Getting reservoir off front master cylinder

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markjenn
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Getting reservoir off front master cylinder

Post by markjenn »

Hi, I've got a 1979 with front brake dragging issues. While I may need rebuilds of either the master or the calipers, I first want to be sure the small return hole in the master isn't plugged. Unfortunately the plastic reservoir sitting on top of the master cylinder assembly has two plastic tabs sticking out, one of which makes it impossible to get a straight shot down to poke the return pinhole with a fine wire. I figured the reservoir should just pop off, but I've huffed and puffed with no luck. I've got some plastic pry tools and have put some serious force into it, but I'm afraid I'm about to break something. Any trick to getting that damn reservoir to release?

Alternatively, if I had a very thin stiff wire that I could put a strategic bend into, I might be able to work around the tab in the way. Any source for a fine enough wire to probe the hole yet stiff enough to make such a bend? Usually I just use a strand from a wire wheel brush held with some needle-nose vice grips, but the strands aren't long and straight enough.

Any suggestions appreciated.

- Mark

steve murdoch icoa #5322
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Re: Getting reservoir off front master cylinder

Post by steve murdoch icoa #5322 »

You should be able to rotate the reservoir halfway which will allow you to get the small pry-bar/screwdriver underneath to pry it up.
Lots of good info here.
viewtopic.php?f=50&t=10696

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tevan
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Re: Getting reservoir off front master cylinder

Post by tevan »

The only way I have found to take them off fairly easy is with a heat gun. I always purchase a new reservoir with new oring once I take it off. I twist it a quarter of a turn and pry it off once warmed up. Of course once off the hole is straight down.

daves79x
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Re: Getting reservoir off front master cylinder

Post by daves79x »

As described, twist the reservoir about 45 degrees, then get the biggest screwdriver you have and pry it off. Position the screwdriver such that you are not marking up the m/c body. Also as stated before, if the reservoir is getting yellow and weather-checked, just get a whole new reservoir kit. In any case, you must replace the o-ring that holds it on. Honda still has them and you will have a leak there if you don't replace it.

Dave

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Re: Getting reservoir off front master cylinder

Post by Larry Zimmer »

Yep -- it takes some 'grunt'. But, that's all that is holding it. You won't break anything. Just be a bit careful, as Dave mentioned, to not bung up the m/c body.
Larry Zimmer
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markjenn
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Re: Getting reservoir off front master cylinder

Post by markjenn »

As always, great on-point advice. Thank you!

- Mark

markjenn
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Re: Getting reservoir off front master cylinder

Post by markjenn »

Front brakes no longer dragging, but I'm not sure what I fixed.

Once I had the reservoir twisted 90-degrees, I could get a straight shot at the the small secondary hole for return fluid. I managed to get a fine wire into it but not sure I could detect that it was clogged. Brakes remained very tight after doing this so I cracked the bleed nipples and was able to get the calipers off the discs. I then removed the pads, separated caliper from the carrier, and worked the pistons back and forth a few times by alternating using the brake lever and clamping with a c-clamp. Put it all back together with the pins re-greased and fresh fluid and it now seems fine. Perhaps the sliding pins were binding.

As an aside, I had a heck of a time loosening the bolts which work the sliding pins - they must not have been removed in 41 years. Took a couple cycles of using a heat gun and rapping on them to get them to let loose. Without heat and impact, I bet I would have stripped the allen heads getting them off.

- Mark

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Re: Getting reservoir off front master cylinder

Post by daves79x »

Again, not to throw cold water, but you'll continually have brake issues if you don't just break down the whole system, clean and inspect everything and likely replace some rubber parts, maybe even caliper pistons if pitted. Good time to consider replacing the brake lines too. Do it right once and change brake fluid every two years and you won't have brake problems.

Dave

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Re: Getting reservoir off front master cylinder

Post by sixofsix »

Yup Dave, you're spot on. The brake system needs to be broken down and inspected. Every 10 years or so you will need new pistons and brake lines and master cylinder overhaul. It is way more calming to KNOW what condition your brakes are in while riding. And this includes the brake spindle re-greasing on the rear and full cleaning of the caliper pins and re-greasing so they just float easily. Nothing like a CBX with good brakes and knowing you will stop when you use them. Sounds basic but lots of folks ride around not knowing what shape every component of the brake system is in including front and rear brake switches. Safety is paramount whilst riding our 40 year old CBX's. Ride those CBX's, they are well engineered!

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