bad caliper?

[StephenVA]

BLEED THOSE BRAKES!

Those of you who have purchased your vehicles without confirmation on the service being completed and have not flushed out the brake fluid, are asking for problems down the road. These vehicles are heavy, create lots of heat and who knows how the last owner drove or maintained the vehicle.

[Scott ZHP]

Originally Posted by kevinkay

Should I fear an issue with master cylinder this being the wheel furthest and not getting enough pull back pressure?
THANKS

Didn't see a response to this so... there's really no such animal as "pull back pressure". The MC and the ABS module control the "push" of hydraulic fluid/pressure; there is no pull back, just absence of push. Once pressure subsides, the piston seal is what retracts the piston a tiny bit back into the bore.

My MGB has stainless pistons, silicone fluid, which is non-hygroscopic and stainless hard lines, still use rubber hoses though. I still bleed once every other year or so in case there's a tiny moisture puddle trapped somewhere.

[kevinkay]

Originally Posted by Scott ZHP

Didn't see a response to this so... there's really no such animal as "pull back pressure". The MC and the ABS module control the "push" of hydraulic fluid/pressure; there is no pull back, just absence of push. Once pressure subsides, the piston seal is what retracts the piston a tiny bit back into the bore.

My MGB has stainless pistons, silicone fluid, which is non-hygroscopic and stainless hard lines, still use rubber hoses though. I still bleed once every other year or so in case there's a tiny moisture puddle trapped somewhere.

AND, if there is a tiny puddle trapped in there - does it work itself to/and effect the furthest caliper from the MC?

thanks!

[Scott ZHP]

Originally Posted by kevinkay

AND, if there is a tiny puddle trapped in there - does it work itself to/and effect the furthest caliper from the MC?

thanks!

With silicone fluid/DOT5, water ends up anywhere, at the low point of either of the 4 corners. With DOT3 or 4, it mixes with and contaminates the fluid, dramatically lowering the boiling point. Under hard braking, when you need it most, the fluid actually boils and you'll get a spongy pedal; sometimes it will go right to the floor. Not fun.

As mentioned, if you have no idea when the system was last bled, it's always wise to bleed each corner, starting with the RR, LR, RF, LF in that order. I used to alternate between ATE Super Blue and ATE Gold until the feds decided that blue brake fluid is illegal and all brake fluid has to be gold. It was easy to tell when you got the old stuff out as the color changed slightly at each bleeder. I guess no one at DOT realized that all silicone fluid is bright purple, lol.

There are also two types of DOT4, the regular stuff and a low viscosity variation that newer ABS systems use. An E53 will have the older stuff; my kids Audi wants the newer one; the thinner fluid is needed for the faster cycle rate of the ABS pump, especially in cold temps. Doubt it would hurt to use the low viscosity version in an E53. Maybe someone already has?

Oh, and Bobby... FCP Euro has Meyle front brake hoses on clearance for about nine bucks each. Just bought a pair. EDIT: looks like they jacked the price back up to $16, lol. I guess they changed their mind.

[kevinkay]

OK......I was ALMOST going to use the 3/4 full bottle of brake fluid that I opened last year.
Since its stored in the basement (very humid) maybe not such a good idea.

just googled "shelf life", some say unopened its unlimited, others say only 5 years!!

AND while I bleed I usually leave the top opened on the reserve and the bottle of fluid opened sitting on the driveway - YEKES! - now I will just imagine it sucking in the moisture like a sponge for that hour its opened.....

[upallnight]

Buy or build yourself a pressure brake bleeder. Plenty of videos on Youtube on how to build one or if you are like me and like to have the tools in the garage, buy a Motive pressure bleeder. Cheaper one can be found at Harbor Freight the tool supplier for many DIYer.

With a pressure bleeder, it's a one man job to bleed the brakes and can be done in 12 minutes, 3 minutes per wheel.

[kevinkay]

installed new $300 caliper, everything perfect, no noise, no heat.

Pulled other rear wheel caliper off, pads not nearly (maybe about 1/2) as worn, (so I have been dragging for while). Maybe more important the pins were in almost perfect condition compared to apposing side.(all pins were cleaned last year).
My conclusion is that the grinding noise that made me look for an issue was probably just a stone or freak occurrence. I think the pins supplied with the rebuilt were inferior which caused this rotor to drag. I probably should have first cleaned up/replaced pins before jumping into a new rotor, But I am a worrier and it would have always been on my mind that I could not trust that rotor.

used right rear rotor for sale?
TAHNKS for all the help and feedback!

[Ricky Bobby]

^Great to hear - so the moral of story is to either buy new calipers from BMW or to just replace the pins on the rebuilt ones after purchase?

[kevinkay]

new $300 caliper from BMW does not come with new pins!
I am still a "light" greaser - old time boat mechanic used to say "wrong grease is better than no grease".
Still stuck in my head - once a caliper is cooked its never the same

[srmmmm]

Originally Posted by upallnight

When did you replace the brake fluid last? Brake fluid is hydroscopic, which means it absorb water.

Sorry I missed your question - I replace brake fluid every 30,000 miles, which is about every 12 months at my mileage accumulation rate. On a calendar basis, I'd do it every three years as a minimum. My calipers have never been apart either.

2002 x5 3.0 305,500 miles
2014 428i 19,700 miles

2004 325i sold at 123,600 miles
2001 325i sold at 66,000 miles

1970 Firebird - Under restoration