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brake banjo fitting flow restrictor?

Started by BK_856er, November 09, 2008, 10:21:36 PM

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BK_856er

Why does the brake master cylinder banjo fitting from an M695 have such a small opening?  I'm no engineer, but it's hard to imagine that you could achieve much flow through that tiny hole.  It almost looks like a flow restrictor.  The S2R800 shares the same part number according to the part diagram.

Is this a strategy to "dumb down" the brakes and make them more newbie friendly?

My wire gauge shows the orifice of the M695/S2R800 banjo (left side) to be 0.60 mm - barely large enough for a small safety pin to pass through.

The orifice of the "normal" banjo (right side) is a comparatively gaping 3.0 mm.

Thoughts?   [popcorn]

BK




He Man

are they both from the same brake? (both front/ both rear)?

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BK_856er

Quote from: He Man on November 09, 2008, 10:38:44 PM
are they both from the same brake? (both front/ both rear)?

The fitting with the small orifice is from the M695 coffin-style brake master cylinder - one per bike.  The other one is typical of what would be found elsewhere (aftermarket, calipers, clutch, etc.) but it happens to be from a front caliper.

It seems that the M695 shares the brake M/C banjo fitting part number (779.1.415.1A) with the Hypermotard 1100S and the 1098S, and probably others, so maybe "dumbing down" is not the most appropriate term.

I still find it odd that the orifice is so tiny!  I have to assume that the actual fluid displacement is quite small.

BK

Speeddog

Fluid displacement is pretty small for a brake, as opposed to the clutch.

I remember the small-hole banjo bolt being an issue from TOB, but I don't remember what the issue was.

Seems it would make it a lot harder to get a bubble out of the line when bleeding.
Perhaps that was the issue.

Brembo must have done it for a reason, drilling a hole that small isn't cheaper than drilling the larger one.
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Howie

Quote from: Speeddog on November 10, 2008, 10:14:40 AM
Fluid displacement is pretty small for a brake, as opposed to the clutch.

I remember the small-hole banjo bolt being an issue from TOB, but I don't remember what the issue was.

Seems it would make it a lot harder to get a bubble out of the line when bleeding.
Perhaps that was the issue.

Brembo must have done it for a reason, drilling a hole that small isn't cheaper than drilling the larger one.

I remember an issue on, maybe the Muli, not sure, where brake pulsation was relieved by changing the size of the restriction.  I think they went smaller.

BK_856er

Quote from: howie on November 10, 2008, 10:36:43 AM
I remember an issue on, maybe the Muli, not sure, where brake pulsation was relieved by changing the size of the restriction.  I think they went smaller.

Thanks, guys.  That's interesting and makes sense.

My aftermarket bleeder fitting employs a large orifice, so if my newly upgraded brake system pulses I'll try the small orifice fitting.

BK