Brakes...

[fintip]

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, I might be in luck?

[craigo]

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

[aviationfred]

Here is a photo of what you are looking for....



Fred

[SlowOldGuy]

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.

[aviationfred]

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

[FJmonkey]

Talking with Kyle he wants to get the adapter brackets to save a little $$% before he gets serious on his mods...

[SlowOldGuy]

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.

[racerrad8]

Which isn't that expensive...

84-87 Caliper Rebuild Kit - $28.99ea
EBC HH Brake pads


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

[Dads_FJ]

Which isn't that expensive...

84-87 Caliper Rebuild Kit - $28.99ea
EBC HH Brake pads


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). 

[SlowOldGuy]

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.

[Pat Conlon]

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...

[SlowOldGuy]

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.

[Pat Conlon]

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.

[RichBaker]

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.

[ribbert]

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.