Rear brake pedal goes down too far.. bleeding?

[Deleted account 191119001]

Just use oil in the system.. it will not boil or go off over time as it won't absorb water... mind you, any water getting into the system would pool and not be taken up by the fluid, making the wet boiling point of the system 100 deg c.. so maybe not the best idea
Do you think keeping the brake fluid warm / hot is an advantage or disadvantage.. if the water could get back out, it may help reduce the water content.. on the other hand, it may just cause condensation to form, adding more water to the system. I think the cycle of hot to cold could have the effect of drawing more in. Maybe that's whats happening to our brake fluid over time?

Tis a point to hot and to cold, this may well be happening with the heat from the exhaust, and then it cools off, so just maybe if that little heat shield keeps it a tad cooler, maybe it will even things out, tis a possibility, I wonder how hot it gets around that area, with no heatshield on, wish I had a heat gun.

 

[Shamone]

My 2014 used to do this - I ended up replacing the master cylinder for a newer used one and that sorted it.


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[Deleted account 191119001]

Moisture in the brake fluid can cause soft brakes when in heavy use due to the water vaporising to gas due to the heat, making the contents of the brake line compressible, which won't be the case while the water is in liquid form.

However, I think a common problem with the GS is a soft rear brake pedal even when the brakes are cold. This seems to be due to some sort of problem, possibly related to the ABS plumbing, that lets air into the system. I had this with my 1200GS, and it only improved for a while after the dealer bled the brakes under warranty. It also improved after the scheduled brake fluid replacement. So far, after 2500 miles the 1250 still seems OK.

My 2017 has not had a brake problem yet Fred, and just had new fluid in 2nd year service so fingers crossed, as it does not happen to all, but would be interesting to find out why it is happening, might also just be as simple as them linked brakes generating to much heat to soon.