Hey all— my '84 1100 has a spongy front break lever pull. I replaced the master cylinder with new, bled both sides free of any bubbles however the pull just won't totally firm up. The lever pulls nearly to the grip. Brake pads have almost new thickness. I have not done anything with the calipers at this point. When I pull the lever though I do hear a mechanical sound coming from both of them. What am I missing?
Is the replacement master an OEM or aftermarket? Different cylinder diameters will affect the required stroke length. Are the brake lines still the original squishy rubber lines?
Chip,
These days, you can get banjo bleeder bolts, which install at the top of the hydraulic lines, next to the master cylinders. Banjo bleeder bolts cost about US$ 25.00 each at the right MC shops, and twice that at the wrong shops. That new bleeder makes a real difference in hydraulic line bleeding. Use all new hydraulic washers, any time you disconnect hydraulic lines.
You can remove the last air from the line(s) if you tie the hand lever(s) tightly back to the handgrip overnight.
Still have those 42 year old rubber brake lines?
As suggested, tie that lever back and it seems there is still air in there somewhere.
More bleeding, more and more.
Jiggle that lever, don't pull it all the way it but just giving it multiple jiggles (and you are only just moving it a touch).
Perseverance is the key Chip :good:
You are using new fluid ?
Quote from: Sparky84 on November 07, 2025, 03:49:53 PMAs suggested, tie that lever back and it seems there is still air in there somewhere.
More bleeding, more and more.
Jiggle that lever, don't pull it all the way it but just giving it multiple jiggles (and you are only just moving it a touch).
Perseverance is the key Chip :good:
You are using new fluid ?
what will be the effect if tie-down the handle?
Quote from: filsurs on November 19, 2025, 10:41:51 AMwhat will be the effect if tie-down the handle?
That lets the bubbles float up to the reservoir overnight where they no longer cause softness in the brake lever. I do this after service too. Also works on the clutch.
The theory is compressing the fluid also compresses the air bubbles. Smaller air bubbles fit through the holes easier, rises up into the reservoir and it self bleads that last little bit.
Wow, I never knew that thxs. Must the reservoir cover be open or closed during this process?
I leave it closed. There is air space under the covers, and when the bubbles make it there you are set.
If you are using DOT3, 4 or 5.1, keep it covered/sealed from the air when possible. They will absorb moisture. This is why we need to change/flush the fluid when it gets dark. This is also why some of us have converted to DOT5 (ok for street but can't take the higher heat of hard frequent braking.
Quote from: FJmonkey on November 20, 2025, 10:59:43 AM.....This is also why some of us have converted to DOT5 (ok for street but can't take the higher heat of hard frequent braking.
Au contraire my simian amigo... DOT 5 has substantially higher wet and dry boiling points than DOT 3/4.
However, DOT 5.1 vs DOT 5 are very close
DOT 5 wet: 356°F
DOT 5.1 wet: 356°F
DOT 5 dry: 500°F
DOT 5.1 dry: 518°F
That said, I have DOT 5 in my '84 and DOT 5.1 in my '89. There is a subtle difference between the two.
Both front brake systems with identical components, Spiegler lines, R-1 calipers and 2001 FZ1 14mm masters.
The lever feel with the DOT 5 is softer (not spongy) than the system with DOT 5.1.
Thxs all.... top
Quote from: Pat Conlon on November 07, 2025, 11:55:47 AMStill have those 42 year old rubber brake lines?
As Pat already mentioned, if the brake lines are original equipment and 42 years old, its probably time to upgrade them.
RPM has you covered with Spiegler braided brake hoses, for the front and rear brakes as well as the clutch line.
There are several options available.
Here is the front brake kit eliminating the anti dive fork feature lines: https://www.rpmracingca.com/proddetail.asp?prod=S-YA0131
We also offer the OE set to run the anti dive as well, just check out the website and search Spiegler.
Randy - RPM
Thanks everyone!!
Did the tie back thing and it solved the issue!! Very cool.
Many times I've seen the front brake caliper seals harden an not allow the piston to move forward as the pad wears.
This can cause a wonky lever feel.
Bottom line, you need to just freshen up your front brake system.
The whole thing.