Washing the soft top

[Nanu]

After a week standing in an Airport car park, the girl needs a wash. Luckily parked her well away from lamp posts and trees so no bird droppings to contend with. Advice needed re cleaning the soft top though.

Intend to give it a gentle scrub with a soft bristle brush and Maguires Gold shampoo then a rinse down using the very lowest setting on the Karcher.

Any advice to the contrary???

PS It has been treated with GTechnic product for weather proofing the hood.

[DMike]

If it’s only dust I would only vacuum and rinse and let the GTech do it it’s magic. Car shampoo would not do any good the soft top I think.

[Scubaregs]

Here's a how to video for vacuuming.

https://youtu.be/Z3w5gVM_4y8?t=20/

[Nanu]

Ok, fell for that one, although I do have a good pair of legs stockings are not my thing, not midweek anyway

Will get STMBO to show me where she keeps the vacuum and give it a go.

[q96169we]

Maguires Gold shampoo

I was told do not use car wash shampoo. They are too strong for the softtop. Also, they don't have any algae/mold killer/cleaner/prohibitor. But if the roof does not have any of these, an diluted automotive APC (all purpose cleaner) should do the job.

I'm about to clean mine (annual clean and protect). I will first vacuum the roof. Then, I use bilt hamber Surfex-HD at 4% and bristle brush. Then vacuum dry the roof to apply GTechnique smart fabric.

During normal car wash, I do not wash the roof as it will wash away the protectant. I just vacuum clean the roof.

[Scubaregs]

No stilettos whilst standing on the roof mind.
After 3 Scottish winters permanently outside, and nothing more than the occasional snow foam and even more occasional actual wash, the top on my 718 looked the same as the day I drove it out of the OPC.

So far the G29 is the same.

[SonnyA85]

So long as it's being re-sealed every year with a waterproofer you shouldn't wash it at all until it's re-proofing time.

The perfect guide would be following.

1. Spray top with steriliser fluid or use a milton tab in a litre of water and spray to kill everything. Make sure you spray in the corners. Leave for 30 mins to do it's thing.
2. Spray with a 1:10 or 1:20 ratio of SURFEX HD (APC) and scrub with a convertible brush. Ratio used depends on how dirty it is.
3. Rinse off with a hose or power washer at a distance or on a low setting. Rinsing with a hose will take a very long time. You can follow the rinse off with a second wash of the roof using a dedicated rag top cleaner or soft top cleaner as they tend to smell nicer and foam up better and then rinse again or use a weak car wash shampoo.
4. Make sure roof is bone dry. Probably best leaving it in the sun for 24 hours.
5. Now you can revive / recolour the roof if it has lost colour otherwise skip this step. Use renovo or liquid shoe polish.
6. Once step 5 is completed if needed and dry. Seal using Fabsil Gold or normal Fabsil or some other Sealer suitable for a soft top. Renovo make one as well.
7. Hoover the roof as part of your normal wash but do not wash it. You may need to use a light brush or cloth to wipe some stuff off. The idea is that it shouldn't need washing just vacuuming or a light brush because it's sealed.
8. After a year has passed go back to step 1.

[q96169we]

waterproofer

This word usually causes some confusion. The roof does not require this to be water tight. There is a layer of waterproof fabric in the roof fabric sandwich which stops the water coming into the cabin.

BMW calls it impregnate agent and what it does is to stop/slow down the most outer layer of fabric from getting wet as well as easier to dry if it's wet, which will minimise the chance of mold or algea growth (dry environment does not encourge these things) so that it will prolong the maintainance interval and also easier to maintain. There is someone don't bother doing this, which is absolutely fine and it will not cause any issue to the waterproof ability of the roof.

Fabsil Gold or normal Fabsil

So, impregnate agent. In one of other thread here (can't remember the specific one), someone mentioned that the waterproof fabric material in the roof fabric sandwich of our Z4 is less compatible with the active ingredient of Fabsil. Thus, if always using this, it may shorten the life of our roof (potentially talking in a 10 or 20 years time scale). I used Fabsil Gold last year. So far no issue and it performed extremely well. Now, I'm in the process of doing this year's annual maintainance and I will use GTechnique smart fabric this time.

Other than above minor difference, I'm doing exactly what you've said. Also agree that you should never wash the roof when washing the car. I just vacuum the roof between annual roof maintainance.

[SonnyA85]

waterproofer

This word usually causes some confusion. The roof does not require this to be water tight. There is a layer of waterproof fabric in the roof fabric sandwich which stops the water coming into the cabin.

BMW calls it impregnate agent and what it does is to stop/slow down the most outer layer of fabric from getting wet as well as easier to dry if it's wet, which will minimise the chance of mold or algea growth (dry environment does not encourge these things) so that it will prolong the maintainance interval and also easier to maintain. There is someone don't bother doing this, which is absolutely fine and it will not cause any issue to the waterproof ability of the roof.

Fabsil Gold or normal Fabsil

So, impregnate agent. In one of other thread here (can't remember the specific one), someone mentioned that the waterproof fabric material in the roof fabric sandwich of our Z4 is less compatible with the active ingredient of Fabsil. Thus, if always using this, it may shorten the life of our roof (potentially talking in a 10 or 20 years time scale). I used Fabsil Gold last year. So far no issue and it performed extremely well. Now, I'm in the process of doing this year's annual maintainance and I will use GTechnique smart fabric this time.

Other than above minor difference, I'm doing exactly what you've said. Also agree that you should never wash the roof when washing the car. I just vacuum the roof between annual roof maintainance.

yeah spot on. You don't need to seal the roof. You are sealing the outer layer to keep the fabric in better condition rather than make the car water tight.

I read that about fabsil and tbh I doubt it makes any difference. Vinegar apparently drys out rubber/plastic but I will use that to clean the drains and window seals. I have about 7 litres of the stuff i need to get through also. I have no real concern about an ingredient not playing nice with the inner of the roof. It only gets applied once per year. I think the roof can handle that.

[q96169we]

I have about 7 litres of the stuff

That's a lot of stuff. It should last for 8 years of use if you don't proof your tent etc.
I don't think it will cause any immediate damage. As you said, I also don't think using that once per year will cause any real concern.

Oh, have to say that if anyone wants to do this, you need about 1 liter of the impregnate agent for our small roof. Unlike other detailing products, which less is usually better, this job require the roof basically being soaked in the impregnate agent then let it dry natually. If you just spray on the surface and not work that in, it will have almost no effect.

[SonnyA85]

I have about 7 litres of the stuff

That's a lot of stuff. It should last for 8 years of use if you don't proof your tent etc.
I don't think it will cause any immediate damage. As you said, I also don't think using that once per year will cause any real concern.

Oh, have to say that if anyone wants to do this, you need about 1 liter of the impregnate agent for our small roof. Unlike other detailing products, which less is usually better, this job require the roof basically being soaked in the impregnate agent then let it dry natually. If you just spray on the surface and not work that in, it will have almost no effect.

someone was selling it half price on gumtree so i thought why not. 2 full 5 litre containers still sealed

[G29Z4]

Recently had quite a roof cleaning problem….
Due to having work done on the house, rather than having the car in the garage I had to put the car on next door’s drive under mature beech trees. Unfortunately it is also in the flight path of pigeons, and they soon began strafing runs. After 24 hours, to my horror, the car was plastered in bird droppings. To add to the problem at this time of year birds are flying by 5am and it was sunny and warm which baked it on very quickly.
My old mx5 cover clearly wouldn’t fit and the car had to remain there. A decorating sheet was used but quickly became “glued” to the roof as fresh droppings permeated it then dried.
After 48hrs little of the roof (or the rest of the car) was visible.
Strangely as my neighbours’ cars are in another part of the drive they’re not affected.
So I had the skip and materials moved and the car came back on our drive, though not in the garage.
To his credit my neighbour offered to pay for any treatment because he was so embarrassed. An offer I clearly could not accept.
Using Auto-Glym and Meguers convertible roof shampoos and a great deal of warm water, there was no choice but to gently rub until the mess loosened up and began to come off. Unpleasant job. And then I started on the bodywork……
When dry and sprayed with cold water it was clear that some of the roof’s natural waterproofing was gone as it wouldn’t bead properly.
Two bottles of Renovo Ultra later and the roof would once more shed water.
All I had then was builders’ dust to contend with!
But deep in the fabric small white marks still remain in places…..

[mr.tourette]

when i had my e85 i tried a few cleaners. Auto Finesse rag top was hands down the best of them, pretty cheao too so definitely worth trying

[Nanu]

Thanks guys, great responses as usual and as expected.

From the feedback, I do not wash the roof unless it needs another coat of Gtech stuff then follow the procedure as suggested by SonnyA85. Other than that vacuum clean but without wearing high heels.

[RobsZed]

Just used the BMW Impregnator, instructions were to dilute 1:10, so 50ml with 500ml of water and was more than enough to brush onto the entire roof. Also the roof dried overnight mostly, impressive stuff!