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Author: Subject: Protecting two painted surfaces bolted together
jps

posted on 27/10/20 at 01:40 PM Reply With Quote
Protecting two painted surfaces bolted together

Interested to know what best practice is for this. For example, my roll hoop is bolt on so the feet of the main bar are flat plate against the flat plate of the shock turret, and my seat subframes contact points are flat plate bolted to flat plate. Everything will be painted.

What, if anything, should I put between the mating surfaces to a) protect the paint and b) avoid any issues with corrosion?

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tims31

posted on 27/10/20 at 01:47 PM Reply With Quote
A thin film of vaseline/Petrolium jelly does the trick.





Build: http://www.martinsfurybuild.co.uk/

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cliftyhanger

posted on 27/10/20 at 02:07 PM Reply With Quote
I use a waxoil type product. Squeezes out but should provide protection
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nick205

posted on 27/10/20 at 02:50 PM Reply With Quote
Either of the above sound fine to me. Personally if the paint is well applied and well cured on both surfaces I've not bothered applying anything else myself.
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jps

posted on 27/10/20 at 04:59 PM Reply With Quote
Thanks for everyones responses, I did think "not needed" was likely a valid response. In some places i've used what I think will transpire to be a reasonably soft, even when fully cured, gloss type for some parts, so expect they could do with something to stop them sticking to one another.

quote:
Originally posted by tims31
A thin film of vaseline/Petrolium jelly does the trick.

I'll give this a go - saves buying another product!

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Charlie_Zetec

posted on 27/10/20 at 06:06 PM Reply With Quote
Anyone who has owned/worked on a Land Rover Defender will understand the galvanic (bimetal) corrosion that happens between steel and ali panels; often the floor and tub reinforcing bars that react with the floor pan itself, and also the chassis/seatbelt mounts and bodywork.

As has already been stated - if each individual parts are painted before assembly, there should be no issue (but a smear of vaseline works well) so all fine. Land Rover unfortunately assembled the car before spraying it, so not ideal. I improved on this, and painted before assembly.

In areas where there was likely to be contact, I used a thin plastic packer/spacer (actually made from a set of cheap aftermarket mud flaps), rubber/nylon washer, or where there was only a small tolerance on movement, a thin (1mm thick) piece of sticky-back closed cell foam (bought as a sheet off eBay).





Artificial intelligence is no match for natural stupidity!

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jacko

posted on 27/10/20 at 06:19 PM Reply With Quote
When I built truck body’s we used to put plastic sheeting between aluminium and steel parts to stop corrosion
Jacko

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tims31

posted on 27/10/20 at 09:10 PM Reply With Quote
quote:
Originally posted by tims31
A thin film of vaseline/Petrolium jelly does the trick.


This also works well on the mounting face of an Alloy wheel to a steel hub to prevent corrosion and the wheel sticking to the hub





Build: http://www.martinsfurybuild.co.uk/

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MikeR

posted on 28/10/20 at 11:12 AM Reply With Quote
Can I be controversial - i thought bolts pulled two faces together and friction generated is supposed to stop them moving, not the bolt.

I get for some areas that aren't critical its a good idea, but for the roll bar hoop or wheel do you really want to stop the friction?

Now waiting for someone to prove me wrong (especially with wheels as my tin top rears were a right bugger to get off earlier in the summer)

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craig1410

posted on 28/10/20 at 01:54 PM Reply With Quote
In my experience it's usually the spigot rings which cause alloy wheels to stick to the hub, not the faces themselves. I personally wouldn't recommend using any grease on the faces but would recommend a light smear on the spigot ring after cleaning off any old grease and crud. Also a light smear on the spigot socket on the wheel will help stop alloy corrosion. The faces should be very clean to ensure an even mount so just give them a scrape or wire brush and clean with a cloth. The last thing you want is any grease being centrifuged onto the brake discs.

On a related point, I have recently stopped using copper grease on my wheel bolts even though this is very common practice. However, if any of the bolts show signs of rust I will clean them with a wire brush then apply a very light amount of oil to the threads before cleaning as much of that oil back off again as possible using a cloth squeezed around the bolt and then rotating the bolt a few turns. The days of brushing a big dollop of copper grease onto the bolts is gone for me.

Lastly, I would recommend using silicone grease in many of the situations where many of us would tend to use copper grease. As some of you will be aware, copper grease is not actually "grease" but is more accurately described as anti-seize compound. It also tends to be hostile to rubber and will cause it to deteriorate. Silicone grease on the other hand actually protects and lubricates rubber components and is also electrically non conductive. It's particularly recommended for brake calliper sliders but I also use it on my wheel spigots because it is really good at preventing the corrosion which causes wheels to stick. Here is the stuff I bought: https://www.amazon.co.uk/gp/product/B01M9GVQ8F

Cheers,
Craig.

[Edited on 28/10/2020 by craig1410]

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CosKev3

posted on 28/10/20 at 03:24 PM Reply With Quote
quote:
Originally posted by jps
Interested to know what best practice is for this. For example, my roll hoop is bolt on so the feet of the main bar are flat plate against the flat plate of the shock turret, and my seat subframes contact points are flat plate bolted to flat plate. Everything will be painted.

What, if anything, should I put between the mating surfaces to a) protect the paint and b) avoid any issues with corrosion?


I would use a very thin smear of silicone/instant gasket type sealer on this myself.

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Dingz

posted on 28/10/20 at 07:59 PM Reply With Quote
Ironically though the only time you should not use silicone grease is on silicone rubbers.





Phoned the local ramblers club today, but the bloke who answered just
went on and on.

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