Has anyone put an 83 master cylinder on an 82 single disc setup? I can only imagine the increased bore would provide more pressure.
Actually, I believe the exact opposite would occur.
Same force (your hand), increased area, equals reduced pressure.
Whatever the setup is on the bore of the 83 it has to push more fluid to accommodate the dual disc setup of the 83
George is correct. Larger bore pushes more fluid but at a lower pressure. Not a good idea.
Steve
yes I understand that aspect. The 83 does have a larger bore but in order to push 2 calipers would it not also need to push equal pressure since the calipers they use are essentially 82's (one in reverse).
I'm not positive, but I suspect what would happen is that the lever wouldn't move as far (I'm having a problem dredging up all of that fluid dynamics and Bernoulli's equations at the moment). You would get 1/2 the travel on the 83 master cylinder as you would get on the 82 (assuming you only had 1 brake.) I'm not sure that would be a good thing. Unless you are actually bottoming out the lever against the grip, the amount of force you can exert on the brakes depends completely on how hard you pull on them. The difference between the 82 and 83 master cylinders will be how far you need to pull the lever to exert that force.
Brian
I know it costa a few bucks... but
Why not just get the whole 83 set up...
You will not believe the difference..!
GlennW
Im not saying that I wouldnt eventually....I'm just not ready for the 150-200 in the front end...then another 90 in lines....not sure about pads...
just asking the questions....really I'd say an entirely different MC would could work out too...
As i think i understand the whole fluid pressure deal:
Small cylinder pushing into a large cylinder: small movement at the large cylinder, higher pressure
Larger cylinder pushing into a smaller cylinder: alot of movement at the small cylinder, lower pressure
(lets talk simple numbers for ease of thinking [on my part of course])
How it applies:
82 setup:
1 diameter MC piston pushing on a 2 diameter caliper piston.
83 setup:
X diameter MC piston pushing on (i assume) two 2 diameter caliper piston.
If yamaha wanted to keep the same brake pressure feel and effect (doubt it) they would have to increase the size of the MC piston by two, meaning X has to be 2 in this case. 2 mc piston pushing on 4 diameter (effectively) brake caliper piston, now:
83 mc on an 82 system:
2 diameter mc piston pushing on a 2 diameter caliper piston. half the brake pressure
That probably doesnt answer what i think you're asking, but you'd get less pressure out of it.
That being said, i dont think brake pressure is the issue, it's pad diameter, tire compound, weight shift, and suspension.
THAT being said, these systems were designed with rubber lines. Rubber=flex flex=high capacity. you needed to push a whole hell of alot of fluid to get the same pressure. Now with your steel lines, all that high capacity is moot. Now you have a MC designed to push alot more fluid that is needed. Effect? 3/4s to half your piston travel is a waste of space. I defy you to get the lever to the grip on an 82 or 83 properly bled system with steel lines.
Solution?
Put an 82 master cylinder on an 83 brake system with steel lines. You'd have a smaller piston pushing on a much larger piston equaling a good multiplication of brake fluid pressure. The reason you shouldnt do this is because with the rubber lines, you'd run out of piston travel , equaling a cutoff in brake pressure. With steel lines that issue becomes moot.
82 mc on an 83 system:
1 diameter mc piston pushing on a 4 diameter brake caliper piston
Tada :D
Quote from: kwells on July 12, 2007, 12:11:45 AM
Im not saying that I wouldnt eventually....I'm just not ready for the 150-200 in the front end...then another 90 in lines....not sure about pads...
just asking the questions....really I'd say an entirely different MC would could work out too...
I feel your pain. Going through the same thing now myself. 'cept I have the 83 front end and the 82 MC problem. Was going to post the same question jus that it was for an 82 MC on an 83 system.
David
I think that the 82 MC would work on the 83 setup. The reality is you don't have to actually move much fluid. The 83 has a larger bore, but to the best of my knowledge the same stroke. The increase in area of the piston as a variable by itself would effectively produce less pressure on the input side. Because it is dual calipers you have twice the output area which increases the output pressure by 2 but the distance the caliper piston will travel is also reduced by 1/2. Here is why I think the 82 WOULD work on the 83. When I pull my lever I really only can pull it back by about 1/3 even when braking hard. On an 83 setup(stainless lines) this would make the lever go back approximately 2/3 back. Also because the 82 has less bore it will actually increase the pressure on the output side compared to the 83 making it work even better. I think on the 83 they had it move more fluid to compensate for the line flex of the dual rubber lines vs the single on the 83. Thus, if this variable was taken out of the equation I think you can actually get more performance out of the 82 MC.
If you notice is is 4:44am and I think I was figuring this out in my sleep.
Quote from: Brian Moffet on July 11, 2007, 02:56:54 PM
I'm not positive, but I suspect what would happen is that the lever wouldn't move as far (I'm having a problem dredging up all of that fluid dynamics and Bernoulli's equations at the moment). You would get 1/2 the travel on the 83 master cylinder as you would get on the 82 (assuming you only had 1 brake.) I'm not sure that would be a good thing. Unless you are actually bottoming out the lever against the grip, the amount of force you can exert on the brakes depends completely on how hard you pull on them. The difference between the 82 and 83 master cylinders will be how far you need to pull the lever to exert that force.
Brian
Brian,
Here's Bernoulli's equations, http://en.wikipedia.org/wiki/Bernoulli%27s_principle (http://www.mcmaster.com/). I think he's more help tuning the carbs... :-\
Pascal was probably who you were searching for. http://en.wikipedia.org/wiki/Pascal%27s_principle (http://en.wikipedia.org/wiki/Pascal%27s_principle)
Here's a simple diagram for visualizing this thread's topic.http://en.wikipedia.org/wiki/Hydraulic_press (http://en.wikipedia.org/wiki/Hydraulic_press)
$0.02
;D
Coil
Quote from: kwells on July 12, 2007, 06:46:37 AM
I think that the 82 MC would work on the 83 setup. The reality is you don't have to actually move much fluid. The 83 has a larger bore, but to the best of my knowledge the same stroke. The increase in area of the piston as a variable by itself would effectively produce less pressure on the input side. Because it is dual calipers you have twice the output area which increases the by 2 but the distance the caliper piston will travel is also reduced by 1/2. Here is why I think the 82 WOULD work on the 83. When I pull my lever I really only can pull it back by about 1/3 even when braking hard. On an 83 setup(stainless lines) this would make the lever go back approximately 2/3 back. Also because the 82 has less bore it will actually increase the pressure on the output side compared to the 83 making it work even better. I think on the 83 they had it move more fluid to compensate for the line flex of the dual rubber lines vs the single on the 83. Thus, if this variable was taken out of the equation I think you can actually get more performance out of the 82 MC.
If you notice is is 4:44am and I think I was figuring this out in my sleep.
Kwells,
It's 3:40 PST but I'm on lunch break. The additional truth of your proposal is that the brakes will lock up with less effort, if the lever does not travel into the hand grip before the pads hit the disc.
Good Morning
;)
Coil
Kwells, if your wanting more stopping power on the cheap, I would suggest looking at adapting a double piston caliper for the single disc. The stock 82 disk, is larger than the 83 disk size, and thus clamping that larger disk that you already have with a better caliper will make a stopping performance increase. It's 4:19 AM PST, I'm getting ready to go to work (have to be in Modesto at 7 to pick-up 12 tons of dried blood meal)
Coil-Im ok with that possibility of locking the disc up earlier...that possibility diminishes once the bike gets going though.
SuperV-Have considered this as an idea but would most likely have to make an adapter plate to get it on once I found a suitable caliper. I dont have a way to get that plate machined though.
Quote from: coilXZcoyle on July 12, 2007, 06:47:56 AM
Pascal was probably who you were searching for. http://en.wikipedia.org/wiki/Pascal%27s_principle (http://en.wikipedia.org/wiki/Pascal%27s_principle)
Here's a simple diagram for visualizing this thread's topic.http://en.wikipedia.org/wiki/Hydraulic_press (http://en.wikipedia.org/wiki/Hydraulic_press)
I had a sneaking suspicion it wasn't Bernoulli. My physics was long ago, I can't remember the names, just the ideas ::)
Brian
On the 82, the area difference between the master and brake cylinder is 9:1, (38.1 mm vs 12.7 mm diameter) That means that the force you apply will be multiplied by 9x when you brake, and you will have to move the master cylinder 9 inches for every inch traveled by the brake pad.
On the 83, the master cylinder diameter is 15.8 mm and the brake diameter is 38.1 mm. Assuming one brake, the force you apply to the master is multiplied by 5.8 times. For every inch you want to move the brake cylinder, you will need to move the master cylinder 5.8 inches. For both brakes, you have double that, so you need to move the master cylinder 11.6 inches for every inch of the brake cylinders, and you get 11.6 times the force you put on the master cylinder on the brake cylinders.
This information is in the service manuals. Available on Lucky's CD ;D
Brian
(new edit, I just realized I hadn't converted these to area...)
ok so this is what I was driving at...
The 82 MC piston area is 126.61 sq mm
The 83 MC piston area is 195.97 sq mm
The Caliper piston area is 1139.51 sq mm for each system. The 83 gets that x2.
If the 82 MC is used on the 83 setup that is (1139.51 x 2) 2279 sq mm / 126.61 giving a ratio of 18:1. The 83 setup gives a ratio of 11.6:1
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.
Now we just need a guinea pig....DaveTN?
Quote from: kwells on July 13, 2007, 03:24:30 AM
ok so this is what I was driving at...
The 82 MC piston area is 126.61 sq mm
The 83 MC piston area is 195.97 sq mm
The Caliper piston area is 1139.51 sq mm for each system. The 83 gets that x2.
If the 82 MC is used on the 83 setup that is (1139.51 x 2) 2279 sq mm / 126.61 giving a ratio of 18:1. The 83 setup gives a ratio of 11.6:1
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.
Now we just need a guinea pig....DaveTN?
I volunteer.
Im going to do some work on the front end this weekend but it will probably be a while before I get it all done. I have to change the fork seals (dust seals on the way, and I have the fork oil seals), but first I have to get the darn bolts out of the bottom. I'm also going to tear down the calipers and rebuild them if needed.
Money's kind of tight at the moment and I'm coming up on mid terms as well as having two papers due. .... ugh.
David
David
Quote from: supervision on July 12, 2007, 07:23:12 AM
Kwells, if your wanting more stopping power on the cheap, I would suggest looking at adapting a double piston caliper for the single disc. The stock 82 disk, is larger than the 83 disk size, and thus clamping that larger disk that you already have with a better caliper will make a stopping performance increase. It's 4:19 AM PST, I'm getting ready to go to work (have to be in Modesto at 7 to pick-up 12 tons of dried blood meal)
SV,
What are you growing? :o ::) :-X How much are you growing? :o
;D
Coil
The mill uses it to make feed, stuff is 85% protean, sounds yummy don't it. looks just like copy machine toner
Quote from: kwells on July 13, 2007, 03:24:30 AM
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
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.
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.
Quote from: kwells on July 13, 2007, 09:02:31 PM
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
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.
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.
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.