Re: 87 325 brake drag/bind/overheat

["Gil Thereault" <giln1oiw@xxxxxxxxxxx>]

Hello,  I had the same problem last March.  I got a lot advice here but 
after swapping out the offending caliper and changing all six brake hoses, 
the problem still remained.  The bottom line was I replaced the master 
cylinder with a rebuilt one and that solved the problem.  The part was 
priced reasonalbly and not real difficult to do. This is with the proper 
tools.  Your caliper should be OK but it may be a good idea so change the 
brake hoses.  I replaced them with the original parts but after I did it, I 
found the stainless hose kits were only a little more money.  Good Luck.  
Gil

86 535i 184k

- ----Original Message Follows----
From: Tony Canike <canike@domain.elided>
To: bmw-digest@domain.elided
Subject: 87 325 brake drag/bind/overheat
Date: Sun, 02 Jun 2002 08:38:00 -0400

Well, after 14 years of flawless operation of the entire brake system, the 
drivers front caliper is binding (smoking hot on highway binding.)  Guess 
all those brake fluid changes paid off, but you can't stop time...   I did 
replace rotors and pads about 2 months ago.   There were sounds of very 
light dragging (occasional squeaks) starting about 2 weeks ago.

Anyway, what's the best way to tell the exact cause of the problem?   I'm 
guessing that the piston could bind, the guide pins could bind, or perhaps 
there is a hydraulic/hose/mastercylinder problem.

When I pull the wheel, apply brakes, release brakes, and try to turn the 
rotor there is significant drag - need tools to turn it.  I opened the 
caliper, pulled the pads, brushed out stuff.  The piston returns with what 
seems to be normal resistance (medium pressure on water pump pliers pushes 
it back).  Guide pins are well lubed and move easily, perhaps with a little 
slop.  Put it all back together, and it still binds after applying brakes.   
Now I find that a rap with a mallet will unbind the caliper - doesn't seem 
to matter where I whack it - a good whack frees it up.

Ok, so I'm over thinking this and should just replace the caliper.  But it's 
Sunday morning, and Sunday mornings are for farting around anyway....

Do the guide pins wear?  (228K miles, 14 years, guess everything wears...)

Do I replace calipers on both sides while I'm at it?

Do I replace the rubber brake lines (original) ?

Thanks,

Tony.




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