Topic: Interchangeable Brake Pistons

[cafe69]

Does anyone know if any other brake pistons from any other make/model will interchange with the piston from a '76 CB550 K? Mine are badly pitted and I don't think I would like to chance reusing them. I am also not wanting to spend a fortune on NOS if I don't have to. I have seen that some of the other models are not quite as expensive.

I tried the archives, but I can't get the page to open---something about the server being busy. Been that way for a couple of days.

Thanks in advance

Butch

[n9viw]

I don't know if this one will work, it may be too big, but what an excuse to go with the bigger 750 brake caliper! Stainless steel piston:
http://cgi.ebay.com/ebaymotors/Honda-CB750-K-CB-750-450-CB450-new-brake-caliper-piston_W0QQcmdZViewItemQQcategoryZ35592QQitemZ4607008026QQrdZ1QQsspagenameZWDVW

[csendker]

Nope, won't work.  I already tried that route - I e-mailed him and got this response:

"Response from dgs38 
Item: Honda CB 750K 750F 750A 750 K F A brake caliper piston (4606489189)
This message was sent while the listing was active.
dgs38 is the seller.

The piston in the auction will not work. I have a brand new Honda piston for your bike: $59.95 plus $4.95 s/h. Doug"

DSS has them for 22 pounds ($39.26), but you have to pop for shipping across the pond (rashly assuming you're in the USA).
 
 
 
 
 

[cafe69]

Thanks for the info. I have looked at all the suppliers and the cheapest I found was at CMS for 50.00 each. I may possibly have another route ! I was talking to one of my fellow employees at work. He runs a CNC lathe out on the floor and is more than happy to help me out by making them out of 303SS. Does anyone know if making them out of solid SS would create a problem? They will be heavier than the originals as they are hollow.

If this turns out to be successful, I would be more than happy to make a few extra sets. I could possibly offer them quite cheap as my CNC lathe man says he could make them out of drops that would normally go into the scrap bin.

Again thanks for the info so far.

Butch

[csendker]

I'm interested!  Mine is toast, so I'm looking for one also, and found they're damn expensive.  I think the closer to the original weight, the better.  The original ones are actually 'cups' with some sort of plug on the open end (at least the one that came out of mine is).  An earlier thread of mine had some discussion as to wether or not the cap is required.  Seems not, just use it open-ended.  I don't know if your guy can mill the inside to match the weight.  I also think the 'dimple' on the working end is important.  Either way, make sure he saves the CNC program; you could make a side business out of this - the guy on e-bay did.

[oldbiker]

If you have a look at yahoo group CB400f forum, there is a guy called Kevin Hunter selling Phenolic pistons for about $24. I haven't used one myself but I've seen plenty of thank you's from people who have bought them.

[dusterdude]

stainless will work fine,the corvette crowd has been doin that for years

[n9viw]

They're supposed to be hollow? Heck, maybe that's why my brakes are so mushy- mine's solid steel! 
Seriously, if you could make them out of hollowed out 303, that's less mass to move, which should provide more force. The pistons on my '83 CB550SC (dual piston front caliper) are hollow, they look like they're either milled aluminum or cast steel. The 'cup' faces the brake pad, so you don't have any more or less volume than with a solid piston. I think Honda went with solid pistons on their early bikes because, let's face it- cutting a chunk off a solid rod of steel and rounding the edges is much cheaper than actually milling or casting a cupped piston.

[csendker]

There's a picture of mine lower in this thread.  Here's the stainless steel kit (for 750's, not 550's) for sale on e-bay.  Note the hollow piston.  The picture of mine insinuates it may be hollow with some sort of cap pressed in.  It is kinda heavy though.

[cafe69]

Sounds like plenty of interest. I will give it a try with the stainless, both hollow and solid.  Hope to get some done this weekend. I have also looked into the phenolic route. I just have to find the right plastic. This is also quite inexpensive if you get the right material. Some of the plastic can be over 200.00 a foot!!   I will keep everyone posted.

Later
Butch

[volz1fsu]

cafe69,
I'm also interested!!

[dusterdude]

my honda piston is hollow that has a metal cap on the end.

[Bob Wessner]

my honda piston is hollow that has a metal cap on the end.

Hmm, this all sounds so familiar. 

[csendker]

Phenolic piston material: http://www.durez.com/product.pdfs/phen.mold.comp/pmc.tech.overview.pdf 

It actually references 'disc brake caliper pistons' in the spec sheet.  I have no clue where to get this stuff or how much it costs in real life ($0.0037/in³ is referenced).  As for the SS attempt, obviously the diameter and length are the top priority, with the working end dimple and weight secondary.  My gut tells me the dimple is probably #2 and weight #3 if there needs to be a ranking.  I suspect the phenolic application doesn't weigh nearly as much as the OEM it replaces.

[csendker]

Sounds like plenty of interest. I will give it a try with the stainless, both hollow and solid.  Hope to get some done this weekend.

cafe69:  Any luck? 

[cafe69]

Well, I finally got a set made. I think they turned out quite well, I don't have any pics at this time. I used some 303SS precision ground material. The piston diameter turns out to be 1.500 and is 34mm (1.339) long. I purchased 12" for about 35.00 US, and should be able to get about 6 more pistons out of that bar. The CNC lathe was actually pretty busy all week, so I took it over to the old engine lathe and did them the old way!

I can make about 6 more of them. I will get them made before I offer them to anyone. Should only be a couple of weeks. And I will try to get some pictures on here so you can see what they look like. Took about an hour to make manually. About a tenth of that once the CNC is cutting them. I will let everyone know when I get them done. Thanks for the intrest.

Butch