4 Bonnet

[John h]

Hi to all purchased this bonnet off eBay few weeks ago in the description said sand blasting damage anyway once I got it home far more damage, than I thought if you look at the pictures is an area at the back of the bonnet just off from the brace the bonnet is apparently what they call oil canning have made a start on this area, trying to heat shrink it and it seems to be working. Just thought I’d post some pictures and see if anyone can offer any help or suggestions.

[Drewmotty]

I assume that you’re using a naked flame to heat the panel? A shrinking disc may be more controllable. 
I’ve never used one but I’ve heard good reports from those who have. 

[John h]

Thanks Drewmotty I have seen them on YouTube being used and you’re definitely right being more controllable I think they sell them on Amazon will look into what they cost. Will post results little bit later. Don’t seem to have the time that I used to have to work on the car unfortunately so may well be a few weeks I do have another bonnet, but the front is all rusted out really bad, I did toy with the idea of cutting this bonnet and just replace the damaged area I think that’s what I’ll do if I’m not pleased with the results on this bonnet 

[stillp]

Whichever you use, don't forget to reinforce the rear corners.

Pete

[John h]

You’ll notice on the blue one, the corners are already bent up a little bit, but that is a good shout. It’s something I hadn’t thought of like I said I will keep updating from time to time let you know how it’s going looked up a shrinking disk online just under £40 for a 4 1/2 inch so very reasonable

[stuart]

5 hours ago, John h said:

You’ll notice on the blue one, the corners are already bent up a little bit, but that is a good shout. It’s something I hadn’t thought of like I said I will keep updating from time to time let you know how it’s going looked up a shrinking disk online just under £40 for a 4 1/2 inch so very reasonable

TBH the bigger 7" version on a polishing mop at the slow 800rpm speed works better.

Stuart.

[Malbaby]

Unfortunately you have a lot of work to do on the bonnet to get it half reasonable again.

As others have suggested, a heat shrinking disc works well.

Before you start the heat process on the top surface, I suggest you reinforce the bonnet as much as you can....Even a jig is worth considering.

You need to keep the bonnet from twisting due to the intended heat repair process...Hopefully the previous over zealous media blasting has not deformed the overall integrity and shape of the bonnet.

This is what I did on a good bonnet.

Plug welded reinforcing strips of 3mm metal along the inside of the outer side edges for almost the complete length...This also negates the common rear bending that occurs due to XS pressure applied when closing the bonnet

Likewise right angled strips at the rear corners.

Also triangulated plates where the front main support meets the side edges.

Plus some other minor reinforcing.

 

12 hours ago, stillp said:

 

 

 

Edited May 21, 2023 by Malbaby

[stuart]

12 hours ago, Malbaby said:

Unfortunately you have a lot of work to do on the bonnet to get it half reasonable again.

As others have suggested, a heat shrinking disc works well.

Before you start the heat process on the top surface, I suggest you reinforce the bonnet as much as you can....Even a jig is worth considering.

You need to keep the bonnet from twisting due to the intended heat repair process...Hopefully the previous over zealous media blasting has not deformed the overall integrity and shape of the bonnet.

This is what I did on a good bonnet.

Plug welded reinforcing strips of 3mm metal along the inside of the outer side edges for almost the complete length...This also negates the common rear bending that occurs due to XS pressure applied when closing the bonnet

Likewise right angled strips at the rear corners.

Also triangulated plates where the front main support meets the side edges.

Plus some other minor reinforcing.

 

 

That wont help when the skin is stretched which is what happens in over zealous blasting Im afraid. I had hells own job to straighten one that that had happened to several years ago.

Stuart.

 

[John h]

They look virtually the same 

[stuart]

48 minutes ago, John h said:

They look virtually the same 

Just two pictures taken at the same time from each end but you can see how the skin had been blasted down onto the frame. It took a lot of work with a shrinking disc and some tapping to get it to look like this.

Stuart.

 

[John h]

No pressure then

[Malbaby]

Good luck.....keep us informed on your progress.

[John h]

Hi all has anybody any suggestions for a supplier of one of the shrinking discs in this country all seem to be from America and obviously a long wait any suggestions please kind regards, Jon

[stuart]

37 minutes ago, John h said:

Hi all has anybody any suggestions for a supplier of one of the shrinking discs in this country all seem to be from America and obviously a long wait any suggestions please kind regards, Jon

Unfortunately thats where I got mine from as well, couldnt find anyone over here to supply.

Stuart.

[Chilliman]

15 minutes ago, stuart said:

Unfortunately thats where I got mine from as well, couldnt find anyone over here to supply.

Yup, same here.

[John h]

Looks like a long wait then ill get on it

[boxofbits]

You don’t need to go to the States. I bought one from Stakesy’s Metalwork Machinery based in Loughborough UK.

This is only a 115mm, but they do various I believe including other metalwork tools, and price is reasonable with good warranty.

**just to add I couldn’t see a 9” disc on their site but they might supply it if asked I don’t know. The equipment/logo looks American anyway. Worth asking.

Kevin

 

 

 

 

 

Edited May 23, 2023 by boxofbits

[John h]

Hi to all I got in touch with Stakesys looked on the website and they had a 4 1/2 inch one there would’ve come in at just under £50 with postage so of decided to give them a call. We are really helpful. They had a 9 inch one available just under £70 with the postage. Hopefully coming today. All I Gotta do then is learn how to use it. So thank you. Kevin forgiven me the heads up on that one. I will post results good or bad

[John h]

Hi to all as promised, here are a couple of pictures just had ago with that shrinker I can’t believe the results I’ve got in just a couple of hours obviously still need a little bit of work with hammer and dolly but I think the oil canning has gone still lots more to do think it will keep me busy for quite some time. Will post pictures as it progresses one way or another 

[stuart]

Well done, take your time and you`ll get there.

Stuart.

[Malbaby]

It's not too late to do the bonnet edge and corner strengthening. 

[Besalu]

Malbaby, do you have any pics of the jig/strengthening set up you mention by any chance?

Stuart, as an alternative to blasting (risk of warping) would you suggest another method of getting back to the bare metal? Such as paint remover/dipping or using an orbital sander?

Richard

[james christie]

There is a softer technique used over here in France called ‘Aerogommage’. No idea what this is called in English-maybe Sodablasting?

Obviously derived from sandblasting it uses low air pressure with a choice of various abrasive materials. Often used for cleaning up wood such as antique furniture, boats etc. which gives an idea of the lack of aggression.

The results were pretty spectacular on a TR3

james

 

[Motorsport Mickey]

Yes, soda blasting is good for paint removal down to metal, but is not aggressive enough where metal is rusted...and leaves it to grow under freshly painted surfaces...shame almost everywhere on a TR.

Also what about where even shot blasting can't get in ? the overlap seams of panels especially on their edges.

Mick Richards

[stuart]

5 hours ago, Besalu said:

Malbaby, do you have any pics of the jig/strengthening set up you mention by any chance?

Stuart, as an alternative to blasting (risk of warping) would you suggest another method of getting back to the bare metal? Such as paint remover/dipping or using an orbital sander?

Richard

I use hot air gun to strip paint first though be careful in the middle of the bonnet as too much heat wont help with warping then DA and small rotary pointed wire brush to get into corners underneath. I have had to remove the frame internally before now on a very rusted panel, though thats an extreme measure. If its not too bad behind the frame then Jenolite poured in and sloshed around will kill the rust then pour bondarust in after.

Stuart.