Topic: Front Brake Caliper - Stuck Piston/Brake Pad

[ZTatZAU]

Thanks for all the helpful suggestions.  I already had a set of the $13 pads in my 4into1 shopping cart; thanks Willbird!  I'm trying to decide what else I'll need before placing my order on Monday.

What do you all thing about caliper pistons?  Does any amount of pitting warrant the replacement of the piston?

And RE: the caliper piston seal... Is the $10 Honda seal any better than the $5 aftermarket seal? 

After a little soaking, pumping, and flushing with some fresh DOT3, my front brake master cylinder is once again pumping clean fluid to a drain pan under the caliper end of the lower brake line.  None-the-less, I plan to order a master cylinder rebuild kit, to have on hand, just in case.

Can anyone share their experience and satisfaction with the any of the following 4into1 MC rebuild kit options?

Generic Reproduction Brake Master Cylinder Rebuild Kit - 45530-377-305 - CB360 CB400F CB450 CB500T CB550 CB750  $19.95

K&L Brake Master Cylinder Rebuild Kit - Honda CB360 CB400F CB500T CB550 CB750  $32.95

Genuine Honda - Brake Master Cylinder Rebuild Kit - 45530-377-305 - CB360 CB400F CB450 CB500T CB550 CB750  $54.95

Do you really get what you pay for on these rebuild kits?  Or is one just as good as another?

BTW:  I'm now back on cleaning my caliper seal groove.  I thought it looked pretty clean; but after all the emphasis, I checked the slot again with a good light and a mirror.  Sure enough, there's still some crud in spots down along the near side bottom corner of the groove.

I appreciate the expert tutelage around here!
ZT

[bryanj]

I wont accept any pitting and fit stainless, never had a problem with any make of caliper piston sel, as to master i am told by a respected uk 750 guy that tourmax make the Honda ones.
Somebody recently asked about rear wheel bearing retainer tool for a 500 and i posted a uk firm that do all the special tools plus stainless caliper pistons with or without seal of which i have used a lot of 500/550/400/etc with no problems

Looked it up

Honda-classics.co.uk

[ZTatZAU]

I wont accept any pitting and fit stainless, never had a problem with any make of caliper piston sel, as to master i am told by a respected uk 750 guy that tourmax make the Honda ones. ...

Thanks for the info Bryanj.  I read a bit about stainless and phenolic caliper pistons and may consider a SS piston rather than the common aftermarket replacements.
ZT

[bryanj]

Well brakes are rather important and you only have one kneck!

[ZTatZAU]

Moved to new thread...
"Brake Caliper Assembly Lube - Again"
ZT

[willbird]

Unless you are dead set on an OEM master I'd suggest just using a complete new repro rather than trying to rebuild the original. Put it on the shelf with a tag on it for later generations :-). This may be sacrilege :-). I got my master apart ok but the 4:1 piston was .001" or more bigger than the bore in the master. Tried to swap the new seal onto the old piston and managed to destroy the delicate little check valve on the end of the piston. I had painted my original master back in early 1990's so it was not anything minty fresh anyway and that played into my decision.

Ordered a new 4:1 master and installed it.

Bill

[dave500]

im with Bill willbird,an old #$%*ed up long sitting corroded well beyond its use by date master cylinder is gonna be a bastard to take apart for a start and maybe an unreliable unit once serviced?ive done plenty and looking back now id just jump straight to any unit with a smaller bore to give better clamping on the disc,if you really want that factory look get a repro if yours is well corroded and youve never done this sort of repair before,save yourself the hassle and ride a safer bike?truely.

[Stev-o]

im with Bill willbird,an old #$%*ed up long sitting corroded well beyond its use by date master cylinder is gonna be a bastard to take apart for a start and maybe an unreliable unit once serviced?

+1...most of us just buy a new master rather than rebuilding.

[ZTatZAU]

Thanks guys!

Unless you are dead set on an OEM master I'd suggest just using a complete new repro rather than trying to rebuild the original... Bill

im with Bill willbird, ... id just jump straight to any unit with a smaller bore... (or) get a repro if yours is well corroded... truely.

...
+1...most of us just buy a new master rather than rebuilding.

I do appreciate the advice but I'm not really planning to open up my OEM M/C unless it comes to that; in which case, I have an aftermarket rebuild kit, new banjo bolt, crush washers, and a rubber boot on hand.  So, I may just discover the validity of your advice for myself.

As I mentioned earlier... I filled the M/C reservoir with fresh DOT3 and after a little soaking, pumping, and flushing with  DOT3, my front brake master cylinder is once again pumping clean fluid to a drain pan under the caliper end of the lower brake line.  Each pull of the brake lever produced a nice stream of fluid into the drain pan and I could feel at least a partially pressurized system at the lever with my finger over the open end of the brake line.

Once it's all back together, and I get to bleeding the system, I should know if the M/C functions properly, needs attention, or perhaps, a replacement.

Thanks again for your replies!  ZT

[willbird]

Thanks guys!

Unless you are dead set on an OEM master I'd suggest just using a complete new repro rather than trying to rebuild the original... Bill

im with Bill willbird, ... id just jump straight to any unit with a smaller bore... (or) get a repro if yours is well corroded... truely.

...
+1...most of us just buy a new master rather than rebuilding.

I do appreciate the advice but I'm not really planning to open up my OEM M/C unless it comes to that; in which case, I have an aftermarket rebuild kit, new banjo bolt, crush washers, and a rubber boot on hand.  So, I may just discover the validity of your advice for myself.

As I mentioned earlier... I filled the M/C reservoir with fresh DOT3 and after a little soaking, pumping, and flushing with  DOT3, my front brake master cylinder is once again pumping clean fluid to a drain pan under the caliper end of the lower brake line.  Each pull of the brake lever produced a nice stream of fluid into the drain pan and I could feel at least a partially pressurized system at the lever with my finger over the open end of the brake line.

Once it's all back together, and I get to bleeding the system, I should know if the M/C functions properly, needs attention, or perhaps, a replacement.

Thanks again for your replies!  ZT

My master worked fine but it leaked, did not really confirm that until the caliper was fully rebuilt and being used.

Bill

[ZTatZAU]

...
That is the fitting that NAPA had, and I have a 1/8 NPT grease zerk threaded into it. I just left it in the caliper when I sand blasted and painted the caliper.

RE: Painting K1 calipers... As most here know by now, I'm just starting my CB750 apprenticeship as I resurrect the K1 I bought new in 1971.  I'm not presently going for a full-on original restoration but, IIRC, the K1s and perhaps the K0s front calipers were black; whereas later 750 calipers were not painted. (Or at least not painted black!)

My black calipers were no longer completely black having lost some of the black finish over the years.  Now, as I'm rebuilding the front caliper, I've found that the brake cleaner I'm using is removing more of the black paint so I just continued spraying and brushing to remove all of the remaining black exterior finish.

My question is, is it advisable to run these (stripped) calipers without any refinishing and not worry about accelerated (or inevitable) corrosion of the bare aluminum finish?  Or should I repaint them, as a matter of course, not so much to appear as K1 original, but rather to protect them from corrosion?

If the latter, what prep, primer, and paint product is recommended.  I assume Willbird's sandblasting was necessary to remove at least some amount of corrosion, whereas the exterior of my calipers don't appear to be corroded at all.  Should I run 'em or paint 'em?

Advice and suggestions are welcome!  ZT

[willbird]

...
That is the fitting that NAPA had, and I have a 1/8 NPT grease zerk threaded into it. I just left it in the caliper when I sand blasted and painted the caliper.

RE: Painting K1 calipers... As most here know by now, I'm just starting my CB750 apprenticeship as I resurrect the K1 I bought new in 1971.  I'm not presently going for a full-on original restoration but, IIRC, the K1s and perhaps the K0s front calipers were black; whereas later 750 calipers were not painted. (Or at least not painted black!)

My black calipers were no longer completely black having lost some of the black finish over the years.  Now, as I'm rebuilding the front caliper, I've found that the brake cleaner I'm using is removing more of the black paint so I just continued spraying and brushing to remove all of the remaining black exterior finish.

My question is, is it advisable to run these (stripped) calipers without any refinishing and not worry about accelerated (or inevitable) corrosion of the bare aluminum finish?  Or should I repaint them, as a matter of course, not so much to appear as K1 original, but rather to protect them from corrosion?

If the latter, what prep, primer, and paint product is recommended.  I assume Willbird's sandblasting was necessary to remove at least some amount of corrosion, whereas the exterior of my calipers don't appear to be corroded at all.  Should I run 'em or paint 'em?

Advice and suggestions are welcome!  ZT

I had painted mine back in 1992 or so, for me blasting the outside and re painting it was an appearance issue.

Even if your anodizing has faded you can test the surface with a multimeter set on ohms, the color is decorative, if the actual anodizing is still doing it's job the anodized surface will not conduct electricity.

The decorative color is just a dye.

Bill