83 MC on an 82 setup

[supervision]

 The mill uses it to make feed,  stuff is 85% protean, sounds yummy don't it.  looks just like copy machine toner

[Brian Moffet]

So, the 82 MC will give an output pressure 35.5% greater than the 83 MC.  This will also require that the piston travel 35% farther as well.
If your brake lever is very solid, this extra travel in order to achieve greater braking would be acceptable to me. 

I think you're going to bottom out your brake lever.

Brian

[kwells]

It may be possible to bottom it out yes, but that would be only if you wanted to.  There would be plenty of braking around the 1/2 point on the lever.

[inanecathode]

I think the brake would lock up before you could bottom the lever. Probably could bottom the lever with some force, hopefully not be popping things apart with the pressure.

[Brian Moffet]

It may be possible to bottom it out yes, but that would be only if you wanted to.  There would be plenty of braking around the 1/2 point on the lever.

Here's my thinking...  If you have 18:1 (which is what was mentioned before), you need to move the master cylinder piston 18 inches to move the brake cylinder 1 inch.  I believe that the pads float around 1/16 of an inch above the disks (1/32 on each side of the disk).  That means you're going to have to move the master cylinder piston 1 inch and 1/8.  Remembering back to rebuilding that sucker, I don't think you have that much room to move the master cylinder.

Either that, or your pads will be floating much less than what I mention, and you're going to be wearing down pads incredibly fast, and be prematurely braking without touching the lever. 

If you do this test, ride it in an area where you don't need to stop using the front brakes first.  I'd hate to see an accident that could be prevented.

Brian

[kiwibum]

Interesting finding this thread after I've just been thinking/reading about changing master cylinder after a conversation with at guy today that plays round with RD/RZ bikes and upgrading the brakes. One of the things he has done is go to a smaller MC. Also found this which may be useful http://www.vintagebrake.com/mastercylinder.htm

Funny about the comment of the RD with worse braking "became an unhealthy 13.3 :1" which is still better than what we have as standard (11.6:1). I'm assuming if 12.7mm worked for the RD with 41mm calipers then the XZ 82 MC should work on the XZ 83 dual 38mm calipers. It would be interesting to see what a 11mm & 12mm would feel like and if they would indeed hit the bars with SS lines on. If I had access to any one of these I would definitely give it a try to see what it's like. I'm thinking about using one of my 400's for a track/race bike just to be able to play round stuff like this. Just ordered some SS Galfer lines from http://www.rg500.com/ and will see what difference that makes first before I do any other changes.

[kwells]

Yes, I have examined the mathematics of what going to a smaller MC for the 83 and think it would work just fine. If your brake lever Travel is NOT utilized then I dont think the setup is getting used to its fullest extent. A super hard lever that starts 1/2 mm from the first pull and only goes back 1 inch total is NOT an effective braking system.  I would much rather have a system that uses 3/4 of the total travel of the lever but gives me the ability to meter my pressure to the caliper to a greater degree.  On my 82 I can only use 1/2 of my total lever travel but notice that I must use a MUCH higher amt of pressure to stop the bike than my Triumph Sprint which has a full lever pull.  Once SS lines are installed the amount of fluid pushed through the lines is less important and the pressure becomes more important.

[kiwibum]

Yeah agreed, I've often been annoyed on bikes with only a short amount of movement on the lever and have normally tried to fit the adjustable brake levers so I can get it close to the bar to start with. I have short fingers and can improve my braking just by being able to use my fingers in a more closed position where I have more strength to pull the lever in. I'm figuring I'm going to have this problem once I fit the SS lines, the movement will be less but since the lever will be at my finger tips I wont be able to take full advantage of the strength in my hands to get better braking. Having a lever that moves further may mean I don't have to worry so much about getting it so close to start with because the first part is easier to pull in anyway. Keen to hear if anyone has a chance to try it out a 11, 12, or 12.7mm MC and how well it works.