6 replies to this topic

[whittlebot]

My brain aches when I mention this subject at work, and I'll probably get the same conflicting advice in here, but at least it will be intelligent/informative and from guys who know what they are talking about! 

I bought my 'pocket rocket' just over a year ago (1996 Mini Mayfair) from a lady who used it as a shopper (hence there being only 8000 miles on the clock) and garaged it over-night. The day after purchase, I took it to my local garage. "take it apart and put it together again, you find anything wrong you tell me". Mechanically in perfect condition. Nothing wrong with the vehicle, whose a lucky boy! Underneath. A rust spot 'here and there' otherwise sound everywhere. I asked them to put it back on the lift so that I could see for myself. And they were right. I wash and wax the car most every weekend, then get on my knees and fire the hose all over it's bum. I don't have a garage so my baby is exposed to the weather, and it doesn't seem to mind.Though I do cover it if frost is forecast. Underseal it myself on the hard-standing. Or pay to have it done. Or do nothing.

jonathan 

  

[tiger99]

Do not under any circumstances use traditional underseal. It is ok for a while and then water gets behind it and accelerates corrosion. It has ruined many cars.

If there are rust spots you need to grind or rotary brush them back to bright clean metal, apply either a good zinc primer such as Zinga or an etch primer, followed by a good coat of epoxy primer and then a modern stone chip, which you can paint over in body colour.

There are other combinations of things that can be used too.

And then lots and lots of cavity wax in every cavity.

[Daz1968]

Dinitrol products are very good, problem is unless you are totally stripping the car applying stonechip and body colour won't be practical.

[slidehammer]

I personally think the modern well know branded underseals are fine, they tend to stay supple and flexible. they can be bought from with added rust inhibitors. The old bitumen based ones are the ones that harden up crack and let moisture behind to reek havoc whilst still looking sound. I bought a new chrome front mud guard for Suzuki as the old one had rotten out from underneath. I undersealed the new one with Hammesrite underseal with added wax oil and it has been used all year round on salty roads and is still in good shape over 20 years later. The main thing is which ever way you decide to go, is to wash the under side off and keep and eye on any potential problem areas and deal with them quickly. I have some small patches on my 21 year old Peugeot that started to flak, so I scapped them off back to sound underseal and put on rust inhibitor followed by fresh underseal. Do it in the dry so you aren't trapping moisture.

[absx2]

I popped a new rear subframe on my daily drive ten years ago and at the same time prepped the original unrepaired floor and rear arches and applied 2K epoxy etch primer followed by 3M stone chip, more primer and a couple coats of synthetic top coat as it was kicking around and can be more pliable than 2K.

It got a good coating of Dinitrol wax and a few extra coats over the years.

The car is out in all weathers and parked facing north so when its wet it stays wet.

On showing it a bit of love before the winter sets in on close inspection on a 2 post ramp there are a few areas that the paint seemed a little out of shape. It had lifted from the panel so using a non metallic scraper I dug the paint off and all is well with just a very fine coating of rust that can be removed almost by rubbing my hand over it so it just goes to show you need to keep you eyes on these things.

I recently did a crash repair on a Rover and on removing the rear bumper I was greeted with the usual Rover paint finish which is basically no paint where you can`t see it and funnily enough there was no rust so it goes to show its not a great idea to put enough coatings on so as to trap moisture.

There is a good reason why front subframes don`t rust so i`ll be going back to spraying waste oil everywhere followed by a dusty car park. 

[FlyingScot]

For the underneath, clean it, wipe the surfaces down with white spirit. Allow to dry then Bilthamber wax (Dynax) the black stuff or clear depending if you can see it. Touch up from time to time and make sure you keep the mud from building up.

It comes in big aerosol cans so it's easy to spray and has a tube extension to get into the sills, companion boxes, rear subframe etc

I try to keep it simple and this works great so far on my fleet.

FS

[Cooperman]

Whatever you do, anything is better than doing nothing!

 

If you could get the car onto a ramp you could wire brush the complete underside including the small  rust spots then treat those spots with Kurust.

Then brush paint it with 2 coats of red oxide primer followed by a top quality 'chassis black' paint.

Finally spray the rear-sub-frame recess area, plus the sub-frame itself, with Waxoyl' or similar. Hose it off regularly and re-Waxoyl every year, checking/repairing the underfloor paint condition at the same time.

Also treat the inside of the sills with Waxoyl or similar, plus inside the doors, inside the rear valence and the enclosed sections at each end of the screen scuttle panel  (there is a small gap to gain access right at the back of the inner front wings). 

 

I have an old Land-Rover Discovery and I have just replaced the outer sills. I painted them as above, then sprayed hot Waxoyl mixed with old engine oil into the sills plus all over the rest of the underside and inside the main chassis members. Some of the oil ran out onto the drive (trouble with 'er indoors over this  ), but it will never rust out as so many Discos do.