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Join Date: Oct 2003
Location: Manchester, England
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911 Cabriolet roof stuck down on passenger side

I have a 1987 911 Cabriolet that hasn't set foot on the road for several years. I do start it up occasionally and run it up and down the drive but I cannot remember the last time I lowered the roof.

Today, I tried to lower the roof but, when I pressed the button, the driver's side tried to lift from the top of the windscreen as normal but the passenger side of the roof remained firmly connected to the top of the screen.

I pressed the button to close the roof and the driver's side (which had raised a little way) appeared to close as normal.

The roof now looks fully closed but the red "roof warning light" is on.

Any advice would be very much appreciated.
Old 03-10-2018, 05:24 AM
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The first step in putting the roof down is This is some checks to see if the roof is already down, Letís assume thatís fine for now.
Then 2 servo motors (Right above the driver and passenger a heads) disengage the locks. You can easily see and hear if that is happening and if not use a screwdriver In the tool kit to open it in order to test & fix

After the locks disengage then the gears in the passenger seat sides begin to lift the roof-The first step of which is lifting the pin out from both driver and passenger front corner. If this much were working you would see the roof lifting.

My guess since this hasnít been used for a few years is that the seals are sticking and giving it a little push After the locks disengage might help.

That should get you started, thereís a number of threads here already that discuss this operation in detail
Old 03-10-2018, 09:59 AM
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The situation appears to be that the passenger-side roof-lock is not disengaging when I press the roof button.

There are two slots (left-hand side and right-hand side) into which I can insert a screwdriver in order to open/close the locks manually. When I insert a screwdriver blade into the driver's side slot and press the roof button, I can feel something whizzing round and touching the end of the blade as the roof begins to lift. However, when I do the same thing on the passenger side I can detect no internal movement at all and the roof remains fixed to the top of the screen.

It looks like I might have to access the left-hand lock motor. If I use a screwdriver to turn the left-hand lock mechanism until it parts company with the top of the screen and then use the roof button to unlock the right-hand side electrically, will that be okay?

Last edited by pbmitchell; 03-10-2018 at 11:22 AM..
Old 03-10-2018, 10:07 AM
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You are probably gonna find that the gear is stripped in the closing motor. I had this with my cabriolet. You don't want to buy a motor (very expensive) It won't hurt to disengage with screwdriver if you can. Vertex Auto in Florida used to sell the gear separately. https://www.**********.com/convertible-cabriolet-top-latch-motor-gear-p-11406.aspx
Old 03-10-2018, 11:46 AM
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You are probably gonna find that the gear is stripped in the closing motor. I had this with my cabriolet. You don't want to buy a motor (very expensive) It won't hurt to disengage with screwdriver if you can. Vertex Auto in Florida used to sell the gear separately. https://www.***********/convertible-cabriolet-top-latch-motor-gear-p-11406.aspx
Old 03-10-2018, 11:48 AM
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Identical problem.......

Quote:
Originally Posted by pbmitchell View Post
I have a 1987 911 Cabriolet that hasn't set foot on the road for several years. I do start it up occasionally and run it up and down the drive but I cannot remember the last time I lowered the roof.

Today, I tried to lower the roof but, when I pressed the button, the driver's side tried to lift from the top of the windscreen as normal but the passenger side of the roof remained firmly connected to the top of the screen.

I pressed the button to close the roof and the driver's side (which had raised a little way) appeared to close as normal.

The roof now looks fully closed but the red "roof warning light" is on.

Any advice would be very much appreciated.

Pb,

I had almost identical problem with my Ď89 cabriolet like yours. The two locking motors overhead should operate at the same time to unlock cabriolet top. Mine had a bad motor and only one side pop up loose. Have you tried to manually crank the motors to open?

I have a special screw driver attached to an electric hand drill that I use to open and close the top. The electric motor is very expensive but bought one. Then found a pair of roller latches to do a manual conversion next time one of the motors fails again.

Tony
Old 03-10-2018, 12:37 PM
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Thanks for the interesting and informative replies, chaps.

I can't use the link supplied by Hermanator ("this site cannot be reached") because Pelican's site software has converted the web address into asterisks but I've found a Cabriolet hood latch motor cog repair kit on a UK website for £130. The fitting instructions look daunting, to say the very least.

Back to the present, I've now managed to unlock the passenger side of the roof, using a screwdriver in the appropriate slot. I've also unlocked the driver's side using the roof button.

Once the roof is fully unlocked, pressing the roof button causes the roof to lift and to move back to its fully open position. Pressing the roof button again causes the roof to lift and return to the top of the windscreen.

At that point, the right-hand side locks down but the left-hand side doesn't.

Interestingly, while I was tightening and untightening the left-hand roof lock, I noticed that pressing the roof button would cause the manual screw mechanism to rotate swiftly, just like the right-hand side lock mechanism does. That spinning is achievable only at certain points of the tightening/untightening process.

The screw head doesn't have a sharp-edged slit to accept the tip of the screwdriver, it's more of a V-shape and I'm worried that that might be due to wear and tear on the screw. Accordingly, I've left the roof in the closed position, but not tightened down on the top of the windscreen just in case it becomes impossible to untighten it manually with the screwdriver.

Any further advice or ideas would be much appreciated.

Last edited by pbmitchell; 03-10-2018 at 02:56 PM..
Old 03-10-2018, 01:06 PM
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Here is the latest update.

This morning, I opened the roof fully to make everything easier to get to and then opened the faulty latch fully with a screwdriver. I then pressed the button to close the roof and it worked perfectly, locking itself down to the top of the windscreen on both sides.

Hoping I'd somehow managed to fix it, I then pressed the button to open the roof but the faulty latch once again refused to detach itself from the top of the screen.

I opened the faulty latch with a screwdriver and opened the roof again. When I pressed the button to close it, the faulty latch did not attach itself to the top of the screen this time.

Fiddling around with the faulty latch, I noticed that with just a little finger pressure I could rotate it through its full travel. The working latch, in stark contrast, is utterly immovable under finger pressure.

It seems Hermanator was barking up the right tree when he suggested stripped gears.

Strange that it closed itself perfectly on that one occasion today. It wouldn't do so yesterday and hasn't done so since.
Old 03-11-2018, 05:37 AM
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Pull the motor/s and bench test it........

Put the motor on your workbench and apply 12-volts. You could see if it closes/opens when energized. Or do a manual test by cranking the drive motor and put pressure on the reciprocating arm to test for resistance. Also check the wire solder connections.

Tony

Last edited by boyt911sc; 03-12-2018 at 08:42 AM..
Old 03-11-2018, 06:13 AM
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The motor does spin when energised.

I've now removed the faulty latch motor and opened it up.

To my surprise, there is no cam on the drive gear and no switch similar to that on the illustrations I can find online. The only electrical contacts are two springy copper arms that are non-adjustable. I have absolutely no idea how they are supposed to work.

There is no obvious damage to any of the cogs.

I have attached a pic.

Having reassembled the motor, I turned the screw slot on the end of the motor shaft with a screwdriver and the latch opened and closed in response.

I then re-fitted the motor to the hood

I then pressed the button to raise the hood and it rose as normal but the faulty latch would not attach itself to the top of the screen.

I pressed the button to raise the roof and the working latch disengaged from the top of the screen but the roof would not go back. I tried the button again and the working latch rotated (although it was some inches from the top of the screen). I then disconnected the faulty motor, pressed the button and the roof went back perfectly.

Having again removed the motor after this failure, I tested its function by turning the screw slot with a screwdriver. I was able to turn the worm gear as normal but the latch did not move – even though it had moved perfectly well when I tested it in this fashion before refitting it.

It seems that the drive-gear/shafts etc are failing for some reason.

The drive gear that meshes with the worm drive will slide up and down the shaft around which it is fitted. I don't know if it's possible for this drive gear to rise up and away from the worm gear when the case is closed.

Also, if the splines joining that drive gear to its shaft are badly worn, they might be failing under pressure.

In either of the above circumstances, the worm drive would not be able to transmit turning power to the latch.

Just a thought?

I've now taken the motor apart again but I'm at a loss as to what to do next.



Last edited by pbmitchell; 03-12-2018 at 09:08 AM..
Old 03-12-2018, 07:42 AM
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I've just tested the drive gear (that meshes to the worm drive) on the shaft to which it is spline-fitted and, although the fit is solid when I try to turn one against the other by hand, I find I can easily turn the gear on the shaft with very little pressure if I hold each part with a pair of pliers.

Further examination reveals what looks very much like a crack in the drive gear.

Also, the splines inside the drive gear look very well worn to me (but I've never seen a new one to compare it with).

I've attached 3 pics and would welcome any comments.





Last edited by pbmitchell; 03-12-2018 at 09:59 AM..
Old 03-12-2018, 09:51 AM
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Not sure if this is helpful, but another factor in the process is that the assembly has two switches that detect when the roof is nearly closed. Those switches, when depressed, redirect power from the motors that raise the roof, to the motors that secure the roof to the top of the windscreen.

From your description, its not entirely clear if that part of the process is working correctly. When you say that the working latch rotated when it was "some inches from the top of the screen" - that shouldn't happen unless you mean that it was close enough to have triggered the switches.

So here is what should happen - from the point of the top being fully opened:

Press the switch to close the top - the top starts moving forward toward the closed position.
At this point, most of us cab owners support the top gently as its closing, to prevent it from slamming shut.
Once the front of the top meets the top of the windscreen, there are two switches that are triggered - this sends the signal to stop moving the top using the rear motors, and to activate the closing motors.

From your description - either the switch on one side isn't being triggered, or its being triggered, but the motor on that side is faulty, or last option, the "brain" module that coordinates this has failed.
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Old 03-12-2018, 10:08 AM
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Thanks for the reply, Magerian.

I think we can now say that the motor is indeed faulty.

Having once more opened the drive motor casing, I can report that the drive gear had jumped up the shaft to a position where it was almost totally free from the shaft splines.

I can also report that, when I push the gear wheel back down to its normal working position (fully engaged with the shaft splines), the gear wheel will turn independently of the shaft.

Looking again at the pics of the gear wheel, the splines do look as if they've been worn away to virtually nothing.
Old 03-12-2018, 11:52 PM
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It looks as if the way forward is to replace the worm-driven gear wheel and its accompanying shaft.

The above parts are available as a kit, together with the gear wheel that attaches to the shaft that comes into the motor body and is part of the external latching mechanism (see pic).

The instructions for the above kit say that both parts must be used in order to effect the repair. Why should this be? If the existing gear wheel on the latching shaft is in good condition and the new shaft that's driven by the worm gear is identical to the one you're replacing, that's going to work, isn't it?

My reason for asking is that I don't want the hassle of having to tap out or press out the latching shaft from its companion gear wheel. An additional complexity to that job is that there is some sort of switch mechanism lying directly on top of that gear wheel (see pics). The mechanism is (presumably) designed to act with the two copper arms with electrical contacts on the end and seems to comprise a black disc upon which is laid a brass disc with a narrow section cut out of its edge.

The black/brass disc is splined to the shaft and will, I think, just lift away from the gear wheel to facilitate replacing that gear wheel.

So, do I need to change that gear wheel?







Last edited by pbmitchell; 03-13-2018 at 07:47 AM..
Old 03-13-2018, 04:35 AM
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I cannot help on your specific questions, since I have never had to disassemble and rebuild that latching motor. All I can say is that while it may not seem this way, you came out pretty well in your diagnosis and fix. Had it been a failed brain module, or failed transmission assemblies, it would be a much more involved and far more expensive solution.
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Old 03-13-2018, 07:39 AM
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The repair kit arrived this morning and the parts appeared absolutely identical to the existing parts in the motor gear.

The existing gear wheel (attached to the external latching mechanism) was in very good condition so I decided not to replace it.

The other existing gear wheel (driven by the worm drive) and its attached shaft were simply not gripping each other and were therefore useless. I replaced these with the brand-new parts from the repair kit.

Upon reinstalling the motor into the hood, I pressed the button and the hood rose and descended upon the top of the windscreen – where the newly repaired motor completely failed to operate.

I was about to take myself off to the local canal and throw myself in when I remembered that I hadn't reconnected the motor to the car's electrical system.

I raised the hood again, reintroduced the relevant electrical connectors to each other and pressed the button again.

The hood rose, descended upon the top of the windscreen and latched down perfectly on both sides.

What joy!

Many thanks to everyone who's contributed to this thread. Apart from all the information and advice, I'm also grateful for the sheer support offered.

Last edited by pbmitchell; 03-15-2018 at 04:37 AM..
Old 03-15-2018, 04:34 AM
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Good job........

PB,

Where did you source the gear repair kit and how much? Thanks.

Tony
Old 03-15-2018, 04:54 AM
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The best deal I could find was at Design911.com

The price was £99 plus VAT plus delivery.

They were very helpful with my initial enquiries and delivered the day after I placed my order.

On the morning of the day of delivery, I received an email giving me a one-hour timeslot within which delivery would be made.

The package was indeed delivered within that time slot.
Old 03-15-2018, 05:17 AM
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As a fellow cab owner, I can completely agree on the joy that occurs when a previously non-operational cab top is back to working. You will get a smile every time you use it.

Just to repeat a few words of caution, to keep it running:

- Be involved in both the opening and closing, by helping it along with your hands
- For instance, when opening, it can occasionally get hung up and not fully clear the windscreen and you have to give it a slight nudge
- When closing, I really like to support the roof when its closing to not let it slam shut. The main reason for this is that there are hidden fail safe microswitches next to the control arms, and I have had a problem where the roof falls too abruptly, trips the switch, and now everything stops working. Its an easy fix, but annoying.
- Make sure you unzip the top (assuming your has the zipper) before opening.

Enjoy open top Porsche cruising !!
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Old 03-15-2018, 06:54 AM
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