Front Master Brake Cylinder Stupid question

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kampinguru
Posts: 84
Joined: Mon Dec 07, 2015 10:15 am
Location: Milton, Ontario

Front Master Brake Cylinder Stupid question

#1 Post by kampinguru » Thu Feb 18, 2016 9:39 pm

I bought a rebuild kit from Yamaha for the front Master cylinder and took the old one apart. The kit comes in a number of pieces. There are two rubber seals that fit over the piston that are in a separate bag and in looking at the old one, one goes on the bottom on the little pin and the other one goes in the middle under the other large ring. The problem is I can not see how to get the middle seal over the large metal ring as it is the same size as the seal. Does the piston come apart somehow? I cannot see how it does. I cant unscrew it. This has to be easy since they dont give you any instructions in the kit and the service manual does not show how to disassemble the master cylinder kit. The top picture is the old piston and the bottom one is the new kit. The red straw shows the seal in question and where it has to go on the new piston. Thanks for any input.
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tacky1
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Location: Pacifica,,

Re: Front Master Brake Cylinder Stupid question

#2 Post by tacky1 » Thu Feb 18, 2016 11:34 pm

Pull the old one over the piston flange, Then pull the new one over again, It will stretch over, Wet the piston with a little brake fluid,
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nath
Posts: 103
Joined: Fri Jan 11, 2008 2:06 am
Location: Perth, Western Australia

Re: Front Master Brake Cylinder Stupid question

#3 Post by nath » Fri Feb 19, 2016 1:30 am

Yea, its rubber, just stretch it over, may need to do half then the next half of the seal or roll it over the ridge

As suggested, lubricating it will make things easier and reduce the risk of damaging it.

kampinguru
Posts: 84
Joined: Mon Dec 07, 2015 10:15 am
Location: Milton, Ontario

Re: Front Master Brake Cylinder Stupid question

#4 Post by kampinguru » Fri Feb 19, 2016 9:04 am

Thank you very much. I didn't think they stretched that much. Works like a charm. There is a very thin washer with the new kit and there is no washer on the old piston. Does anyone know what it is for and should it be used or not? Thanks

Moxon
Posts: 33
Joined: Mon Mar 14, 2016 5:18 pm

Re: Front Master Brake Cylinder Stupid question

#5 Post by Moxon » Mon Mar 21, 2016 6:47 pm

I find that warming the rubber bits slightly helps as well. Not heat gun or even hair dryer, but rather leaving them in the sun etc.

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