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View Full Version : Bit of a smell in the garage today


chris.richard
December 16th, 2003, 09:03 AM
I was almost got by a gotcha that I didn't see coming, but should have.
I've got the car up on 2-foot (60cm) stands to make it easier to work on. I'm working on the front bulkhead at the moment, so i've taken off the front body, and today stripped out the steering rack and front suspension. As I dropped the last corner of the front suspension, it lightened the front of the car so that it was not balanced any longer, and the whole thing pivoted on the rear stand, the front went away up in the air, and the back went down until the exhausts hit the floor. I grabbed it just at that point, and pulled it back down again. Luckily it did not slide off the rear stand (which is on castors) otherwise the whole chassis would have been on the floor. I think that all that happened is two divots out of the concrete, and flattened off exhaust trumpets; I don't see anything wrong with the exhaust mountings, I think I caught it in time.
Moral of the story - think about what is happening to the centre of gravity when you remove all the weight off the front. I have the rear stand under the crossmember at the front of the engine bulkhead, this seems to be where the c of g is with the heavier 24v engine and a naked front end!
It's turning into much more of a restoration project than I'd hoped - there is a lot of rust on the front bulkhead, inside and out, and on all of the front chassis. It's all superficial as far as I can see. The powder coating is all stripping off in sheets. I wonder if it was prepared properly before coating? The problem is the bits of metal covered by the glassfibre. Without dismantling the whole tub, it can't be treated, so I.m trying to incarcerate it in Waxoyl at the joints so that no air can get in to these bits. I think this is largely the result of the carbeing stored under a tarpaulin outside for several years. That and being driven without any weatherproofing strips on the doors and windows; not to mention having needless large holes drilled in the front bulkhead and not blanked off or grommeted - the water has come in through these, hence the rust inside, I think. Keep your Stratos inside! As if you'd do anything else!

CorseChris
December 17th, 2003, 01:33 AM
Oooops :o

Glad you caught it Chris.

IMVHO and limited experience, powder coat is absolutley no good whatsoever on fixed chassis parts. Even the best-prepared chassis is going to suffer it falling off in sheets at some point. My Marcos (and every other one I ever saw) had huge chunks falling off after less than a year. Paint is far better I think. Last steel parts I had powder coated had gone rusty and were covered in 'crows-feet' after 6 months of being stored in the garage, let alone seeing any action on the road. I stripped them, blasted them, etch-primed them and painted them with a 2-pack chassis black.

I have had much better success with nylon coating of suspension components though. The front uprights on the Westfield still look like new 12 years after I built it. Shame the same can't be said for the powder coated chassis......

Andrew Way
December 17th, 2003, 04:35 AM
A lot of commonly used powder coatings are porous and when left outside the metal beneath will rust and lift the coating off. The powder coating does make a great primer which is why I scotched all my new HF3000 suspension components and got a friend to spray them.

chris.richard
December 20th, 2003, 12:39 PM
So the sensible thing to do is to topcoat all the chassis as soon as it comes through the door from the manufacturer.

How do you nylon coat components?

stableblock
December 20th, 2003, 01:30 PM
Hi
Powder coat works very well but:

It needs proper application - many people don't leave it in the oven long enough or allow the material to reach the required temperature.

There are different powder coats for different purposes:

Epoxy has the best chemical resistance but will 'chalk' rapidly in sunlight.

Polyester resists sunlight the best but is less good with chemicals - salt etc. Tends to require higher temps.

Combined epoxy-polyester coats offer a balance of both.

Semi gloss finishes are better for chassis than matt or gloss, there is more pigment which gives a stronger coating.

All finishes need proper preparation of the material underneath. If applied to clean grease free steel they will stick well but if scratched through there is nothing to stop the steel rusting and they will just peel off.

A phosphate coating (zinc is ideal but iro is ok) is the best pretreatment for steel giving excellent adhesion and good corrosion resistance. Most sprayers don't have the facilities to do this though. With proper pretreatment the finish will protevt well even with quite severe scratches

Aluminium or galvanising is worse for adhesion, proper pretrteatment is essential - alochrome type pretrteatment being best.

As with all things in life you get what you pay for!