Convertible soft top re-bond glass rear window Audi VW Mini and other Brands
The convertible glass rear windows of Audi (TT, A3, A4, A5, etc.), VW (Beetle, Golf, etc.), Mini (R 57) and many other brands are glued directly to the soft top fabric. The bonding comes off completely or partially after about 10 years. Causes are normal environmental influences (e.g. solar radiation, humidity, etc.) and frequent impregnation with solvent-containing protectors from the spray can. Solvents harden the adhesives and thus reduce adhesion. The use of incorrect cleaning agents (containing acid or solvent etc.) will damage the bond. A new soft top costs up to 5000 Euro / USD incl. installation. We have worked intensively on this topic and developed a do-it-yourself repair solution.
In order to have a clean finish to the soft top window, the soft top fabric was folded and glued at the factory. If this gluing has also come loose, the glass adhesive is extremely stressed. Each time the soft top is opened and closed, the soft top fabric is removed almost vertically from the glass window. We strongly recommand to renew the fold gluing and the glass window gluing, to achieve long-term durable repair result. A new gluing of the fabric fold is complex. In order to get close to the fold gluing, the inner headliner (not available on all vehicles!) must be completely or partially removed. In the lower area of the glass window, the headlining can be removed relatively easily. In the upper range as well as on the right and on the left the headlining must be removed from the frame of the glass window. This is possible, but requires some experience and craftsmanship. It's easier when the window is completely detached. In this case, the fold is fully accessible and can be fixed and re-glued with the help of foldback clips. Then, step by step, the window can be re-bonded to the fabric.
We have tested almost all commercially available types of adhesive on used original tops. All adhesives have more or less failed. The main problem was the resistance to high temperatures. The soft top and window can heat up to 80°C to 90°C (167°F to 194°F) when exposed to sunlight. Commercially available adhesives are according to manufacturer's specification temperature resistant up to 80°C (167°F). But be careful, these manufacturer's specifications are greatly exaggerated. Also the products offered on Ebay and Amazon as "special adhesives for convertible glass" have failed here.
In the forums various epoxy adhesives are recommended. These are offered either in tubes or in syringes without automatic mixing tubes. But without a fine balance it is not possible, to mix these adhesives 1:1. If the mixture is not correct, the adhesive will not adhere well. Air bubbles are also automatically added during manual mixing, which is not optimal for curing and function. Epoxy adhesives are completely rigid when cured and cannot absorb expansion and vibration. Epoxy adhesives in addition, are thin liquid and run on sloping repair spots.
In the USA car glass adhesives (e.g. from 3M) are very popular. These adhesives are flexible and have very good adhesive properties, but are very difficult to process, because extremely viscous. A thin application is not possible without loss of adhesion. The repair can only be carried out with thick layers.
So we have tested special industrial adhesives. The CABRIODOC 2K Rapid Adhesive is supplied in professional syringes with 1:1 automatic mixing tube and is reclosable. The usual curing time of 24 hours was also reduced to 12 hours. The CABRIODOC 2K Rapid Adhesive is easy to apply and doesn't run. After complete curing, the black adhesive is highly flexible and temperature resistant from -30°C to + 90°C (-22°F to 194°F).
We strongly advise against repairs with commercially available adhesives and silicone. It does not last and a professional repair is no longer possible afterwards. The "wrong" adhesives can no longer be completely removed and the "professional" adhesive can no longer adhere. Adhesion to silicone is also completely impossible. If you have already carried out such a repair, we can only give you the following tip: Try the repair again with the same adhesive. Remove the adhesive where it still adheres mechanically, except for a thin residual layer. Where it no longer adheres, remove it completely, mechanically or with a suitable cleaner. Then, if available, obtain a bonding agent or primer from the adhesive manufacturer. Apply this and wait until fully flashed off. Then apply the adhesive again and use our clamping tools to ensure the necessary hold until the adhesive has cured.
A special tool is required for professional bonding. The soft top cover must be fixed to the glass window with the necessary pressure until the adhesive has cured. We have developed a special clamping tool with suction cup for this purpose. 5 pieces are sufficient for a 30 cm (12 inch) long repair. If wooden spatulas are used, 60 cm (24 inch) are possible.
Working instructions - Repair instructions
The repair requires patience and some manual skill. Take your time and follow the instructions exactly. Preparation work is most important. Only in this way, the repair can be successful.
For the repair you need the following additional aids:
Powder-free disposable gloves, acetone, vacuum cleaner and something to cover the body.
If the glass window has come off completely, folding clamps are additionaly required.
Check whether only the gluing on the glass window has come loose or also the fold gluing of the soft top fabric on the back. In this case, the fold gluing must be repaired first. Only after complete curing the glass window can be re-bonded.
The ambient temperature must be between +10°C and +30°C max. (50°F and 86°F max.) The soft top must be absolutely dry. Do not apply the adhesive at high humidity. Do not apply the adhesive under direct sunlight. Optimal repair environment: Dry garage.
Attention! The adhesive has a application time of approx. 25 minutes. During this time, the parts must be joined together. After 25 minutes the adhesive no longer adheres. In the case of longer detachments, the repair must be done step by step. The 25 minute rule also applies to the remaining quantity in the mixing tube. Use new mixing tube if necessary. The mixing ratio for the first 2 cm (0.8 inch) is not yet correct. The adhesive is therefore unusable and must be disposed. The adhesive can be further processed after 4 hours, but not yet fully loaded. Between the single adhesive sections you have to wait 4 hours. After 12 hours the adhesive is completely cured.
Cover the working area extensively (e.g. with an old bed sheet). The cover can be clamped under the hood. This prevents scratches and adhesive residue on the vehicle.
Cleaning glass window
The soft top and window must be clean and dry. There should be no impregnation protector residue on the window, otherwise the suction cups of the clamping tool cannot adhere, so test suction before repairing.
Re-bond fabric fold
If necessary, first reglue the fold of the soft top fabric. This also applies to the areas where the window bonding is still intact.
Completely or partially remove the interior headliner.
Soak the cleaning cloth lightly with acetone. Clean the fold and let it flash off. Do not use household solvents (e.g. nail polish remover, nitro thinner, turpentine etc.). If necessary, use only isopropyl alcohol as an alternative.
Prepare the adhesive. Apply adhesive in wavy pattern with approx. 2 mm (0.08 inch) height to one side of the fold. After pressing, the adhesive should cover the entire width of the fold. The adhesive may swell out of the fold about 2 mm (0.08 inch).
Fix the fold on the window with the clamping device. Lightly moisten the suction cups of the clamping device with water and place them at a slight distance from each other and carefully tighten the clamping screws. The clamping tool can be removed after 4 hours.
If the window has come loose completely, the clamping devices cannot be used. In this case, the fold can only be fixed and rebonded with foldback clips until it has cured. After this, the window can be re-glued step by step with the fabric.
Re-bond fabric to window
Pre-clean the repair area with a vacuum cleaner between the soft top and the window. Over the years a lot of dirt has accumulated here.
Cover the windscreen generously with paper masking tape to protect it from scratches.
Prepare the bond area. Expand the apparently intact bond by approx. 5 mm (2 inch) to the right and left, as the old adhesive no longer adheres completely here. Use the sanding fleece between the fabric and the window to remove most of the old adhesive. However, it is not necessary to remove the old original adhesive completely. Do not remove the black primer. The black primer protects the adhesive from reflecting UV rays.
Clean the repair area again with the vacuum cleaner between the soft top and the window. This is the only way to remove residues of the old adhesive and the sanding fleece.
Remove the masking tape, otherwise the suction cups of the clamping device will not adhere.
Soak the cleaning cloth lightly with acetone. Carefully clean the repair area with the cleaning cloth between the fabric and the window up to the corners. To make work easier, the cleaning cloth can also be wrapped around a wooden spatula or similar tool. Then air off the cleaning area for a few minutes. Do not use household solvents (e.g. nail polish remover, nitro thinner, turpentine, etc.). If necessary, use only isopropyl alcohol as an alternative.
Prepare adhesive. Apply the adhesive to the black area of the window in a wavy pattern with a height of approx. 2 mm (0.08 inch). Work in the adhesive on the right and left at the ends of the new bonding with the brush in order to achieve an optimal transition to the intact old bonding. After pressing, the adhesive should cover the entire black surface of the window. This is the only way to achieve a 1 cm (0.4 inch) wide and full-surface bond. The adhesive should swell out about 2 mm (0.08 inch) onto the window. The adhesive must be removed from the window mechanically with the scraper after complete curing of 12 hours.
Lightly moisten the suction cups of the clamping device with water and place them at a slight distance from each other and carefully tighten the clamping screws. Remove after 4 hours.
Carefully remove the excess adhesive after 12 hours with the scraper. First, cut the adhesive vertically at the edge of the soft top with the scraper and then scrape off the rest flat. The excess adhesive should not be removed with solvents or other chemicals. A small residual film of the adhesive usually remains on the window. This can be removed very carefully with some acetone and the cleaning cloth. However, no acetone should get onto the new adhesive.
We sell the complete repair sets exclusively through our EBAY-SHOP. Direct orders are unfortunately not possible due to organizational reasons.
CD 2K Rapid Adhesive black 35 g (1.2 oz) double syringe resealable + 3 x mixing tubes for approx. 250 cm (98 inch) long and 1 cm (0.4 inch) wide bonding | Temperature resistant after curing from -30°C to + 90°C (-22°F to 194°F) | Processing time 25 min. | Can be further processed after 4 hours | Final strength after 12 hours | Shelf life (cool and dry) 6 months
CD Clamping device set with 5 pieces + 5 spatulas for a 30-60 cm (12-24 inch) long bonding
CD Cleaning cloth set with 3 pieces
CD Abrasive fleece
CD Paper masking tape
CD Mini Scraper
NOT included: powder-free disposable gloves, acetone (alternatively isopropyl alcohol), vacuum cleaner and something to cover the body (e.g. an old bed sheet)