Experimenting with a bikini top - costs and benefits

Speedy6111 said:

The two back straps need some fixing points which I’m working out. For now they are held through the rear hoop holes.

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There should be a pair of staples the same as the ones you will have fitted to the shark tooth rail which mount to the rear capping panel above the anti-loose catch (in your previous pic you can see the pair of rives which get replaced by the staple)

You can see what I mean in these adverts:
Link 1
Link 2

I can take some more detailed pictures of mine this evening if you need.

dag019 said:

There should be a pair of staples the same as the ones you will have fitted to the shark tooth rail which mount to the rear capping panel above the anti-loose catch (in your previous pic you can see the pair of rives which get replaced by the staple)

You can see what I mean in these adverts:
Link 1
Link 2

I can take some more detailed pictures of mine this evening if you need.

Click to expand...

Thanks very much for this. I did consider this approach but I want two things from the mounting points: more toward the corners so the diagonal straps clear the rear seats better. Secondly more strength than rivets so I can get some good tension in the straps.

I have a plan that I think will work well, using the rear corner holes normally used for the hood sticks, and some marine roller buckles. Hard to describe so I’ll put up a photo once done.

Speedy6111 said:

Thanks very much for this. I did consider this approach but I want two things from the mounting points: more toward the corners so the diagonal straps clear the rear seats better. Secondly more strength than rivets so I can get some good tension in the straps.

I have a plan that I think will work well, using the rear corner holes normally used for the hood sticks, and some marine roller buckles. Hard to describe so I’ll put up a photo once done.

Click to expand...

I know the sort of thing you are referring to, would definitely be interested din the finished result.
The ones one the back of mine are riveted but they are not standard pop rivets and instead are the the that split and curl giving a tighter fastening. The ones on a friends series 1 are secured with small cap head bolts, so they do not have to be riveted.

Speedy6111 said:

Thanks very much for this. I did consider this approach but I want two things from the mounting points: more toward the corners so the diagonal straps clear the rear seats better. Secondly more strength than rivets so I can get some good tension in the straps.

I have a plan that I think will work well, using the rear corner holes normally used for the hood sticks, and some marine roller buckles. Hard to describe so I’ll put up a photo once done.

Click to expand...

You don’t need to get that much tension in the tilt, it will tighten itself as it shrinks.

Do you want me to take a photo of mine later? They are solid with two rivets and they have been on since new (nearly 30 years)

flat said:

You don’t need to get that much tension in the tilt, it will tighten itself as it shrinks.

Do you want me to take a photo of mine later? They are solid with two rivets and they have been on since new (nearly 30 years)

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Thank you - yes I’d be interested to see that.

On tension - the goal here is to be able to remove the bikini quickly as well as put it back. So I feel I need some way to slacken then retighten the straps like you would with a tent guy line. Once the canvas has shrunk I’ll still need that adjustability - maybe more so as there may be less natural give in the fabric.
It’s a cheap experiment as the marine slide buckles are £5 the pair, so I can try it out and see how it goes.

Speedy6111 said:

Thank you - yes I’d be interested to see that.

On tension - the goal here is to be able to remove the bikini quickly as well as put it back. So I feel I need some way to slacken then retighten the straps like you would with a tent guy line. Once the canvas has shrunk I’ll still need that adjustability - maybe more so as there may be less natural give in the fabric.
It’s a cheap experiment as the marine slide buckles are £5 the pair, so I can try it out and see how it goes.

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Here you are, position of staple and the inside of the tub. It appears to rivet through the tub and the capping - they are the 2 above the anti Luce bolt bit

flat said:

Here you are, position of staple and the inside of the tub. It appears to rivet through the tub and the capping - they are the 2 above the anti Luce bolt bit

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And if you are worried about the rivets pulling loose, Although not aware of that being a problem you would use nuts and bolts.

Speedy6111 said:

On tension - the goal here is to be able to remove the bikini quickly as well as put it back. So I feel I need some way to slacken then retighten the straps like you would with a tent guy line. Once the canvas has shrunk I’ll still need that adjustability - maybe more so as there may be less natural give in the fabric.

Click to expand...

Unless I am missing something here the straps should already have a method to quickly slacken and re-tighten in the form of the securing buckle?

dag019 said:

And if you are worried about the rivets pulling loose, Although not aware of that being a problem you would use nuts and bolts.



Unless I am missing something here the strapsshould already have a method to quickly slacken and re-tighten in the form of the securing buckle?

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@flat - thanks for the photos they help and confirm that the staple placement is too inboard for my liking.

@dag019 - yes, I’d already considered bolts rather than rivets. As to the securing buckle - they are pretty weak, and will hold a strap in place but aren’t much good for pulling against to achieve and maintain tension.

I might be over engineering this, but the bikini top really only has two straps to keep it in place. In addition any wind effects getting underneath are going to exert quite a lot of force on the straps and attachment points.

Speedy6111 said:

@dag019 - yes, I’d already considered bolts rather than rivets. As to the securing buckle - they are pretty weak, and will hold a strap in place but aren’t much good for pulling against to achieve and maintain tension.

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If you are looking for more tension then you can achieve with the standard buckle arrangement I would begin to be worried you will will put more tension into it than the stitching will take. I have in the past managed to pull straps off by over tensioning them with the normal buckle. Especially as the bikini hood is designed to use these staples and the straps will be in line with these. If you move out to the corners the stitching will not be loaded evenly and will be at more risk of failure.

Speedy6111 said:

I might be over engineering this, but the bikini top really only has two straps to keep it in place. In addition any wind effects getting underneath are going to exert quite a lot of force on the straps and attachment points.

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On this point a bikini top is not held on by an less than a full tilt which has had the sides and rear rolled up. I regularly travel around in mine like this if the weather is nice and have never and any issues. For the additional cost it would be it might be worth fitting the standard staples and then deciding if there is any issue?

You genuinely don’t need to tension it as much as that much.

On a defender you have:
- front clamp above windscreen
- front hoop to windscreen tensioning straps
- 3 clips above each door
- the tensioning straps down to the back of the tub

That’s plenty - I have had 3 types of roof (full tilt, bikini and truck cab) and have had them in all weathers and all speeds and not had a problem. I do the straps firmly but not over tight. The stock buckles are definitely strong enough to over tension, my full tilt has a rip where I overtightened it with a stock buckle.....

You definitely don’t need to tension them more than the stock straps and buckles.

Your definitely over thinking and over engineering this.

Just fit it and see how you go, it doesn’t need to be drum skin taught. You will be surprised!

Speedy6111 said:

they are pretty weak, and will hold a strap in place but aren’t much good for pulling against to achieve and maintain tension.

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More than adequate for the job.

Cheers

@flat @neilly - thank you both - comments noted!
I’m waiting for various bits to arrive so I can update early next week when they are here. I’ll get some staples too ;-)

Ok. Marine slide buckles arrived. Here is the first experiment.
The two spare bits of webbing drop down inside the tubes on the tub and are joined at the bottom with a buckle. The buckle is too large to slide up the tubes.



The rest is self explanatory, but I will reiterate that putting the straps toward the corners means they clear the rear benches.

If I do put them in the “official” position nearer the tailgate the rear most bench position is essentially unusable. Deflection at the attachment point on the hood is very minimal so I’m not worried about the stitching there.

Getting a little tension (not too tight!) is very easy with these locking buckles.

Potential problem may be the straps in tubes rubbing. Lots of ways to fix that.

Interesting set up. WRT the hoops on the full tilt I spent some time fitting some anchor nuts to the mounting bolt holes for the hoops to save all the fumbling with a socket up in the body channels. This reduced the time needed to get to the full roof/cab frame stripped state from over an hour to less than half an hour. Well worth the effort.

Sputnik01 said:

Interesting set up. WRT the hoops on the full tilt I spent some time fitting some anchor nuts to the mounting bolt holes for the hoops to save all the fumbling with a socket up in the body channels. This reduced the time needed to get to the full roof/cab frame stripped state from over an hour to less than half an hour. Well worth the effort.

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This is a good tip, I changed all the small
nuts and bolts for thumbscrews or wing nuts on mine for the same reason.

I would worry about the strap wearing where it comes up the tube, maybe look at sleeving it somehow or making something so the strap does come out of the tube in the same way

Or bolt a staple on the tub capping maybe?

flat said:

I would worry about the strap wearing where it comes up the tube,

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Speedy6111 said:

Potential problem may be the straps in tubes rubbing. Lots of ways to fix that.

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I agree with both of these, I would not even test drive it like that as when the strap is flapping in the wind (which it will) the tube edge will very quickly cut through the webbing and your new hood will need repairing. You could try making a plastic or rubber insert which slots into the hood tube and provides and nice rolled edge to protect it.

Is some thing like this suitable.
https://www.ebay.co.uk/itm/Trailer-Parts-Floor-Lashing-Ring-Cleat-44mm-Trailer-Tie-Down-Point/112774924962?hash=item1a41e8caa2:g:VVkAAMXQ56ZR-21A&_sacat=0&_nkw=van+floor+tie+down+points&_from=R40&rt=nc&_trksid=m570.l1313 or this
https://www.ebay.co.uk/itm/8mm-10mm...+bolt+10mm&_from=R40&rt=nc&_trksid=m570.l1313

Thanks all.

Yes, the edge of the tube may be an issue. So far it seems fine. At least the strap that goes through the tube is completely separate from the main hood - it’s just providing a mounting point for the slide buckle. If it does fray unexpectedly I just need 10 inches of webbing to replace it - there will be no damage to the main hood.
I’m not getting much movement on the straps - in part I suspect because I can use the slide buckles to increase the tension enough.

Sputnik01 said:

Interesting set up. WRT the hoops on the full tilt I spent some time fitting some anchor nuts to the mounting bolt holes for the hoops to save all the fumbling with a socket up in the body channels. This reduced the time needed to get to the full roof/cab frame stripped state from over an hour to less than half an hour. Well worth the effort.

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@Sputnik01 - good idea. How did you attach the anchor nut? Rivets?

Similar but different - on the chain plates for the tailgate - there was originally a pin and split pin arrangement to hold the chain to the chain plate. I wanted to be able to remove the chain without removing the plate from the tub, so welded a nut to the plate. Now I can use a high tensile bolt which just unscrews when I want to remove the chain.

Can’t do this for the hoop so interest to know how you secured the anchor nut.

Brief update: I’ve had the bikini on and off a couple of times. Taking it off is 2 mins, putting back perhaps 5. Single handed is fine, quicker with 2. I’m very happy with the ease and flexibility. No rain tests yet though!

No wear at all on the straps that I have attached to the tub (see posts above) however as a precaution I’ve sleeved them with a double layer of bicycle inner tube.

An unexpected side benefit is how nice it is to have a tailgate to sit on. Went out with some friends last weekend for a night drive and we ended up in a field, stargazing and using the truck as a mobile picnic bench.