Hi All; Have put about 300 miles now on my 2020 new Bonneville. One issue I have noticed is that occasionally, I will squeeze the front brake lever and it almost squeezes to the throttle lever. A quick release or two and it is back to normal where I can feel the resistance again. I am not a mechanic so I could use some advice. I was going to wait until my 500 mile checkup to address this since it does not happen often, but I think about it a lot. I viewed a Youtube video where this person depressed the lever and tied it up overnight to dispel any air bubbles. I tried that but it didn't work. In 2.5 hours or riding yesterday, the squishy brake feel only happened once. I do notice a couple of bubbles in the sight-window of the brake fluid reservoir and do not know if that is normal. (an extra note......My bad but a few weeks ago, I was balancing the bike to check the oil level and it tipped over. Broke off the tip of the front brake lever. Don't know if that upset anything else, causing this issue?) Thanks in advance for any input.
If there are no leaks evident the only things that can cause a spongy lever are air in the system, bad seals in the master cylinder or old fluid. Your bike is new so the fluid will be OK. When your bike fell over I guess it"s possible that the outlet on the reservoir was breifly uncovered and the lever ws operated when it hit the ground, so allowing air into the system but, usally, when air gets in, the spongy feel is there all the time until the systems bled. I can't see how the fall would damage the seals. I'd try bleeding the system, it's easy enough and see how that goes. Can't see how locking the lever on overnight will dispell any air in the system, where's it going to go? I've just changed the fluid on the ZZR as it was several years old. The leaver didn"t feel that bad but certainly improved with the new fluid. The bike has ABS but the bleed procedure is no different to a bike without it.
The squishy lever tells me there is air in the hydraulic system. ONE you will need to bleed the air out, but TWO how did it get in there ? Need to have your mechanic check that out. The master cylinder may be defective interally or a leak somewhere else. ...J.D.
Thanks much...Yep, I will have the dealer do it all at the 500 mile 1st checkup. Appreciate the response.
Thank you. I did inspect all brake parts after my "tipover" All looked pristine, not even a scratch. Probably because I had dresser/crash bars installed.
I know when I upgraded the front caliper on mine I had a tough time bleeding all the air out. Works great now. ...J.D.
One of the problems with some self bleed kits consisting of a bit of blocked off tube with a slit in the end, is that unless you close off the bleed valve every time you release the handlebar lever, air gets sucked inside the calliper via the valve threads - the exact same place you're trying to expel unwanted air from.
there is a way to bleed the brake I've seen on another sight .zip tie the lever closed and leave over night and the air in the caliper will rise back into the reservoir over night
I can't see how that would work. With the lever squeezed, the line to the calliper is sealed and shut off from the reservoir. He says at the beginning of the vid that if a bike is laid up for long periods it can "keep air out of your system" and I'd go with that. Any air trapped in the calliper won't necessarily rise up the line and if it does, how does it get into the reservoir and dissipate? I think I'll stick with a conventional bleed approach, it's very easy anyway compared to the faff of bleeding car brakes.
Any air will likely be at the top end near the lever and conventional bleeding, trying to shove that air all the way down the line and out through the calliper, would take ages and to be done properly should involve some activation of the ABS unit, so if it wasn’t going to be dealt with at the dealer my suggestion would be to “back bleed” the system by pushing SLOWLY the pistons back in the calliper(s) and thereby pushing fluid back up the line so that the air is expelled into the master cylinder and allowed to escape. A few gentle taps on the hydraulic line should encourage the air to rise into the reservoir.
This may be bike specific but on the ZZR the ABS has no bearing on the bleed procedure and isn't even mentioned in the FSM. I did mine the other day in a few minutes with the traditional 'open the nipple, squeeze the lever, close the nipple' operation. The highest point on a calliper is (should be) the bleed nipple and it's possible to get air trapped behind it which will not rise up the line to the reservoir. Compared to a car or larger vehicle, the braking systems on bikes are obviously much shorter and hence easier to bleed. On the car I use a Gunsons pressure bleeder, I've had for donkey's years, which pressurises the reservoir and forces new fluid through. It will also fit bike reservoirs but it's just not worth the effort of setting it up.
Thanks everyone. An update on the brakes. Had the bike in for the 1st 500 mile service. Of course my primary concern was the "spongy front brake." They bled the brakes and thought all was fine.....UNTIL the next morning when they were spongy again. The dealer was about to rebuild the Master Cylinder with all new seals when they called Triumph. Triumph said that they would send the dealer a brand new Master Cylinder and that they would pay for the installation as well. I thought that was great customer support. I mean it is a brand new bike and it is surely a safety issue. Haven't got the bike back from the dealer yet but they assure me this will solve the problem. Let's hope so.
Update2: Since the dealer replaced the master cylinder, the brakes have been great. No further problems.
