Author Topic: Better brakes (Read 6580 times)

duane · « **on:** June 21, 2007, 05:24:39 PM »

I never have been fond of the front brakes on my b4. I have a steel braided line, tried a different rotor, replaced the master cylinder's piston, replaced both piston and seals in the caliper and all kinds of other stuff. I don't need schooling on air bleeding or maintenance.

I'm considering this.
My question: The OEM master cylinder piston bore is 14mm, right? What would happen if I used an after market master cylinder with a piston bore that's larger, say 15mm or 16mm? I've read before, "Be careful, be careful!" Well, ya, but what's it like?
Thanks.

Banditmax · « **Reply #1 on:** June 21, 2007, 06:03:18 PM »

15mm means your gonna be exerting less pressure on the fluid so you'll have to move the lever further to get the same effect.

pmackie · « **Reply #2 on:** June 21, 2007, 06:19:45 PM »

A larger bore will move more fluid. Usually only required when you need to move more pistons on the caliper end. In this case, it should mean less movement at the lever before the brakes are fully engaged, but you will need more "squeeze" on the lever to get the same braking effect, probably NOT what you want.

A smaller bore will generate more psi in the system for a given "squeeze" but won't move as much fluid. So usually the master and calipers have to be close in design.

I'm not fully familiar with the 400. Does it have 2 piston, sliding calipers like the 600? Or are they opposed piston calipers, (usually 4 or 6 pistons) like the 1200 and current sport bikes?

Some others here might have experience using other master cylinders with good success.

To increase braking performance, I have found the following helps:
1. Upgrade to steel braided lines (you already did this)
2. Move the master cylinder bracket "inboard" away from the throttle grip. This allows you to put greater pressure on the master due to increased leverage.
3. Change to different pads. On my 600, I went to EBC HH pads. No more ultimate power, but they had greater initial bite.

This combination on my 600 changed me from a 4 finger squeeze for decent stopping power to 2 finger squeeze in most situations.

To get even more force, you are looking at hardware changes, like:
a) larger diameter rotors, would require modified caliper mounting.
b) different calipers, such as 4 piston, opposed, monoblock, if you can find something to fit.
c) radial master cylinder, assuming it works with your existing calipers.

gsxr400 racer · « **Reply #3 on:** June 21, 2007, 07:11:18 PM »

simplified go buy a used newer gsxr master with the cup and you will be impressed

duane · « **Reply #4 on:** June 21, 2007, 11:09:26 PM »

Jay, do you pay attention to the size of the cylinder bore? Thanks.

tomacGTi · « **Reply #5 on:** June 22, 2007, 12:03:23 AM »

You DO NOT want to go to a larger bore MC.

What will happen is the lever feel will go from progressive to feeling like wood. The Bandit's MC should be 13mm and most other bikes are 5/8 and above (17-19mm). You will be moving more fluid with less lever travel so pretty much the brakes will either be fully on or fully off. There is no happy medium.

I experimented with this a little bit last year when I upgraded to a four-piston front caliper. I had tried to use a b12 front master which was 5/8 and no matter what I tried to do, I had to squeeze so damn hard to get the bike to stop and when it did, there was only about 1/2" of lever travel before it was on it's nose. Different strokes for different folks, not me though.

I didn't go into trying a radial caliper (they get expensive) and kind of gave up researching cross-usable radials from other bikes. YRMV. Your best bet as far as a brake improvement would be either more aggressive pads or look into a Japanese/Brit front end with the dual front brakes. Of course you might as well go USD once you add it all up.

-Randy

duane · « **Reply #6 on:** June 22, 2007, 12:29:00 AM »

Quote from: "tomacGTi"

The Bandit's MC should be 13mm and most other bikes are 5/8 and above (17-19mm

Thanks for the input Randy. Does the Service Manual tell you what the bore is? I can't find the spec anywhere reliable. What did you experiment with and what did you settle on for brake components on your B4? Thanks again.

tomacGTi · « **Reply #7 on:** June 22, 2007, 12:36:41 AM »

Bore is usually printed on the MC itself.

You'll see raised letters near the pump saying 1/2 or 13mm etc. Just about all of the large manufacturers do it like Nissan and the like. Also, the reason there's a larger bore is to move more fluid (duh) when you have more pistons. If you move up bore without increasing pistons, you're just taking away lever travel (see why they'll feel like wood?). Fluid is incompressible, so it has to go somewhere.

Before I swapped over to the four pot via caliper spacer and a GSXR 750 brake, I was running the stock caliper with HH rated pads. Much better than the organic that was in there. If you haven't done a pad swap yet, try that, worlds of difference once broken in.

With the four pot, it's the same but the power is easier to bring on because it uses four smaller pistons versus a small progressive and a larger piston. Yes it also has more power but it's not like a full-on radial either. I'm running more aggressive pads as well. I'm also more of a squeezer versus a grabber (more Schumi than Alonso on the brakes) so take that with a grain of salt as well.

-Randy

b4cruz · « **Reply #8 on:** June 22, 2007, 01:18:28 AM »

I found these to compare:
http://www.yoyodyneti.com/ProductInfo.aspx?productid=10.4620.23

I don't know how this one works:
http://www.yoyodyneti.com/ProductInfo.aspx?productid=10.5053.53

I completely stripped the screws on top of my
MC. I might be able to eat up just the head and
slide off the cover, but I might mess up and
destroy the housing too. Do most single disk bikes
have 13mm MC setups? It seems the cheaper
monsters with single front disk come with
standard 13mm MCs.

If I can't pull out the screws without destroying the
housing I was hoping to scour some junk yards &
salvage any 13mm front MC from a single rotored
Frontend. With luck I may find one with a 34 inch
SS line hooked up to it already! Are there any other
designs that might work better on the B4?

I just spent a decent sum on z6 tires and I've
fallen in love with the little german elephants!
The bike's real now! The tires costed more than
the blue book on my scrathed up b4. But at this
point I think even a $120 Kenda set would cost
more than the blue book on it too.

So the bikes lasted this long, I'd like to complete
it with a better single front brake.

-b4cruz

turbofb · « **Reply #9 on:** June 22, 2007, 01:43:03 AM »

I run a Shindy (Nissin) 5/8 bore MC to actuate my two 6 piston calipers.It works very well and only needs 1 finger to get the back tire up.Of course,this is extreme overkill for a B4,but it works very well.

Randy is right,dont go bigger without matching things on the slave (caliper) end.With no brake assist,like cars have,your lever effort and feedback will be bad.
Think of it like a hydraulic floorjack.....a longer handle might require you to stroke 3-4 feet,but you can lift thousands of pounds with two fingers and vary the speed and effort of each stroke easily.A short handle will only need stroke a few inches for the same work,but youll have to put all your weight on the thing, and youll have no control over modulating the input.

gsxr400 racer · « **Reply #10 on:** June 22, 2007, 08:39:35 AM »

nope i never have checked the bore sizes i have always used gsxr masters if i build a old clunker it gets a master from a gsxr they have never done me no wrong. and i always brake with one finger i would say your lines could be bad ive seen tons degrate internaly

tomacGTi · « **Reply #11 on:** June 22, 2007, 10:11:39 AM »

Yep, most single caliper appilcations are for a 13mm master cylinder.

The Brembo one should work fine and also there is one on ebay for about $30. Differences are that sometimes the lever is fixed and not adjustable for reach. Another place to look is at the GS bikes from Suzuki of recent vintage. They're all single front as well and virtually identical, just on a different fork leg.

Things to remember for a different master:

-brake light swich
-lever reach adjust if you have smaller hands
-coffin or slave style reservoir
-radial or longitudinal pump: affects feel as well

-Randy

Thief400 · « **Reply #12 on:** June 23, 2007, 01:31:49 PM »

I find this thread rather interesting as I have alway found the stock brakes rather good, They perform stoppies and I could always get the rear tire off of the gound while apex clipping. Yes I did Put a whole 750 Katana front end on my bike but I did it more for the better suspension than I did It for the dual front brakes. I did however use the stock Bandit master cylinder with the Katana calipers. I now have ture 1 finger braking.
One question that I do have is what are you using for pads, the stock ones are best, they eat the rotors but provide the most power. Another thing is if your changing between different pads you have to clean the rotor with brakekleen and fine steelwool to get the brake pad material out of the rotor as this can effect braking grately as most different pad materials are not compatable!!

duane · « **Reply #13 on:** June 23, 2007, 03:40:15 PM »

Everyone is asking what pads I'm using....

The......

answer.....

is......

EBC HH!

Those FA129 organics from EBC are underwhelming, they border on crap. My race bike has HH's too and I like them.

Hey look at that, it does say 1/2! Thanks Randy!

Another question is what does the circled "2k" mean? My Kawai, single caliper-dual piston, same master cylinder (I believe) has a circled "1k" Also it's unusual the manufacturer, Nissin in this case, use a fraction of an inch instead of a metric value like everything else on the bike.

Thief400 · « **Reply #14 on:** June 23, 2007, 04:27:54 PM »

I tryed those for about a half a day they are crap!!!!!
Clean the rotor like I told you and install a stock set of pads and you will be happy