# E46 m3 underside restoration - primers



## ngy (Mar 12, 2010)

In the middle of getting my m3 sorted and I have fully stripped the underside to take care of any rust, there are some patches which I've stripped with wire wheels and preperstion wheels back to bare metal and then treated with BH deox gel.

I have bought upol acid#8 etch to go over the treated metal and the end game is to use upol raptor tinted to body colour (imola red).

I'm just not sure which primer to go over the etch?


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## The happy goat (Jun 26, 2019)

Do you need one? Acid 8 is a primer


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## ngy (Mar 12, 2010)

The happy goat said:


> Do you need one? Acid 8 is a primer


I thought so as only using it on the areas which I've tabekn back to bare metal. The rest will be keyed and I assumed I'd need a different primer


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## 91davidw (May 6, 2006)

Watch Driftworks as they do a underside restoration on the V10 E46 M3 conversion. 
There's a few vid's on prep but the one linked is what they used mostly Dinitrol products.

Hope this helps?

Cheers 
David


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## mikechesterman (May 25, 2013)

ngy said:


> In the middle of getting my m3 sorted and I have fully stripped the underside to take care of any rust, there are some patches which I've stripped with wire wheels and preperstion wheels back to bare metal and then treated with BH deox gel.
> 
> I have bought upol acid#8 etch to go over the treated metal and the end game is to use upol raptor tinted to body colour (imola red).
> 
> I'm just not sure which primer to go over the etch?


I do this all the time as a restorer and for our "best" level of rust treatment (10 year warranty on it, so its a proven procedure), this is what we do:

Take everything to bare metal

Cut out and replace any metal that requires it

Treat all "pitted" metal with Bilt Hamber Hydrate 80

Coat with a hot zinc gun

(the hot zinc gun is mega expensive and no DIY'er would realistically have it, so Bilt Hamber Electrox is the next best thing that can be sprayed through a regular gun or brushed on)

Coat with Lechler Green TI Primer

Coat with Raptor (either black or tint with body colour)

Finish off with Bilt Hamber Dynax. Use S50 in the hidden cavities and use a solvent to clean it off where it oozes out onto seen surfaces when you don't want it to be seen. Then use UC all over the finished surfaces

Massive fan of Bilt Hamber stuff as it's all lab tested and the results can be viewed by anyone.

From the position you're in, even after using Deox, I'd apply Hydrate 80 where necessary, then coat the whole underside in 2 coats of Electrox (Buy a tin and brush it on, buy it in aerosols or if you want to spray it through a gun don't use normal thinners, use pure Xylene, which I bought off Amazon personally), flat that, then coat the whole underside in a nice thick coat of Lechler Green TI primer, flat that, then on with your Raptor and finish off with a Dynax Treatment (Dinitrol came second in the lab test with Bilt Hamber and I wouldn't have an issue with recommending it, but Bilt Hamber Dynax would always be my first choice).

Then top up the Dynax annually, or as often as you think is necessary.


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## ngy (Mar 12, 2010)

Awesome advice, thanks! 

Is the lechler brush on or spray with a gun?

At what stage should I seam seal? Before the primer?


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## mikechesterman (May 25, 2013)

Lechler will need to go through the gun,

Seam seal after primer, just prior to your Raptor going on.


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