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MGB Front Brakes not releasing...GOING CRAZY..

To: "British Cars Digest (postings)" <British-cars@autox.team.net>
Subject: MGB Front Brakes not releasing...GOING CRAZY..
From: Jim Fink <hershfld@isisa.oit.unc.edu>
Date: Wed, 28 Sep 1994 10:34:27 -0400 (EDT)
Well, Its going to be brake lines next....they are old and crudy looking..

on a '69 B that has sat for 8 years prior to 2000 miles of daily driving 
in last three months.....and those miles apparently done on front brakes 
only, as I discoverd frozen rear cylinders..so Heres the history/scenario...

Had a flat....., yeah well......off we go.....

found out front brake pads were thin, replaced with good thick newish..pads.
bled brakes, found out rear cylinders frozen, no fluid passing to rear...
replace seals in rear cylinders, cleaned up ok and rears work fine now...
although it is a bit of a hard push to get fluid out the back cylinders.

drive car, seems fine at first, but front brakes start heating up with front 
disks...wheels tighten up toward a lock-up slowly ..and hot, release brake 
fluid pressure at either front caliper and both wheels immediately loosen 
up, drive the 1/2 mile back home....

rebuild master cylinder..(s) try two, get good used cylinder,,,finally get 
new 
rebuilt cylinder, still same problem....(very fast at replacing Master Cyl.'s 
now though)

Clean out pressure switch, get new seals (o-rings & Pres plastic switch)

still persists,

try different working calipers, same, so..rebuild orig.s with new pistons, 
all seals, new rubber brake lines on front, bleed, bleed master at bench, at 
pressure switch, at wheels, bleed bleed one gallon of dot 4 by now.....!

still persists ..........getting very depressed...crazy, sledge hammer 
time..... HELP.....

So, what changed with the rear brakes coming into play that causes the 
front to gradually tighten & not loosen up till fluid pressure 
released, or untill car sits for a few hours? 
 
There is some slight pressure drop but is a slight drop/leak enough to cause 
immediate 
tightening, within a few miles of diving...? If car sits for a few hours, I 
can take pedal to floor on first pump of brakes, and I have seen a very 
slight dampening around one line connection at the three-way in back,
where the line exits its' connector, one drop a day or so..is this enough to 
prevent the front part of system from fully disengaging / to tighten up...?

....found smooshed rear tow-truck hook assisted 
brake line on back, replace with better one, although this is the one 
with the slight leak, pedal feels better, still 
tightening on front, so, 

now to check restrictions/leaks on other rear line and 
preparing to replace all brake lines.....what else is there.....the lines 
are connected correctly at the master cylinder....the front of the master 
cylinder...is connected to the front side of the pressure switch and the 
rear to the rear side.....this is how my other "working" car is connected..

well....any sense that restrictions/slight leaks to rear of brake system 
could keep front brake from releasing...?

also serviced wheel bearings and trued the rotors, one still has a slight 
warp, but not very bad.....afterall they worked when the pads where thin 
and the rear cylinders where frozen......

baffled and headed for brake line work, boy,,,,sure will be new brake 
system when and if the Demons of Lucas give me FREEDOM.......
Any suggestions welcomed......I do have a sledge hammer..!

I recall the discussions on steel line replacement c/o Tery A, etc. back 
around my moving time, I also wonder, as a road remedy till I can take 
the week and $$'s or so to have lines done, are the VB copper brake lines a 
road worthy option, for $60. they seem a very tempting quick replacement item, 
and sure, may need carefull observation and possible replacement in a few 
years, but, has anyone tried these copper lines...any feedback on 
them...They are thicker to compensate for softness of copper, they have 
correct connectors, YES ?.. .

Thanks....


Jim Fink

'69 MGB
'71 MGB




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