Changed brake pads tight on rotor?

[F5 Dave]

Arrgh, brain fart, Reckless is quite right I forgot about these (problem with having too many bikes, - - - not that there is such a thing of course in case the wife is reading). I was picturing my GasGas Trials bike calliper in my mind, I knew it was wrong but all I could think of Hebo rather than Nissin as on my EC200.

[Rupe]

thanks heaps for everyones help.

The brakes were mushy before I changed the pads, so I don't think it's from boiling the fluid.

I have cleaned the pins the caliper slides on with wire-wool, and regreased them.

I'll try popping the the pistons, and cleaning them behind them next.

Thanks for the tip of tilting the bike danger I'll try that once I've cleaned behind the pistons. By the way it states dot 3 or 4 in the manual, is it better/ok to use 5.1?

Still not sure why the pads are wearing at the rear though.

[homer]

while were talking break pads ,I used to get vesrahs
there were really good ,does anyone have bad wrap about them today or are they still a good pad to use as i will get more of them in future

[Buddy L]

Thanks for the tip of tilting the bike danger I'll try that once I've cleaned behind the pistons. By the way it states dot 3 or 4 in the manual, is it better/ok to use 5.1?

.

heres a shameless copy and past of a bit of imfor that might come in handy.



Automotive brake fluid has many responsibilities. Corrosion protection and lubrication of brake system components are only a portion of the role brake fluid must play.
All automobiles that have a hydraulic braking system must use brake fluid in order for the brake system to operate. The type of fluid used can depend on the type of vehicle and the demands of the vehicles brake system.

The two most common brake fluids used in the automotive industry are fluids that contain Polyalkylene Glycol Ether and fluid that contains Silicone or Silicium-based Polymer. Both Fluids are common but very different in regards to the manner in which they perform. Fluids containing Polyalklene Glycol Ether are more widely used and are the only fluids that should be used in racing brake systems.

Because brake systems may reach extreme temperatures brake fluid must have the ability to withstand these temperatures and not degrade rapidly.

SILICONE BASED FLUID
Fluids containing Silicone are generally used in military type vehicles and because Silicone based fluids will not damage painted surfaces they are also somewhat common in show cars.

Silicone-based fluids are regarded as DOT 5 fluids. They are highly compressible and can give the driver a feeling of a spongy pedal. The higher the brake system temperature the more the compressibility of the fluid and this increases the feeling of a spongy pedal.

Silicone based fluids are non-hydroscopic meaning that they will not absorb or mix with water. When water is present in the brake system it will create a water/fluid/water/fluid situation. Because water boils at approximately 212º F, the ability of the brake system to operate correctly decreases, and the steam created from boiling water adds air to the system. It is important to remember that water may be present in any brake system. Therefore silicone brake fluid lacks the ability to deal with moisture and will dramatically decrease a brake systems performance.

POLYGLYCOL ETHER BASED FLUIDS
Fluids containing Poly glycol ethers are regarded as DOT 3, 4, and DOT 5.1. These type fluids are hydroscopic meaning they have an ability to mix with water and still perform adequately. However, water will drastically reduce the boiling point of fluid. In a passenger car this is not an issue. In a racecar it is a major issue because as the boiling point decreases the performance ability of the fluid also decreases.

Poly glycol type fluids are 2 times less compressible than silicone type fluids, even when heated. Less compressibility of brake fluid will increase pedal feel. Changing fluid on a regular basis will greatly increase the performance of the brake system.

FLUID SPECIFICATIONS All brake fluids must meet federal standard #116. Under this standard is three Department of Transportation (DOT) minimal specifications for brake fluid. They are DOT 3, DOT 4, and DOT 5.1 (for fluids based with Polyalkylene Glycol Ether) and DOT 5 (for Silicone based fluids).

MINIMAL boiling points for these specifications are as follows:



Dry Boiling Point Wet Boiling Point
DOT 3 401ºF 284º F
DOT 4 446º F 311º F
DOT 5 500º F 356º F
DOT 5.1 518º F 375º F







Racing brake fluids always exceeds the DOT specifications for dry boiling points. Wet boiling points generally remain the same.

DOT 3 VS. DOT 4 and 5.1
AFCO's 570º brake fluid is a DOT 3 type fluid. However, it has a dry boiling point that is 52º higher than DOT 5.1 specifications, 124º higher than DOT 4 specifications and 169º higher than DOT 3 specifications. AFCO's 570º fluid meets or exceeds all DOT 3, 4, and 5.1 lubrication, corrosion protection and viscosity specifications.

AFCO's 570º racing fluid meets but does not exceed federal standards for wet boiling point specification; therefore, its classification is DOT 3. Because AFCO's 570º fluid is intended for use in racing type brake systems that undergo frequent fluid changes, exceeding federal standards for wet boiling points is of little concern. Racing brake fluids always exceeds the DOT specifications for dry boiling points. Wet boiling points generally remain the same.

WET VS. DRY BOILING POINT
The term boiling point when used regarding brake fluid means the temperatures that brake fluid will begin to boil.

WET BOILING POINT
The minimum temperatures that brake fluids will begin to boil when the brake system contains 3% water by volume of the system.

DRY BOILING POINT
The temperatures that brake fluid will boil with no water present in the system.

MOISTURE IN THE BRAKE SYSTEM
Water/moisture can be found in nearly all brake systems. Moisture enters the brake system in several ways. One of the more common ways is from using old or pre-opened fluid. Keep in mind, that brake fluid draws in moisture from the surrounding air. Tightly sealing brake fluid bottles and not storing them for long periods of time will help keep moisture out. When changing or bleeding brake fluid always replace master cylinder caps as soon as possible to prevent moisture from entering into the master cylinder. Condensation, (small moisture droplets) can form in lines and calipers. As caliper and line temperatures heat up and then cool repeatedly, condensation occurs, leaving behind an increase in moisture/water. Over time the moisture becomes trapped in the internal sections of calipers, lines, master cylinders, etc. When this water reaches 212º F the water turns to steam. Many times air in the brake system is a result of water that has turned to steam. The build up of steam will create air pressure in the system, sometimes to the point that enough pressure is created to push caliper pistons into the brake pad. This will create brake drag as the rotor and pads make contact and can also create more heat in the system. Diffusion is another way in that water/moisture may enter the system.

Diffusion occurs when over time moisture enters through rubber brake hoses. The use of hoses made from EPDM materials (Ethlene-Propylene-Diene-Materials) will reduce the amount of diffusion OR use steel braided brake hose with a non-rubber sleeve (usually Teflon) to greatly reduce the diffusion process.

THINGS TO REMEMBER
Brake fluids dry boiling point is more important then wet boiling point when used in a racing brake system.
Passenger cars very rarely will undergo a brake fluid change making the wet boiling point more important.
Racing brake system fluid is changed often and a system with fresh fluid will most likely not contain water.
Because of this, racers should be concerned with the dry boiling point.
Racing fluid exceeds DOT 3, 4, and 5.1 dry boiling point specifications.
Never use silicone based fluids in racing brake systems.
Using racing brake fluid will increase performance of the braking system.
Never reuse fluid. º Never mix types or brands of brake fluid.
Use smaller fluid containers that can be used quicker.
If fluid remains in container be sure to tightly seal and do not store for long periods of time.
Purge system (complete drain) and replace fluid often.
Immediately replace master cylinder reservoir cap following any maintenance.

[Reckless]

thanks heaps for everyones help.

The brakes were mushy before I changed the pads, so I don't think it's from boiling the fluid.

I have cleaned the pins the caliper slides on with wire-wool, and regreased them.

I'll try popping the the pistons, and cleaning them behind them next.

Thanks for the tip of tilting the bike danger I'll try that once I've cleaned behind the pistons. By the way it states dot 3 or 4 in the manual, is it better/ok to use 5.1?

Still not sure why the pads are wearing at the rear though.

Firstly the pads are most likely wearing at the rear because both halves are not pulling evenly. By cleaning the slide pins etc you could quite well have solved this issue.

Secondly if everything seems like its working well (returning etc) after the repairs you have done so far and there is no leaking fluid from the pistons you could Just try changing the fliud. Ie bleed them and keep bleeding until the new fliud comes through the bleed nipple. This will chase out any air and replace old moisture soaked fliud with new. That will have given them as good a service as you can without a complete strip down and as good as most brakes get anytime. That should solve your problems I would guess. Just depends on how far you are confident to go.

Dot 5.1 has a higher boiling point but we would never push or bikes to this level. But for the same cost or a few cents more why not have it in anyway.

[Subike]

Have had this problem with my XS Yamaha,
After a bit of cussing and frustration, i visited our XS web site
This is what I found
It could be of use to some of you that are having binding problems after replacing pads and or fluid

http://www.xs11.com/forum/showthread.php?s=&threadid=14

Hopefully that link will take you to a good detailed page that may help many of you when you service your brakes.
The principiles may in application differ from manufactuers, models etc
but if it helps anyone else
then good

[Subike]

this is another link for the subject of which fluid to use.
Dot 3 - 4 or 5 ?

http://www.xs11.com/forum/showthread.php?s=&threadid=1

as you will see there is a major difference that should not be over looked

[Danger]

No one said to use Dot 5.
Dot 3, Dot 4 or Dot 5.1 is the fluid to use, not Dot 5. They are different fluids.

[Danger]

Dot 5.1 has a higher boiling point but we would never push or bikes to this level.

I disagree. The rear brakes in particular, but also the front brakes on a dirt bike ridden hard get extremely hot. Think brake dragging on a long set of whoops (if you can find them these days lol), or on the brakes almost continuely in tight trees. I have boiled my rear brakes to the point that I have had no braking. The rotor turns black and smokes. I need to bleed my rear brakes every few rides (at times during a ride that places big demands on the brakes) depending on the abuse they have had. I service my brakes at least once a month.

[worm]

changed the pads on the dr tonight as they were shagged and put new ones in and they are pretty tight on the rotor i can turn the wheel by hand but it is pretty hard so something not right.
ive changed them before and they were sweet the last time i did it.
could it be the pistons are full of shit and they aren't retracting fully?
any help appreciated.

SBF

I had the same problem on my DRZ.. just pushed the pistons out and gave em a good clean with warm soapy water and a toothbrush, pushed em back in. Worked a treat!!

[Rupe]

Popped the pistons out and gave it all a good clean the other day. And although it's better than when I first put the pads in, they still rub.

Just going to ride it and see what happens. Thinking I may just buy some nissin pads at a later date.

Thanks for everyones help

[barty5]

just a thought is the rotor ture not out of shape or is the drag the whole way around when the wheel is spun freely??

[Rupe]

just a thought is the rotor ture not out of shape or is the drag the whole way around when the wheel is spun freely??

I don't think the rotor is perfect mate, but it drags the whole way round.

[F5 Dave]

If it got highly overheated it could 'cone' so it was dragging all way round say on the outer surface on the left & inner on right, but this is unlikely unless you have been motarding it. They all drag to an extent, but there is drag & drag.

[Danger]

Hmm I might give that a try too.

So what happened?