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Discussion Starter · #1 ·
As I have mentioned in a previous post, I got a bike for cheap that has been sitting for a couple decades. I finally get around to ordering a new set of cheap levers to get it running again and I encounter the outcome of the master cylinder reservoir not having a cap on it for forever, and the banjo bolt on the caliper not being connected. Needless to say, I'm replacing everything.

But with the expense of a replacement caliper, I would instead like to rebuild it. My plan is to use a C clamp to get it unstuck from its mid range position, then fill the system with brake fluid and pump it to its closed position. Then I would like to replace the seals.

I've seen a few posts that talk about which seals to use, as I would prefer not order pistons unless necessary.

Does anyone have a LINK for recommended seals for rebuilding the caliper, both with and without pistons?

Also possibly a link for a banjo bolt? As that was missing from the caliper.
 

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82 GL500, 78 CX500
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As I have mentioned in a previous post, I got a bike for cheap that has been sitting for a couple decades. I finally get around to ordering a new set of cheap levers to get it running again and I encounter the outcome of the master cylinder reservoir not having a cap on it for forever, and the banjo bolt on the caliper not being connected. Needless to say, I'm replacing everything.

But with the expense of a replacement caliper, I would instead like to rebuild it. My plan is to use a C clamp to get it unstuck from its mid range position, then fill the system with brake fluid and pump it to its closed position. Then I would like to replace the seals.

I've seen a few posts that talk about which seals to use, as I would prefer not order pistons unless necessary.

Does anyone have a LINK for recommended seals for rebuilding the caliper, both with and without pistons?

Also possibly a link for a banjo bolt? As that was missing from the caliper.
You might try soaking the caliper with some penetrating oil and let it soak anywhere from twenty-four to forty-eight hours. That worked for me with an early 78/79 mastercylinder. The caliper piston might then come out with some compressed air. Try it safely though.
 

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Discussion Starter · #3 ·
You might try soaking the caliper with some penetrating oil and let it soak anywhere from twenty-four to forty-eight hours. That worked for me with an early 78/79 mastercylinder. The caliper piston might then come out with some compressed air. Try it safely though.
Won't that dissolve the seals some?

And do you have a link for the seals you used?
 

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Won't that dissolve the seals some?

And do you have a link for the seals you used?
As far as the seals and even the hose, I'd get kits to replace all the seals on the caliper and rebuild the cylinder. The hose you might be able to find information in the tech forum for getting either an actual new replacement hose for that year, or the parts to fabricate one of your own. I am in the process of rebuilding the caliper and cylinder off a 78 and I do plan on replacing all the seals and hose for it. I really can't see the need to take a chance on something that is well over thirty years old.
 

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Discussion Starter · #6 ·
As far as the seals and even the hose, I'd get kits to replace all the seals on the caliper and rebuild the cylinder. The hose you might be able to find information in the tech forum for getting either an actual new replacement hose for that year, or the parts to fabricate one of your own. I am in the process of rebuilding the caliper and cylinder off a 78 and I do plan on replacing all the seals and hose for it. I really can't see the need to take a chance on something that is well over thirty years old.
The kit is what I’m curious about. Which kit you’re using?
 

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if its really stuck a trick I've used a few times is putting a grease fitting where the bleed screw goes then using a grease gun to pump it out. works like a charm just a bit mess clean up.
 

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If using compressed air to pop out a piston I always put shims (like worn down brake pads) in the caliper so that the piston can only come out a little at a time. Pistons pop out with a lot of force, and any stray brake fluid will spray out, too, so cover the caliper with a rag. You may want to invest in an female 1/8" NPT to male M10x1.25 so you can hook up a quick connect to keep your fingers away from anything that could pinch you. This will also let you hook up a grease gun.

My CX's and CB's have all been rebuilt using Brakecrafters kits you can find on ebay or from their website. I even had a problem with how one of their stainless steel pistons was manufactured for my Yamaha FZ700 and I ended up sending out my old pistons for them to reproduce, at no cost to me besides shipping!
 

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Discussion Starter · #10 ·
if its really stuck a trick I've used a few times is putting a grease fitting where the bleed screw goes then using a grease gun to pump it out. works like a charm just a bit mess clean up.
I was able to squeeze them open with a c clamp. Rust mud came out the inside.

Does anyone know where to get brake pads? I seem to only have 1.
 

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Discussion Starter · #12 ·
Ebay, David Silvers for the pads.

I rebuilt a pair last night. The pistons were good so were reused. Ditto the seals.

How do your parts look?
I dont have a picture handy, but the caliper sat with the banjo bolt out for years i'm sure, and 2 winters outside. With a tarp. But weather surely played a role on the brake caliper.
 

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'84 CX650E that is evolving into a GL500
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My plan is to use a C clamp to get it unstuck from its mid range position, then fill the system with brake fluid and pump it to its closed position. Then I would like to replace the seals.
Push the piston into the caliper just enough to lift it off of the disc to minimize damage to the bore from debris that gets past the seals.

I don't advise using air to remove brake caliper pistons unless you have absolutely no other choice. I use an old master cylinder with a short brake line for pumping the pistons out (when I change brake fluid or bleed brakes I save the old fluid in a clearly marked bottle so I can use it for this - no sense wasting clean fluid if you don't have to), shown below removing the pistons from a 2 piston caliper from a later model. When I can't get one to budge that way I have a banjo bolt with a grease fitting (zerk) that I use to pump grease into the caliper (I prefer this to screwing the zerk into the bleed screw hole).
207577


Once the piston(s) are out clean them thoroughly and if the chrome is intact you can re-use them but if there are any pits in the surface expect to buy replacements. You also need to clean the inside of the caliper thoroughly, including the grooves where the rubber parts go (those must be surgically clean).

I've re-used old rubber parts in the past but I have learned that it is usually false economy because the old rubber is no longer flexible enough to keep moisture out so they need to be rebuilt again sooner.

I can't recommend a kit for your caliper (all of mine are 2 piston) but I bought an Italyracing brand kit on eBay the last time and as far as I could tell the parts were as good as the genuine Honda ones I've had for a fraction of the cost and it even included a bit of red grease for assembling them (if you don't have that silicone grease is the recommended lubricant for all of the brake parts, including in the grooves for the rubber rings and a thin application on the piston to help it slide in)(no, it doesn't contaminate the brake fluid).
 

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The kit is what I’m curious about. Which kit you’re using?
You can check several sources such as 4into1, Partzilla, and others. For some reason there is supposed to be a difference in the master cylinder from 78 to 79. But I haven't figured that out yet. So far I haven't found any differences. But there is a big price difference between a kit for a 78 and a 79 master cylinder.
 

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If using compressed air to pop out a piston I always put shims (like worn down brake pads) in the caliper so that the piston can only come out a little at a time.
This is my process for dual-piston calipers, too. If you just blow one out with air, there's no resistance to move the other.
Start with a 1x board, then a wood shim, finally a metal putty knife. By this point, you can usually pull the pistons out by hand.
 

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That wouldn't have worked for most of the 2 piston calipers I've rebuilt. You need to make sure you don't pop the first one out until the 2nd has moved most of the way out.
You pretty much repeated what Randall said so I bet it would’ve worked on the calipers you rebuilt.
 

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I like the single pot calipers, both 38 and 43 mm.

The twinpots have garbage weather protection and seem to need rebuilding every 5 minutes.

Most twinpot CXs I've ridden had garbage brakes. I suspect because many have one seized piston.
 

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I've learned how to make them pretty reliable in bad conditions. And in years past I've rebuilt single pot calipers in the fall and had them start sticking before spring because water got inside the boot and couldn't get out (Suzuki calipers but I don't imagine Honda single pots would be much better).

But all this talk about 2 piston calipers is irrelevant to dhoepp's '79.
 
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