Sandblasting/Restoring/Painting the Suspension

[SilverSpear]

Hey guys,

I have finally tackled the suspension parts. All bolts and nuts, and some other bits will either get zinc-ed or replaced. As for the big parts, I cleaned them using a fixed wire brush grinder, dipped them in a rust eating compound. Next will sandblast and paint them.

Here is the dilemma. I have read lots of articles about powdercoating, some of its drawbacks is that it gets chipped real bad hence not suitable for the car's suspension. I have explored many options with the "good" brands that are available in this part of the world. The brands are PPG, DuPont, Johnston's, Oxford Paints, Sherwin Williams, Rustoleum and Lechler. Only wished POR-15 was available, I would have chosen it in a heartbeat.

The best combination I was able to come up with, is PPG D834/835 for an epoxy primer and Rustoleum 9800 Industrial DTM Urethane Mastic as a top coat (even though the 9800 is self primed). The only drawback of the 9800 (besides its $150 gallon cost) is that it comes only in Gloss and NOT Semi Gloss. The other Epoxy options for the top coat are not recommended since epoxy paint is not flexible and will get cracked when used on coil springs and other parts.

Here is the datasheet of the Rustoleum 9800, what do you guys think? I REALLY need your opinions: http://www.rustoleum.com/tds/9800%20System_RO-71_2078990.pdf

[mdsalemi]

Spear,

After 12 years and over 13,000 miles, my powder-coated suspension parts have held up exceedingly well. No chips, rust or anything--and contrary to what some say, if you do get some kind of damage you can touch it up with paint.

Personally I've found great value in the robustness of powder coat and have used it on engine-bay internals as well, and wheels. It's quite cost effective.

[wwheeler]

I agree completely with Michael. The biggest advantage to powder coating IS chip resistance. I have accidently hit powder coated parts many times with tools and never chipped them. That is why you go to the extra trouble to powder coat because of the durability. The only time I have ever heard of powder coating chipping is either poor preparation or bad application. Every bit of my rear axle and attaching parts are powder coated. I would have done the fuel tank but the flower pot is plastic and probably wouldn't take the heat.

That being said, the biggest drawback to powder coating suspension parts is keeping the coating away from attaching points. When a bolt/nut etc. is torqued down on a powder coated surface, it will peel away at that point. Paint will usually smear under the torque. You have to mask the area under the bolt/nut and then the problem is solved. Yes it is a bit of pain, but the durability is outstanding.

[SilverSpear]

Thanks guys for the feedback. That is weird, all the net is talking about the suspension/brake calipers chipping with powdercoating. Not just a few forums, all forums actually.
Now I am at a loss. But to be honest I am still leaning towards PPG epoxy and Rustoleum urethane since I DON'T trust the method that is used to apply powdercoating in Lebanon. I know they will cut short the process somewhere, either a cheaper primer or no primer or something about the heating temperature... I will end up getting sc...

Oh yeah, I do have a air compressor, a spray guy and a clean space, will be doing the process myself according to their data sheets.

[jameshoward]

My two penneth...

I powder coated my replacement rear axle, and it looks superb and will survive world war 3. The only thing I would echo is wwheeler's point about not getting any coating on any parts that connect to anything etc. I have had a nightmare removing powder coating from bolt holes and mating sufacess. Poor prep on my part - you don't know what you don't know, etc.

I've knocked 7 bells out of some of the coated areas and it doesn't chip. I didn't coat callipers or brake parts. There are issues relating to powder coating some metals as some coasters heat items too much and - critically - don't allow them to cool properly. There's quite a fuss - and a good many lawsuits - relating to powder coated alloy wheels that have cracked or broken whilst being driven. So powder coating should be undertaken advisedly and by folk who know what they're doing I would suggest.

[mdsalemi]

...I should add that I have a very, very good powder coater that is quite close to me and specializes in automotive aftermarket stuff, (read that: hot rod) and they do all kinds of stuff.  About the only thing I've had him do is "chassis black" on my fan shroud, battery holder, suspension bits, air cleaner, etc. I also had him do the magnesium fan in silver, simply because the extremely rough casting was a magnet for dirt, grease and road grime.  Now it is smooth, looks nearly the same, and is easy to wipe clean.

http://www.exoticcoatings.com/
http://youtu.be/2j3Gsp8NC0s

They did my pressed aluminum wheels, preserving the integrity of the part numbers around the bolt pattern and not adding any texture via sandblasting.  These guys know what they are doing which is why I keep going back.

[wwheeler]

My steel wheels are also powder coated. I have mostly done satin black as Michael. In addition, I have used a silver on many aluminum parts including oil, fuel filter and fuel regulator housings and almost all engine parts on the front. It took me a long time to find just the right color but it has worked out well. It is called Bengal silver from Tiger/drylac. Been on there for four years with no trouble at all.

I did not powder coat my brake caliipers as I did not work to screw up the bore sizing either from heat or powder overspray. Besides, they have some really good High temp paints that look good and chipping isn't a problem there.

That is wierd about the forums. There must be some commonality between them because I don't have any issues at all.

As Michael said, the other great advantage to powder coating is how easy it is to clean!!! The wheels with brake dust on them come clean with a quick wipe with a microfiber brush.

There is nothing wrong with paint if you have the talent, equipment and so forth. It is easier and the original. I just like the durability of powder coating when I can.   

[SilverSpear]

Guys, thank you for the additional info. I only wish we had ALL the good brand names you guys have in the US.

Today I passed by a classic car restorer and took a great deal of his time asking questions about the restoration process and so on. He had in his shop a 1970 280SL, a rolled 190SL, an old 60's 4 door Jag and a superbly restored E-Type in British Green. Gave him few pointers about the 280SL  which he didn't know before.

We spoke about powdercoating, and he said he tried the PPG, DuPont and .... dunno what. Even though he cleaned the parts really well with a specialized solvent, used the proper primer and top coat according to the exact requirements of the datasheet, all parts bubbled only within 3 months and he had to do the entire process again. He tried many combinations from different manufacturers and paint centres, he always had bad issues with it, either cracking, peeling, bubbling, etc... It must be some rotten/expired products that are getting the country. I wouldn't be surprised if the powder used is of Chinese cheap crp rebottled in branded names. Now he is simply using PPG's primer D834/835 and a normal black coat (Glossy, and told him to use Satin as it is the correct color for the undercarriage parts).

I am currently in discussion with POR-15 and will be assisting them in penetrating the Middle Eastern market starting from Dubai and Lebanon. Already found them an excellent local partner who is already carrying Rustoleum, Johnston's and Oxford Paints. Well this is what I do in real life, expand businesses 

Whenever I start with the painting process, will keep you updated folks.

[wwheeler]

I have a home powder coating kit for small parts. I have done it many times with great success. No peeling at all. My finishes aren't as good as the pros because of the equipment, but a whole lot cheaper.   

[SilverSpear]

Yeah the concept is really easy, its not like NASA science. You can even use your home oven as long as it fits the part in question.

[mdsalemi]

Yeah the concept is really easy, its not like NASA science. You can even use your home oven as long as it fits the part in question.

Spear, I've talked about the process extensively with my powder coater; the process to yield perfect results is a bit more complex than many think it is, as is high quality painting. In the case of bubbles, usually this is the base metal outgassing; there are specific pre-treatments needed for this and maybe your guy just doesn't know or have the experience. Different metals require different pre-treatments; experience is a better guide than the powder's instruction sheet I think.

You can read a little about this here: http://alloynet.com/uploads/Powder_Coating.pdf