PORSCHE TECHNICAL TOPICS
Fitting a Targa rear ’screen
I spent a fascinating day with Paul Ralhan (below) of Glasstec recently – precisely a year to the day since we first met to collaborate for a 911 & Porsche World feature. (See pages 86–90 in the November 2017 issue for the resulting how-to story on fitting 993 Carrera front and rear windscreens, such that they no longer creak like some ancient wooden sailing ship.)
Our ‘patient’ this time was a 911 Targa nearing the end of a full repaint and reassembly job at Riviera Autobody in Ewelme, Oxfordshire, and to which Paul had been commissioned to refit the iconic but also famously awkward rear windscreen. (Actually, the main reason we had met there, not far from where I live, was so that he could also fit a new front screen to my VW Passat. And let the record show that although I could possibly have had that done by Paul on the strength of the insurance policy, I chose to have him undertake the job – at my own expense – so that I could be sure it was done properly, and not least with a genuine VW part. The car is, for numerous reasons, a keeper.)
I came back with dozens of pictures and, tempting though it was to put together another full how-to story, I thought you – and particularly the air-cooled 911 Targa owners among you – might like to see just a few highlights. Pour encourager les autres. Or maybe even to discourage, where necessary. Either way, the moral of the story is as straightforward as the job is challenging. You might well be able to remove your Targa’s rear windscreen yourself, but unless you are 100 per cent confident in your abilities to replace it satisfactorily, and also have the patience of a saint, then pay a professional – and a genuinely competent professional, at that – to put it back for you.
The first problem – and I am assuming that by this stage the body shell of your Targa will be in exemplary condition, and above all structurally sound and ‘straight’ – is to fit the new (genuine Porsche only, please) sealing rubber to the edge of the glass. That would be demanding enough at the best of times, such is the complexity of the inside of the extrusion, but is here compounded by the presence of the wires to the various sections of the demisting elements, all of which must be routed so that they sit in their correct and often separate channels. (And you will have first equally carefully detached the wires from the old rubber, of course, with the precision approaching that required of a heart surgeon.)
Paul’s technique, plainly honed from handling the task perhaps a dozen times, is to trial-fit the rubber, at this stage not worrying too much about the wires, but just carefully noting and/or physically marking where they have to be placed. This also proves that the rubber is fit for purpose. There followed, with the rubber still partially in position on the edge of the windscreen, further deft work with a pointed pick and a scalpel to make all the necessary holes, apertures and recesses inside the new rubber – being very careful not to remove too much material, or to damage any of the visible areas. Or even the invisible ones, come to that, if they happen to play a part in the overall sealing process.
Paul had to do some delicate soldering, as well, in order to deal with one of the terminals bonded to the edge of the glass that had lost one of its two projecting tabs. He managed it, of course, albeit with some difficulty thanks to the age of the components, but I think that by then I would have given the whole thing up as a lost cause, and resigned myself to living without the marginal benefit of a heated rear window. There can’t be too many early Targas that still routinely stand outside on frosty nights, and then need to be ready to go at a few moments’ notice. (And without a heated front windscreen, still a luxury in far too many supposedly well-equipped
modern cars, you will in any case have to wait until the heater blower has safely cleared the front glass.)
Finally, with all of the wires routed and tucked into their channels and, after some further work with a hooked pick, with the edge of the glass sitting neatly in its own dedicated slot, Paul had the rubber fully and correctly in position, and was ready to begin the process of fitting the assembly to the car. Er, except, of course, that he wasn’t. Or not quite. Still to be added to their narrow slot in the outside face of the rubber seal were the two anodised-aluminium filler strips, and while this task would surely have become second nature to the poor factory staff who must have done it day in, day out, even for someone as experienced as Paul it brought the risk of pulling the rubber itself back off the glass, and so having to start all over again.
The trick, perhaps rather counter-intuitively, was not to smother everything with some seemingly helpful silicone spray, but actually to remove from the rubber all traces of any previously applied grease, including the inevitable sweat from one’s own fingers. (And they will be sweating, believe me.) Then, and beginning from the middle of the windscreen – previously marked with the help of some yellow tape – Paul was able gently to work the end of the first similarly grease-free extrusion into position with one hand, simultaneously holding the next few inches of rubber, such that it couldn’t slide off under the inevitable pressure. Fit the cover for the joint, slide the end of the second trim under it and repeat the process, and that was it. Easy…
OK, so now the glass was ready to fit to the car – or it was as soon as Paul had taken the precaution of securing the outside face of the rubber to it with some heavy-duty gaffer tape, anyway. (Don’t fit an additional strip of tape on the inside. It will naturally be more difficult to remove within the confines of the cabin, but more importantly would also prevent you either ‘stringing’ or, as
Paul chose to do, hooking the lower lip of the extrusion over the flange on the body shell.) ‘These screens would have been fitted using the tried-and-tested cord method,’ said Paul, ‘and I am quite happy to do exactly that where it’s required. But here I think it’s just going to be more trouble than it’s worth. And even if you are very careful – and lucky – there is always a risk of tearing the rubber.’
My next few pictures tell their own story. Two, and at one point three, strong blokes, pushing, shoving, pressing and certainly sweating to hold the glass in position on the shell. And Paul, crammed into the rear of the ‘cabin’, slowly but surely easing the vital edge of the rubber seal over the tantalisingly small metal flange that ultimately holds the entire window assembly in place at three-figure speeds. (The bolt-on stainless-steel cover for the roll-over hoop retains the leading edge of the rubber and glass against the slipstream, but the lower rear edge is secured by nothing more than the associated leverage, and not least gravity. And this system was used right the way through to the very end of 964 Targa production, remember.)
Finally, after about half an hour, the glass was safely in. It would be some time before that stainless-steel cover was installed, but Paul fitted the additional short trims at the base of the hoop, conscientiously protected the full length of the anodised strip with some non-adhesive masking tape, and quite reasonably downed the best part of a large bottle of water. I’d have needed something a lot stronger. And probably psychiatric help, too. PW