Bonnet Panel Gaskets

[Leekade]

I’m in the final throes of putting my car back together after a bare metal respray. I’m wanting to put a rubber gasket between the centre bonnet panel and both wings to prevent the potential metal on metal rubbing (I know I’m going to have to do both edges, or parts of, due to the chrome finisher which run down to the headlights).

Has anyone else done this and can you recommend a specific product?

Thanks

Adrian

[Geoff Allam]

Why not just use thick rubber washers instead of the special thick steel washers where the bolts go through. Much simpler and same result. Not that there would be any rubbing of the flanges once the bolts were properly tightened anyways. A good heavy coat of epoxy primer followed by topcoat should be more than sufficient.

[johnetype]

I used nylon washers when I reassembled my bonnet for the same reason and they work well.

Rubber washers will allow too much flex.

[abowie]

Bad idea; you will just get rust in there and you won't be able to fit the chrome trim.

The panels are separated by 3mm thick washers which should be painted. This prevents water pooling in there.

[265bhp]

+1 for nylon washers....seemed obvious to me..less material to be subject to rust

[christopher storey]

I am not keen on the idea of nylon washers, because I feel they may be too malleable/compressible, and will allow the nuts and bolts which secure the wings to the centre section to loosen over time . If you do use them, then I suggest a regular spanner check of at least a representative sample of the fastenings

[Leekade]

Many thanks everyone, I’ll have a little rethink as to what solution I employ.

Cheers

Adrian

[bitsobrits]

I am not keen on the idea of nylon washers, because I feel they may be too malleable/compressible, and will allow the nuts and bolts which secure the wings to the centre section to loosen over time . If you do use them, then I suggest a regular spanner check of at least a representative sample of the fastenings

I wouldn't be worried about this at all in this specific application. In the early part of my career, I worked as a design engineer for a company that produced production machinery for a variety of industries. Nylon was frequently used in the food industries as a semi- structural component and a bearing material in many applications as it has similar properties to basic aluminum, including compressive strength, without the corrosion worries. There are of course different grades of nylon, but even the most basic have a compressive strength of 40-50 MPa, which is harder than the softer grades of aluminum which are close to 30 MPa.

[Series1 Stu]

I can't agree with that comment.

Even the weakest aluminium has a tensile strength of 130 MPa whereas a polyamide (say, Nylon) would have something like 40 MPa tensile strength. Compressive strength is not commonly quoted as it is generally a given that materials are stronger in compression than in tension.

Worse than this though is nylon's propensity to creep under load, so it will change shape and a washer under compression will get thinner in time and therefore reduce the holding load of the joint. Okay, so all materials theoretically will creep under load but metals not to such an extent as plastics materials.

When you change the nylon bushes in your dash panel or all those ones in the 3.8 Kelsey Hayes brake set-up you will see that they have not so much worn as they have deformed under load.

You might get away with nylon spacers but I wouldn't risk it with the thought of having to take it all apart and start again.

Regards