Master Cylinder: 9/16 bore on a 15mm bike?

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Mar 2, 2011 | 07:25 AM

Dew Me

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Master Cylinder: 9/16 bore on a 15mm bike?

Harley says my ABS Brembo's are a 15mm bore but the m/c I want is only made in 9/16 or 11/16. 9/16 is about 14mm so how much difference is that gonna make to my braking since it is supposed to be 15mm? Or is it not possible? Anyone have any thoughts?

Mar 2, 2011 | 07:34 AM

geezer glide 56

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If you are running dual disc you need the 11/16 bore m/c

Mar 2, 2011 | 07:44 AM

Dew Me

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From: Maryland

Quote:

Originally Posted by geezer glide 56

If you are running dual disc you need the 11/16 bore m/c

Information is spotty so I can't say you are wrong. I know that conventional knowledge says you are right. From what my research is telling me conventional wisdom went out the window when Harley brought Brembo on board. Brembo being European deals in metric only.

Mar 2, 2011 | 08:50 AM

Dew Me

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Nobody with Brembo's have changed out their m/c?

Mar 2, 2011 | 08:53 AM

Energy-Dude

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If the bore is to small, your lever pull will be longer to push the fluid into the calipers. This needs to be a matched system for sure! I've run into the same problem on multiple car projects.

Mar 2, 2011 | 09:35 AM

Dew Me

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From: Maryland

Quote:

Originally Posted by Energy-Dude

If the bore is to small, your lever pull will be longer to push the fluid into the calipers. This needs to be a matched system for sure! I've run into the same problem on multiple car projects.

Thank you. That makes sense. I called Performance Machine about it yesterday. That is who I want to buy m/c from. He confirmed the 15mm thing but was clueless as to answering my question. He said when they have done controls on recent baggers they switch out calipers, rotors, wheel, and fender. Sure, cuz I have an extra $2K sitting around! *LOL* He said he would talk to an engineer and get back with me.

Mar 3, 2011 | 05:11 AM

geezer glide 56

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From: Mississippi

Harley only has 2 bores for the master cyl. 11/16 for dual disc and 9/16 for single disc ...All of the Harley s I have changed bars on that had brembo brakes...That rule still applied.