Attaching GRP bodywork [Archive]

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voucht

10th July 2014, 12:13 PM

Hi,

2 questions:

1 - I fitted the nose cone but have only 4 attach points:

2 M6 bolts going through FF1 and the lower back face of the nose cone

https://farm4.staticflickr.com/3898/14432750477_0ea70c9756.jpg (https://www.flickr.com/photos/99498333@N06/14432750477/)
2014-07-09_08-43-14 (https://www.flickr.com/photos/99498333@N06/14432750477/) par Voucht71 (https://www.flickr.com/people/99498333@N06/), sur Flickr

2 M6 studs in TR1/TR2, at the rear end the side faces.
https://farm4.staticflickr.com/3862/14617058334_7bb762c8a3.jpg (https://www.flickr.com/photos/99498333@N06/14617058334/)
2014-07-10_12-14-06 (https://www.flickr.com/photos/99498333@N06/14617058334/) par Voucht71 (https://www.flickr.com/people/99498333@N06/), sur Flickr

Is that enough? The problem is I can't find any other attach points without having to go through the GRP where it will be visible, which I absolutely want to avoid. I could add 2 more points at the front par of the side faces (about 200mm in front of the studs), but I will no be able to access the bolt with the air filter and its conducts fitted.
What do you think?

2 - Are rivnuts acceptable on GRP? I made a try on a piece of GRP with a M5 steel rivnut (7mm out. Diam.), and nothing cracked when I crimped it.

https://farm3.staticflickr.com/2927/14432531618_ecf5a94878.jpg (https://www.flickr.com/photos/99498333@N06/14432531618/)
2014-07-10_12-24-21 (https://www.flickr.com/photos/99498333@N06/14432531618/) par Voucht71 (https://www.flickr.com/people/99498333@N06/), sur Flickr

But I don't know if it is solid enough. I'd like to attach the bulkhead panel to the scuttle with rivnuts inserted in the scuttle edge, so I won't need to remove the dashboard of I need to separate the bulkhead panel from the scuttle. I've plan 11 attach points.

https://farm6.staticflickr.com/5577/14618621982_11efe150ec.jpg (https://www.flickr.com/photos/99498333@N06/14618621982/)
2014-07-10_11-58-11 (https://www.flickr.com/photos/99498333@N06/14618621982/) par Voucht71 (https://www.flickr.com/people/99498333@N06/), sur Flickr

There will be almost no constraints on these points, as the horizontal face of the bulkhead panel is attached to the chassis, and so is the scuttle. However, the bulkhead panel supports quite a bit of weight: the expansion tank, the original big Sierra fuse and relay box and the ECU are attach to it.

Is this acceptable to your mind?

Thanks a lot.

flyerncle

10th July 2014, 01:22 PM

Try using thin sheet rivnuts in small diameter as they have a thick flange,you could drill the panels the same dia as the flange head and this would possibly be level with the top of the panel depending on thickness.

You might want to place a bit of thin ally behind them in f/glass.

SeriesLandy

10th July 2014, 01:30 PM

I used rivnuts around the scuttle lip for the bulkhead and I have the same fixings for the nose as you so I don't see it being a problem.
Hth

voucht

10th July 2014, 01:50 PM

Thanks for the answer.
do you mean rivnuts like this one:
https://farm3.staticflickr.com/2897/14596614966_a1c72db44a_z.jpg (https://www.flickr.com/photos/99498333@N06/14596614966/)
IMG_0188 (https://www.flickr.com/photos/99498333@N06/14596614966/) par Voucht71 (https://www.flickr.com/people/99498333@N06/), sur Flickr

https://farm6.staticflickr.com/5542/14596615176_fc3ccc5921_z.jpg (https://www.flickr.com/photos/99498333@N06/14596615176/)
IMG_0189 (https://www.flickr.com/photos/99498333@N06/14596615176/) par Voucht71 (https://www.flickr.com/people/99498333@N06/), sur Flickr

The ones I have are in aluminium. Do you think it is better than the countersunk steel ones I published in the first post? If you do, I'll have a go with them.

Thank you :)

SeriesLandy

10th July 2014, 06:16 PM

voucht

10th July 2014, 08:39 PM

Sorry for the short reply earlier, I was queuing for some food at a show. I used aluminium ones on all of my car as they are easier to set than the stainless ones.
If you look carefully along the top edge of the bulkhead you can see how many fixings I put in, they went straight into rivnuts on the scuttle lip. These rivnuts were put straight into the grp and I haven't had any problems yet (only done 100miles).

I also ended up using m6 stainless hex head bolts as its much easier to get a spanner into most places than an allen key.

Thank you Steve. No need to apology, your first reply has been actually very useful. It confirmed me that putting rivnuts on GRP was not a completely silly idea, as I was doubting :)

So this afternoon, I finished the work. I was planning to use the ally rivnuts as Paul suggested too, but I had only 5 left, so I finally used my plated steel countersunk ones. And it looks to be working pretty well.

https://farm4.staticflickr.com/3861/14621742762_6215151ecf_z.jpg (https://www.flickr.com/photos/99498333@N06/14621742762/)
IMG_0204 (https://www.flickr.com/photos/99498333@N06/14621742762/) par Voucht71 (https://www.flickr.com/people/99498333@N06/), sur Flickr

https://farm6.staticflickr.com/5509/14435637578_c8811aeb2e_z.jpg (https://www.flickr.com/photos/99498333@N06/14435637578/)
IMG_0206 (https://www.flickr.com/photos/99498333@N06/14435637578/) par Voucht71 (https://www.flickr.com/people/99498333@N06/), sur Flickr

I also prefer using hex head bolts, but when they are visible, I prefer the dome head bolts because they are better looking, even if, as you say, they are much less easy to handle because of the allen key.

So now, the 2 side panels are on, as well as the scuttle, bulkhead and nose cone. I hope I can finish the rear tube tomorrow, and perhaps the rear arches this week-end!

Thank you very much for the help.

SeriesLandy

10th July 2014, 10:39 PM

For the hex bolts I meant, scuttle to top rail, nose cone to top rail, bottom of the side panels to the chassis and inside the arches.
Any bits that would be seen like side panels to top rail I used countersunk stainless Allen bolts.