12/07/2010

How to repair sunroof on a Porsche 944 (Square Dash model)

THE WHY

Before I bought my 944 I did a fair amount of research on the net to find out about the things to look out for when purchasing a car of such an age. Amongst some of its well know weaknesses the sunroof lifting mechanism happens to be one of them. There also happens to be TWO versions of the 944 sunroof lifting mechanism, one for the earlier Square Dash model and one for the later Oval Dash model. A lot of the forums and tutorials on the web will often cover the Oval Dash model only which has a habit of stripping the white plastic gears (two gears, one in each lifting arm), and a simple fix for it can be found here. The Square Dash model does NOT have these gears and uses a different method to lift the roof. A good tutorial for fixing both versions exists in the official Porsche Workshop manual (contained in this tutorial) and here at Clarks Garage. I used both of these sources to help understand and fix the sunroof on my Square Dash 944 and have therefore provided more detailed pictures to supplement these existing guides.

THE TASK

You'll need the following:

Philips cross-head screwdriver
Flat-head screwdriver
Cleaning wipes/cloth
Degreaser

THE HOW TO

(Amateur mechanic job time: Approx. 1-3 hours)


Having taken the complete mechanism apart I discovered several faults on mine, these were as follows:

1. Broken drive dog (Shown further down post)
2. White transfer box mounting holes disintegrating


3. Both black lifting arm boxes mounting holes disintegrating


4. Main drive coil and left lifting arm coil missing several coils where it engages white transfer box



Luckily I managed to source items 2-3 in one 2nd-hand lot on ebay, and item 1. I was easily able to get from Porsche.


Tips for reassembly:

Once all the new parts arrived I cleaned out all 3 drive tubes using pipe cleaners and degreaser, then degreased all the coils themselves. I also cleaned all the accumulated dirt from the drive motor and slide rail too.

I then re-greased the drive tubes and coils as well as the lifting arms themselves.

The next step involved attaching the the new drive dog (white plastic square in photo below) to the new main coil I'd received. Luckily the new coil I received had the modified screw-in connection (upper picture) for the drive dog as opposed the old crimp style version (lower picture) on the broken coil.


Once the drive dog was attached I then threaded the coil into the drive tube in the boot (shown by right-hand orange arrow) so that went all the way back into the car. Left-hand arrow is the power connection for sunroof motor.


The drive dog was then slid into the rail on the motor assembly with the correct length of coil (305mm).


The motor assembly was then mounted back in position


Next I moved back inside the car to assemble the lifting arms and attach them to the transfer box. I made a slight modification the lifting arm boxes by securing them with zip ties after they had been secured together. I did this because the fixing holes on the previous pair had disintegrated where the screws had either been over tightened or the pressure of the arms had made the boxes explode. The zip ties therefore help spread the strain the screws come under.


Now finally, the transfer box is quite a tricky part to piece together with one pair of hands especially as all 3 drive tubes and their coils have to be lined up correctly. To make up for the lack of an extra pair of hands I used a 3 zip ties to hold the two drive tubes (that are attached to the lifting arms) in place in the transfer box before I inserted the drive gear and then finally the main drive tube (in the space shown by the orange arrows).





Once the whole mechanism was assembled and secured it took a bit of trial an error lining the lifting arm boxes up with the insertion point in the roof. This was achieved by packing them out with a few large shilling washers (shown by orange arrow).


The last piece in the jigsaw involved setting the limiter on the microswitches back on the motor assembly (shown by orange arrow).

9 comments:

  1. I think this is quiet better than the 933 model otherwise almost looks same.

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  2. I'm struggling with this issue now on my 924s (1987). What is the definition of a "drive dog"? Is that the end near the motor that holds the cable housing?

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  3. The 'drive dog' is the white plastic square (4th photograph down) attached to the end of the coiled cable.

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  4. Thanks for doing this, Dave. This is better than the manual. :-)

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  5. No worries, glad to be of help

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  6. This is a thorough step-by-step procedure, Dave! I just want to ask something though. My husband has a 968 and is thinking of replacing his sunroof. Does the same set of instructions apply on that model? That car has been with him for years and we don’t want to mess it up by blindly removing the parts. Thanks a heap!

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  7. Thanks for the question, however I'm afraid I don't the know the exact answer. There are some similarities in parts between the 944 and 968, about 20% according to Wikipedia, but whether or not that includes the sun roof mechanism I don't know. If it does then it is likely to be based on the newer version of the 944 sun roof mechanism mentioned in the first paragraph of this tutorial (there are some links to follow) and not the one I have written the tutorial on. I would go on the Pelican Parts forum and put a question on there to see if someone more knowledgeable. Hope that helps.

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    Replies
    1. Can you help me I hope? 1984 944 sunroof works ok but while driving up a hill, the top will go up on its own. Then on level or down hill it will go back down?

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    2. Sounds like an electrical problem to me, maybe you've got a loose wire somewhere that makes contact when the car is at an angle like going up a hill which causes the sunroof to lift. Other than that I'm stumped as there's no logical reason it should do that.

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