Subframe preservation

[BARNPOT2000]

Well, I've finally found a moment to lift the rear and take a butchers at the underside of the engine bay/Subframe area. I'll try and post a picture or to later, for you to critique 😉.
What is the usual treatment recommended to preserve an original sub frame to prolong its life as much as possible? My first thoughts were to rub her down treat any rust with a  neutraliser and paint with maybe red oxide primer then black waxoyl underseal, any thoughts on this please?

[1979scotte]

@Carolyn will be along shortly to offer advice but it needs filling.
They rot from the inside.

[Carolyn]

As Scotte insists:

I did a lot of research on this.  One thing I discovered is that our American Cousins don't have so much of a rust problem as we do.  Even the Canadians, with their severe winters get off better than us.  They use white road salt.  (bear with me...).

The subframes rot because road filth, including our very corrosive red phosphate-laden salt, gets in through the open top corners.  So does water.  That powerful electrolytic mixture sits in the bottom of the subframe,.  Now we put a 'Bunsen burner' underneath in the form of the exhaust.  If you remember high school chemistry, heat speeds up chemical reactions.

The result is a hole in the subframe.

My solution is to remove some of the rubber bungs and wash it out with plenty of water.  Let it dry and pour in a good dollop of Waxyoil (taking care to first replace bungs under the bottom and to tape over the little drain holes that are hidden under the suspension attachment points So the Waxyoil doesn't run straight out.  Take a good quality sealant and seal up the four open corners.

Rust requires oxygen and water. Keep those out and it can't rust.

I prefer to do the exterior by removing and treating any rust, painting with zinc primer and then a good hard top coat.  I'm not a fan of sticky goopy stuff all over the bottom of the car.  but that's only a personal preference.

[Ardent]

I was going to say exactly the same.

[fawtytoo]

I was going to say exactly the same.

Me too. Word for word.

[BARNPOT2000]

I will attempt to upload some photos here. Bear with me as these are my first attempts..
https://live.staticflickr.com/65535/51320242338_189ea8d71b_m.jpg

https://live.staticflickr.com/65535/51320038781_12bee6f20f_m.jpg

https://live.staticflickr.com/65535/51320039046_0f98b16faf_m.jpg

Ok so could someone please advise how I get them to show in message straight away?

How does the condition of this subframe look to members please, I thought it wasn't too bad but I cant guage it really?

[Ardent]

The displaying is basically taking your links and wrapping them in the img tags

When posting. Get your link that ends jpeg, click the insert pic icon and paste the link.

Easy to show not so to type.

[Ardent]

Re the sub.
Looks good from here.

If not the full Carolyn option. You could opt for some bilt hamber dynax S50.

[Bossworld]

Doesn't look bad at all, what's it like directly above the catalytic converter?

[BARNPOT2000]

Doesn't look bad at all, what's it like directly above the catalytic converter?

Thanks, ill take a look again tomorrow.

[onion86]

Doesn't look bad at all, what's it like directly above the catalytic converter?

That's what I was going to say, it's the bit there that's the major issue, the rest may look fine.

[Iain]

Mine looked very similar to that. I had the hole above the cat, but not too difficult to cut out and weld a patch in. Thats if you have a welder, they come in very handy and the hobby ones are not too expensive.

Cleaned, rust treated and painted mine on the outside, and i have a can of the bilt hamber stuff waiting to go on the inside.

[BARNPOT2000]

Doesn't look bad at all, what's it like directly above the catalytic converter?

Doesn't look bad at all, what's it like directly above the catalytic converter?

Thanks, ill take a look again tomorrow.

Here's a couple of pictures showing subframe just behind the main cat, is this the weak spot? You cannot view this attachment.You cannot view this attachment.You cannot view this attachment.

[Carolyn]

Doesn't look bad at all, what's it like directly above the catalytic converter?

Doesn't look bad at all, what's it like directly above the catalytic converter?

Thanks, ill take a look again tomorrow.

Here's a couple of pictures showing subframe just behind the main cat, is this the weak spot? You cannot view this attachment.You cannot view this attachment.You cannot view this attachment.

That's the nearside (passenger side) one it's the off-side one that has the bother, where the cat passes under the subframe.

[BARNPOT2000]

Am I any "warmer"? You cannot view this attachment.You cannot view this attachment.You cannot view this attachment.

[Snelbaard]

I have an idea: Perhaps I could make aftermarket tubular steel rear subframes, seeing as the OEM ones are prone to rust out. Would any of you be interested in those? It would take a bit to develop, but might be worth a try.

[J88TEO]

About time!
I was wondering why no one ever comes up with an aftermarket one...alu or steel!

[Gaz mr-s]

Am I any "warmer"?

Pic 1 is the one....strangely unmarked...not sure I've ever seen one as good. It doesn't look pretty elsewhere, but looks just surface.

I used Bilt Hamber Dynax on the inside & painted external with black Por15. Some folk paint it with a 'louder' colour, - can  work...

Some advocate spraying a rust converter inside.  Take your pick.

[Snelbaard]

Could anyone in the know give me a quick rundown on the differences between the pre- and post facelift ones? Would an aftermarket subframe based on the post-facelift one work on all cars?

[Frank Rabbets]

Trouble with waxoil is that it only works on new and unpolluted surfaces. On rust it dries out to a wax which is waterproof and traps any salt and residual water underneath causing a big problem. Best solution is to spray with hot soapy water inside and out after removing all the bungs then dry out with a good hot engine and run. Next put the bottom bungs in and fill with gear oil. Then spray the outside with gear oil. Drain and dry off as much as possible with a fluffy towel. Oil does not dry out and keeps all those little corrosion holes in the metal filled. Leave the bungs out. I've been fighting rust since about 1960. Ought to be a law against it. Saved the rusty brake pipes and sills on my 1995 Land Cruiser with above method. No new corrosion for years now.
My MR2 cross member is very rusty outside but clean on the inside.

[Joesson]

I have an idea: Perhaps I could make aftermarket tubular steel rear subframes, seeing as the OEM ones are prone to rust out. Would any of you be interested in those? It would take a bit to develop, but might be worth a try.

I remember seeing a "one off" on  Spyderchat. As I see it Insurers may be reluctant to accept such an element. More fundamental is the cost and availability, currently around £350 the UK with availability unknown.

[Joesson]

Trouble with waxoil is that it only works on new and unpolluted surfaces. On rust it dries out to a wax which is waterproof and traps any salt and residual water underneath causing a big problem. Best solution is to spray with hot soapy water inside and out after removing all the bungs then dry out with a good hot engine and run. Next put the bottom bungs in and fill with gear oil. Then spray the outside with gear oil. Drain and dry off as much as possible with a fluffy towel. Oil does not dry out and keeps all those little corrosion holes in the metal filled. Leave the bungs out. I've been fighting rust since about 1960. Ought to be a law against it. Saved the rusty brake pipes and sills on my 1995 Land Cruiser with above method. No new corrosion for years now.
My MR2 cross member is very rusty outside but clean on the inside.

The other" problem" with Waxoyl is that itneed s to be warmed up for application and consequently when the weather is warm it softens and can drip.
Spraying the underside of cars with various oils, preused and otherwise, for underbody protection was something offered in the days of leaf springs. Gear oil would not be my choice of a travelling companion in these days of more advanced chemistry.
As others have mentioned, Bilt Hamber is a Company that has specialised in combating corrosion with seemingly good reviews and was my choice.
As with all things though, preparation is key and sloshing what ever onto visibly loose corrosion and flakey paint is not the way to do it.

[Bossworld]

I have an idea: Perhaps I could make aftermarket tubular steel rear subframes, seeing as the OEM ones are prone to rust out. Would any of you be interested in those? It would take a bit to develop, but might be worth a try.

I think while replacements are still available from Toyota it's unlikely to be cost effective. The other unknown is how long the replacement Toyota items last - presumably if the stock one has managed 15+ years on most cars, another 15 years will see the bulk of the cars into the breakers' yards anyway?

[BARNPOT2000]

I have an idea: Perhaps I could make aftermarket tubular steel rear subframes, seeing as the OEM ones are prone to rust out. Would any of you be interested in those? It would take a bit to develop, but might be worth a try.

I think thats a great idea. I reckon a great many owners would be interested and, at some point, we may all need a replacement.

[1979scotte]

I have an idea: Perhaps I could make aftermarket tubular steel rear subframes, seeing as the OEM ones are prone to rust out. Would any of you be interested in those? It would take a bit to develop, but might be worth a try.

I think while replacements are still available from Toyota it's unlikely to be cost effective. The other unknown is how long the replacement Toyota items last - presumably if the stock one has managed 15+ years on most cars, another 15 years will see the bulk of the cars into the breakers' yards anyway?

My 06 that I bought in 2014 needed welding so if you get an uncared for example they don't last long.