vincematthews
Member
Ever wondered about refurbishing the rear hatch (as described in various sites on-line? Well I did until various rattles, squeaks and fizzes, not to mention the fact that the glass had lost contact with the frame along the bottom edge and most of the way up both sides drove me to tackle it.
Not knowing much about bonded windscreens (apart from a similar experience with an Alfasud 1200 'sieve'!) I rang round the 'professionals'. Most regarded it as too risky especially as it was a Porsche, but one said he'd come and have a look. I got a choice of either an open ended quote of £180 or more with no responsibility for the glass if it broke while it was being unbonded - or - £76 inc for putting it back together after I'd done all the risky jobs; I choose the latter.
WARNING: Do not read any further unless you've got loads of time to dedicate to your 924 and are a very patient person!
I took off the hatch and laid it outside down on a soft beach mattress in the carpeted living room (what? just get her to go out shopping for the day!) so the inevitable manhandling to get the thing apart would not result in scratches or worse.
The trims were a right pig to get off because the aluminium corrosion products had built up underneath and made it a lot more difficult. I found a small sharp wood chisel useful to lever the trim away from the frame on the underside, working my way slowly along each of the 4 trims starting from one end.
The next and most risky task was getting the glass away from the frame. This would have been even more difficult if it had been bonded better or bonded over a greater length. The only safe technique (IMHO) was to use a sharp, thin as possible blade to cut the bonding mastic between the glass and frame parallel to the glass. Any sort of levering action, with any sort of tool, to separate the glass would almost certainly break it. This is still a very long tedious job where no matter how frustrated you get, you must keep saying to your self (first sign of madness? [
]) "this is glass - take it easy". The above worked fine until I got to the final stretch between the 2 hinges where the glass was so tight against the frame that even the thinnest blade I had wouldn't fit. Having got so far, I wasn't going to give up and was able to lift the, by now free, bottom edge (where the lock pins are) of the frame up and support it about 6" above the glass. This was as much as I dared to stress the glass / frame bond but allowed just enough gap to get a blade in.
There then followed cleaning up the glass and frame. Get all the black paint and mastic off the glass. It will come off the Heated Rear Window side strips too if you are very careful. Next remove the corrosion and any old mastic from the frame, mask up the L section where the new mastic & glass will go and respray the rest; this is to stop corrosion and is for cosmetic reasons too.
At this point, the professionals were invited back, primed the frame and glass, ran the mastic into the frame and set in the glass (all off the car). To get the trim strips on they used suction cups to turn over the screen onto its outside face (over a concrete yard!! I couldn't watch). The trim strips were very difficult to fit and took them up to three goes to get them on properly using a rubber hammer. Tip: When you bend the inside of the trim up a bit to take it off, don't close it back up too much before refitting. They did preliminary cleaning up of the mastic edges and left me to do the final trim. They recommended leaving the screen on its outside face for a couple of days so the mastic would set completely without distorting the frame. They used a slow curing mastic (£25 for two tubes) which apparently gives a better bond than the quick set stuff used for roadside repairs. They spent 3 hours on it, so, with the cost of materials they didn't actually charge a lot for their labour.
The mastic comes off the glass easily once completely set and can be trimmed if you use a very sharp blade (don't score the glass underneath though). The screen now looks a lot better and has cut the interior noise a lot - success. Would I do it again - I hope not . . . []
BTW, I maybe an anorak but even I am embarrassed to admit how long this job took!
Not knowing much about bonded windscreens (apart from a similar experience with an Alfasud 1200 'sieve'!) I rang round the 'professionals'. Most regarded it as too risky especially as it was a Porsche, but one said he'd come and have a look. I got a choice of either an open ended quote of £180 or more with no responsibility for the glass if it broke while it was being unbonded - or - £76 inc for putting it back together after I'd done all the risky jobs; I choose the latter.
WARNING: Do not read any further unless you've got loads of time to dedicate to your 924 and are a very patient person!
I took off the hatch and laid it outside down on a soft beach mattress in the carpeted living room (what? just get her to go out shopping for the day!) so the inevitable manhandling to get the thing apart would not result in scratches or worse.
The trims were a right pig to get off because the aluminium corrosion products had built up underneath and made it a lot more difficult. I found a small sharp wood chisel useful to lever the trim away from the frame on the underside, working my way slowly along each of the 4 trims starting from one end.
The next and most risky task was getting the glass away from the frame. This would have been even more difficult if it had been bonded better or bonded over a greater length. The only safe technique (IMHO) was to use a sharp, thin as possible blade to cut the bonding mastic between the glass and frame parallel to the glass. Any sort of levering action, with any sort of tool, to separate the glass would almost certainly break it. This is still a very long tedious job where no matter how frustrated you get, you must keep saying to your self (first sign of madness? [
]) "this is glass - take it easy". The above worked fine until I got to the final stretch between the 2 hinges where the glass was so tight against the frame that even the thinnest blade I had wouldn't fit. Having got so far, I wasn't going to give up and was able to lift the, by now free, bottom edge (where the lock pins are) of the frame up and support it about 6" above the glass. This was as much as I dared to stress the glass / frame bond but allowed just enough gap to get a blade in.There then followed cleaning up the glass and frame. Get all the black paint and mastic off the glass. It will come off the Heated Rear Window side strips too if you are very careful. Next remove the corrosion and any old mastic from the frame, mask up the L section where the new mastic & glass will go and respray the rest; this is to stop corrosion and is for cosmetic reasons too.
At this point, the professionals were invited back, primed the frame and glass, ran the mastic into the frame and set in the glass (all off the car). To get the trim strips on they used suction cups to turn over the screen onto its outside face (over a concrete yard!! I couldn't watch). The trim strips were very difficult to fit and took them up to three goes to get them on properly using a rubber hammer. Tip: When you bend the inside of the trim up a bit to take it off, don't close it back up too much before refitting. They did preliminary cleaning up of the mastic edges and left me to do the final trim. They recommended leaving the screen on its outside face for a couple of days so the mastic would set completely without distorting the frame. They used a slow curing mastic (£25 for two tubes) which apparently gives a better bond than the quick set stuff used for roadside repairs. They spent 3 hours on it, so, with the cost of materials they didn't actually charge a lot for their labour.
The mastic comes off the glass easily once completely set and can be trimmed if you use a very sharp blade (don't score the glass underneath though). The screen now looks a lot better and has cut the interior noise a lot - success. Would I do it again - I hope not . . . [
]BTW, I maybe an anorak but even I am embarrassed to admit how long this job took!
