check ur brakes like a pro!

[sublunacy]

Doing brake upgrades? maintenance? Fast Bikes Like Fast Brakes and Healthy Riders.

Never mix DOT 5.1 Brake Fluid w anything else. its a different animal/ 5.1 loves water and gets dangerous when its had to much. its made of silicon fluid. Don't get it!
What you want is DOT 3,4 or 5 not 5.1
Dot 5 is the purest but Dot 4 is good. Check with current supply for an apropriate price level for you and your vehicle.
------FYI- these are brakes! don't do what i am suggesting unless you are a qualified technition I:I

heres a thread on how to Get ur brake pistons mobile again, and check the working condition without removing the piston from the caliper. Could or should be done with the regular mantenance schedule (6 months??) or when pads need replacement.



Raise the caliper remove the pads check and relube. Basic service.All listed clearly in from any service manual.
Then I always try sliding the brake caliper piston back and forth about ten times with air pressure{{[always place piece of wood in caliper to stop it from shooting out or cutting ur finger off or worse*}}

Then you can feel for yourself how nicely the piston slides back and forth, telling what condition the caliper is in. I allways do this to any disc caliper. The seal only moves as the pad wears out, the piston does not "slide" thru in heavy use like eveyone thinks. The piston seal flexes and slightly rolls on the piston as the piston makes its 1/8 travel. Because of that the piston and seal bind, corrode/ oil film oxidizes leaving more gunk..... piston starts getting more and more friction till one day you realize your brakes have sucked for 6 months but you didn't really notice.

Moral of this story is that moving parts that move very little get the worst build up of Dirt.

Ok so if the piston moves really easy back and forth, About one or two fingers to slide it back in right, feels smooth enough for more time in the field, then put it back together and your done.

If its difficult to move then either find a replacement caliper or What I do is pop the piston all the way out clean everything, check the seal. and Polish the piston with 1000 grit to get the oxides off it then a quick hand polish with a polishing cream. Done, put the piston in the caliper, check with air pressure to check its working condion.

Hope you guys like the Thread if i think of more i will add it. Im not a disc brake qualified technition, this is from my 15 years knowledge proffesional and personal, of offroad hydraulic disc caliper serviceing.

 

[Awk08]

good info bro, got any specifics on how to pressurize them with air ???

i build gsxr rear hydro kits for these blasters, and any good preventive maintenence/shorcuts are more than welcome

 

[sublunacy]

thanks. Pressurized air tank with regular air nozzle / hand pump won't do it.
I have cut short rubber hose and put over air nozzle. Or piece of cloth rapped around the nozzle works fine too. Lately i use nothing because my nozzle is tappered- just ram it home Jim. *What i mean is the seal doesn't need to be tight!*
Start with the pressure set around 25 PSI- If the piston does indeed slide easy/ 25 psi is enough. thats what i use to test a good caliper. With low pressure you can see where the ruff points are or none at all.
i have used between 25 psi up to 100 psi for the sticky stubborn pistons.


Where is the hidden gunk that needs cleaning? 1- Remove seal and 1000 grit it too if it has junk on it, and it will.
2-behind the seal, try to do your best,First a scribe/ i finish there with a qtip, it will fit in the groove on its side and you can do a few rotations. just do your best there.
3-on the piston like i said. it will have small bumps of oxide that will not come off with polishing cream alone. nothing less than 1000 grit but it removes the hard stuff that seems stuck forever.
4- lastly the piston bore will look clean but it is allways worse than the piston for various reasons. So Eyeball it, gentle sand, gentle quick polish.


Lastly i would like to add and this is purely hypothetical { when the piston and seal is out, place it over the piston/ in its normal radial position, Note how much larger the seal is than the piston. There is quite a gap isn't there? thats Normal so does a new one. But as the seal wears out it expands, Makes the piston sticky but otherwise OK.
My guess is Seals lifespan in the area of 15 years trouble free. Why do seals get larger not smaller? I have heard the answer to that is that rubber seals are absorbant an will slowly uptake like a spong, there for getting larger. Keeping the fluid changed regular intervals is the best thing.
I can't remember for sure but i think brake fluid only lasts 2-4 years. Brake fluid is supposed to keep the system clean. Old fluid is the leading cause of caliper and master cylinder failure in my opinion.

 

[Awk08]

good stuff bro, havent had any, of the over 70 gsxr calipers, come in stuck or bad, master cylinders are a different story, i've found the old fluid crystalized bad in them, and used a similar cleaning, light sanding with 1000 g paper will clean them up too

gotta try this air pressure thing next time though, thanx for the info
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