So, I have a shot at getting a pair of calipers from a friend for super cheap. I just want to make sure I've got this right, and I think there's about a 50% chance I'm completely wrong.
He pulled some gold calipers off of a '91 FZR600. He also says he thinks they were aftermarket; they say "Sumitomo" on them.
Would those fit the 3CV forks and/or the earlier forks with the adapter plate to get them onto the older rotor that comes with the earlier forks?
He's offering them for $30, which seems like a steal--impression is that they're working, but I don't mind rebuilding calipers to save money anyways, and they should probably be rebuilt anyways while they're off.
To buy or not?
According to this list (http://www.fjowners.com/index.php?topic=5657.15), I might be in luck?
Those calipers are the same as what was stock on the 3CVs and beyond. Those won't work with the 16" wheel on the 87s or earlier.
The nice ones are the blue or gold spots found on the R1/R6s. Take a quick look at the gallery and you'll spot (excuse the pun) the ones I'm talking about.
CraigO
Here is a photo of what you are looking for....
(http://i119.photobucket.com/albums/o145/aviationfred/BlueSpot.jpg)
Fred
Kyle,
You can't fit the monobloc calipers on '86 fork sliders. Your best bet is to get a good set of pads for your stock calipers. As long as they're not comtaminated with fork oil, you can often get away with rebuilding the stock calipers and simply cleaning off and reusing the seals.
Replacing the stock seals is VERY expensive. Try some Ferodo pads or HH pads if you want better performance. The coefficient of friction between the pad and the disc is way more important than the number of pistons pushing on the pad.
DavidR.
Kyle, The use of Blue/Gold spot calipers on your FJ will require one of two changes. 1st, I would say the more favorable would be to source a set of 89/90 forks and swap them in. This would allow for the Blue/Gold spots to be a direct bolt on and allow for a 17" wheel install if you chose. Your 16" wheel will still work in the 89/90 forks. 2nd, is to source a set of brake hanger adaptors. Following is a link to Ebay UK where I found a set currently for sale.
Fred
http://www.ebay.co.uk/itm/YAMAHA-VMAX-FJ1100-BLUE-SPOT-FRONT-BRAKE-HANGER-CONVERSION-FOR-EARLY-VMAXS-/261123197350?pt=UK_Motorcycle_Parts&hash=item3ccc27c9a6#ht_257wt_1172 (http://www.ebay.co.uk/itm/YAMAHA-VMAX-FJ1100-BLUE-SPOT-FRONT-BRAKE-HANGER-CONVERSION-FOR-EARLY-VMAXS-/261123197350?pt=UK_Motorcycle_Parts&hash=item3ccc27c9a6#ht_257wt_1172)
Talking with Kyle he wants to get the adapter brackets to save a little $$% before he gets serious on his mods...
Quote from: FJmonkey on November 26, 2012, 07:54:33 PM
Talking with Kyle he wants to get the adapter brackets to save a little $$% before he gets serious on his mods...
If money is a concern, a better and cheaper solution would be to clean up the existing calipers and put in a good set of pads.
But I already said that, guess no one's listening.....
Here's a brake test:
Which setup gives more powerful braking (for a given master cylinder size)?
1) A caliper with 4 2-inch diameter pistons (new style 4-piston caliper), or
2) A caliper with a 2 3-inch diameter pistons (old style 2-piston caliper)?
DavidR.
Which isn't that expensive...
84-87 Caliper Rebuild Kit (http://www.rpmracingca.com/proddetail.asp?prod=M%2FC%3ACaliperKit%281%29) - $28.99ea
EBC HH Brake pads (http://www.rpmracingca.com/proddetail.asp?prod=M%2FC%3AFA88HH)
He can rebuild the calipers for less than the adapter plates.
Also the HH pads work great and is still what I am using on my 86 with the 16" wheel. There are many members here that can attest i do not have any issue being out braked into the corners.
Randy - RPM
Quote from: racerrad8 on November 26, 2012, 09:58:51 PM
Which isn't that expensive...
84-87 Caliper Rebuild Kit (http://www.rpmracingca.com/proddetail.asp?prod=M%2FC%3ACaliperKit%281%29) - $28.99ea
EBC HH Brake pads (http://www.rpmracingca.com/proddetail.asp?prod=M%2FC%3AFA88HH)
He can rebuild the calipers for less than the adapter plates.
Also the HH pads work great and is still what I am using on my 86 with the 16" wheel. There are many members here that can attest i do not have any issue being out braked into the corners.
Randy - RPM
Agreed with Randy - My '84 with SS lines and EBC HH pads had great stopping power and feel.
And to answer slowoldguy, the surface area of the 4 pots should be 25.13 sq in. and the surface are of the 2 pots should be 18.85. So my guess is the 2 pots would have more stopping power (with same master).
John,
You got the answer correct, but your math logic is slightly flawed.
On a caliper, you want to maximize piston area to produce more force.
The 4-piston caliper has a total piston area of 12.56 square inches.
The 2-piston caliper has a total piston area of 14.14 square inches.
Therefore, for a given pressure generated by the master cylinder piston, it will act on more surface area on the 2-piston caliper and create more pad clamping force.
A small piston in the master cylinder creates more pressure in the fluid for a given lever squeeze force. Down at the caliper, this pressure is converted to pad clamping force by multiplying by the piston surface area. Therefore you want larger piston area in the calipers.
DavidR.
You are not done yet me buckos,
How about continuing to follow the load path... to the rotor....so, let's talk about the size (area) of the brake pads....
... carry on...
Nice try Pat, BUT (that's a big but),
The clamping force is a function of the coefficient of friction and the normal force. It is NOT affected by (nor is it a function of) the contact area. A larger contact area reduces the STRESS on the rotor, but does not increase the clamping force.
However, it could be argued that a larger pad has a larger coefficient of friction, but that's also debateable. For example, a smaller pad in an HH material might provide the same CoF as larger set of standard pads. The caliper with the larger piston area (the 2-piston caliper in my example) would provide superior stopping power.
DavidR.
Quote from: SlowOldGuy on November 26, 2012, 10:31:59 PM
Nice try Pat, BUT (that's a big but),
The clamping force is a function of the coefficient of friction and the normal force. It is NOT affected by (nor is it a function of) the contact area. A larger contact area reduces the STRESS on the rotor, but does not increase the clamping force.
So the clamping force, as measured at the surface of the rotor, is the same regardless the size of the brake pad?
IOW, equal caliper piston sizes, equal m/c's, equal coefficient of friction on the pads BUT two different pad sizes, one large and one small, and you say the clamping force as measured at the rotor, is the same?
You say " ..the larger contact area reduces STRESS on the rotor..."
Yep you are right..'cause the clamping force is less...it's spread out over the larger area of the pad.
My point is that the pad areas are different between the 2 piston vs. 4 piston calipers and that should be taken in account.
And.... The reason for going to the Monobloc calipers has NOTHING to do with clamping force, and everything to do with increased controllability (aka; modulation) of the brakes. The monoblocs/R1 MC made minor changes in braking force into a corner much easier than the original 4-pots and MC combo.
The 1st time with the monobloc combo that I had to get hard on the brakes in traffic, I squealed the front tire. It was a surprise, but I had no eye-opening, pants-filling, OH SHIT moment. 1st time I locked the front tire with the original 4-pots, there WAS a huge OH SHIT....
I think trail-braking thru a corner is easier with the monoblocs, as well.
Quote from: RichBaker on November 27, 2012, 12:26:23 AM
And.... The reason for going to the Monobloc calipers has NOTHING to do with clamping force, and everything to do with increased controllability (aka; modulation) of the brakes. The monoblocs/R1 MC made minor changes in braking force into a corner much easier than the original 4-pots and MC combo.
The 1st time with the monobloc combo that I had to get hard on the brakes in traffic, I squealed the front tire. It was a surprise, but I had no eye-opening, pants-filling, OH SHIT moment. 1st time I locked the front tire with the original 4-pots, there WAS a huge OH SHIT....
I think trail-braking thru a corner is easier with the monoblocs, as well.
I did each part of the brake upgrade, m/c with adjustable lever, lines, calipers and pads separately with a long time between each.
Each part improved the brakes in feel or efficiency but I reckon the blue dots made the least difference.
I suspect some do several of these things at once and attribute all the improvement to the calipers.
A also suspect some would be replacing calipers that aren't working properly.
I recently changed over my original and reconditioned 4 piston calipers running EBC HH pads with blue dots and standard pads and felt I had taken a step backwards.
I had to wait a few weeks for my new pads and did 4000 k's ( a couple of trips) with this configuration including a weekend in the mountains so I had plenty of opportunity to use them.
The harder I used them the less I liked them. My discs became glazed and were discolouring from heat.
New pads are now fitted and the brakes are fantastic. Disc surface no longer shiny and the feel and efficiency is brilliant.
If I was doing it again I would do the m/c, hoses and pads and move the calipers down the wish list a bit and spend the $180 they cost on something else to improve the bike first.
This only applies of course to later bikes already fitted with 4 piston calipers.
And for those who think all HH pads are the same:
A quote from oldktmdude
When I first fitted the blue spot callipers to my'85 (about 2 years ago), I bought a set of Goldfren HH sintered pads to use in them. (mainly due to the low price) Up until today I was very satisfied with them. Finally wore them down, so on the strong recommendations of alot of members here, I bought and fitted EBC HH sintered pads. WOW what a difference! I had good braking before but now I have GREAT BRAKING. Hard to believe that there could be so much difference between pads that are supposed to be of a similar compound. A big thankyou goes out to those who recommended the EBC pads. Regards, Pete.
Unless I'm missing something, a given pressure in the braking system spread over any number of pistons of any number of sizes will end up being the same force per unit of area at the piston. Otherwise you're violating thermodynamics and creating energy somehow. Force in = Force out, excluding leaks and shit.
The monobloc calipers actually do increase the amount of force going to the pads, but that's by reducind the loss (the caliper resists expanding away from the rotor better than the older designs do).
Stick new pads in it, spend the money elsewhere for now. Strong, controllable brakes trying to control bald tires through a worn-out chassis.... etc.
Quote from: fintip on November 25, 2012, 07:00:10 PM
So, I have a shot at getting a pair of calipers from a friend for super cheap. I just want to make sure I've got this right, and I think there's about a 50% chance I'm completely wrong.
He pulled some gold calipers off of a '91 FZR600. He also says he thinks they were aftermarket; they say "Sumitomo" on them.
Would those fit the 3CV forks and/or the earlier forks with the adapter plate to get them onto the older rotor that comes with the earlier forks?
He's offering them for $30, which seems like a steal--impression is that they're working, but I don't mind rebuilding calipers to save money anyways, and they should probably be rebuilt anyways while they're off.
To buy or not?
According to this list (http://www.fjowners.com/index.php?topic=5657.15), I might be in luck?
Sumitomo is the manufacturer of all three types of caliper in discussion here, so no need to think of them as "aftermarket"...
As I understand it, the FZR600 calipers you refer to would probably be of the type that has a SINGLE pin retaining the pad, is that what they are? Whereas the FJ 4 pots have 2 pins...
My belief is, although I've not personally sized it up, the FZR600 (single slider pin type) caliper bolts straight on to the earlier 16" fork lowers with no adaptor plate required and will align with/match up to earlier small discs.
In all the theoretical calculation formulas I've ever read regarding brake design for race cars and bikes, pad area means nothing and is not taken into consideration in the relevant engineering formulas.
Whereas brake rotor diameter, brake to rotor friction coefficient and pounds per square inch force
are the only variables in the equation.
To double the pad area is to halve the psi force @ pad to rotor contact. That's not to say it doesn't affect pad or rotor wear rates though.
oops, duplicate post... :shok:
Pad size increases/ greater surface area against the rotor, are subject to to deflection like any other application of force. Andy's "leaks and shit" speaks to this. To exaggerate to the extreme to illustrate the point, imagine a pad that was clamped, as normal, on, let's say a single piston caliper, but the pad surface covered the entire rotor, all the way around. There would certainly be a significant, measurable difference in clamping force opposite the caliper, as compared to under the piston at the caliper. Why: deflection, the pad farthest away from the caliper would 'bend' away from the rotor, or more precisely not clamp as much, as compared to the section of pad under the piston. The larger the pad, the greater the opportunity for deflection -not to mention the additional un-sprung weight trade off.
There is a reason why motorcycle, (and car for that matter), engineers use smaller pads as compared to the size of the rotors. Throughout history, large pad 'experiments' have met with failure and ultimately were replaced with more conventional smaller pad brake styles in later versions.
My $0.02
Dan
Quote from: ribbert on November 27, 2012, 07:26:47 AM
I recently changed over my original and reconditioned 4 piston calipers running EBC HH pads with blue dots and standard pads and felt I had taken a step backwards.
I had to wait a few weeks for my new pads and did 4000 k's ( a couple of trips) with this configuration including a weekend in the mountains so I had plenty of opportunity to use them.
The harder I used them the less I liked them. My discs became glazed and were discolouring from heat.
ribbert,
It sounds like the "standard pads" that you used first in the monoblocks were contaminated. Were those pads the stock Sumitomo G-G. Were they the pads that came with the used monoblocks, or were they fresh and new? I've had one set of monoblocks (out of the four that I've retrofitted to some of my/our bikes)glaze discs, and in that case it was because the pads had been soaked in fork oil.
My point in all of this is that its a good idea to use new pads when first mounting a pair of monoblocks.
Quote from: WestOzXJR on November 27, 2012, 09:07:38 AM
My belief is, although I've not personally sized it up, the FZR600 (single slider pin type) caliper bolts straight on to the earlier 16" fork lowers with no adaptor plate required and will align with/match up to earlier small discs.
Wouldn't be real hard to compare the two by measuring the distance between the mounting bolts. Early forks require 83mm between the centers of the bolts that mount the calipers, iirc.
I think the FZR600 calipers are on the same 83mm centers as the early FZR400. From what I was looking at, the FZR600 calipers should fit the 84-87 FJ if they're the earlier ones, so pre-91 models should fit.
Which means that they're not really an upgrade, or they won't fit without faking it a bunch. Meh. Do it properly, upgrading the forks, wheel, and brakes all together, or just slap good pads in and change the fluid, job done.
Quote from: andyb on November 27, 2012, 11:51:30 AM
Do it properly, upgrading the forks, wheel, and brakes all together, or just slap good pads in and change the fluid, job done.
+1
Quote from: andyb on November 27, 2012, 11:51:30 AM
Do it properly, upgrading the forks, wheel, and brakes all together, or just slap good pads in and change the fluid, job done.
I'm thinking if you are going the cheap route, just pads and fluid, and have no intention to do the other 'proper' modification steps anytime soon, then new braided brake lines is in order as part of a bare-bones, minimum stuff to do list. The old ones are at least, depending on your model year, 20 years old!
Quote from: andyb on November 27, 2012, 07:47:13 AM
Unless I'm missing something, a given pressure in the braking system spread over any number of pistons of any number of sizes will end up being the same force per unit of area at the piston. Otherwise you're violating thermodynamics and creating energy somehow. Force in = Force out, excluding leaks and shit.
The monobloc calipers actually do increase the amount of force going to the pads, but that's by reducing the loss (the caliper resists expanding away from the rotor better than the older designs do).
Disclaimer: I'm NOT a brake system designer; however, the mechaincs and physics of the system are straightforward.
Andy,
Your first statement is correct. The pressure (force per unit area) is the same on ALL piston surfaces. However, the force generated as a result of that pressure is a function of the TOTAL piston surface area that's exposed to the pressure. As the previous calculations show, the caliper with 2 3" pistons has more area than the caliper with 4 2" pistons. Therefore the "old style" 2-piston caliper , in this example, has more braking force at the brake pad.
Whether that higher force results in "better" braking performance is dependent on pad coefficient of friction.
For Pat,
First, be careful mixing Force and Stress in the same context, they are related but are NOT the same thing.
A larger pad is desireable for several reasons. It spreads that clamping force over more area thus reducing the total mechanical pressure (stress) on the rotor. Thus the rotor "should" wear less with larger pads.
Larger pads also provide more surface area to dissipate heat to the rotor instead of the caliper. That's also why the hollow side of the piston is facing the brake pad; less piston area exposed to the braking heat thus less heat conducted into the brake fluid.
So, how do you get bigger pads? Larger piston seems reasonable, and it is to a certain extent. Grow the piston too much and you have to start growing the diameter of the rotor (more unsprung and reciprocating weight).
Solution: Add more smaller pistons along the swept surface of the disc. This touches on Dan's warping pad. If you could provide pistons all the way around the disc, you could have a pad that's also the size of the disc. But that's not very practical, or even required.
With multiple smaller pistons, the rotor can actually be decreased. The lower stress from spreading out the clamping force combined with better heat transfer means smaller rotors can be used without affecting performance.
Comparing the old 2-piston caliper to the newer 4-piston and even the monoblocs, the 2-piston area is greater than either of the 4-piston calipers. Therefore, when keeping the stock 5/8" size master cylinder, braking force will DECREASE when "upgrading" to the newer calipers.
The force will decrease, but overall performance can actually increase due to better (modern) pad composition. Which gets me back to my original point. The pad composition is far more important than the number of pistons pushing on it.
The monobloc calipers HAD to have a smaller m/c in order to retain braking performance. It is a better system and, as Arnie points out, has better modulation.
But, has anyone noticed that for the last few years Yamaha has been putting 15mm master cylinders on most (if not all) of their front brakes? Maybe someone at Yamaha "thinks" they've been giving riders too much front brake power? Just a thought.
DavidR.
fzr400 rr twin spot calipers will fit, hard to find and wreckers want $85 each for them, have to be the rr model as normal fzr400 ones wont fit, , these are for the 16" front wheel fj,s