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911 Cabriolet roof stuck

The inner part of that gear should have splines to lock it to the shaft .. i take it the gear doesnt free wheel ?

How many wires goto that motor ?

If only 2 then there IS not a switch even though the diagram says there is ..

If 4 then there IS a switch .. 2 for the motor and 2 for the micro switch .

The gear doesnt look split .. but it has a mark from the image .. if it locks to the shaft sline then its ok .

Can you power up the motor so that it spins .. connect some wires from the battery or use a power probe .


EDIT ..

Just a thought but can you fit the right hand motor to the wire plug for the left hand .. then operate .. if the right hand motor works when connected to the left side then its still that unit thats at fault .
 
There are splines on the inside of the gear wheel but they look very worn to me. The gear wheel does turn its shaft but the grip between the two isn't great and if any big resistance is felt, the gear wheel jumps up the shaft, off the splines.

There are four wires going to the motor.

The motor does spin when the dash-switch is pressed.
 
4 wires means there is a switch there .. the motor only needs 2 .. positive and negative .

Swop the motor side to side and see what it does .

The gear should be tight on the shaft .. it has to drive a lever under tension at the end of the day .. if loose then its slipping and wont work .

And i have to leave .. back tomorrow night .
 
Your insistence that there is a switch has led me to examine the mechanism in greater detail.

If you look at the pics I've posted, you will see there are two little arms made of copper. There is also a black strip lying along a short section of the outside edge of the gear wheel attached to the external latching mechanism. It must be the action of this black strip on those two copper terminals that acts as a switch. Yes?

I'm not sure what you mean about swapping the motor side to side. I know it's receiving power when connected to its own side. I don't understand what more I can learn about it by connecting it to the other side. I'm no expert, as you can probably tell.

In the meantime, I've reassembled the motor and refitted it to the hood.

I pressed the button to close the hood and it rose perfectly, landed on the top of the screen as you would expect, and both latches began the closing procedure.

The working latch closed perfectly but the faulty latch moved only halfway through its intended travel before giving up the ghost. Keeping my finger on the button caused the motor to keep spinning but the latch would not move any further forward – and it wouldn't move backwards either.

My interpretation is that either the increasing resistance as the latch moved into its locking plate at the top of the windscreen caused the worm-driven gear to jumped up the shaft away from the splines (it does that when tested with the case open) or that the increased resistance was too much for the aforementioned splines and they simply started slipping.
 
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.
 
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?
 

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Ok .. dont worry about the switch in that unit .. i missed the part about the motor working but not operateing :oops:

Gear wheel is slipping so thats the fault ..

Its a matched pair as far as im aware .. you might find if you try and fit a new gear to your old shaft it wont fit .

Also its a little hard to say if the shaft has also worn enough to cause a premature failure if you just fit the gear .
 
Thanks for the reply, Demort.

I hope I haven't confused you with my description of what I'm thinking of doing.

As shown in the pic, the kit comprises a gear and a gear/shaft combination.

I'm not thinking of connecting the new gear to the existing shaft.

My idea was to use the new gear/shaft combination (both parts joined solidly together as shown in the pic) but not to use the other gear to replace the existing gear that sits on the shaft attached to the external locking mechanism.

That would mean that the slipping union of the existing shaft and gear driven by the worm drive would be completely replaced with the new shaft and gear.

The new shaft, turned up by the new gear, would then turn the existing gear that drives the external locking mechanism.

Hopefully, that makes it a little clearer.
 
Hell im always confused these days .. not sure if its old age or spending too much time on here lol .

Anyway you can get a fixed gear will be fine .. it seems to me you have found the problem and have a solution :thumb:
 
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.
 
Hi All. The roof on my 1989 911 3.2 Cabriolet has also stopped working Phil so I sympathise! Reading this thread, am I right in thinking you can put the hood up and down manually whilst waiting to have it looked at by a pro? If so can someone give me a short guide on how to do that? My problem is that I could open the roof but when I try to close it, it only rises 2 inches! Cheers, Robin
 
If you look at the rear seats and then let your eyes go to the carpeted inside wall of the car adjacent to either seat (just to the rear of the upper back of either front seat) you will see a round, black plastic cap about 2 inches in diameter set into each wall.

1. Remove both caps and you will find a nut under each one.

2. Using the wheel nut wrench from the toolkit, loosen both nuts about two turns.

3. Lift the hood forward and put it down on the windscreen frame.

4. Operate the rocker switch until the indicator light goes out and the hood is secured to the windscreen frame.

Happy motoring! :thumb:
 

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