LR072856 High Mounted 3rd Brake Light - what sealant/silicone adhesive to use?

[twr7cx]

What sealant or silicone adhesive is used when replacing the LR072856 High Mounted 3rd Brake Light? I assume something like Sikaflex 227 would be detrimental to the next time the light housing needs to be replaced.

[Pippin]

What sealant or silicone adhesive is used when replacing the LR072856 High Mounted 3rd Brake Light? I assume something like Sikaflex 227 would be detrimental to the next time the light housing needs to be replaced.Sikaflex was a complete failure when I saw my new HM Light spiralling through the air in my rearview mirror and it was professionally fitted. The windscreen shop covered the cost of a new replacement but refused to fit it. I did it myself using clear gutter silicone after a test on the broken one and it has held firm for two years so far. Nick

[DiscoJeffster]

I used sikaflex and copious amounts of it, plus prepared the surfaces really well including alcohol wipe down etc. mine has never leaked or come off. I think in the above case it wasn’t the adhesive’s fault but the person who applied it ineffectively. If you follow the instructions and look how much the factory uses, it’s a lot.

[Pippin]

I used sikaflex and copious amounts of it, plus prepared the surfaces really well including alcohol wipe down etc. mine has never leaked or come off. I think in the above case it wasn’t the adhesive’s fault but the person who applied it ineffectively. If you follow the instructions and look how much the factory uses, it’s a lot. The person that applied it did use an activator before fitting with Sikaflex but the bond was very week. If you are fitting one yourself it's wise to do a test on the old one first just to be sure.

[Jpdv]

Forget 227. Sikaflex 296 is the professional marine glass bond. If that doesn't stick, there's something wrong with your process. It's rated as suitable by the international maritime organisation... That's an approval for where people might die if it fails... (I build wooden boats as my other passion). 3M also do some outstanding adhesives with a bit of flex/temp 'give' in them, but not sure which one would be right for glass/acrylic. The one that is used on wood is affectionately known as 'the devil's toothpaste' - once it's cured, most boatbuilders accept that the bond is unbreakable if you want the substrate to survive...literally - you cut it out and start again.

[Stuart02]

I'm interested to know how you go/went getting the old one out? Heat it up first or just smash and scrape away?

[PerthDisco]

I'm interested to know how you go/went getting the old one out? Heat it up first or just smash and scrape away?

Complete demolition and then knife out the old adhesive with a scalpel

[DiscoJeffster]

Yeah that’s how I did it

[Stuart02]

I'm not sure I'm brave enough!

[Eric SDV6SE]

I'm not sure I'm brave enough!

It will be therapeutic

[DiscoJeffster]

My advice. Wear eye protection. See what you can do about stopping shards entering the door cavity. I had an annoying piece stuck inside the door that rattled each time I opened and closed the boot until I removed it via the door card.

And use more sealant than you’d ever think reasonable.

[Stuart02]

It will be therapeuticHa you're right. I should just wait til I'm angry with the car...

[Pippin]

Ha you're right. I should just wait til I'm angry with the car...If you'd had it fitted by my windscreen guy you wouldn't have any difficulty removing it![biggrin]

[twr7cx]

Forget 227. Sikaflex 296 is the professional marine glass bond. If that doesn't stick, there's something wrong with your process. It's rated as suitable by the international maritime organisation... That's an approval for where people might die if it fails... (I build wooden boats as my other passion). 3M also do some outstanding adhesives with a bit of flex/temp 'give' in them, but not sure which one would be right for glass/acrylic. The one that is used on wood is affectionately known as 'the devil's toothpaste' - once it's cured, most boatbuilders accept that the bond is unbreakable if you want the substrate to survive...literally - you cut it out and start again.

The issue is that while I want it to stick, I also don't want to shoot myself in the foot the next time I have to remove it. These lights have a tendency to get small cracks and leaks over time so it will need to be replaced again in the future. I need a sealant that will hold it as firmly as it needs to be held, but no extra to be a pain to remove again later on.

[PerthDisco]

The issue is that while I want it to stick, I also don't want to shoot myself in the foot the next time I have to remove it. These lights have a tendency to get small cracks and leaks over time so it will need to be replaced again in the future. I need a sealant that will hold it as firmly as it needs to be held, but no extra to be a pain to remove again later on.

Only if you bash into something and break it. There is no half sticking with these things only all or nothing. It’s the equivalent of a windscreen.