dingy Posted May 12, 2011 Share #1 Posted May 12, 2011 (edited) I obtained a rear brake master from a 99 VMax. Actually got it just for the reservoir. I wanted to see if I could make it work in place of the stock one, minus the level indicator. Got it and a spare starter relay for $31 shipped. So not a bad deal. This thing is in excellent shape, so it got me pondering mounting it on the scooter. Couple of issues, both solvable. The center to center distance of the mounting holes is different, stock looks to be about 52mm & VMax looks to be about 40mm. This seems like it could be fixed with an adapter plate. There is also a c/l offset difference 7 or 8mm. This offset would be beatifically as it would give room to insert the adapter plate. Now question is, should I or shouldn't I . The brakes on the rear could stand a little more grabbing power to them. I have locked the rear wheel by really stomping on them. A little more would be nice, but I don't need an extremely touchy system that will be lock up prone. The bike currently has a 88 master in it which has a bore of 17.46mm. The VMax has a 12.7mm bore, same as RSV. The decrease in bore size would give me more force on the rear pads. It would also decrease the volume of fluid pumped. The brakes have been delinked & it has a quad piston rear caliper. The setup with the VMax master would be equivalent to an RSV setup. Or, would I be better going to a 83-85 rear master, which has a bore dia. of 15.87mm. Or just leaving it be, and hope I am able to ride it this summer. Gary Edited May 12, 2011 by dingy Link to comment Share on other sites More sharing options...
Condor Posted May 12, 2011 Share #2 Posted May 12, 2011 Leave it be Gary.... Go ride.... Link to comment Share on other sites More sharing options...
skydoc_17 Posted May 12, 2011 Share #3 Posted May 12, 2011 Hey Gary, You currently have the Identical rear caliper that the Second Gen. has. If you put the same Master Cylinder as the Second Gens. have on your bike, I would say that your rear brake would be just as "touchy" as the Second Gens. are. But, if you send me a print, I will make the adapter bracket for you! Aluminum OK? (I personally would try the MKI VR Master Cylinder) Earl Link to comment Share on other sites More sharing options...
dingy Posted May 12, 2011 Author Share #4 Posted May 12, 2011 Not sure what I am gonna do with it Earl. The 1st gen master sounds like a nice middle ground. And it would be a bolt on change. Like I mentioned, it was just an after thought about using the master itself. I am waiting on an appt. with a Nuero surgeon to see about fixing my back issue. I may not get to ride at all this year. Bike is in pieces, gas tank is off it. About last thing I did to it was mount the rear coils on it. Which I have since decided to do away with and use the COP's setup. Front end still needs to come off to replace seals, put R1 calipers on, remove anti locks, install Condor Brace. All the plastic is off so when I can, it will be easy to do. Gary Link to comment Share on other sites More sharing options...
GaryZ Posted May 12, 2011 Share #5 Posted May 12, 2011 Gary, I have de-linked my brakes and presently have the rear master hooked to the rear brake using the original port and the front port blocked. My rear brakes barely function. Assuming the stock rear master is a 30/70 split (rear/front), I am thinking moving the rear brake to the 70% port might be a good improvement . . . Link to comment Share on other sites More sharing options...
dingy Posted May 12, 2011 Author Share #6 Posted May 12, 2011 Gary, I have de-linked my brakes and presently have the rear master hooked to the rear brake using the original port and the front port blocked. My rear brakes barely function. Assuming the stock rear master is a 30/70 split (rear/front), I am thinking moving the rear brake to the 70% port might be a good improvement . . . Two options. 1st Hook brake line to where front brake line was. 2nd Remove the proportioning guts from the rear master and keep line hooked to where it was. either way and you will 100% of what rear master can deliver. Gary Link to comment Share on other sites More sharing options...
StuD Posted May 13, 2011 Share #7 Posted May 13, 2011 The bike currently has a 88 master in it which has a bore of 17.46mm. The VMax has a 12.7mm bore, same as RSV. The decrease in bore size would give me more force on the rear pads. It would also decrease the volume of fluid pumped. Or, would I be better going to a 83-85 rear master, which has a bore dia. of 15.87mm. ? The larger the bore, the larger the volume of brake fluid, the greater the force at the brake pad? I ask because the trike I'm working on has drum brakes & I'm having trouble getting stopping power at rear. (delinked front brake) :canada: Link to comment Share on other sites More sharing options...
dingy Posted May 13, 2011 Author Share #8 Posted May 13, 2011 Stu, The larger the bore of the master the less force is generated at the brake calipers. Gary http://i1007.photobucket.com/albums/af193/gdingy101/hydsystem-1.jpg Link to comment Share on other sites More sharing options...
Squeeze Posted May 13, 2011 Share #9 Posted May 13, 2011 The Vmax Master works just fine on a 4 Pot Caliper, without being too touchy. Link to comment Share on other sites More sharing options...
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