Rustproofing/longevity underneath a car

[Welly]

I had a chance to get under the Volvo last week on next-doors' MOT ramp at work. The floor pan underseal looks in good shape and the rest of the suspension components look quite good; they are the black-painted pressed steel type but with some* surface rust on the edges where the paint is thin.

Thinking long term I'd like* to get under the thing and give it a jolly good jimmy with a stiff brush, clean up, and then.....what? a lick of satin black? something a bit more protective?

I thought about spraying all the nuts/bolt heads/threads with spray grease which is ok but don't really want to 'grease' all the sussy arms even though that would keep them rust free.

Any recommendings welcomes.

[jonsowman]

The underside of my Coupe had quite a lot of surface rust when I bought it, due to it having done about 200 miles in the previous year.

A lot of time was spent wire brushing and cleaning, and then a really thick coat of Waxoyl Underseal. It doesn't really ever dry, it's like a tacky rubberised coating over everything. So it's very resistant to water and being scratched off by stones etc. The underside all looks like this now:

[Welly]

I see, so everything gets a good coat of the stuff, I suppose it protects bolt heads enough and can still be undone when needed.

I asked the Mechanic why all car sussy seems to rust so much.........."they want us to keep buying new cars" was his answer.

[jonsowman]

Sounds about right!

The front subframe was the worst on mine. Not sure why really

Yep, it does make getting bolts undone a little more faff occasionally (sometimes the hex driver won't fit over the bolt). But it comes off very easily.

[FarmerPug]

One possible reason why suspension parts rust is because they move so much, springs especially its hard to get paint to stay on them for an extended period of time, not to mention the fact they are exposed to all the nice chemicals on the road.

Waxoyl is good stuff, but i recall using a black tin of stuff, i think tetrosyl, on the 106, real thick gloopy stuff but once dry it was still flexible yet wasnt going to wash off.

[steve_earwig]

Waxoyl I reckon, although there was something that's meant to be better on AS but I can't find it.

Many years ago a colleague of my dad's noticed that the cars in the breakers that looked like they'd had long standing oil leaks seemed to be much less rusty than the others, so he sprayed the underside of his car with used engine oil. I hope he didn't have a pretty driveway...

[FarmerPug]

I think this is the better than waxoyl stuff, saved it in my ebay watch list so i wouldnt forget the name, still havent tried any though
http://www.ebay.co.uk/itm/161081731306? ... EBIDX%3AIT

Used engine oil with a bit of parafin is a good old school trick the parafin dries but leaves a nice oily waxy coating behind, i also like copper grease, treated the 305 to some the other day, it picks up grime/ bugs and shite but does a very good job of stopping rust getting any worse:

[steve_earwig]

Ah yes, that was it, bilt hamber, cheers Frank

[dirtydirtydiesel]

Dinatrol products are the ones I've been using for the last 20 years, very good stuff that last time I looked was best product
in the Practical Classics test year in year out .
Also Rustbuster products come highly recomended by Practical Performance Car.

[Welly]

Just been looking at the Dinatrol stuff, reassuringly expensive I guess? I've spotted a 'rust converter' spray/primer, would it be worth a quick misting of something like this before the layer of underseal shiz?

[Rolebama]

I have always had great success with Waxoyl covered with Body Schutz. (Wait till the Waxoyl has 'dried' before putting Body Schutz over the top.) A very messy job, and I buy a big cheap plastic tarp to do it on, which gets thrown away afterwards.

[steve_earwig]

I suspect that rust converter)primer really needs as much rust removing first, otherwise it won't do much. There are specific rust converters out there, probably nothing as good as grinding all the rust off though.

[Welly]

I was thinking: wire brush the worst/clean then a mist of rust converter followed by the Waxoyl type stuff?

[steve_earwig]

If you're Waxoyling it I wouldn't bother with the paint, the Waxoyl will sink into the rust and stay but it won't penetrate paint...

[Welly]

So if I squirted waxoyl over some rust it'd stop it nomnom'ing further? something's niggling my mind about rust spreading under rust proofing*

What I mean is I could be careful to wire brush everything up but there's bound to be bits missed and these'll get blown-over with the black stuff forever.