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Cabriolet rear window bond repair guide

Cabbyfan Aug 10, 2015

  1. Cabbyfan

    Cabbyfan Active Member

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    Hi everyone,

    Some of you will know my read window glue failed due to age. Fingers crossed it is now fixed so I knocked up a guide to help others. There is a PDF you can download or look below.

    Link to PDF is here - coming soon !

    Audi A4 Cabriolet 2003 roof rear windows glass repair guide (applies to many other vehicles too)
    · Common fault on older Audi cabriolets and other soft tops is the fabric coming away / unbounded from the glass rear window.
    · There is no official fix for this from Audi other than a new roof skin.
    · Options are new roof skin from Audi - £2000 approx I believe but do check.
    § OR breakers yard roof – risky as it will probably have a the same issue.
    § Buy a OEM 3rd party new skin - £600 approx excluding fitting
    § Fix it yourself.
    · What WONT work is
    o Silicone sealant
    o Gorilla Glue – it expands on application and is impossible to control.
    o 3M double sided tape – I tried it and it failed in under a day.
    · What will (probably) work – a single part polyurethane black adhesive used for fitting car windscreens. However the preparation is key to this working.
    (My roof had failed on both sides)

    [​IMG]
    Things you will need
    Tape – I used the blue car sort tack detailing tape (all the tape in my pictures is this). I used it so it wouldn’t leave a sticky residue on the roof fabric.
    Clamps – I bought some deep G-clamps (the blue ones in the pics) – they need to be deep to reach the edge of the glass. They were about £9 each on EBay and other places. I also used a couple of slide sash type clamps too.
    Plastic sheet – Once the roof is partially open I covered the rear deck section with plastic sheeting to protect it from spills etc. The chemicals used in this process are very sticky and aren’t easily removed from trim and paintwork etc.
    Gloves – see above lol.
    Pillows – Used to support the glass and take the strain away from the joint as it cures.

    [​IMG]

    Wood – you will need a chunky piece of wood to support the rear of the roof once open. SAFETY – THE ROOF ONLY STAYS IN POSITION A FEW MINUTES ONCE OPEN AFTER WHICH IT WILL RELAX INTO A NEAR CLOSED POSITION – DONT GET YOUR FINGERS OR ARM STUCK. The wood block stops it closing. Have a wider flat piece as well to spread the load. Avoid the seal as well on the underside of the roof.
    I opened the roof so the glass was about horizontal and then used pillows to take the weight off the glass. This is also important as it allows the wooden former to be inserted over the fabric and to clamp onto the fabric/glass joint. If the glass is pulling down under its own weight you wont get the wooden former in. This is also why its important to tape the fabric so the adhesive wont glue the former to the fabric.
    [​IMG]

    Plywood former - made a wooden former to aid clamping the joint. I got a large piece of paper and traced the window and then cut it from thin ply with a jigsaw. I make 2 one for each side for ease. The upper edge of the former corresponds with the line of the fabric as it overlap the glass. Once clamped onto the former this pushes the fabric directly onto the glass bonding area.

    [​IMG]

    Sealant – I used a Dinitrol 500 kit that came with a bottle of 520 (activator and cleaner) and 530 (glass paint primer). It was £15 on eBay.
    [​IMG]

    The repair process
    Pick a warm and dry day. You will need a good 4 to 6 hours for this if you use this method. You can leave it for longer if you wish, the longer the better.
    Prepare the surfaces.
    This bit is very important – you need to make sure when you bond the glass back you maintain the original straight lines where the fabric was originally bonded or it will look like an obvious repair. I used blue tape on the glass window to mark where the fabric needed to line up to. This also gives a masking line for the black paint Dinitol 530 primer (more on this later).
    I also used blue tape on the fabric to protect it from the adhesive, I very slightly ran it over the edge towards the glass too.
    [​IMG]
    [​IMG]

    Where the glass has come away there will be what looks like a brown or black fabric strip on the glass. I removed all this with a sharp bladed scraper (try to get a razor blade one rather than a cheap paint scraper). The aim here to remove anything that is loose or that you think will give way at a later stage.
    On the fabric side I just made sure there was nothing loose or any remains of an old repair like silicone or glue.
    Once clean use the Dinitol 520 to wipe down the glass where the bond will be and I also wiped the underside of the roof fabric too. Wipe this all off with a CLEAN cloth after 2 or 3 mins.
    Then you can paint on the Dinitol 530 primer paint. Don’t use too much it needs a thin coat which dries in about 10 to 15 minutes. It MUST be completely dry before applying the adhesive. I applied it to the glass and the fabric.
    Before applying the adhesive DO NOT touch the surfaces after applying the primer paint.
    Have some strips of blue tape ready – you will need this to tape ACROSS the joints to pull the fabric in line with the tape on the glass showing where the fabric should sit in straight lines (ie how it was originally bonded). Don’t worry about the adhesive sticking to it, it will come off.
    Applying the adhesive
    Put on 2 or 3 pairs of disposable gloves. As soon as you get adhesive on a glove remove it, you do not want adhesive on the fabric or your skin.
    I didn’t use the nozzle supplied, I used a normal sized one and ran 2 small (4 to 5) mm beads along the glass. Don’t put too much down or it gets very messy. Make very sure you get adhesive onto the glass in the very bottom corners all over as this is the weak spot.
    Be careful not to apply too much as if it leaks out under the fabric it will stain the headlining.
    Fixing and clamping
    Once adhesive is applied and tape is in place to hold the fabric seams straight, I used the 4 clamps to hold the fabric / glass under compression for about 4 hours.
    Be careful as the glass it curved so if your wooden blocks or former are too stiff you could break the glass. The aim here is to pinch the joint tight as it cures and not clamp it very tight. It is to stop movement of the fabric so it sets in the correct alignment.
    ][​IMG]

    The Dinitol 500 skins over in an hour to so (depends on temperature). Once skinned and I was happy I removed the tape so to remove as much excess adhesive as I could. Again a razor scraper can be used to remove excess adhesive and also the primer. As long as the tape on the fabric has stayed in place you should have no adhesive visible on the fabric itself.
    Leave it clamped for at least 4 hours, longer if possible.
    I wrote this guide the day after I did my own roof, time will tell if it has worked. It should look like this.
    [​IMG]
    [​IMG]
     
    Last edited: Aug 10, 2015
    CHEZ, technics100 and rjm180 like this.
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  3. rjm180

    rjm180 Active Member

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    Nice write up Cabbyfan. Thanks
     
  4. Cabbyfan

    Cabbyfan Active Member

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    Cheers :)
     
  5. Cabbyfan

    Cabbyfan Active Member

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    Hello Admin - I was going to edit my original post to include a dropbox link to the PDF but I don't see an edit button anymore ?
     
  6. DrStrange

    DrStrange Well-Known Member

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    Hi Cabby Fan.

    Excellent write up and for all your hard work and effort..I hope you never have an issue ever again! I dread to think what a pain this is.

    Thanks for sharing all the info.

    Note: The edit button should be next to the LIKE QUOTE REPLY buttons on the right of your originl post ---->
     
  7. Cabbyfan

    Cabbyfan Active Member

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    Thanks Dr, the real pain was the water under the carpet but its all been lifted and dried now so all good.

    I don't have an edit option mind, it seems to have disappeared for me !
     
  8. DrStrange

    DrStrange Well-Known Member

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    Glad that it has.

    oh dear..the infamous water under the carpet which can take ages to 'dry out'.

    At least its all 'water under the bridge' so to speak haha:tearsofjoy:
     
  9. Cabbyfan

    Cabbyfan Active Member

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    I took the seats out and lifted the carpet, and put fans in to circulate air. Need to squeeze as much water out as you can first tho !
     
  10. DrStrange

    DrStrange Well-Known Member

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    Complete:respekt: for doing this!
     
  11. Cabbyfan

    Cabbyfan Active Member

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    Cheers !
     
    DrStrange likes this.
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  13. Cabbyfan

    Cabbyfan Active Member

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    Hi everyone, been a while !

    Just thought I would post an update, it has been nearly 18 months since my repair. I have the roof down a lot in the summer and I am happy to report the repair is still holding, looking good and watertight !

    Roll on next summer !
     
  14. DrStrange

    DrStrange Well-Known Member

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    Fantastic news dude.

    Its a testament to your hard work repairing it in the first place.

    :)
     
  15. Cabbyfan

    Cabbyfan Active Member

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    Thanks Dr :)

    Had it MOTd today, failed at first due to headlight lenses. Garage charged me £35 to polish both sides up and now sorted. Result ! Apart from that no advisories woohoo:) not bad for a 2003 car.
     
    DrStrange likes this.
  16. Pops848

    Pops848 Active Member

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    Do they look like new? Maybe I'll pay to get mine done, £35 is worth not having to get dirty and spend a day sanding and polishing haha
     
    DrStrange likes this.
  17. DrStrange

    DrStrange Well-Known Member

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    Agreed with Pops.

    Any photos of the finished article?

    :)
     
  18. Pops848

    Pops848 Active Member

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    I'm getting to the point where if it's cheap enough I'll pay it.
    Paid £50 to have some brake pads fitted other week, years gone by I would've always done it myself but now it's not worth getting my hands dirty, cold, wet and run into potential problems for the sake of £50
     
  19. Cabbyfan

    Cabbyfan Active Member

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    No worries, I will get some pics and post here tonight. MOT was passed so all good.
     
  20. Cabbyfan

    Cabbyfan Active Member

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    Hi, images...

    [​IMG]

    [​IMG]
     
  21. DrStrange

    DrStrange Well-Known Member

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    Absolutely. I guess I too could learn how to do it but If I knacker anything (i have heavy hands) then it will cost more to fix than to just pay an expert to do it.
     
  22. DrStrange

    DrStrange Well-Known Member

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    Cheers Dude.

    I'd say thats a job well done. Looks great and pratically like new!

    Thanks for the pics..
     
    Pops848 likes this.
  23. Pops848

    Pops848 Active Member

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    Local guy wants £150, daylight robbery. It will take around 3-4 hours I estimate, cost of materials somewhere in the £30 region. If he said £100 I would have thought about it, £80 or less I'd go for it no doubt but at £150, I'd sooner try myself, it's easy enough to do
     
  24. Cabbyfan

    Cabbyfan Active Member

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    I had my car MOTd at the Ford main dealer opposite my work and it was them who charged me £35 to polish my lenses. It took them about 30 mins to do it. Cant complain as you can see the result is spot on.
     
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  25. DrStrange

    DrStrange Well-Known Member

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    Yeah..at £150, try it yourself!

    Haha, you can buy a cheap 2nd hand set in better condition for less!
     
  26. stevey83

    stevey83 Active Member

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    Thread Revival!!! I need to do this on my rear glass, but im having trouble finding the clamps at a reasonable price. Does anyone have any links, all the ones i have found on ebay that will clamp deeply are all £25 +
     
  27. Darashen

    Darashen New Member

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    I used this guide to do the rear glass on my wife's cabriolet last year. I used a slightly different clamping method.

    Ebay or amazon for suction clamps, Sealey re006 box of 6 will do both corners at the same time.

    You can put strips of wood or metal bar between them to improve the grip. I put cushions under the glass to push it upwards and left the clamps on overnight.

    The most important part of the process is making sure you get all the old glue off the glass and as much as you can off the canvas. You need a really strong cartridge gun as the glue is really stiff.

    Huge thanks to Cabbyfan for posting the original guide.
     
  28. stevey83

    stevey83 Active Member

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    Those clamps are a lot cheaper. Mine has come off on the sides and completely along the bottom. Do they add enough pressure? Did you add them either side of the glass or only on the top?
     
  29. Darashen

    Darashen New Member

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    I put a block of wood between the rear deck and the bottom of the roof to raise it slightly and take the tension off the canvas.

    The clamps are applied to the outside only. The were surprisingly strong given how flimsy they feel before they are under tension. They are bulky so spend some time working out the best position before applying the glue. Once you have the suction cups in place take the arms off the clamps to give you room to put the glue on the glass. It helps to have an assistant to lift the canvas whilst applying the glue. Once the glue is on you can start positioning the canvas on the glue and putting the clamp arms back on one at a time.
     
  30. stevey83

    stevey83 Active Member

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    Thanks for the reply! I’ll get some ordered and have a go. It’s this or replace the hood!
     
  31. AudiAnnie

    AudiAnnie New Member

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    I had an almost complete disconnection of rear glass from roof, and used 3M Single Step Primer, and 3M Windo-Weld Superfast Urethane. Had to do the repair in 3 stages, and then spent a day cleaning up the overflow but a total success. I had tried with another product first that didn't even last for the time it took to lower the roof into the boot. Cabbyfan is absolutely right in respect to cleaning every last trace of old glue from the glass, and cleaning the roof fabric - I found alcohol wipes to be very effective.
    My baby is a 2003 A4 B6 3.0 Cabrio with the devils transmission (CVT)
     
  32. stevey83

    stevey83 Active Member

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    Snap same as mine!
     
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  34. Cabbyfan

    Cabbyfan Active Member

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    Major thread revival .. My glass is still in place
     
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