mounted. This is where the strut can rotate during operation.

In other words, the strut is not mounted on each end but the middle and the rod end.