Core Moto lines change then test drive front wheel locks up on ABS 2017

[mabupa]

I keep thinking about this thread and scratching my head. How can a line change cause brakes to lockup? I hope there is a resolution on this or curiosity will kill me.

 

[sixpack577]

I keep thinking about this thread and scratching my head. How can a line change cause brakes to lockup? I hope there is a resolution on this or curiosity will kill me.

Air in the lines and then filling the master cylinders.
The air will slowly cause the fluid level to rise, and hydraulics is basically pushing fluid back and forth in a line, and once that fluid has no place/room to return to, the brakes cannot release.
Fluid from another line is holding pressure against and into the abs pump, and it has a valve that closes, the air pocket is in the line between the pump and mc, and once the valve closes behind it, there is nowhere for that forward moving air and fluid to return to.
I havn't had brakes lock, but I have witnessed the effect when bleeding abs brakes, and why I say that you must use the abs exit line bolts as bleeders.
Otherwise, once you stop bleeding the mc, and top off the fluid, the fluid level starts to rise in the resivor, as the trapped air is moving forward towards the mc, and whether you top off the fluid or not, but adding fluid to a low resivor from bleeding is obvious standard practice, as you have lost fluid bleeding at the mc, regardless if the calipers are already correctly bled.

 

[sixpack577]

The air in the line has caused the mc to fill to capacity, and the brakes work with the fluid between the calipers and the mc.
The fluid cannot travel out of the mc and back towards the exit line of the abs pump, against it's direction of flow, and if it did, it would be Very slow, and take a while before the brakes would begin to release, as the abs is pulsing fluid, And Air towards the mc very quickly.
The only backwards travel is the empty space in the mc resivor, take away that return space...and the brakes can't release.

 

[michael parris heuberger]

The air in the line has caused the mc to fill to capacity, and the brakes work with the fluid between the calipers and the mc.
The fluid cannot travel out of the mc and back towards the exit line of the abs pump, against it's direction of flow, and if it did, it would be Very slow, and take a while before the brakes would begin to release, as the abs is pulsing fluid, And Air towards the mc very quickly.
The only backwards travel is the empty space in the mc resivor, take away that return space...and the brakes can't release.

Hi. A few of my cars had ABS never liked it. Would diaable it so the car would stop. The ABS on my work truck comes on way to early. It does work on the Honda OK.

 

[GIXERHP]

Have you tried bleeding the fittings at the ABS PUMP?

 

[LC4CARL]

I swapped the flex lines on my BMW 325. Got air in the ABS. I could not get it out. Had to pay a shop. Even they said it was a PITA.

Random moto ABS memory: We were dual sporting. My buddy had a white-knuckle ride down a gravel decent when he forgot to switch off the ABS on his BMW GS.

 

[DuraBusaTom]

I keep thinking about this thread and scratching my head. How can a line change cause brakes to lockup? I hope there is a resolution on this or curiosity will kill me.

I put on a Brembo MC and bled the MC and calipers. Maybe I can test tomorrow.

 

[DuraBusaTom]

Have you tried bleeding the fittings at the ABS PUMP?

I did this today. I will test soon.

 

[Dopey]

Yes yes yes, I addressed all that in my posts. Personally outside of a rainy day I see little benefit in abs. Like most driving aids it was invented to save stupid people from making obvious mistakes, like following too close.

I used to feel that way and wasn't really sure how I felt about it when I bought my busa and it had it and I felt like it shouldn't because of my ego I guess. But it wasn't long into owning it that I made a left turn of a side street onto a main road with my wife on the back and a lady on the opposite side decided she would pull out in front of me then panicked and just stopped dead in front of me. It was such a short distance and I was just straightening the bike there was no other iron but to fully slam the brakes, I've ridden long enough and they enough to know had I not had abs the wheels would of locked up and skid and would of ended up being one of those "had to lay her down" scenarios and there was absolutely no other option or way out of that situation for anyone that would of been in it. Thankfully the abs did what I does and slowed the bike quickly with no locking up and me and my wife were completely fine aside from a little high blood pressure and that's when I realized there's a lot of "nanny" features I don't like that newer bikes have but abs is one that fit street riding I find is good to have. Now of course there is gonna be scenarios where it could be better to not have abs but not many in the streets and there's definitely no way anyone can do what the abs does as well as it does in the street regardless of their skill but again there's some scenarios where locking the tires could be the better thing. I look at it kind of like when I used to think I could shift so fast without using my clutch I didn't need a quick shifter and then I got one and found out just how wrong I was