Front brake feel varies

G'day from Australia!

I have an unusual brake feel issue in the front of my 5th gen. On the first brake application it's a bit spongy (it stops the bike alright, but the lever comes back too far for what I like). On the second brake application it's nice and hard. It stays this way until I leave the brakes alone for a minute, and then it's back to being a bit spongy again. It doesn't matter if the bike's moving or stationary - it makes no difference (ie: not caused by the discs spreading the pads).

The things I've done to the brakes are:
* All new discs and pads
* All new caliper seals (all calipers)
* All new brake fluid
* Bled brakes according to Honda manual, then bled some more, and some more, and yet more...
* Bled the banjo bolt at the master cylinder
* Leant the bike over as far as I could to the left without spilling brake fluid everywhere and "tickled" air bubbles backwards out of the master cylinder (this took it from being disgustingly spongy to the way it is now)
* Tied the lever back overnight

When I got the bike the brakes were rock hard, but they went slightly spongy when I gave them a good hard squeeze to see how far the lever would come back. I now have a master cylinder kit to put in, but I thought I'd ask if anyone has any other ideas to try before I pull the system apart and have to start all over again.

Also, the new master cylinder kit seems to have casting flash going down the plunger shaft (in the spiral area). Presumably this area isn't supposed to have the casting flash, so I should carefully get rid of it first, so it doesn't trap air at those points. Thanks in advance for your help.

 

Update: I've put in a new master cylinder kit, and it didn't make any difference. A friend with more experience on bikes had a feel of my lever pressure and thought it was fine. I also went for a ride on a '00 to '03 Gixxer 750 while my bike was getting the head stem bearings replaced (All Balls tapered rollers), and I realised that I have way better brake feel than some bikes do...

Seemingly I'm looking for the holy grail of brakes: starting to apply just after the brake light comes on, and progressive feel, while being impossible to bring the lever to the bar...

In other words, the solution was "rider recalibration".

Cheers,
Danny

 

change to SS brake lines and you'll notice the difference to a solid feel. Plus linked braking may be part of it.

 

Stainless Lines are great, changes every-thing. You re-built the entire brake system so your good to go! I usually reserve dah-banjo-bleeding to nights when I have too much rum though ; )

 

I have experienced this on my 6th gen. It happened first at a track day where the bike was sitting in the sun during lunch. Not sure if the heat changes the viscosity of the fluid a bit and allows the pads to seperate.
Happened again after sitting in the garage for a week..
Both times I just released the brake and reapplied (smoothly) and it went back to normal.. I suspect the linked brakes do have something to do with it because I have never experienced this with any other brakes, even in extreme conditions..

 

It's interesting that you say this, chickunfut... The last couple of days in Melbourne have been hot (yesterday was 41deg C, or 106deg F), and the brake feel was more squashy than normal. Brake power was fine, but the squashiness wasn't nice to feel.

I suspect it's the brake lines expanding with pressure from the master cylinder, and the hot weather makes the lines more flexible, so the system feely more squashy. It looks like I'll have to get a set of braided lines.

 

really, it seems like the only things left are
that it is normal, given the bike is new to you, it may just be a change from what you had
or that you have a small leak somewhere
or given the age of the bike you may have really soft brake lines, can you tell if they are O.E.?

 

The brake lines are the original ones. The markings indicate the same year of manufacture as the bike, so I think they're getting a bit soft in their old age (14 years and 97,000km).

 

I would say that that it is time to change those lines out, preferably for some kevlar or steel braided ones

 

Only thing I can think of would be a little air but it sounds like there ain't no air in there!

If concerned I guess new lines would be the next thing

 

They stood up to Superbike School on Sunday, but I'm sure the brakes would feel better if I had braided lines.