I was in the process of rebuilding a front brake master cylinder tonight, and as I was walking the seal up and over the piston into its groove...it SNAPPED. I've never had one do that before.
So that's a $25 rebuild kit in the trash, and now I have to wait a week to get another one. Of course they don't sell just the seals on their own, I have to order a whole new kit.
Simple recommendation - hindsight is also wonderful. Before you install the next one - drop it in a cup of hot water and leave it for a few minutes - fish it out- then install it - the heat will make the seal a little bit more supple - a few drops of brake fluid on the piston will also aid installation.
But - sorry to hear you had a "blue" moment - I think we all get them from time to time - mine are quite frequent when I stuff things up - and there is no one else to blame (not within earshot anyway).
Simple recommendation - hindsight is also wonderful. Before you install the next one - drop it in a cup of hot water and leave it for a few minutes - fish it out- then install it - the heat will make the seal a little bit more supple - a few drops of brake fluid on the piston will also aid installation.
But - sorry to hear you had a "blue" moment - I think we all get them from time to time - mine are quite frequent when I stuff things up - and there is no one else to blame (not within earshot anyway).
cheers
I always lubricate with brake fluid, but I came to the same conclusion as you - I was doing this while sitting in my cold garage, my mistake was not warming the thing up first. I should have clued in when it was so much harder to get the thing on than it usually is.
I would expect any good auto parts store or hydraulic parts supply house would have O-Rings in stock and should be able to match one up, need to measure the width and match up OD and ID, just make sure to tell them it being used in brake fluid so they can select a proper material.
Steve K
Edgewater, FL
And the Lord said. "Thou shalt have dominion over all of the animals, except of course the cat."
M61A1MECH wrote: ↑Sat Oct 20, 2018 10:09 pm
I would expect any good auto parts store or hydraulic parts supply house would have O-Rings in stock and should be able to match one up, need to measure the width and match up OD and ID, just make sure to tell them it being used in brake fluid so they can select a proper material.
It's not an O-ring, unfortunately. It's a very specific seal made for this application: It is closed on one side, open on the other, and the outer edge is chamfered, so one side is smaller than the other. This makes it act as a pump inside the chamber when you pull the lever.
You can see one installed on a GL1100 piston here:
M61A1MECH wrote: ↑Sat Oct 20, 2018 10:09 pm
I would expect any good auto parts store or hydraulic parts supply house would have O-Rings in stock and should be able to match one up, need to measure the width and match up OD and ID, just make sure to tell them it being used in brake fluid so they can select a proper material.
It's not an O-ring, unfortunately. It's a very specific seal made for this application: It is closed on one side, open on the other, and the outer edge is chamfered, so one side is smaller than the other. This makes it act as a pump inside the chamber when you pull the lever.
You can see one installed on a GL1100 piston here:
That sounds like and looks like what is called a lip seal, most O-ring manufacturers like Parker and Apple make them, I doubt it is special size just for Honda, designers and engineers normally design hardware around existing seal designs, for the price of the rebuild kit, it worth a look see.
Steve K
Edgewater, FL
And the Lord said. "Thou shalt have dominion over all of the animals, except of course the cat."
M61A1MECH wrote: ↑Sun Oct 21, 2018 1:20 pm
That sounds like and looks like what is called a lip seal, most O-ring manufacturers like Parker and Apple make them, I doubt it is special size just for Honda, designers and engineers normally design hardware around existing seal designs, for the price of the rebuild kit, it worth a look see.
That's exactly right. But finding the right diameter, inner diameter, thickness, chamfer angle, material...I don't have the specs, and I wouldn't want to take the measurements off the old worn one (or the new, broken one).
Are there no part numbers on the seal for you to google?
I was trying to find a seal kit for a Maggura master cyl' and, very usefully, the seals had part numbers on them.
Sidcar wrote: ↑Mon Oct 22, 2018 2:45 am
Are there no part numbers on the seal for you to google?
I was trying to find a seal kit for a Maggura master cyl' and, very usefully, the seals had part numbers on them.
Sid
Nope. There was a part number on the plastic bag that it came in, but that didn't match anything I could find.
Verily it would seem thou art stuffed!
Still, as I say through gritted teeth when I hand over another small fortune for a motorcycle part,
"It's only money"
Motorcycle: 1977 Honda 550K. Sold. 1986 1200 Aspencade. Purchased as a non current brand new in the box 1988. Sold. 2006 1800 Goldwing 2017 BMW 1200 GS Adventure...
Simple recommendation - hindsight is also wonderful. Before you install the next one - drop it in a cup of hot water and leave it for a few minutes - fish it out- then install it - the heat will make the seal a little bit more supple - a few drops of brake fluid on the piston will also aid installation.
But - sorry to hear you had a "blue" moment - I think we all get them from time to time - mine are quite frequent when I stuff things up - and there is no one else to blame (not within earshot anyway).
cheers
I always lubricate with brake fluid, but I came to the same conclusion as you - I was doing this while sitting in my cold garage, my mistake was not warming the thing up first. I should have clued in when it was so much harder to get the thing on than it usually is.
Next time try getting permission to do simple rebuilds inside where its warm at the kitchen table...ha!
Simple recommendation - hindsight is also wonderful. Before you install the next one - drop it in a cup of hot water and leave it for a few minutes - fish it out- then install it - the heat will make the seal a little bit more supple - a few drops of brake fluid on the piston will also aid installation.
But - sorry to hear you had a "blue" moment - I think we all get them from time to time - mine are quite frequent when I stuff things up - and there is no one else to blame (not within earshot anyway).
cheers
I always lubricate with brake fluid, but I came to the same conclusion as you - I was doing this while sitting in my cold garage, my mistake was not warming the thing up first. I should have clued in when it was so much harder to get the thing on than it usually is.
Next time try getting permission to do simple rebuilds inside where its warm at the kitchen table...ha!
When I got the replacement, I took it inside and took my time in the warmth of my basement workshop. No problems the second time around.
Motorcycle: 1977 Honda 550K. Sold. 1986 1200 Aspencade. Purchased as a non current brand new in the box 1988. Sold. 2006 1800 Goldwing 2017 BMW 1200 GS Adventure...
I always lubricate with brake fluid, but I came to the same conclusion as you - I was doing this while sitting in my cold garage, my mistake was not warming the thing up first. I should have clued in when it was so much harder to get the thing on than it usually is.
Next time try getting permission to do simple rebuilds inside where its warm at the kitchen table...ha!
When I got the replacement, I took it inside and took my time in the warmth of my basement workshop. No problems the second time around.
I recall the time my aunt caught me washing motorcycle parts in the kitchen sink about 40 years ago. Didn't hear the end of that for weeks...haha!
Just saw this post Admin , and I fully empathize . Been there , done that , too . Being from the Buckeye state originally , I've done more than my share of nights in cold garages working on stuff .
One of my mentors ; a grizzled old H-D biker-type told me that when I started to take the cylinder apart , to put all the "new" stuff in a container with the brake fluid I was going to use , and by the time I had the parts clean and ready to install all the new O-rings and cups , they would be pliable and good to go . He was right .....Never broke or tore another one . No matter the temp . I'd suggest letting the stuff "soak" for at least a hour , but that's just me .
