Stainless Steel Caliper Pistons

[crazy steve]

A few of you may have seen this guy on Ebay selling CNC SS pistons to fit the XS11. $24 each with $9 shipping to the US, not such a great deal. But if you contact him (info@twowheelsfrank.de) for a full set of three, he'll knock the price down to $22 each and $18 shipping. That works out to less than Partsnmore who wants $29 each, and theirs aren't SS and doesn't include shipping.

I'm going to order a set and ban rusty/jammed calipers hopefully forever.

The only issue I can see is on some other lists I'm on, guys have used SS pistons and had problems with a slightly too-rough surface finish and had some leaks. But it was also reported that if you polished the outer surface, this disappeared. This guy is in Germany, so I'm counting on 'teutonic' pride for a quality part.

'78E original owner

[redbone]

yes, it would be great not to deal with stuck/rusty calipers/pistons all the time.

DOES THIS guy machine these parts himself??

[crazy steve]

I believe he does. His Ebay seller name is 'Kenosha_Kid' if you want to look at the listing and he has 100% feedback. He's also got a website (www.twowheelsfrank.de) but it's in german, so no help there. Looks like he specializes in 650 parts mostly.

'78E original owner

[mxmikie]

its not the piston that rust its the caliper that is why when they made the new pistons for the corvette in ss they also made a insert sleeve for the caliper to stop the rust alum corrodes so if you powder coat the caliper or jet hot coat them you will be done with the corroding problem

[TopCatGr58]

its not the piston that rust its the caliper that is why when they made the new pistons for the corvette in ss they also made a insert sleeve for the caliper to stop the rust alum corrodes so if you powder coat the caliper or jet hot coat them you will be done with the corroding problem

Hey MXMikie,

I've read many of your posts, and they have seemed quite knowledgeable, but I have to differ with this one! You did say something about Alum Corroding in the above, but it wasn't very clear?

Below are photos of a Special Caliper that I took apart several years ago.
NOTE the heavy RUST on the inside/cup/pad side of the piston prior to it being removed, along with some spots of rust where the outer seal fits into the piston's groove..most of it came from the metal ring in the seal.

Then note the innards of the caliper housing and bore which are aluminum, so they don't RUST. They can corrode, but it doesn't really make any sealing contact with the piston. Just that big square edged rubber seal that fits down inside the groove in the caliper is what makes the seal with the piston. And corrosion likes to build up under that ring in that groove, which can cause the seal to bind/grab the piston too tightly preventing the piston from releasing the break easily!

Also, NOTE the SS stamp on the inside/bottom of the piston....appears to be Stainless Steel, YET, plenty of rust on the pad contact side. The inner portion that was in the brake fluid wasn't rusted though, but don't believe that SS doesn't RUST!
T.C.

[tarzan]

I doubt that "SS" means it is stainless.It looks more like a part number to me.I have had several of them out and they don't look like stainless to me.

However you are right TC, 400 series stainless will in fact rust.300 series will not rust.
I have considered making some pistons for an 850 I'm working on.316 or 303
would be my choice.But steel lasted for 30 years, so maybe just a new rust free part.
Ric

[crazy steve]

I'll have to agree with Tarzan; the stock pistons are not SS. They might be plated with SS, but I doubt it. All the OEM caliper pistons I've ever seen are steel with a hard chrome plate on them. Which explains why they rust so badly in the 'hollow', as you can't get plating to go into a hole.

And the reason you'll see 'Vette calipers (and some others with a similar design) sleeved is because the seal is located on the piston, not in the bore. If you get any bore damage, the caliper is toast. The sleeve was a way to save an expensive part. The only problem is, the sleeves have had a reputation for coming out of the bore under hard braking, which needless to say ain't a good thing.

I ordered these pistons today, when they get here I'll post a review....

'78E original owner

[Spider]

So that's a "bad idea" consensus on the powder coat? I'd like to do what I can to "bulletproof" my brakes before next season. I've already done a master cylinder replace, and stainless lines. Bike's going to be outside(covered) in some pretty harsh conditions for about six months this spring/summer, so it seems the calipers are now the weak point.

Also, not to change the subject, but I have to quickly change the subject. What's a good way to flush the front line splicer? There was some nasty crud in the braking system, and I'd like to flush it out of there(there's still residue in there). Don't know if WD40 or penetrating oil(to break up the crud) or similar is an option. I'm thinking brake-fluid in a spray-bottle and a toothbrush?

Okay back to subject. I look forward to the review on the stainless replacements, since I'm also considering them.

[petejw]

Spider,
Only use brake fluid to flush the system out,
connect the hose up2 the master cylinder and
flush, cover the end of the hose with your finger
and proceed as you would if you were bleeding them.

[oseaghdha]

If you start with a clean system, and keep the fluid changed out regularly you shouldn't have caliper problems.

I flush mine out once a year.

[jmnjrpa]

The best process for aluminum is anodizing. Problem with anodizing is 1/2 of it imbeds in the material and 1/2 on the outside. Simply put, you must allow for the .0005/.002 buildup on the outside. A maximum of .004 plate is recommended. Anodizing is much harder than aluminum and can be done in a rainbow of colors. Most plating houses charge about $40/50 per lot so you can get all calipers and a few other parts done for one charge. A light etch process is done prior to anodize to insure the part is clean.

On stainless steel, it is not rustproof steel. Stainless is rust resistant but some grades are much more than others. The harder stainless steels are less resistant to rust (which is oxidization on steel the same chemical reaction as corrosion on aluminum). Iron oxide and aluminum oxide are the result of this process. While iron oxide is quite hard, aluminum oxide is by far harder and is used in cutting tools, grinding wheels and blast media.

A flash plate of hard chrome (.0001/.0003) is more than sufficient to resist corrosion on steel. The reason the inside of some pistons are not plated is merely a cost issue. The manufacturer is saving money at your expense since hard chrome is not cheap and is heavily EPA regulated.

[xschop]

SS Calipers

316H or 316Ti stainless would be choice for a caliper piston... and if you want even more performance, drill the caliper perimeter with small 1/16" holes spaced @ 3/16" apart to reduce heat transfer from the pad back into the fluid....Recently did this to a set of Lexus LS430 monoblock calipers I adapted to my Chevy Powered Porsche.

[crazy steve]

The best process for aluminum is anodizing. Problem with anodizing is 1/2 of it imbeds in the material and 1/2 on the outside. Simply put, you must allow for the .0005/.002 buildup on the outside. A maximum of .004 plate is recommended. Anodizing is much harder than aluminum and can be done in a rainbow of colors. Most plating houses charge about $40/50 per lot so you can get all calipers and a few other parts done for one charge. A light etch process is done prior to anodize to insure the part is clean.

I'll agree with the above, but unfortunately if you do this on castings you can run into problems. Castings are rarely 'homogenous' i.e. the metal isn't equal in density/composition throughout. This seems to be a particular problem on the XS (no doubt caused by Japanese reliance on 'recycled' material); I noticed this when I polished a bunch of previously-painted parts for mine. I ended up with numerous 'defects' in some of the parts that wouldn't polish out. So when you apply a color or even clear, the metal will absorb it differently in different places, leading to a blotchy finish. You usually won't run into this on forged or extruded aluminum, as the 'squeezing' process tends to make the metal more homogenous.

You can buy a 'home' anodizing kit for as little as $200 (and I seriously looked into one), but seeing how nearly all aluminum items on bikes/cars are cast, I passed on it.

'78E original owner

[Spider]

Spider,
Only use brake fluid to flush the system out,
connect the hose up2 the master cylinder and
flush, cover the end of the hose with your finger
and proceed as you would if you were bleeding them.

Thanks. I think I'll hook an old line up to the splitter and bust that crud out of there. Maybe some compressed air too. It's REALLY nasty. I've got to get it clean though. No point in new masters and new hoses and clean calipers if you're splitters filled with muddy sandy garbage.


Spider

[jmnjrpa]

True Steve,

but this issue shows up worse in lighter shades rather than the black or dark shades normal to parts like brake calipers. One could always powder coat after to achieve both good looks and a durable part. This condition manifests itself in welded parts also.

Cast parts tend to have pits and rough exterior. These imperfections are rarely very deep. If this were not so, brake calipers would be one of the last applications for cast metal.