Mitchelkitman,

Just to put you out of your misery, Jeremy got back to me about that screen, (as I knew he would!)

And it was around 6 inches too wide, or 150mm, if you prefer.

I know DaveCymru has used them with fibreglass on his Countach build.

So maybe drop him a PM if he doesn't see your request for info.

See here:
http://www.madabout-kitcars.com/foru...vnut#post38282

Cheers, Paul. :)

Thanks Paul I'll do that

I would be very wary of using rivnuts on GRP, I should imagine they would be one of the best ways to start spider cracks. I always used bonded on fastners to spread the load rather than focus them

<warning - waffle ahead!!>

Rivnuts..... ahhh, wonderful things. I'm always amazed i managed to build my Sammio without them! That said! I have tried to use them in all sorts of situations over the past year or so on the Countach, so i can give you a few examples of how they work "in reality".

I've mainly used aluminium rivnuts as I've not had much need to fit anything onto steel and i was warned at the start not to mix dissimilar metals. But i have used one or two steel ones in steel tubing and they are a lot more permanent than the alloy ones and a lot harder to squeeze!

The aluminium ones i have used a lot in alloy sheet and alloy box to mount panels, i.e. inside my front luggage area and they work a treat. Although you have to remember that as they are aluminium they are quite soft and I've noticed with panels that i take on and off a lot (at least the brakes are now fixed!) they can loose their thread and i have had to replace a few already.

As PaulL said I have also used them in fibreglass, primarily to hold my rear air intakes in place as well as a few other bits-n-bobs.
While the fibreglass in that area is a good few mm thick (6 to 8mm) and non-visible what i found was while they are good to attach panels, if they are removed/refitted just a few times then it is the rivnut that comes loose in the fibreglass.
I have now had to bond a few in place to stop this and this behaviour seems to be quite common when squished (technical term!) as they can quite easily eat up the surrounding fibreglass. Although it's worth mentioning that there is no starring or cracking in those areas after a good year of being in place!


But you piqued my interest about thin fibreglass so i just popped to the garage and had a quick test. :)

I found a bit of 4mm fibreglass (that looks remarkably Sammio grill shaped!) and fixed a 7x12mm rivnut into it to see what would happen!

http://i49.photobucket.com/albums/f2...psb94152da.jpg

i didn't have to squeeze too much to get a very firm fixing and on the front side it looks fine with no cracking

http://i49.photobucket.com/albums/f2...pse6dad9c4.jpg

On the rear side it also looked really good and you can see that it doesn't have to expand massively in order to get good purchase. I also couldn't see any sign of cracking when i was in the garage.

Although.... when i came down and was uploading the pics you can clearly see on this one that the backside is stressed (i really regret writing that on this forum! :) )

http://i49.photobucket.com/albums/f2...ps3e4621ce.jpg

That seems to show some stress around the rivnut, but seeing as it's only been in place a few mins i've no idea how that would develop over time? TBH i'd not want to mount anything heavy on it!

Best of luck with whatever you do, just post pics so that we can all have a good ponder (and steal any ideas that work! :) )

Dave

I think the minute that gets any stress applied (vibrations etc) there will be star cracks. Look at the damage stones cause when hitting the underside of wings etc.

They are a very neat solution though. I used steel ones as part of a roof rack project I developed and I elt like Popeye by the end of it! they are hard work!

I used several on the GRP caravan I built, and they have worked well. I didn't buy a setting tool - If you do a search on the net there are instructions on making a simple tool from strip of steel and nuts. I'd recommend if fitting more than 50 it would be worth investing in a tool though (one like a pop-rivet gun)

I used 'well nuts' to secure my flyscreen to the body.

http://www.ebay.co.uk/itm/WindScreen...item48444875b5

As they're rubber they absorb vibration so I'd suggest they might be worth considering as a long term solution for fixing things in a fibreglass body.

They've been in place for the 1,500 miles I've done in my Spyder this year (so far) with no problems.

Just a thought (I haven't tried this) but if the hole in the panel were drilled slightly oversize and the rivnut set on to a thin washer on the back it would alleviate the stress on the GRP and act as a captive nut? (Obviously you'd need access to both front and back of the skin so wouldn't work in a blind situation) Next time I'm looking for a removable panel solution I'll try it and report back.

I have used these on numerous race cars of mine over the years and to be honest now avoid them if possible. My experience is that the first time you need to undo a fastener in a rivnut one of two things will happen
A. The fastener will be seized solid into it
B. the rivnut will merrily spin in its hole

If i have to use them now i always use PU adhesive as well as setting them with the tool. I also use a scrap of ali as a backer when using them in GRP or the like. I also copaslip all fasteners before inserting them in a rivnut and rely on a plain washer us a spring washer to make sure they don't come loose.

The well nits towed used are good for GRP and the like and are easily available from most motorcycle and scooter shops as they use them a lot in the GRP and plastic fairings.

You may also want to investigate Dzus fasteners as they do a vast and varied range commonly used on race cars for quick removal panels.
HTH

Mac

AndyP57
Thanks for your input. It gives me more to consider.

Viatron

I'm glad I can benefit from your experience.

I only wanted to use rivnuts to secure the wind screen ( mounted in a steel frame), and the heat shield on the sill.

As Dave cymru said, the heat shield would most likely be okay, as its all in stainless steel it may never ever need to come off.

But the wind screen, hmmm, I am now leaning towards well nuts like Towed used.

I'm not at that stage yet, but as always I am trying to plan ahead .

I used the rubber (well?) type nuts once and the panel quickly came loose. They work like a rawlplug in that they expand a little when the screw is tightened? I'd certainly NOT use them for anything heavy.

Another solution would be to use Anchor nuts like these:

http://i1360.photobucket.com/albums/...psf6833803.jpg

floating:
http://i1360.photobucket.com/albums/...ps09cb30c3.jpg

or fixed:
http://i1360.photobucket.com/albums/...psc2824b3c.jpg

Viatron's comment reminded me that the original builder of my Countach had used wellnuts for an access panel in my front luggage area and when i came to unscrew it a few months ago they either just turned in their holes or fell apart as the rubber had perished over time.

Admittedly they must have been in place for at least 10 years and more likely 15, so not an immediate problem for you, but worth mentioning :)

First of all I would like to thank all you fella’s that gave me good advice on the rivnuts / well nuts issue.

It looks like Mr Towed was the only satisfied customer!

I paid a visit to my local motor bike workshop as instructed, where I think the old boy there, used to build bikes for King Henry the VIII, and he would not touch well nuts with a barge pole, which surprised me.

The outcome of all this is, that I am sure that rivnuts and well nuts have their uses, But one of them is NOT fitting Scottie’s windscreen on!

( N.B It’s much bigger and heavier than Mr T’s.)

Access to the place where the screen needs to fit the car body is very limited,
But even if I have to cut individual access holes for each ‘king nut, I will bolt the screen on with stainless steel bolts and nuts in the conventional way.

Today was so cold; I sat inside by the wood burner!

But I became so hot and bored that the ice cold concrete floor in the tent began to look attractive, so off I went for a while.

When I finished for the day, the ex soldier’s steel helmet looked more at home On the Jaguar than it would have on the battle field, so I was satisfied.
Here are some pics to illustrate that point:

[IMG]http://i928.photobucket.com/albums/a...psb52d3fd0.jpg[/IMG]
[IMG]http://i928.photobucket.com/albums/a...ps83aaae18.jpg[/IMG]
[IMG]http://i928.photobucket.com/albums/a...ps232f8e3f.jpg[/IMG]
[IMG]http://i928.photobucket.com/albums/a...pse7e02dc4.jpg[/IMG]
[IMG]http://i928.photobucket.com/albums/a...psd3fa1eab.jpg[/IMG]

What more does a man need?

Do you have access to the back of the panel that your windscreen will attach to before you actually fit the body to the car?

If so it might be worth bonding a strip of metal across the width of the screen with a series of nuts welded to if at measured intervals.

This will both add rigidity and give you a series of solid metal bolt points at known intervals. It might be a pain to do it but you will only do it once rather than trying to replace broken fixings in the future.

I had considered that WCA, although he body is not bonded on yet, I a REALLY reluctant to take it off again, and will most likely go the route I wrote of earlier.
Why can't you use stick on plates on your car??

I can but they are not road legal...

...except sometimes they might be.

It seems to depend on which copper pulls you over. As they bring in more cameras and auto recognition software the more likely they are to nick you as they cannot apply common sense.

Mmmm, I take your point, Financially better off within the law for sure!