stock brakes - do they suck?

[alex.s]

went on a nice downhill ride through some twisties the other day and noticed (with near full pads) my brakes seemed to get rather hot, and after a bit, started to slip a lot easier... i had to pull much harder to get them to work at the same efficiency... which makes me wonder, do our stock brakes suck? i ordered a stainless steel line, but im wondering if i should go further... i've seen people with fancy brembo calipers and people who've put two disks up front... is this worth it? maybe i'm asking for too much from the little ninja?

--alex

[TheDuck]

I don't have any concerns about my brakes... but I do have complaints about the nose dive when braking.

Depending on your type of riding style or riding place (track vs street) you may find that your brakes are either ok, or inadequate. For most of us the stock 250 brakes are just fine. Unless you are an erratic rider and like to stop/go/stop/go/stop/go lots and lots you shouldn't have a problem. ( I have a friend that drives a Kia like that, he wears out his brake pads and also gets terrible gas mileage because he's a twitchy driver... in a Kia! A car that is supposed to be CHEAP to operate!)

Of course if you ride on a really tight track and you expect that you'll be more demanding of your brakes, then yes, you may want to change out the calipers, lines, master cylinder the works! But if you're gonna go that far you might as well rip a whole front end off of a 636 or equivalent and upgrade the crappy 250 forks at the same time... this option is almost plug 'n play, too.

[Alex]

I found the stock pads just fine, and they only got a little toasty after some very significant twisty downhills, but nothing to worry about. With lesser pads (non-HH), I found that they got overheated way too quickly and required much more braking force. Now back to HH (EBC FA197HH's), and they feel just fine once again. All brakes will fade if subjected to enough heat in a short enough time, but there's nothing particularly poor about the ninjette's brakes. The stainless line can make the feel at the brake lever a little more precise, but won't affect whether or not the pads fade a bit after high heat.

[ninja250]

No problems with my breaks really so far..
I might like it if my front brake kicked in a little earlier in the lever pull though.

I'm pretty sure I can adjust that.

I ride fairly aggressively in the turns but I've never scraped knee yet or hit the chicken strips.

Every time I try feels like the back end gets loose. lol
Must not be leaning enough or something. Not a priority to scrape the strips off.. or drop my bike.

[bdavison]

First things first...
Work on learning downshifting and use engine braking. What you were experiencing is known as "brake fade" and it can be dangerous if you overdo it.
It can get to the point where it boils the brake fluid, then your ride will get really interesting. Downshift and use the engine to slow down, and keep off the brakes as much as possible on long downhill runs. If you start noticing substantial fade, pull over and let them cool off before you lose them all together.

As far as the brakes go....the first thing you might want to do is flush and replace the brake fluid with some good clean NEW!!! high quality Dot 4. Check your pads, and make sure they are still in spec, and the rotors too. Make sure they are clean too. A clean bike is a good running bike.

As far as upgrades. Upgrades to brembo would be my first recommendation. Brembo are by far the absolute BEST brakes you can get. Period. You could run dual calipers on the front if you can find a kit or something to do it. I dont know if brembo makes a dual kit for the ninja 250r or not. In reality, dual calipers on the front of a 250r is a waste in my opinion unless you are doing stoppies or something. The other thing is rotors...the stock rotors are semi-petal rotors so they work pretty well, but there are some better designs that dissipate heat better.
SS brake lines will help a little, since they wont flex under pressure. But...you cant see leaks with SS lines...so you'll have to keep an eye on them real close. Personally...I think they are more of an asthetic than performance mod on a stock setup, but can be useful if you are running upgraded master cylinders or calipers.

[silver_bullet]

I haven't really had a problem with the brakes but I've probably only driven it 600 miles or so. We will see i nthe spring when it becomes my commuter bike and the 600R becomes more of a weekend bike

[wyckedflesh]

Once I changed the front fork springs to match my weight, I have not had any issues with my brakes what so ever. Most of the extreme fork dive went away as well. Lots of elevation changing canyon runs of hard on and off the gas and brakes, track days and I am still on the original pads. I find the traction of the front tire to be the limiting factor now.

[randomwalk101]

Brake fluid boiling yooooo
get dot 5 or some synth type with higher bp...change out more often though.. Butthats the trade off. I guess you never race car or some track before?
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[Snake]

I do not have any problems with my brakes fading but I do use engine braking as bdavison suggested.

[alex.s]

this problem only occurs on 'spirited' downhill runs... and its not a problem during "normal" operation.
I do use engine braking, but when pushing the bike down hill, the brakes get abused quite a bit coming into corners.
I think it sounds like the only real solution here (outside of upgrading the entire front brake system) is to avoid punishing the brakes so much on downhill twisties.
I will try upgrading to a higher BP brake fluid when i install the new SS line and see if that helps...

[Alex]

The brake fluid is likely fine; if it's not boiling now, improving it won't markedly improve braking performance. It is still a single disk, that isn't terribly large, with a low-to-midrange caliper on it. It can only absorb and release so much heat energy over time, and it sounds like you are coming up against those limits from time to time.

[alex.s]

Hmm... I don't like limits... how do we break them? replace the calipers with something that isn't "low-to-midrange"? or would it require bigger/more disk surface area to release more heat quicker? is there a way to tell if its boiling? would the reservoir be boiling or would it only be in the brake line?

[Alex]

It's not boiling. If it were boiling the braking performance would go to almost nothing very quickly, and the lever would turn to complete mush as you squeezed it. They are just fading. Disk brakes, actually all brakes, work by converting kinetic energy into heat energy and then releasing that energy to the surrounding air. At some point, if it has absorbed more heat than it can release, the effectiveness of the pads on the extremely hot disk goes down. The larger the disk(s), the more heat energy it can absorb (as well as the larger the force that can be placed on the wheel, as the pads have more leverage further out from the wheelcenter).

A steel line won't hurt. Better pads (EBC FA197HH are a great choice) will help a bit. Bleeding the system well helps quite a bit, in making the lever feel better upon application and having it perform more consistently.

Other than that, there isn't much that will work out financially. Not possible to just slap another disk on the same wheel, so if someone does go to a double disk setup, it usually involves swapping out the entire front end. Keep in mind that the dual disks don't allow the bike to stop any quicker, as the single disk allows the bike to brake at the limit of the front tire's traction already; it's just that more disk mass will allow more hard braking in a short period without fading as quickly. There are some pics in our gallery of ninjettes with new front ends, I've seen ones with an R6 front end, and even a Busa front end.

[alex.s]

hmm what do you think of this one? http://www.ninjette.org/forums/showthread.php?t=28216

a custom bracket in the center of the wheel to attach a second oem brake pad and a mirrored caliper... do you think someone would be better off just replacing the entire front end?

[bdavison]

It starts in the caliper, just behind the pistons. Heat from the pads gets transferred to the piston, and then to the fluid. You would be surprised at how little it takes.

Brake fluid is not compressable...thats why it works....
When it starts to boil, gas bubbles form in the brake fluid. Gas IS compressable, and thats where you get the loss of response.

Of course, brake fade (loss of available friction from overheating) will occur first.

Thats where DOT levels come into play. The new gen ninja 250r's come with DOT 4 in them already. DOT 4 has a higher boiling temp than DOT 3...and DOT 5/5.1 is even higher. The problem with DOT 5 is it requires higher pressures...so it doesnt work well in systems not designed for it. Stick with DOT 4 in your ninja. Just make sure its NEW, CLEAN, GOOD QUALITY, and the system is properly bled.

[wyckedflesh]

AS I mentioned, replace your fork springs to something adjusted for your weight. The reason is that the stock springs are on the soft side. This causes MORE weight transfer to the front wheel then the bike is balanced for. That makes the front brake work harder then intended.

With your forks at the right spring rate, when you apply the front brake, the dive is more manageable and more linear. This lets you feel the action of the front brake more in spirited braking. Since your problem is in Downhill riding, again, having a front fork at the right spring rate will keep the bike more balanced at the incline, so when you add front brake, your less likely to bottom out.

Watch the pros work. You will see that they are very smooth on their braking. Its not abrupt and sudden, but smooth and linear. A pro on a stock bike won't pogo the front end into a corner. The whole bike squats under control. Even when you watch a pro take a bike to the extreme limit and the rear starts floating side to side across the pavement, the bike still looks level.

Outstanding equipment is a band aid. It may improve the physical braking, but if your skill is below that level, then you will never see the improvement. I can still remember running around a track on a 410lb bike with drum brakes front and rear. I can stop my Ninja as well as I can my Ducati. It is in the practice. Up hill, down hill the only thing that should change is your initial braking point and pressure.

Now with that said, start with a new line, fresh fluid and a very good solid bleed. Change the pads when it is time to a better quality. IF that isn't good enough, take your bike to a suspension specialist to get some idea of how out of balance your bike is. Spot on or as close as it is going to get? THEN think about a Caliper and Rotor conversion to a larger set. A 250 does not make enough power or weigh enough to really need twin disks in a Street only application. A race only bike might be different if your racing 250 two smokers and slicks.

[sharky nrk]

a lot of good information has been relayed on here already. A few things to consider, the friction force that actually acts opposite of the forward momentum force of the bike is generated between the tires and the road. You didn't mention what tires you were on. Stock? or more performance oriented. A braking system that is perfectly within its limits on very sticky street rubber can quickly become overwhelmed with the additional energy provided via a higher coefficent of friction of aggressive rubber.

What you seem to be describing sounds much like brake fade associated with overheating of the brakes in relationship to pad compound. Brake pads are designed to provide a certain coefficent of friction against the iron rotor surface at a certain temperature. If you get outside of the temperature range (relatively cold or hot) performance will suffer. The thermal energy that is created in braking has to be transfered somewhere. Initially it is transfered to the rotor itself. The rotor has a certain mass to it and a certain thermal conductivity with the air moving around it. If your heat input is greater than the heat output via airflow and surface transfer the temperature of the rotor increases. This build up of thermal energy and increased tranfer to surrounding items (pistons in the caliper, caliper body, fluid, ect) will move the braking components outside their intended operating ranges.


Now all that being repeated again your options are very simple. You can either increase the ability of the system to absorb and transfer the thermal energy: more rotor mass, more surface area, more thermal transfer to the air; increase the component's intended operating temperature: pad compounds designed to operate at higher temperature; or decrease the necessary energy to slow you down. You can add rotor mass via another rotor, a thicker rotor, or a larger diameter rotor. Neither of these are simple or cheap in particular. A higher temperature compound pad is an easy change but generally you can move the thermal operating envelope around but not so easily find a good and inexpensive pad that widens that envelope. There are also tradeoffs, moving the envelope higher your low temperature performance may suffer, you may have more rotor wear, noise, dust ect.

You can also decrease the necessary energy requirement. This can be by slowing down (less momentum force), stiffer front fork (less weight transfer to the front wheel), more rear brake (less weight transfer to the front wheel more thermal energy directed to the rear wheel), using engine braking to supplement brake application, ect ect ect. Slowing down sucks and your rear brake application is dependent on available traction on your rear tire.

A few things to note, brake fluid brakes down and needs to be changed and bled frequently. Boiling your fluid is far less likely than overheating your pads, and fresh, bled fluid is less likely to boil. A stainless line will help feel but do nothing for the thermal ability of the system. Additional braking force unless coupled with a greater thermal sink or greater thermal transfer will do nothing to help the thermal ability of the system.

[MKlein3004]

man i was just about to say all of that....LOL

all that is actually very true and good information for anyone looking to upgrade or just gain knowledge of a braking system.

Hey Neil, guess what i am doing with my hands and my face.

[TheDuck]

Aww c'mon... change out the whole front end to one from a 636! The steering stem from the 250 will need to be pressed out and into the 636 triples, but as a perk your fender from your 250 will match the bolt holes on the 636 forks! Slam it on! It should look factory then!







DISCLAIMER: Just because you have a 636 front end doesn't mean you can do 12 o'clock wheelies or ride without a helmet.

[Rayme]

Originally Posted by TheDuck

Aww c'mon... change out the whole front end to one from a 636! The steering stem from the 250 will need to be pressed out and into the 636 triples, but as a perk your fender from your 250 will match the bolt holes on the 636 forks! Slam it on! It should look factory then!







DISCLAIMER: Just because you have a 636 front end doesn't mean you can do 12 o'clock wheelies or ride without a helmet.

This. looks.. BAD ASS !

[TheDuck]

Originally Posted by Rayme

This. looks.. BAD ASS !

I already have too many projects or mine would already have one... gimme a little time.....

[TheDuck]

Oh forgot to mention, the front wheel look/style/design of the '05-'06 636 matches the rear wheel on the '08-'09 250. What you see in the photograph above are the earlier forks from an '03-'04 636 with the respective wheel from that year.

That is only important to people that are really anal about asthetics. The big discs somewhat cover the wheel anyways so its tough to tell the design unless one looks really closely.

[Rayme]

Originally Posted by TheDuck

Oh forgot to mention, the front wheel look/style/design of the '05-'06 636 matches the rear wheel on the '08-'09 250. What you see in the photograph above are the earlier forks from an '03-'04 636 with the respective wheel from that year.

That is only important to people that are really anal about asthetics. The big discs somewhat cover the wheel anyways so its tough to tell the design unless one looks really closely.

So its a real simple install most of it? This sounds like a cheap upgrade if one is to sell the stock parts back...

[TheDuck]

Originally Posted by Rayme

So its a real simple install most of it? This sounds like a cheap upgrade if one is to sell the stock parts back...

Yeah it should be real simple with only a few minor niggles.

1. You will need a machinist or someone with a press to switch the steering stems.

2. You'll find that the 636 forks are a little longer than the 250 ones, but thats ok... lower the front by letting the tubes stick up out of the top tree. OR leave it stock 636 height, and raise your rear with a longer shock... I haven't researched it yet, but I think maybe the 636 or 10R shock might work, stay away from the crappy SV650 shock. I don't know how dorky it might look up tall though... like the Versys.


I'm sure the Versys is a great bike, but it reminds me of this:


3. If you lowered the front put your 636 clipons on TOP of the top triple so that they clear your dash properly.... OR get a set of Suzuki TL1000 or Honda CBR929/954 (Honda ones are taller) clipons and put them between the trees, they should give you the rise you need and will look cleaner.

Everything else is easy... just bolt the rest of it all on.

I LOVE parts-swapping. I've built entire CHEAP frankenbikes from ebay winnings, lol. I should write a book or a reference guide of swappable parts between brands/models of all bikes.

Couple things came to attention. Speedo sensor and ignition keyswitch. I have no idea how to get these working until I have parts in hand.

[Rayme]

TheDuck, thanks for all the info. Do you mind asking you if you used the 636 clip on gears and switch, or you use the whole top parts and "handlebar" of the 250R ?

[TheDuck]

Originally Posted by Rayme

TheDuck, thanks for all the info. Do you mind asking you if you used the 636 clip on gears and switch, or you use the whole top parts and "handlebar" of the 250R ?

Did you read my posts entirely? lol

First, I haven't done it yet.

Second, the 250 bars won't fit on the 636 trees. You'll have to use the 636 clipons or the other clipon options I suggested.

[Rayme]

Originally Posted by TheDuck

Did you read my posts entirely? lol

First, I haven't done it yet.

Second, the 250 bars won't fit on the 636 trees. You'll have to use the 636 clipons or the other clipon options I suggested.

Whoa sorry, I missed the end paragraph of your last post

[TheDuck]

Originally Posted by Rayme

Whoa sorry, I missed the end paragraph of your last post

Haha! Its ok. Lets rip a front end off!

[whylee]

I would assume you need the master cylinder from the 636 also?

[TheDuck]

Originally Posted by whylee

I would assume you need the master cylinder from the 636 also?

Yes, or something from another bike of a similar size. Perhaps a GSXR600, or maybe even a ZX10R. Those should work just fine.



I think I should start my own "fork swap howto."

[Vatos_locos]

why not just to put a 4 piston caliper for start to see if this will improve your brakes http://cgi.ebay.com/ebaymotors/GOLD-...Q5fAccessories

[sharky nrk]

I had just posted a nice long informative post and my internet locked up, so you guys get the short non-equation filled version.

Long story short: braking force at the rotor is the result of the hydraulic force (piston area and force), effective radius of the rotor, and coefficent friction of the pads, minus losses. Increasing the number of pistons does very little to improve the braking force unless you have an increase the cross sectional piston area. It also does very little to improve the thermal efficiency of the system. You gains are simply in feel and modulation due to stiffness of the caliper body and tuning of the piston sizes for force application.

[Vatos_locos]

ok i got it but would be better to have 2 more pistons and one ss brake line to transfer more pressure to the caliber plus better brake pads ?

[TheDuck]

Originally Posted by Vatos_locos

ok i got it but would be better to have 2 more pistons and one ss brake line to transfer more pressure to the caliber plus better brake pads ?

Yes, you'd probably have a much larger brake pad on dual piston caliper. That means you have more contact surface area. Less effort would be required on the brake lever to acheive the same amount of friction, but the disc will probably heat up faster because of the increased pad size and pinching force.

In an emergency situation in traffic, yes it will stop somewhat faster, but on a track with a lot of tight turns there may be little advantage.

Thats one of the advantages of dual rotors. Each side has to work half as hard as a single thus heats up less quickly, much less brake fade!

But remember, no matter what kind of brake you have on the front, you will still be limisted by the amount of grip of the front tire on the road, and even the little dual piston caliper 250r brake can easily lock the front wheel up if you squeeze it hard enough!

[Vatos_locos]

that is what i was thinking off now lets blend a bigger brake rotor in the recipe ( more piston in the caliper, ss line ) would it worth the cost for the upgrade ?

i still havent found a bigger better brake rotor

[TheDuck]

Originally Posted by Vatos_locos

that is what i was thinking off now lets blend a bigger brake rotor in the recipe ( more piston in the caliper, ss line ) would it worth the cost for the upgrade ?

i still havent found a bigger better brake rotor

A '98-'03 R1 (or '04-'07 VMax also, with different design) right hand side rotor will fit. Like the '08-'10 Ninja 250 it has a 6 bolt pattern and is a flat disc with no offset. The bolt hole circle diameter will be the right size, but the bolt holes themselves will have to be drilled out 2mm. (Big deal!) Either one of those will take you from the factory 290mm disc to a 298mm... not really worth it... but it sure would look cool with a gold floating disc on it. It might even fit in the stock caliper, oh and its a little lighter and has a better design and will probably cool better.

A '03-'09 Yamaha FJR1300 (ebay NEW , USED)will also need the bolt holes widened 2mm, but it has a 320mm external diameter. This is the biggest *ALMOST FIT* disc for the 250 I have found! Thats 30mm over stock, or 1-3/16" to you imperial guys. So if wanna go this route and you're anal, buy the brand new single one, if your a d1ck, buy the pair and sell the second one to your friend for what you bought the pair for.

I believe the '04-'05 R1 disc could also work with some modifications. The inner diameter will fit on the 250 wheel, and there is no offset. It has a different bolt pattern, but it has a 310mm diameter, a 20mm increase over stock. I don't have one of these on hand, but bikebandit's microfiche shows 5 bolt holes... maybe you can redrill one of these for 6 holes? This might be a cheap alternative to buy a used one of these and make it fit.

I'm sure there are some other discs that might work with a little hacking, but no matter which you choose you're going to have to come up with your own caliper mount bracket... if you're buying brand new parts you'll spend a fortune, + the fab costs for the bracket. But if you're handy, or have access to a shop, I say start cuttin'!

[TheDuck]

UPDATE:

A disc from a '06-'09 Hyosung GV650 will also fit! Direct bolt on! The outside diameter is 300mm vs the 290mm of the stock 250. Interesting trivia, I dunno where you'd find one though, haha.

[Vatos_locos]

wow thats a lot of feedback. ok i see but if we put a bigger rotor larger than 290mm we will need something for the caliber to move it farther from the fork is this correct ?

[TheDuck]

Originally Posted by Vatos_locos

wow thats a lot of feedback. ok i see but if we put a bigger rotor larger than 290mm we will need something for the caliber to move it farther from the fork is this correct ?

Yeah, I know some stuff, haha.

Yep, more than likely the caliper will have to be moved outwards. You can experiment with the 298mm disc. You might get real close! Anything larger will definately need a caliper bracket and if you go with a bigger caliper you'll probably need a special bracket to mount it anyways.