Bonnet Hinge Repair

[morebeanz]

I have a repeating problem in that the drivers side bonnet hinge keeps breaking. My indie has repaired the mounting point on the bonnet a few times now with mat and resin, but it is just not strong enough.

Has anyone built a reinforcement or a revised mounting?

[Luckyone]

Yours could be different, but I found my bonnet caught on the body when the bonnet was just at the hight for attaching the stay, if opened any more it just ripped my newly fixed hinges out again. I took the bonnet off & re-shaped the inside lip of the bonnet where it caught. I added a load of new matting behind the area I wanted to reshape then sanded through with a flap disc till I got the shape I needed for clearance, checking I still had enough material on the back as I went, adding more as needed. It's mat black there so just a quick go with a rattle can & it looks just the same.
You achieve the same effect by moving the hinges in the body till it doesn't catch any more, but I found this left a gap that too big for my liking with the bonnet shut.

[FarmyardPants]

Luckyone said:

Yours could be different, but I found my bonnet caught on the body when the bonnet was just at the hight for attaching the stay, if opened any more it just ripped my newly fixed hinges out again. I took the bonnet off & re-shaped the inside lip of the bonnet where it caught. I added a load of new matting behind the area I wanted to reshape then sanded through with a flap disc till I got the shape I needed for clearance, checking I still had enough material on the back as I went, adding more as needed. It's mat black there so just a quick go with a rattle can & it looks just the same.
You achieve the same effect by moving the hinges in the body till it doesn't catch any more, but I found this left a gap that too big for my liking with the bonnet shut.

That's interesting as my bonnet was always a bit high at the nose (a bit proud of the wings) so I went to adjust the hinges and discovered what you just described, that it has to be that way otherwise it catches at the lower front. There's a lot of leverage there and so could easily rip out the hinges. Luckily I noticed it and left it as was (plus the bonnet's been removed/replaced at garages since). I am interested in the idea of grinding some away so I can have the bonnet sit flush.

[morebeanz]

I suspect that this is how the original damage was done, but I have been meticulous in checking how I open the bonnet ever since.

I think that once damaged, the mere application of resin is not enough to repair it.

Is it feasible to completely rebond the mounting points? Preferably with metal reinforcement?

[JensenA]

I repaired mine using a paste made of Fibre glass resin and Baby Powder - no matting at all. Mix enough baby powder just to make the 'paste' thick enough to work with, grind away the area you want the paste to stick to to give it a good key. It's easier with the bonnet off and upside down so the paste stays where you out it.

[Luckyone]

FarmyardPants said:

That's interesting as my bonnet was always a bit high at the nose

Yeah sorry I forgot it was over six years ago I did it, it was the bonnet being to high, not the gap that made me do it. Have a blast yourself, as long as your careful about where you put the bonnet down when you take it off (old carpet or something) you’ll be fine, the area you need to trim is well away from the out side paint work.

morebeanz said:

I suspect that this is how the original damage was done, but I have been meticulous in checking how I open the bonnet ever since.

I think that once damaged, the mere application of resin is not enough to repair it.

Is it feasible to completely rebond the mounting points? Preferably with metal reinforcement?

You can be as meticulous as you like when opening it but it just takes one overzealous MOT man & they are bust again if there isn’t any clearance at the front edge when open.

I just used isopon P40 to re-bond the hinge bolt in place, it has fibreglass matting already in the mix for you to give it a bit of extra strength, it’s been fine for years. Fibre glass resin and Baby Powder sounds good to though. As JensenA says it’s better with the bonnet off, but also because the hinge is far less likely to get moved as the bonding agent is drying. If it does move when drying it will not last five minutes…

If you want an ultra strong solution you’ll need to cut a triangle out of steal plate that fits in the flat area in side the bonnet hinge mounting area (flat once you’ve removed the bonded in hinge that is). Mark & drill a hole in the plate where the hinge bolt goes through, then weld a nut to the back of the plate. Rivet the new plate all round its edge in place inside the bonnet. If you don’t have a welder I’m in Coulsdon Surrey & would be happy to.

[morebeanz]

Thanks for the offer, much appreciated. I will have a look at this despite being nothing like a fabricator, simply on the grounds that it pisses me off that something so simple doesn't jet "work"!

I'll check back in once I've had a go...