Brake Dust, lots of it

[LowRyter]

I just took the Greenie on a 1500+ mile rt trip (OKC - Springfield IL).  I had the front tire changed before I left.  Anyway, the right front brake is shedding brake dust everywhere.  A day's ride and it's black, all over the rim, even on the fork and fender.  I am not riding the brake and much of the ride was on open highways where the brakes were barely used. 

 

I would check it when I stopped, neither the rotor or the caliper was hot.  I did a few brake checks in the twisties and no fade.  No fade at any time for the entire trip.

 

It's a dirty and strange problem for me and my three (Guzzi) riding buddies to figure out.

[Cabernet]

How old are the pads? Wonder if the bonding agent could go off over time.

Have you replace a disc? Years ago I replaced a disc on my VX800 with a bargin basement cheapy. It ran fine on organic pads. Put some sintered in and it devoured them in a days couriering. Got some more organic in and fine again.

 

 

Sent from my D5803 using Tapatalk

[LowRyter]

Cab-.  Thanks.  The discs are original. Can't remember when pads were changed but plenty of pad left (at least on the outside).  The only difference is the tire was changed, the calipers removed and reinstalled.  I can only guess that the pads are somehow crooked or misaligned or some debris is causing the pads to not fully retract.  But the grinding is so slight that it's not affecting brake performance.  

 

Having written that, it doesn't seem possible.  

[docc]

A front tire change is a perfect time to clean and equalized all the piston movement. Shops aren't going to do that for the cost of a tire change.  The pistons do get retracted to reinstall the calipers and, if the pistons are not moving evenly, could cause the pads to engage the rotor unevenly creating a reduced contact area and sudden wear variation.

 

Probably a good time to clean those pistons, maybe consider a pad change if they are rather old (original?).

[LowRyter]

Thanks Docc.  Cleaning the brakes was my first thought.  This situation would cause brake wear but not affect brake performance?

[docc]

It's the kind of difference in performance I only notice (how much better) after I clean them and equalize the piston movement.

[LowRyter]

Thanks Docc, I meant by performance that the brakes didn't fail or fade.  Thankfully the issue was just messy brake dust.

 

Got to look at them and the inside pads are shot.  Getting new pads tomorrow and will inspect and clean the calipers up.

[docc]

Thanks Docc, I meant by performance that the brakes didn't fail or fade.  Thankfully the issue was just messy brake dust.

 

Got to look at them and the inside pads are shot.  Getting new pads tomorrow and will inspect and clean the calipers up.

Every time I clean up my eight pistons, the difference in feel is remarkable. I do it every front tire change now and it always makes me happy!

[LowRyter]

prolly should change the fluid too........

[mznyc]

 

Thanks Docc, I meant by performance that the brakes didn't fail or fade.  Thankfully the issue was just messy brake dust.

 

Got to look at them and the inside pads are shot.  Getting new pads tomorrow and will inspect and clean the calipers up.

Every time I clean up my eight pistons, the difference in feel is remarkable. I do it every front tire change now and it always makes me happy!

 

Docc,how far do you break them down? Take off the hoses,pull pistons,re-bleed.Or keep intact,just spray with brake cleaner,scrub and blow out.What do you lube the pistons with?

[coreytrevor]

I wouldn't take the calipers apart unless the pistons are not moving freely. If you are good about keeping the fluid fresh the calipers can go for many years without needing to be pulled apart. Also, don't lube them with anything. If you do, whatever you use will get into the seals and probably make them swell. Then you will get to rebuild the calipers.

 

What I do is push 1 or 2 pistons out at a time, just past where they normally extend. I use a small brass bristle brush to clean off the junk, and use a 90 degree snap ring plier inside the pistons to turn them so they can be cleaned all the way around. Be careful not to let the pistons come out too far.

 

[gstallons]

You can put ONE or TWO drops of brake assembly lube on the exterior of the piston as it is being rotated pushing it back to the bottom position . NOTHING ELSE .

 And do one piston at a time .

[LowRyter]

I've got the new pads installed, cleaned and lubed the calipers and pins.

 

I think these were the original Brembo pads (41k miles).  I can't ever remember changing them since I bought the bike with 12k miles on it.   The rears were shot when I got the bike.  It appears the culprit was a misaligned pad.  The edge on the right left inside pad was ground down.  Actually the pads still had some meat left and could've gone more miles.

 

The bikes stops and goes well.  

 

I've taken the bags off the bike and adjusted the air pressures to 34 front and 38 rear (from 31.5/39 with the bags on).

[docc]

 

 

Thanks Docc, I meant by performance that the brakes didn't fail or fade.  Thankfully the issue was just messy brake dust.

 

Got to look at them and the inside pads are shot.  Getting new pads tomorrow and will inspect and clean the calipers up.

Every time I clean up my eight pistons, the difference in feel is remarkable. I do it every front tire change now and it always makes me happy!

 

Docc,how far do you break them down? Take off the hoses,pull pistons,re-bleed.Or keep intact,just spray with brake cleaner,scrub and blow out.What do you lube the pistons with?

 

Sorry for the slow response while I was away at the South'n Spine Raid . . . Thanks coreytrevor and gstallons for the excellent replies!

 

I don't remove the pistons, but spray them off with CRC Brákleen before retracting the pistons (remove the old fluid from the reservoir first), chock the pistons and move one-at-a-time in and out out spraying cleaner on the circumference. I am relying on the fresh brake fluid (simply "DOT 4") for the lubrication.  I keep moving from piston to piston until they all  move out uniformly.  Clean and polish the pad pins, a light smear of silicone grease on the pins.

 

I never thought to rotate the pistons, use a brush, or assembly lube. What a great forum. Always learning!