Bonnet fit

[ShaunW]

My fibreglass bonnet fits where it touches and that about it. I suspect many are similar. 

The problem is that it sits very high in the centre, it either rattles or at speed lifts even higher. I don't feel like embarking on a big job at this time of year reshaping the frame etc but was wondering if anyone had any ideas about how to hold it down, for now. It only takes a few pounds of pressure and it sits quite nicely. 

A captive nut on the panel you can see through the vents and a bolt that goes through the vents with a small saddle on it? Don't want to weld a nut on because the paint is visible, is there a fitting that's a nut you can trap in a drilled hole?  Thought about a magnet but I don't think it'll hold. 

And ideas? I wouldn't even mind a nice centre catch being visible. 

[dougbgt6]

I have a metal bonnet and it vibrated in the middle. I put a spare bit of door seal all the way across which stopped it. It packed out the sides and brought the centre down, not sure this will be enough for yours though!

Doug

[Badwolf]

Does your fibreglass bonnet have the two conical rubbers on either side,near the windscreen bulkhead. There should be two receiver plates on either side for them to locare into. My GRP bonnet doen't have the cones.. my steel one does... but needs paint. The GRP is currently packed with 4 rubber pads as a temporary measure....25 years on.

[ShaunW]

It's got the conical rubbers and the outer edges close to the right level. I did try some packing in the middle but it takes an inch or more and just pushes it even more out of line. 

[Pete Lewis]

A nut to fit in a drilled hole..  yes look up rivnut  or rivet nut   

You need a tool to rivet the nut in the hole or some will colapse by using a bolt witha nut on the crush the nut  in place 

Similar to how a pop rivet operates but they are threaded to takena bolt or stud

Many sizes are available

Pete

[ShaunW]

Thx Pete. After a bit more research I could rivet on one of these.... Nut plate 

Is there much under that section of the body directly under the bonnet rear vouvres? Within say about an inch.  Shame there's an even number of vent slots, it'll have to have it about 1/2" off centre lol. 

 

[Pete Lewis]

Could you  fit some bonnet pins so its quick release 

Pete

[Dick Twitchen]

My GRP bonnet did the same and I fitted 2 quick release pins outboard of the bonnet vents.  The pins go through the horizontal part of the bulkhead near where the curve is, adjacent to the clutch master, if that's clear.  Been fine this past decade.  One tip is to remember that the the bonnet describes an arc as it closes so the pin may not be vertical to go through the slotted plate fixed to the bonnet or else make a bigger slot.

Dick

[Colin Lindsay]

Is there much flexibility in your bonnet ie if you undo both side catches does it drop down along the top to where it should, or is this a permanent curve due to the moulding and so keeps the same profile?

 I'd worry that if you try to pull the centre down, the pressure will go elsewhere, resulting in stress cracking or bowing out somewhere else. 

[ShaunW]

Dick, I thought about bonnet pins but with so much flex it could be tricky lining them up. I also don't really want to make a permanent mod to the bonnet for a (hopefully) tempory issue. 

Colin, yes that's a concern but the bonnet is all crazed anyway so I'm not too concerned. Unclipping the catches helps a little but not so much that holding the middle down puts too much outward pressure on them. 

[ShaunW]

Well I've installed my temporary solution and I must say it's worked really well. I thought I had a whole host of rattles but now the bonnet isn't flapping about they've all gone. Great improvement in the general feeling of confidence in the old girl. 

Now.... I'm not saying that my mod would sail through any concourse d'elegance and the stunning work some of you guys do does make me slightly nervous about bringing my work to the show-and-tell but here goes. I'm harbouring a small concern about stress taking its toll on the louvres but it doesn't seem too bad and although the paint looks OK in photos, I'm planning some proper refitting and maybe a blow over next winter so this will do for now. 

The aerodynamically aligned wingnut was best thing I had in the spares dept, maybe a giant clock key would have people guessing about her eco credentials.

If you use the diy plastic, don't forget to oil the cling film otherwise it just sticks to the plastic (D'oh). Good stuff actually, starts as a paste, turns to a putty, then sets rock hard and I've made a few small things with it.

[ShaunW]

hehe I wasn't planning on that bit of clingfilm getting away was I

...I know the form and finish on that saddle isn't very special, but I found it quite difficult to work with. It's like concrete but if you apply enough friction to make any progress, it'll melt.

sorry the pics are so huge but they came straight off my phone. It would look a lot better in a lot worse photo. With hindsight maybe a simple flat plate would look smarter.

[dougbgt6]

Shaun,

Huge pictures are good for myopic eyes! The bigger the belter.  I would be worried about the louvers distorting over time, perhaps a longer plate, or an additional long plate underneath?

Also the ideal base for a bonnet ornament. 

db