If it is just the front brakes locking up, you =may= have some corrosion
between the dust seal the fluid seal on the caliper pistons. Such corrosion
can make the piston a very tight fit so that it doesn't retract slightly as
it should when the brakes are released. This is not necessarily an
expensive disaster. My calipers had this, but the pistons and bores were
fine otherwise. Some VERY careful work with some small squares of sandpaper
got everything back as it should be. New kits in the calipers and they work
great and don't leak.
If releasing the fluid pressure as you have done doesn't free the brake,
then the problem has got to be in the caliper itself. Once you've bled off
the pressure, the master cylinder is completely out of the picture as far
as locked brakes go.
Tom Zuchowski
----------
> From: Philip Hubbard <phubbard@carroll.com>
> To: spridgets@Autox.Team.Net
> Subject: RE: Brakes - Confused
> Date: Saturday, June 27, 1998 3:46 PM
>
> At 06:43 AM 6/26/98 -0700, you wrote:
> >the car has been sitting for a long time). If you suspect the master
> >cylinder, make sure that the pedal is returning all of the way and that
> >there is free play at the push rod before you overhaul the cylinder. If
> >you pull the clevis pin on the master cylinder push rod and the brakes
> >free up, the problem is lack of free play between the rod and the piston
> >in the master cylinder. If you worked on the front suspension, check to
> >make sure that you didn't put a kink the flex lines when you put the
> >front end back together. If I were a betting person, I would bet on the
> >master cylinder. - Jim
>
>
> Jim,
>
> It looks like you may be the lucky winner in the "Guess what's wrong with
> my car now?" contest. I'm thinking master cylinder. Here's why:
>
> Both front brakes are locked tight and used to be fine when the car was
> last on the road. Both calipers going at once with identical symptoms?
> Seems unlikely.
>
> Working on driver's side, I loosened the line at the chassis. Brake
fluid,
> but no unlocking of the brakes. Tightened back up and asked list advice.
> Loosened bleed screw until brake fluid coming out. No change in locked
up
> brakes.
>
> Went to passenger's side. Undid bleed screw and took it completely out
for
> a moment. No change in brakes on that side.
>
> Have to think it is master cylinder. So, I plan on sucking out the old
> fluid somehow (maybe just a hose and syphon - will that work? it sure is
> cheap) and taking a look at the mc. I'll check for play as suggested in
> hopes that the mc is not bad, but just needs an adjustment.
>
> Questions:
>
> 1) If I need to fix the mc, is there any point in rebuilding? Should I
> just buy a new one instead? I know they aren't exactly cheap, but I saw
a
> deal for about $140. Maybe better just to go new?
>
> 2) Wheel cylinders - with front disc brakes, do I have them up front or
is
> it only on the back? Don't see them listed in catalogs except for back.
>
> 3) Why would the mc go bad just sitting in my garage? Brakes were fine,
> them both fronts go at once and no driving in between though I did roll
it
> into the garage about 15 feet one day. :)
>
> Thanks all for your help. MG 98 looks grim indeed as I know I won't get
> near finishing this weekend and that leaves only one more to go. OTOH, I
> have from July 3 through July 13 off and I've got to believe I could get
> the car back on the road working on it each day during this period.
>
> Philip
> Burgundy 1974 Midget
>
>
> PS Anyone in the NY metro area (I'm in E. Rutherford, NJ) who wants to
hang
> out, drink beers and work on my car has an open invitation. :) I'm
joking
> around, but serious. :)
>
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