Is this caliper salvageable?

EdwardC · Jun 11, 2015

I'm helping a friend with an old '79 CB650 that's having some issues with the front brakes locking up. I pulled off the front caliper and notice the there's a lot of crusty yellowish-brown build up around the boot. I can easily take the boot off. I pop out the piston and there's more crusty build up. It looks like there's some kind of corrosion on the caliper around the inner seal. The metal doesn't seem totally pitted, but it's pretty grungy. I used a pick and lightly scraped out some of the build up.

This is my first time doing something like this, is the caliper toast? Can I clean it, get a new seal/boot and reinstall it?

If it's usable, any suggestions on cleaning?

Thanks for any comments!

Trav · Jun 11, 2015

The bore looks sketchy. As a rule i don't rebuild calipers on motorcycles, to me its not worth the risk.

cashmoney · Jun 11, 2015

Replace the caliper - in most cases rebuilt or even new calipers are available at reasonable cost.

Robenstein · Jun 11, 2015

Originally Posted By: Trav
The bore looks sketchy. As a rule i don't rebuild calipers on motorcycles, to me its not worth the risk.

I agree...the same reason I don't patch tires on bikes. If something goes wrong and the repair fails, the consequences are much worse on two wheels versus four.

Look around for a good used one or a rebuilt.

FastGame · Jun 11, 2015

I'm with the replace the caliper guy's.

EdwardC · Jun 11, 2015

Thanks guys! I'll look for a replacement. I felt the same way, brakes aren't something I want to take any risks on.

Apparently the 1979-81 CB650s are kind of an odd bird, but I think I found that parts from a CX500 will fit. Off to the Bay I go.

Thanks again.

Kuato · Jun 11, 2015

Motorcycle front brake already locking up?

Replace!

CT8 · Jun 11, 2015

The piston is the sealing part. On a M/C without a second thought I would spend the $$$ for a new caliper. May as well change the Master cyl while the wallet is open . Brakes are important.

EdwardC · Jun 11, 2015

Oh yeah, master cylinder and new stainless brake lines are already ordered.

To be honest, I think that the locking issue is more the master cylinder. I opened the cap and there were little black floating chunks in it, I assume the passages were clogged. It had the original rubber hose too, complete with a 12/78 date printed on the side.

I found a replacement caliper on eBay, my only concern is that it's still a risk, the listing says its from a working bike, but who knows the actual condition.

Thanks again!

Trav · Jun 11, 2015

Thats the risk with used parts, it could be really good or a dog. All you can do is wait and see.

Donald · Jun 11, 2015

The cylinder in a caliper is just cast iron. It can be honed. But the piston is usually plated. If the plating is worn or pitted, the piston needs to be replaced during the rebuild.

Smoky14 · Jun 12, 2015

I've rebuilt a lot worse, let your skill level be your guide.
Smoky

EdwardC · Jun 12, 2015

Originally Posted By: Smoky14
I've rebuilt a lot worse, let your skill level be your guide.
Smoky

I think I might do it just to see if I can. I have a replacement on the way, but I'll try clean out the bore and see how it looks.

Any tips on cleaning it out? I'm thinking steel wool/high grit sand paper. The seal grooves are the tough part though.

Robenstein · Jun 12, 2015

I am not a fan of steel wool. If you have an O Reillys around get a couple of the 3m hand pads. One maroon and one grey. They wont leave behind little shards. They are pretty cheap too and last forever.

EdwardC · Jun 12, 2015

That's a good call, I'll grab some of those synthetic scouring pads, does sound like a better idea than steel.

Might try a brass wire brush for the grooves, maybe a brass wire wheel on a dremel.

I'll probably try a couple parts washes too, maybe even a simple green soak. some of the gunk seems to be just a dried build-up that can be scraped off.

BigCahuna · Jun 12, 2015

They sell a hone for brake cylinders. Works just like the cylinder ones. The cylinder is what you need to have clean without corrosion or pitting. You can use emery paper for the groves as they just need to not have any crust buildup on them. Kits are for sale on Ebay. Used calipers might be in the same shape as what you have.,,

EdwardC · Jun 12, 2015

I suppose now that I'm thinking about cleaning the caliper, I get the piston looked at for viability. It is overall in very good shape, but it has definite pitting, the dark spots in the picture are into the metal..

What do you guys think, would this be usable?

FastGame · Jun 12, 2015

I think that piston is fine, I would use it until it proves otherwise.

cashmoney · Jun 13, 2015

Given the bike's age I might try to see if there are any modern upgrade parts that might fit that front end. The 70s-early 80s stock disk brake systems on most MCs were pretty bad - very grabby and not linear in application.

BusyLittleShop · Jun 13, 2015

The choice is your friends but that caliper can be rebuilt...
its always better to rebuild a known part than taking a carp
shoot with a salvaged part which may require rebuilding...

1)Soak the caliper with mineral spirits...

2)Replace the caliper seal and boot...

SEAL 45215-533-004 $13.50
BOOT 45109-425-003 $10.58
http://www.ronayers.com/oemparts/a/hon/50bfe5d6f87002341cac0edf/front-brake-caliper

3)Assemble the caliper and test for leaks...

Is this caliper salvageable?

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