Topic: SS Vs. Chrome Plated CB750 Caliper Piston

[Simpson]

Few months ago, I purchased the more expensive replacement SS caliper piston from Yamiya. After seeing how chrome pitts over time it seemed like a good solution. Pitting leads to grabbing of the brake etc... So I order the 100 dollar piston and install.

http://www.yamiya750e.com/index.php?main_page=product_info&cPath=33_86&products_id=363

The last month of riding I have been noticing increased grabbing as time goes on. Finally last week my rotors are getting roasted and it has troubles riding 2up. Upon inspection in dis-assembly, the SS piston seems to have some scoring where the ring seal slides. I buff the piston and clean the caliper and it seems to be doing it again. Today I again, buff out the scratches on the piston, polish and clean the entire caliper. I'm starting to think I should have stuck with Honda original parts.

Thoughts or experiences?

[Hinomaru]

I don't have any experience with the Yamiya stainless caliper piston. However, back in 2006 I replaced my badly pitted original Honda caliper piston with an aftermarket stainless steel one and a new OE caliper seal on a 750K4. The piston was made from grade 304 stainless and I use DOT 3 fluid. It's been working just fine without any issues.  Rubber can be abrasive and stainless steel can score/gall under certain conditions. I wonder what grade of stainless steel Yamiya is using and if you have an aftermarket caliper seal. Perhaps a mismatch of materials is causing your problem?

 

[Gorms]

When I built my bike, the original piston was badly pitted.  I bought a phenolic piston from a member here and its great.  Wont corrode, much lighter, and it works perfectly.

[steam-powered man]

+1 on the phenolic piston; perfect fit, superb finish, $34 shipped. 

[Simpson]

+1 on the phenolic piston; perfect fit, superb finish, $34 shipped.  

Where did you get it? After going through mine twice it still sticks for about 30 seconds...

[MCRider]

Few months ago, I purchased the more expensive replacement SS caliper piston from Yamiya. After seeing how chrome pitts over time it seemed like a good solution. Pitting leads to grabbing of the brake etc... So I order the 100 dollar piston and install.

http://www.yamiya750e.com/index.php?main_page=product_info&cPath=33_86&products_id=363

The last month of riding I have been noticing increased grabbing as time goes on. Finally last week my rotors are getting roasted and it has troubles riding 2up. Upon inspection in dis-assembly, the SS piston seems to have some scoring where the ring seal slides. I buff the piston and clean the caliper and it seems to be doing it again. Today I again, buff out the scratches on the piston, polish and clean the entire caliper. I'm starting to think I should have stuck with Honda original parts.

Thoughts or experiences?

Maybe you've addressed this, but its not obvious in your post...

What about the fluid return valve in your MC? THat is by far the biggest reason for pistons to grab or hang up.  THe piston itself is pretty benign and foolproof. Nice to have a better one, but the master cylinder has to be behaving properly or no piston will work properly.

[scottly]

My experiences with stuck/dragging calipers, and I've had a few, on different bikes and calipers, I found were due to corrosion (look for a white substance) of the aluminum caliper bore. I would lightly scrub the bore with fine scotch-brite, flush with brake cleaner, clean the piston, and put it back together. I never had to replace a piston.

[BeSeeingYou]

Stainless and aluminum can be a bad combination in some instances.  304 would be a minimum but it may be an inferior grade like 18-8.  Another thing about stainless is that it needs oxygen to keep it's stainless properties.  Robbed of this like under the rubber seal and in the presence of moisture it can pit and corrode.  I would go plastic or stick with the chrome steel.

[Simpson]

Few months ago, I purchased the more expensive replacement SS caliper piston from Yamiya. After seeing how chrome pitts over time it seemed like a good solution. Pitting leads to grabbing of the brake etc... So I order the 100 dollar piston and install.

http://www.yamiya750e.com/index.php?main_page=product_info&cPath=33_86&products_id=363

The last month of riding I have been noticing increased grabbing as time goes on. Finally last week my rotors are getting roasted and it has troubles riding 2up. Upon inspection in dis-assembly, the SS piston seems to have some scoring where the ring seal slides. I buff the piston and clean the caliper and it seems to be doing it again. Today I again, buff out the scratches on the piston, polish and clean the entire caliper. I'm starting to think I should have stuck with Honda original parts.

Thoughts or experiences?

Maybe you've addressed this, but its not obvious in your post...

What about the fluid return valve in your MC? THat is by far the biggest reason for pistons to grab or hang up.  THe piston itself is pretty benign and foolproof. Nice to have a better one, but the master cylinder has to be behaving properly or no piston will work properly.

I just rebuilt the MC with Honda parts. The piston works when I clean it up for short periods.

[Simpson]

+1 on the phenolic piston; perfect fit, superb finish, $34 shipped. 

Where do I get one of these wonderful items?

[MCRider]

Few months ago, I purchased the more expensive replacement SS caliper piston from Yamiya. After seeing how chrome pitts over time it seemed like a good solution. Pitting leads to grabbing of the brake etc... So I order the 100 dollar piston and install.

http://www.yamiya750e.com/index.php?main_page=product_info&cPath=33_86&products_id=363

The last month of riding I have been noticing increased grabbing as time goes on. Finally last week my rotors are getting roasted and it has troubles riding 2up. Upon inspection in dis-assembly, the SS piston seems to have some scoring where the ring seal slides. I buff the piston and clean the caliper and it seems to be doing it again. Today I again, buff out the scratches on the piston, polish and clean the entire caliper. I'm starting to think I should have stuck with Honda original parts.

Thoughts or experiences?

Maybe you've addressed this, but its not obvious in your post...

What about the fluid return valve in your MC? THat is by far the biggest reason for pistons to grab or hang up.  THe piston itself is pretty benign and foolproof. Nice to have a better one, but the master cylinder has to be behaving properly or no piston will work properly.

I just rebuilt the MC with Honda parts. The piston works when I clean it up for short periods.

Its been a while since I've done one, so maybe someone else can add to this. But I don't think the act of replacing the parts will clear a blocked return valve. You actually need to stick a wire in the hole from the reservoir side and clear the passage. The test is to remove the cap and bladder, slowly squeeze the lever and upon releasing you should see a small current of fluid arise from that hole into the the pool of fluid.  A partial blockage could give the symptom you relate and cleaning the piston could cause it to work a little better for a while.

OCICBW but if your piston is as clean as you say, I can't see it being a problem. I've seen some pretty ugly ones that worked fine.

[Simpson]

Few months ago, I purchased the more expensive replacement SS caliper piston from Yamiya. After seeing how chrome pitts over time it seemed like a good solution. Pitting leads to grabbing of the brake etc... So I order the 100 dollar piston and install.

http://www.yamiya750e.com/index.php?main_page=product_info&cPath=33_86&products_id=363

The last month of riding I have been noticing increased grabbing as time goes on. Finally last week my rotors are getting roasted and it has troubles riding 2up. Upon inspection in dis-assembly, the SS piston seems to have some scoring where the ring seal slides. I buff the piston and clean the caliper and it seems to be doing it again. Today I again, buff out the scratches on the piston, polish and clean the entire caliper. I'm starting to think I should have stuck with Honda original parts.

Thoughts or experiences?

Maybe you've addressed this, but its not obvious in your post...

What about the fluid return valve in your MC? THat is by far the biggest reason for pistons to grab or hang up.  THe piston itself is pretty benign and foolproof. Nice to have a better one, but the master cylinder has to be behaving properly or no piston will work properly.

I just rebuilt the MC with Honda parts. The piston works when I clean it up for short periods.

Its been a while since I've done one, so maybe someone else can add to this. But I don't think the act of replacing the parts will clear a blocked return valve. You actually need to stick a wire in the hole from the reservoir side and clear the passage. The test is to remove the cap and bladder, slowly squeeze the lever and upon releasing you should see a small current of fluid arise from that hole into the the pool of fluid.  A partial blockage could give the symptom you relate and cleaning the piston could cause it to work a little better for a while.

OCICBW but if your piston is as clean as you say, I can't see it being a problem. I've seen some pretty ugly ones that worked fine.

I was hoping that the MC was the problem when I first started trouble shooting. The two connecting holes seem clear of blockage. When moving the lever I can see the piston moving through it, additionally I can see the current squirting up on release. The piston grabs less every time I clean it up. Right now, If I go in the garage the tire will move freely. If I pump the brakes a few times moderately, it releases fine. If I pump them average to hard for an extended time, like 5 seconds of more, they start to stick for 5-10 seconds... maybe more....

[Simpson]

This is killing me, because the rest of my bike seem to be running great and I would really like to be riding more....

[MCRider]

This is killing me, because the rest of my bike seem to be running great and I would really like to be riding more....

Sorry, I've known others with mysterious problems. Hard to diagnose from a distance. I guess you've replaced the rubber Oring in the caliper that the piston slides through? Its responsible for pulling the piston back away from the disc. Finally, you've adjusted the swinging arm properly so the slave pad has clearance?

I realize you've probably done all this, I'm just swinging for a hit here.

[Simpson]

This is killing me, because the rest of my bike seem to be running great and I would really like to be riding more....

Sorry, I've known others with mysterious problems. Hard to diagnose from a distance. I guess you've replaced the rubber Oring in the caliper that the piston slides through? Its responsible for pulling the piston back away from the disc. Finally, you've adjusted the swinging arm properly so the slave pad has clearance?

I realize you've probably done all this, I'm just swinging for a hit here.

Thanks much for the ideas!!! after battle in the garage, exercising it and bleeding (5 times), dis-assembly, replacing banjo washers, replacing leaky brake switch... Not that this should help in theory, but it "seems" to be working now???
 
Hopefully it hold for awhile

[Jerry Rxman Griffin aka MuthaF'er]

Did you put the correct lube in it?

[Simpson]

Did you put the correct lube in it?

Honda Brake Fluid Dot 3?

[Toxic]

+1 on the phenolic piston; perfect fit, superb finish, $34 shipped. 

Where do I get one of these wonderful items?

OK .... I'll be yet another person to ask... where do you get these?

[Really?]

Forum search for Phenolic turned up this http://forums.sohc4.net/index.php?topic=66881.msg736356#msg736356

[eurban]

Stainless as a concept is good.  I had a set of stainless pistons made up for my GL front end and they have worked beautifully for over 4 years.  I am not certain what grade was used.  Can you compare the original piston with the new one?  Compare the ODs, compare the OD in the seal groove, compare the width of the seal grooves and their location on the piston, compare the overall heights.  If things are different then pehaps that is where your problem lies.  If all this checks out then perhaps your replacement seal is out of spec or perhaps your brake pad (you put new ones on right?) is rubbing in its bore.  Too much paint on the pad base?
Sounds like you have already gone over the MC but just to make sure, there are two holes in the bottom of the resevior.  One is relatively large and one is relatively tiny.  Make absolutely sure that the tiny one is clear.  A small sewing needle should do the job.

[dusterdude]

interesting issue,its funny tho that stainless steel brakes corp has been making stainless piston conversions for corvettes for about 30 years or so.

[754]

I am starting to suspect either;
 Piston may be a bit bigger
 or, Crud in the groove (pretty hard to see) making the fit of the parts tighter than needed.

 Does piston appear to be same surface finish?..if it is a rougher surface it may not slide into running position properly..

[Loki]

email this guy, hes a member of the forum Kevin400F and i just bought my phenolic pistons off him.

kthunter01@sbcglobal.net

[Simpson]

I cleaned the groove out 4 times. Scrubbed with toothbrush and rags around it over and over. Replaced the seal with a new one. It seems to be working better for now. Maybe I have some crud in there acting an abrasive. I roasted a almost new rotor a tad.   From the sounds of it, SS should be a good solution and I need to sort out the issue. The rags did seem to pull out some discoloration. Just have to keep at it.

[Simpson]

email this guy, hes a member of the forum Kevin400F and i just bought my phenolic pistons off him.

kthunter01@sbcglobal.net

I like the sounds of this replacement part!