Page 1 of 2

GT750 front brake master cylinder - best repair manual

Posted: Sun May 22, 2011 3:48 pm
by barko1
The 74 I just acquired has a dysfunction (no lever resistence front brake. Gooped up inside, disassembled part, the two screw in the bottom of the reservoir. Figure it probably needs a rebuild, I know I need the rubber fluid thingee (??) that sits in the reservoir, but how does it come apart? Does the black piece on the front, where the hose would connect, screw out? I haven't got a service manual yet, not really ready to do much to it just now, but if you can refer me to which manual I might get that would be a good start. Thanks

Re: GT750 front brake master cylinder - best repair manual

Posted: Mon May 23, 2011 7:04 am
by Coyote
There is an exploded view here: http://motorcitypowersports.com/fiche_s ... &fveh=1875" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;
This may help. To rebuild the MC, you need the piston cup set (part #1)

Re: GT750 front brake master cylinder - best repair manual

Posted: Mon May 23, 2011 10:34 am
by barko1
Thanks much, how does the piston come out?

Re: GT750 front brake master cylinder - best repair manual

Posted: Mon May 23, 2011 10:40 am
by oldjapanesebikes
There is a circlip deep in the recess on the plunger side. Real pain to get at. :?

Re: GT750 front brake master cylinder - best repair manual

Posted: Mon May 23, 2011 12:33 pm
by H2RICK
Ian +1.
Eventually I swallowed my pride and, after many years of messing with inferior tools, I bought the genuine Suzi long-nosed circlip pliers that are specifically made for removing that master cylinder circlip. At the time, I paid about $42.00 for them.....but my life has been considerably less stressful since then...:shock: :lol:....so it was money well spent, IMO. It's also amazing how many new "friends" I have once they find out I have a set of those pliers. :wink:
PS: these pliers can also be used for any other deeply recessed internal circlip you run across e.g tranny bearing retaining clips, etc.

Re: GT750 front brake master cylinder - best repair manual

Posted: Mon May 23, 2011 8:29 pm
by barko1
So something like this http://www.dinodirect.com/circlip-pliers-e5531.html" onclick="window.open(this.href);return false; might help? Naturally my $400 bike will cost $4000 in parts and $4000 in garage updates :roll:

Re: GT750 front brake master cylinder - best repair manual

Posted: Mon May 23, 2011 9:24 pm
by oldjapanesebikes
I think mine cost around $5 :D , but yep - something like that.

Re: GT750 front brake master cylinder - best repair manual

Posted: Tue May 24, 2011 6:16 am
by Coyote
Go to the hardware store and buy a pair of plain old internal snap ring pliers. While there, pick up two 3/32 allen wrenches. Cut the 'L' off the allen wrenches and grind the tips to fit the holes in the snap ring. Replace the pliers tips with the modified allen wrenches. That's how I got at mine.
I already had a pair of internal / external reversable snap ring pliers made by Channellock, so I was only out the cost of the allen wrenches. Iv'e got a pic of it somewhere. Ill see if I can dig that up and post it.

Re: GT750 front brake master cylinder - best repair manual

Posted: Tue May 24, 2011 6:49 am
by Coyote
Ah, yes. Here it is. Isn't that piston just lovely? As you can see, I had to extract it with needle nose vice grips, but also in the pic is the modified snap ring pliers.

Image

Re: GT750 front brake master cylinder - best repair manual

Posted: Tue May 24, 2011 7:48 am
by H2RICK
Barko1, those pliers are kind of like the Suzi ones.....except the pliers in your pic are for OUTSIDE circlips, not inside, so they wouldn't work for master cylinder disassembly.

I have a set of those like in coyote's pic but they didn't work satisfactorily in some cases.....for me, at least.
For myself, I'm always big on getting the correct tool for a particular job.....and the Suzi pliers have worked admirably.
Cousin Fred (buffalo-guy) also has a set and he uses his waaayyyy more than I use mine, him being the Buffalo guru of all of Canada. :wink:

Re: GT750 front brake master cylinder - best repair manual

Posted: Tue May 24, 2011 12:52 pm
by barko1
Is there some sort of Canadian Buffalo thing going on?? I'm new to all this and there seems to be quite the contingent from the Great White North :o And I just ordered some parts for my x6 and they are from Canada, must be some sort of conspiracy! Anyway thanks for the pics, I have some snap rings so I'll get out and inspect and see what I can do. And I've been to Canada the last three years even though I can usually see Mexico from my house. And I am heading back this summer, Labrador!

Re: GT750 front brake master cylinder - best repair manual

Posted: Wed May 25, 2011 7:52 am
by tz375
The other way to get that pesky piston out is to remove the banjo bolt and fill the thing with wd40 or your favored release agent. After leaving to soak for a while, insert a pin punch through the banjo bolt hole and gently tap teh piston out.

Re: GT750 front brake master cylinder - best repair manual

Posted: Wed Aug 24, 2011 6:48 am
by RING_DING
Coyote,
After you got the piston out, how did you go about cleaning out the master cylinder chamber? I am about to extract the piston out of mine and I suspect it's going to look similar to yours.
Cheers

Re: GT750 front brake master cylinder - best repair manual

Posted: Thu Aug 25, 2011 7:00 am
by Coyote
Hot soapy water and a tooth brush. Lacquer thinner on a q-tip on the stubborn spots. What ever you do, DO NOT use a back and forth motion or it will leak. Minor pitting if present can be smoothed up with a small wheel cylinder hone and kerosene.

Re: GT750 front brake master cylinder - best repair manual

Posted: Thu Aug 25, 2011 9:07 am
by Scorch
And, do not use gasoline for cleaning any of the rubber brake parts. The brakes will not build up pressure if you do.