How to protect your new subframe from rust?

[Bodgeroo]

Hi all so my new subframe has arrived from Mr T. But I can see it will rust in weeks without some further protection. Thoughts of powder coating as a expensive option £80 , hammerite on the outside and waxoil on the inside or POR15? Do I need to bear in mind the proximity to a hot exhaust when choosing the paint/rust protection.

What did you do and has it worked?

[1979scotte]

Dynatrol is it that has been recomended by some.
Waxoil also but i found with my turbo that it got so hot it all melted.

[Ardent]

Dynax S50 another good option for the inside.
Hammerite for the outside

[1979scotte]

Dynax S50 another good option for the inside.
Hammerite for the outside

Thats probably what i was thinking of.

[cptspaulding]

Dinitrol inside & Rustbuster epoxy mastic 121 on the outside.
The latter won Classic Car magazine best that protection product a couple of years back.

Sent from my KFGIWI using Tapatalk

[Bodgeroo]

Rust buster epoxy mastic 121 seems the real deal having just googled it. Very tempted with this for the outside. I know waxoil works but not when it's near an exhaust, as scotte says it will probably melt out. I suspect dynax s50 will do the same. I have some acf50 but I don't think this is fit for the job, perhaps too thin.

[Bossworld]

I've done two coats of black Hammerstein smooth on the outside. Was a bit difficult to see where I was painting first time out admittedly lol.

I also used some spray cavity wax from Toolstation, was about £4 for the can. Guess we'll have to see if it just melts back out but it forms a plasticine like layer. Used it on top of the hammerite for good luck as well

[Ardent]

I suspect dynax s50 will do the same.

Can confirm no issues with the S50. Plus I running with some extra heat from the turbo.

[lamcote]

What do people think about drilling a couple of holes in the bottom at the two lowest points of the subframe allowing any water that may collect inside to drain out?

[Ardent]

Thought the same thing. But bottled it.

[JoeCool]

I did this:



I think this subframe looks sexy.



And have just filled it with dynax s50. Looks mint, can't believe it's second hand. Should outlast the car I reckon.

[Alex Pope]

I'm at the same stage - old cross-member came off today.  No bolts seized - result!  Got a replacement from Rutland MR2.  JoeCool what did you use to paint yours in the images above?

EDIT:
Just ordered Dynax S-50, ACF-50 and some Hammerite (black).

[MisterK]

I've used rust prevention primer to start on top of Mr T's efforts, then 2 coats of black Hammerite.  The weld gaps are sealed with black Tigerseal & the interior sprayed with Dinitrol.  Being fitted by Steve at D1 Customs next Friday.

[JoeCool]

JoeCool what did you use to paint yours in the images above?

I used an engineering shop who media blasted it, prepped it and powdercoated it!! IMO for a hard wearing rust proof finish nothing else comes close. Cost £40 to do, bargain.

[Alex Pope]

I ordered the Hammerite from Amazon last night 9.20pm and selected normal delivery.  It just arrived.  That's incredible!

[Carolyn]

What do people think about drilling a couple of holes in the bottom at the two lowest points of the subframe allowing any water that may collect inside to drain out?

Nothing wrong with the idea, except (depending on where and how you park up) the lowest point might not be the lowest point...   I still maintain that the best way to prevent internal rusting is to seal the thing so water or water vapour can't get in.  Yes the exhaust heat does accelerate the rusting process (most chemical reactions are speeded up by heat). However for the oxidation reaction to occur, water and oxygen are required.  No water, no oxygen, no reaction.

[Bodgeroo]

What are people doing with the rubber bungs? Transferring them over? I have decided not to completely seal it up along the welds. If air can get in then so can water vapour and I would prefer it comes out. It can only do this with ventilation. Reminds me of a loft cavity. Hot and cold temperature differences will cause condensation and it will need ventilation to get rid of any condensation in the crossmember.

[JoeCool]

I am transferring mine over. Toyotas solution lasts 11+ years. My sub frame is better protected, and will my car be on the road in 2030?

[Bodgeroo]

I am transferring mine over. Toyotas solution lasts 11 years without rust. My sub frame is better protected, and will my car be on the road in 2032?

Exactly my thoughts. Bungs being transferred over. Not sealing holes next to welds.

[ChrisGB]

Sealing the thing is going to be impossible IMO. The trouble with moisture is it pumps in and capillary action carries it in, but it can only evaporate out. What generally happens with nearly sealed items heat cycling is that moist air gets drawn in as they cool, the moisture condenses and pools, reheat expands air but leaves moisture pool, repeat until properly wet environment inside. Big vent holes and good internal anti corrosion coating appeal more to me.

[Bodgeroo]

One free cross member from a 2004 model with 70k, one careful owner and some slight surface rust. Any takers?   s:D s:D  

 View from above


Below


And some slight rusting

[1979scotte]

Thats a bad one.
Threads like this are important to get the message across.
Check your subframe!

[lamcote]

Do they all rust in exactly the same place? If so where exactly is it and why is it so catastrophic? Is it simply that water is collecting and pooling inside, leading to it rusting from inside to out?

[JoeCool]

They appear to rust in the same place, yes. It's the flat spot on the bottom where the suspension arms mount. It's water pooling inside. It's catastrophic because it's a suspension mount point and the MOT man doesn't like it (and of course it's dangerous)

[1979scotte]

If my 50k mile 06 plate needed a new one then so could anybodies.
I have said it so many times.
Its more important than checking 1zz oil usage.
That isnt going to kill you mid corner.
Just your engine.