Brake fluid indicator issues

[Rich_in_Tampa]

Got my 2005 LT back from the dealer and at my next ride I routinely checked the brake fluid indicator on the handlebar reservoir. No fluid level could be seen at all, no matter how I moved the bar, center stand, etc. Everything seemed OK with no warning lights, etc.

I took it back to the dealer, who said that they probably over-filled it during the servicing. Then he said that in fact they do not routinely drain and refill "that part" (the front part?) of the brake fluid reservoir, only the "rear part" but maybe in doing so this put pressure on "the front part" resulting in over-filling. Anyhow, he drained a little fluid and now the fluid level is readily visible in the handle bar indicator.

Finally, he said it is really the rear indicator you should watch, the one inside the right side bag which requires removal of the seat to properly see.

I'm no expert, but this whole explanation left me skeptical and a bit confused. Can anyone clarify???

[JATownsend]

The front reservoir holds the fluid that enables the control circuit, while the rear reservoir holds the fluid that actually presses on the brakes. So, as the pads wear the rear fluid goes down. And, the float is quite sensitive to loss of fluid. A teaspoon makes a difference.

The front fluid control circuit is a trapped or closed loop with no loss, except for a leak or failing component.

[mneblett]

The front reservoir holds the fluid that enables the control circuit, while the rear reservoir holds the fluid that actually presses on the brakes. So, as the pads wear the rear fluid goes down. And, the float is quite sensitive to loss of fluid. A teaspoon makes a difference.

The front fluid control circuit is a trapped or closed loop with no loss, except for a leak or failing component.

Right general idea, but a couple differences with the '05s. The rear reservoir, visible through the hole in tupperware at the front of the right saddlebag when the lid is opened) now only supplies fluid to the foot brake master cylinder (the rear control circuit). The front and rear wheel circuits have their supply reservoirs integrated into the Integral pump unit, which is under the left side cover, next to the battery.

In theory, the levels in the control circuits will never go down, because they are isolated from the wheel circuits (which supply the fluid required to compensate for pad wear).

The comment about the wheel circuit causing the control circuit to go up is pure hogwash -- there's no way it can do so. And don't buy into the "no routine fdrain/fill" stuff -- the control circuits need to be bleed regularly, just like any other brake system.

For more info on the similar '02-'04 Integral system arrangements and bleeding, see the HOW link to a bleed procedure document