Hi everyone!

I´m experiencing a strange brake fault:

Front brakes;
Low brake power, get worse at late evenigs.
Have tried to screw the setting but the result is still bad.
A little oil on the discs was discovered and I did clean them but
the brakes is still bad.

Rear brakes; Low to no brake power, setting does´nt matter,
Installed HRC rearbrake reservoir and new brakefluid.
When I push the brake caliper back the amount of oil in the reservoir
increase but when the caliper returns the brakefluid stays in the reservoir.
No oil leaks.

Edit: the bike has been standing still a couple of years.

Does anyone know what can be wrong?

Happy for a answer!

"Oil" on the discs is a bad thing, even if you clean it off. It's most likely contaminated the brake pads, and regardless of whether the "oil" leak has been fixed or not, the pads are probably now shot.

You need to trace the source of the "oil". It could be a damaged/leaking fork seal (fork oil), or a damaged/worn caliper seal (brake fluid - it can look a little like oil) which is much more serious!

The uneffectiveness of either front or rear brake system can be due to other factors too if a bike is stood for a long time. Brake fluid is hydroscopic, meaning it absorbs moisture from the air over time, and this is why it should be changed at least once a year. The seals in the calipers and the master cylinders can perish too, especially if the dust covers are worn or damaged.

Without doubt the single most important part of the bike is the braking system. Any faults shoud be addressed before attempting to ride the bike again, even if it means replacing the master cylinders, calipers, pads, hoeses, or even discs.
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Andy.
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Thanx for the reply!

front brakes; Yes oil is not a good sign. I was thinking that the oil came
from the front forks that where leaking before (now fixed).
Now it seems I was wrong.

Agreed! Brake system is THE most important part of a bike so I just have
to start tear the brakes apart to find out whats wrong with them.

However, what can be wrong with it if it´s not (only) the seals?

I would still recommend changing the pads. They can absorb the fork oil or brake fluid easily over time, and that will seriously reduce their effectiveness.

I'd take the calipers/hoses/master cylinder off as a complete assembly and try to carefully "pump" the pistons out by operating the lever. Use a thin alloy or wooden block in place of the pads to prevent the pistons popping out of their housing if you don't want to completely dismantle the system. This should get the pistons out far enough to thoroughly clean them. Doing this on the bench is far preferable to trying to work on the bike in my opinion, as if you pop a piston you don't run the risk of getting fluid all over the wheel or bodywork.

I've seen plenty of older NSR master cylinders in need of a rebuild kit. I personally wouldn't bother rebuilding one now unless I wanted to restore an NSR to showroom OEM spec. Your money is better off spent on a newer radial master cylinder off something like a CBR1000RR. I fitted one to my MC21 recently and was astounded that even a numpty such as myself could actually "feel" the difference over a conventional master cylinder!
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Andy.
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Do the brakes feel hard or soft? It just sounds strange that the front and rear have failed together.
Have you bled the brakes properly?

If its anything like my rear brake its a joke at the best of times.

Front should be good though.

If the lever is hard and there is no braking force I'd side with Andy and change the pads (after youve cleaned the disks). I'd be chaning them anything if there has been oil kicking around anyway.

The other thing, and it sounds stupid but it has been done. Are the pads in the right away around? They don't tend to work so well backwards.
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If I have to take the carbs off once more...

Funny story (well, not really funny!), but a friend of mine called the other day to say he'd just had to check some brakes on a Hi-Lux for a customer of his who was complaining that they had started to screech. He said they only been fitted a week ago and were fine, but the screeching noise began a few days later and was getting worse. Turns out the pads in the rear were in back to front, and the little bit of friction material protruding through the backing plates and the bonding agent had been enough for them to work quietly for a couple of days!
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Andy.
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So are you running fresh fluid in both front and rear brakes? What is your pad and rotor thickness like for both?

If any of my brake pads have been contaminated with oil, I will replace them straight away, and give the rotors a very good clean with brake cleaner, even if it appears to be clean, there is residual oil left on the rotors that can reduce braking capacity.

When you flush the brake fluid, make sure that you do get fresh fluid free of air bubbles and contaminants coming out of the bleed nipple. Your rear brake sounds like there is an air pocket, so I'd try to keep bleeding it. What is the technique that you are using to bleed your brakes?

Sorry if I'm telling you to suck eggs, but sometimes someone has to ask the silly questions

I´l try to make it short!

The levers are soft , both front and rear.
All pads is in correct direction.
New front brake pads will be fitted after a good cleaning.
(If i don't see whats wrong when I change them)
(Thickness is good now though).
Front has old brakeoil, not changed.


Rear pads are a little worn but still there is enough material.
Rear brakes properly flushed with fresh brakeoil.No bubbles or contaiminants. My technique is to hold a thumb on the bleeding nipple and
hold down the brake lever while I remove the thumb and let the oil out in a can. Then I do this till I feel it has been completely flushed.

Thanks for the good tips everyone!
I still think that is strange that both front and rear brakes both react the same.
My guess is that it´s something with the mastercylinder or crap in the system...
I will do as Andy suggested for the moment and see if something turns up.

I will consider to get a mastercylinder from cbr1000rr if it´s wrong with my existing one.
Thanks for that tip!

Now there are´nt any stupid questions so if you think you know what can be wrong, please let me know!

Not sure about your bleeding technique, but this may be of some help:

http://race-lines.co.uk/bleeding/
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Andy.
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Is that a bit of shamless self promotion Andy?

If it was me doing the job, I wouldn't feel confident with the brake bleeding technique you are using since you'r thumb does not provide a good seal, and it gives the brake fluid an opportunity to be contaminated by your natural oils and moisture in your skin. If you have found it to work properly, then keep using it

Andy's link is a good technique, make sure you use a clear length of hose from the bleed nipple to the was brake fluid container. This will let you see if there are any air bubbles or contaminants in the fluid.

A newer (compared to the original NSR) master cylinder I think will always feel better due to less wear and whatnot. I think a radial m/c will again feel so much more responsive compared to a standard m/c.

Just for some more food for thought, I have seen a set of good (4mm thick) rotors with worn brake pads feel terribe....to the point where a real firm squeeze can get the lever millimeters away from the bar.

nxrsr20 wrote:
Is that a bit of shamless self promotion Andy?

It did cross my mind a bit, but I do offer Members HEL Performance brake line kits considerably cheaper than anyone else on the planet!

Besides, we do keep getting even less shameless people trying to advertise on the site for free without offering anything back!

To be honest though, a half decent bleeding guide was more the priority than a possible sale to be honest. Like you said, not trying to teach anyone to suck eggs, but not everyone has had to bleed brakes before, or been shown a good way to do it.
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Andy.
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Yeah I know, the technique I use for bleeding my brakes is from
Stoneage haha.

Thanks for that guide it will be very useful!
I just need to get a good bleeding tool that is suitable for bikes.

Can I install mastercylinders from CBR1000RR from both front and rear?

Acually I liked the tip with the steel braided Brake lines as I think its time that i get some with a more suitable length. And I want to be a member

Okey.. Here is an update of my problem...

Front brake seem to have the same issue as the rear.
When I deattached the front calipers from the discs and took away the pads
there was no oil leaks, there was only some dust.
At this point I tested to "pump" the lever so that the brake pistons should move outwards,
but it just went 1 mm out and then went back again just like the rear brakes.

I think that it could be the mastercylinders both front and rear or
it could be rust on the inside of the brake pistons/calipers?

I don´t know , any ideas please?

Brake fault solved!

It turned out to be air pockets (a lot) in both front and rear
brakesystem after all. But one could´nt use the bleeding nipple to
get rid of the air, because some how a amounth of oil passed the air pockets.
The airpockets was located right after the mastercylinder so
I had the flush the system by loosening the brake line connections.

Anyway, my brakes are working like new again

Thanks for the reply´s!