Sticking, Squeaking Front Brakes

sorry wireman :ohmy:
i agree with 650ed on this one.

dot5 has a higher boiling point because it does not absord moisture.
you would need to get your rotors red hot to need it to prevent brake fade due to boiling fluid or to evacuate any moisture from the system.

if the engingeers decided dot 3 or 4 was acceptable, i would have to agree with them.

imo, a bike is not heavy enougph to warrant this.

(plus we all know getting a good, hard front brake lever is a pita after flushing the front brakes )

at least it is for me!

ive torn apart enough 30-40 plus year old brake systems to see what dot3-4 fluid turns into,even in a well cared for system.the dot5 fluid in my dads 78 chevy 4x4 truck with 500,000 plus miles on it has been through 5-6 clutches,on its second motor,many sets of brake pads(never needed to turn rotors yet)hes too cheap to flush the brake fluid so it been running the same dot5 we put in there in the early 80s,he just cracks the bleeder valves to push pistons back when he changes the pads and tops her off.this truck has the origional mastercylinder,origional calipers and wheel cylinders and stops as good as any new truck ive ever ridden in.if all fails spill some dot3-4 on your paint and see what happens,then do same with dot5 and compare results

I was curious about the great fluid debate so I did some casual online research and found this:

When adding new brake fluid, be sure it's the appropriate type for your vehicle; it will be listed in the owner's manual or marked on the reservoir cover. Conventional glycol-based formulas are designated as DOT 3 and DOT 4, which differ mainly by their boiling points. While the two are compatible, DOT 4 has a higher boiling point, so if your vehicle is designed for DOT 4, don't substitute DOT 3. If DOT 3 is recommended for your car, you can use either type. Castrol also markets a brake fluid called LMA, for Low Moisture Absorption. This is formulated to last longer than conventional types because it takes longer to reach its saturation point, and also boasts a higher boiling point.

It's important to note that DOT 5 brake fluid, which is silicon-based, is NOT compatible with conventional fluid and should NEVER be added to a system using DOT 3 or 4. DOT 5, which has a purple color, doesn't absorb moisture, and has a higher boiling point. It's NOT recommended very often for late-model cars because its lack of moisture absorption INcreases the chance of corrosion, and since it can be compressed, it can cause the brake pedal to have a spongy feel. It's also much more expensive.

Here's the link for the whole article:
www.type2.com/library/brakes/brakef.htm

Post edited by: anarki650, at: 2007/05/31 00:02

whoo there big fellow! :blink:
not trying to argue, there is great benifts to dot 5 and i see it all the time.
i just think it is overkill for a bike.
i ran dot 5 in my dragcar and never had a problum.
dot 3 or 4 is no problum on paint if you have baking soda and water in your house.
you have obviouslly (spellcheck) had good success with it and if it works for you, then by all means run with it.
but i think were getting off topic here.
we need to adress his brake noise first and see if he pipes up that any of our advice helped him before we get in a pissing contest over the best brake fluid.



:woohoo: :laugh: :laugh: :woohoo: :woohoo: :woohoo: :woohoo: :woohoo:

kawsakiman wrote:

whoo there big fellow! :blink:
not trying to argue, there is great benifts to dot 5 and i see it all the time.
i just think it is overkill for a bike.
i ran dot 5 in my dragcar and never had a problum.
dot 3 or 4 is no problum on paint if you have baking soda and water in your house.
you have obviouslly (spellcheck) had good success with it and if it works for you, then by all means run with it.
but i think were getting off topic here.
we need to adress his brake noise first and see if he pipes up that any of our advice helped him before we get in a pissing contest over the best brake fluid.



:woohoo: :laugh: :laugh: :woohoo: :woohoo: :woohoo: :woohoo: :woohoo:

no big deal!isnt a certain amount of brake drag normal with disc brakes?

Skyman:

After all that debate on brake fluid.

Check to make sure your calipers are free to move side to side on the two bolts that go through the caliper and the mount bracket. They should be clean and well lubed with silicone brake grease. There are four small O rings and rubber boots to keep up on those bolts also.

I was thinking that the caliper pistons were gunked up form the rust that you get from dot 3 , I and friends have been using dot 5 for a long time, I have even seen brakes sit up for over a year with dot 5 in, the lever and brakes felt fine we bled it just because, the fluid was clean as the day it was put in, any time I work on the brakes on the bikes I change it over, have had it in the rear of the 1000 for over 2 years never had issue one

Thanks to everyone for your advice.

What I did last night is I pulled the calipers off the wheel, stuck a prybar between the pads and pushed the piston open. Then I pumped the brake lever a few times to push it back out. I repeated this several times on both calipers to make sure everything was moving/flowing correctly.

I put the calipers back on. This morning, on my ride to work, the noise was gone. I'll keep a close eye on it. But for now, it seems better.

hi there,

stay close on that, u dont wanna end up face down on the road because of a locking caliper cilinder.. the cilinders should move quite nicely if one of them dont then do a rebuild. I did the front and rear brakes 2 weeks ago and if u got all the parts ready its a breeze. (that reminds me that i should have made pictures of every step of the way )

Dot 5 can be successfully used in a motorcycle if the beaking system is being replaced or completely rebuilt with seals made for silicon fluids. There is a huge advantage that is being missed here... DOT5 will NOT harm paint at all. My brother uses it in vintage Harleys because if a leak occurs in the MC it will not damage any paint on the tank. The real difference in a DOT 5 or DOT4/3 system is the type of seal material used. Althogh most DOT 4/3 brake systems can run DOT 5 as long as they have been cleaned and purged. BUT it is always a good idea to follow the manufacturers recommendations EXPECIALLY regarding brakes.

For that matter ATF, sythetic motor oil, and even water could be put to use in brakes, but the seals and pistons must be made to suit the fluid. Brake fluid is an engineered petrolium product designed to have the right viscosity, compessibility (or lack there of), thermal stability/conductivity and is hydroscopic to absorb moisture. Long story short, use the fluid the system was design for.

As has been said the likely culprit are the caliper pistons dragging.

These have a tendancy to develop rust pits if the fluid has not been change regularily. This prevents them retracting properly when pressure is released.

Try a secure some new ones and the seal kits. Replacement is not a terribly hard job to do. Remove calipers from the sliders but do not disconnect the hydraulics. Use the hydraulics to pump the old pistons out and then dismantle the calipers. The dust and fluid seals are easy to replace but the caliper body will probably need cleaning as white crud seems to build up in them. The only trick is reinserting the piston. Insert both fluid and dust seals in caliper and then open the dust seal mouth as wide as possible and slide in piston. This last bit can be a bit tricky as to get the seal mouth open wide enough I needed an extra pair of hands. Quality time for Missus in garage?

Best of luck!

UPDATE

Okay, since it looks like it is going to be raining here all week, I figured now's the time to get the brakes fixed.

So I took apart my calipers. I used the air pressure method suggested by KZCSI (and the factory manual) to expel the piston. WOW! :woohoo: You weren't kidding about the force of expulsion. That thing was like a bullet. I just gave it a real quick shot of air and POW!.

The pistons actually look great. Very clean and smooth with no pitting on the outer surface of the piston. There was some rust on the inside, however.

I think the problems I've been having are being caused by the slider bolts. There is some corrosion and gunk in those holes. So I'm going to try to clean those out, lube them up good with silicon grease, and put it back together. I know I should repalce the seals, but they're so frickin expensive. I'm going to first see if a cleanup job will take care of the problem.

Anyone here got a problem with that? :whistle:

Post edited by: Skyman, at: 2007/06/04 01:11