Front brake caliper piston

[florence]

I have stripped my front brake and, yet again, the piston has gone rusty and needs replacing.  This is something I have replaced about three times now, all for the same reason.  Admittedly, I do ride my bike all year round so I'm sure the road salt doesn't help, but, does anybody know of a way of protecting the piston from the elements but which does not ruin the seal?  I was thinking of, maybe, a silicon grease or something but do not want to experiment with something as important as brakes!  Any ideas would be appreciated before I put the thing back together again.

[SteveD CB500K0]

There's a guy on the US site who makes these from phenolic resin.

I believe that he buys Nissan parts and turns them down to the Honda spec.

Steve

[UK Pete]

They do stainless steel ones for the 750, it might be worth try to find some for your 550, other than that regular caliper removal and regrease everything with brake assemley grease
Pete

[totty]

These guys have been recommended to me by several people, they don't list the 550 but they don't list a Scimitar either and they do pistons for them so they may be worth a call http://www.ssbrakepistons.com/

[Seamus]

Careful with stainless steel as some grades are attached by salt.

[Yoshi823]

I was surprised to not see a piston kit from these people... http://www.wemoto.com/bikes/Honda/CB_550_F_F1_F2/75-80/

But the OEM part shouldn't rust quickly...Dave Slivers do them http://www.davidsilverspares.co.uk/parts/part_62213/

[florence]

Thanks for that.  I did order mine from Dave Silver and it's on the way.

I have found they rust all too easily.  It only needs to be a small spot of rust in the working area and then I don't trust it.  Maybe I'm being too careful?

[Spitfire]

I replaced the piston in my CB750F1 with a stainless one from a guy on US eBay, the front brake piston for the CB750F1 are very difficult to source, I went the stainless route so I would not have to do it again. The back of the piston and caliper I lightly cover with silicon brake grease (from Brembo).
If there is rust on the contact area with the seal then it will not "heal up" so best to replace it

Cheers

Den

[Yoshi823]

Is the piston dust seal damaged on the caliper?

I thought that the piston for the 750F1 would be the same for the similar calipers on the 750K7, 550F1 & F2, 500T etc etc?
http://www.davidsilverspares.co.uk/parts/part_52251/
http://www.davidsilverspares.co.uk/parts/part_62213/
http://www.davidsilverspares.co.uk/parts/part_61411/
http://www.davidsilverspares.co.uk/parts/part_13841/

[Spitfire]

Unfortunately the F1 front brake piston is different, I checked out the brakes on late CB750's and came up with a chart showing interchangeabilty, the K7 and K8 are the same piston but no one had them at the time I was putting mine together. The caliper itself is also fairly elusive,so I have a spare refurbisheed one in the loft.
http://www.sohc.co.uk/index.php?topic=1562.0

Cheers

Den

[Yoshi823]

That's interesting...i'd like to see what the differance is between the two types of pistons then. I wonder if it's just something like the dust seal groove in the piston, or a part that isolates the piston from the heat of the pad under heavy braking.

Wemoto do a stainless piston kit though... http://www.wemoto.com/bikes/Honda/CB_750_F_F1/76-77/

From what I can see from the pictures the internal part of the 750F1 piston is hollow, as against the solid looking item for the 250/400/500/550 Honda piston.

I reckon I can make a 750F1 piston if I had an original, together with a 400/500/550 one. I have my big lathe working now so this manufacturing this wouldn't be difficult.

[Seamus]

There was a similar thread on the US site
http://forums.sohc4.net/index.php?topic=66855.0

Probably worth a read

Cheers

Seamus

[Spitfire]

Just looked through some of my old posts on this site and the US one and back then I also found a site that stocked brake pistons. You ordered by size rather than make and model, the one I got looked good but I went the stainless route instead.
There is a photo of the new piston alongside the original F1 piston in the thread as well.

http://forums.sohc4.net/index.php?topic=23037.msg244536#msg244536

Cheers

Den

[captaindonutbikes]

i just got hold of one of the phoelic pistons from Kevin is the us. that coupled with a reconditioned caliper and a new brake seal should see me right.

[florence]

Sounds good...

I put my caliper back together with a standard piston in the end.  I then went to bleed the brakes and the bleed nipple snapped off which made me rather cross.  However I have found someone who can remove them with acid which does not damage the aluminium.  I don't know if others have heard of this and if it is useful?  i expect you know about it already.