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Treating Inside Box Sections


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#1 foreverfixin

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Posted 06 August 2018 - 08:12 PM

I got a complete new floor pan from M-machine in Summer 2017 and have only recently removed it from its packaging. As you guys may know these new floor assemblies come with no protection except for the tunnel which is an e-coated Heritage item. I found a few areas of surface rust which has been removed and I've put some non-porous primer on all round. However, I can't be certain that the inside of the main crossmember isn't rust free but I'm wondering what I can do to overcome any that is in there, little though it may be. So, has anyone else faced this situation and, if so, what have they done? The only thing I can think of so far is to squirt a load of Dynax S80 in there, access being through the various pre-drilled holes. As the floor is not yet in the car I'm thinking that I can get it in the back garden and turn it all ways whilst pumping the stuff in there to ensure complete coverage. The same goes for the two crossmember 'extensions' containing the jacking points to which there's no access as the outer sills are already in place, although I can drill a couple of holes. Any thoughts anyone?

#2 sonikk4

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Posted 06 August 2018 - 08:27 PM

Mmm as its not fitted to the car i would be tempted to force epoxy primer in there and once its hardened some topcoat followed by Dynax or similar.

 

It will be messy but at least with it not fitted to the car you can flip it on its side etc to try and get some semblance of an even coat. I would not rely on the E coat as the basis for any protection at all.



#3 harrythehat

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Posted 07 August 2018 - 06:46 AM

Have been rust treating as a matter of fact whilst rebuilding box sections and any other orifice I can get anti rust into

 

a couple of thoughts come to mind as read threads on whats good and whats not

 

does it really matter what anti rust compound is used?

 

had an old Anglia once total rust bucket with exception to underneath as it had a bad ish oil leak twas like brand new because of this.

 

I use a mixture of engine oil and waxoil, only time it gets messy if used to much oil, or pumped too much in, 



#4 foreverfixin

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Posted 09 August 2018 - 11:21 AM

Thanks for your replies guys. If there is a bit of surface rust inside the crossmember will epoxy primer neutralise it? Or, encapsulate it sufficiently that it won't be a problem later? I can see an oily product doing so but not sure about epoxy. My 'schutz' gun came with a flexible tube with an end fitting that looks like it's meant for spraying inside voids so will give it a go when I finally make up my mind. Yes, I can see it's going to be messy but hey-ho I can't leave it untreated. Years ago I used to use engine oil as an underseal but it stinks for ever so maybe not great for the passenger cabin.

#5 pete l

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Posted 09 August 2018 - 01:17 PM

Paint is the way to go. But I reckon it would need degreasing, derusting, drying, painting and then the box section wax protection.

 

Without paint it won't last long.

 

Without derusting the rust will continue.

 

can you post a pic of it ?

 

Are the ends of the box section open ?



#6 Bat

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Posted 09 August 2018 - 04:07 PM

Hi,

Just a word of warning here, waxoil and probably other similar things will melt and then catch fire when you're welding...

Cheers  :proud:



#7 harrythehat

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Posted 09 August 2018 - 04:55 PM

limited oxygen in box sections  for fire

just have to watch externals and take usual precautions no problems



#8 absx2

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Posted 09 August 2018 - 08:43 PM

I popped the rear seam finishers off the back of my 47 year old mini last week to find NO paint other than a very thin black coating so i`m thinking if it has lasted all this time without rusting paint is not the way to go.

The car is old English white and i have drowned it in oil for the 14 years i have owned it but the 33 year prior to that has done it no harm.

 

I have worked on a few HGV`s this year with a fair amount of rust hiding under epoxy primer. It seems to track along under the paint the same as powder coated parts suffer from.

Hopefully bad prep as the vehicles are in constant use so are not in the shop for long. 



#9 bluedragon

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Posted 10 August 2018 - 07:24 AM

That's correct, epoxy primer will not neutralize or render rust inert. The most it can do is delay corrosion by blocking it from exposure to oxygen, but it won't last. Epoxy needs to be applied over rust free surfaces for longevity.

 

In the USA there is Eastwood Internal Frame Coating. https://www.eastwood...oz-aerosol.html

 

This product is useful and has some rust neutralizing properties, though I still wouldn't depend on it if the box section had heavy corrosion. It would work well on something that was just installed and had flash/surface corrosion though from limited post-install exposure to ambient humidity.

 

Dave


Edited by bluedragon, 10 August 2018 - 07:25 AM.


#10 pete l

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Posted 10 August 2018 - 01:51 PM

I popped the rear seam finishers off the back of my 47 year old mini last week to find NO paint other than a very thin black coating so i`m thinking if it has lasted all this time without rusting paint is not the way to go.

The car is old English white and i have drowned it in oil for the 14 years i have owned it but the 33 year prior to that has done it no harm.

 

I have worked on a few HGV`s this year with a fair amount of rust hiding under epoxy primer. It seems to track along under the paint the same as powder coated parts suffer from.

Hopefully bad prep as the vehicles are in constant use so are not in the shop for long. 

 

Hard to imagine a 33 year old mini on original sills, unless you live in sunny california.



#11 absx2

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Posted 10 August 2018 - 03:20 PM

 

I popped the rear seam finishers off the back of my 47 year old mini last week to find NO paint other than a very thin black coating so i`m thinking if it has lasted all this time without rusting paint is not the way to go.

The car is old English white and i have drowned it in oil for the 14 years i have owned it but the 33 year prior to that has done it no harm.

 

I have worked on a few HGV`s this year with a fair amount of rust hiding under epoxy primer. It seems to track along under the paint the same as powder coated parts suffer from.

Hopefully bad prep as the vehicles are in constant use so are not in the shop for long. 

 

Hard to imagine a 33 year old mini on original sills, unless you live in sunny california.

 

 

No Pete, the rear body seam finishers not the sills. Original inner sills and floor pans by the way :)



#12 foreverfixin

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Posted 13 August 2018 - 09:48 PM

Right, after considering all the comments I have decided to cut an access in the top of the crossmember midway between the sill and the tunnel on both sides of the floor so that I can see inside. Then I will be able to get my arm in to degrease, remove any surface rust if required and paint out with epoxy. Then I'll weld the cut outs back in and touch up the paint through the existing holes. That will just leave the two cavities containing the jacking points to deal with for which I haven't yet devised a plan but will work something out I'm sure. All this being before installing the floor assembly in the car, after which I can pump in some Dynax. I did see that another forum contributor had his floor delivered with the crossmember only tacked in position but by then it was too late for me!

 

43971911822_81334c3472_z.jpg



#13 Bat

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Posted 14 August 2018 - 07:24 AM

That's correct, epoxy primer will not neutralize or render rust inert. The most it can do is delay corrosion by blocking it from exposure to oxygen, but it won't last. Epoxy needs to be applied over rust free surfaces for longevity.

 

In the USA there is Eastwood Internal Frame Coating. https://www.eastwood...oz-aerosol.html

 

This product is useful and has some rust neutralizing properties, though I still wouldn't depend on it if the box section had heavy corrosion. It would work well on something that was just installed and had flash/surface corrosion though from limited post-install exposure to ambient humidity.

 

Dave

Hi,

This may be available from frost restoration in the UK, they carry a range of Eastwood products.

Cheers  :proud:



#14 Verderad

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Posted 14 August 2018 - 08:57 PM

Would probably be a better job to drill out the spots holding the cross member in place. That way you can paint all of the inside and the floor.
Easier to finish than welding back in the holes cut in the top that will burn off some of the paint.

#15 foreverfixin

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Posted 14 August 2018 - 09:41 PM

Removing the crossmember by drilling out the spot welds is a good idea but it's only spot welded to the horizontal part of the floor. Elsewhere, i.e. the sloping parts of the floor, vertical inner sills and around the tunnel it has been seam welded. This would make it extremely difficult to remove without doing 'collateral' damage.

How about leaving a margin around the access holes and covering with overlapping plates bolted or fixed with self-tapping screws? This would avoid burning off the paint, but would there be unacceptable reduction in structural integrity?




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