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Re: Bad Brakes

To: Bob Howard <>
Subject: Re: Bad Brakes
From: Paul Root <>
Date: Sun, 01 Sep 2002 11:51:56 -0500
Last week I finally did my rear brakes. Mine's the servo unit, so,
its a bit different, but I got my brake light working. Or should I say, 
it doesn't come on driving, but does for the hand brake.

I use an EZBleed, and I like it a lot. It works so fast, the first time,
I didn't believe I'd finished.

I backed the pressure sensor out 3 flats, bled all four corners and then
tightened it back up. The brakes work great.

Bob Howard wrote:

> Zach,
>   The rear brakes must be adjusted right in order to get the brakes to
> bleed out satisfactorily. Why this should be more important in MGB than
> in other cars I can't say, but spend the time to adjust them before
> trying to bleed again.  Question--how far up does handbrake pull (or did
> it pull before you started this job) in order to lock the rear wheels? 
> 3-4 clicks is what the book says the handle should lift if brakes are
> adjusted properly. 
>    You installed the MC, then filled and tried to 'bench bleed' it? 
> Since you are working at an awkward position and are probably trying to
> be ultra careful about spillage, I am guessing that the MC still has some
> air in it.  If you have plastic threaded bleeder screws, try attaching
> clear hose to them to re-direct the fluid back into the MC. You can then
> press a lot of fluid through the MC and watch it carefully for any sign
> of bubbles. 
>     The brake light comes on (imagine that--somebody has one that
> actually works) when the pressure in the front and rear lines (systems)
> differ.  There's a little shuttle thing inside the sensor that gets
> pushed to one side by uneven pressure, and that causes a switch to switch
> on the light.  
>    If you are not getting pressure in the rear system because of 1)air in
> the MC, 2)air in the rear system or 3)out of adjustment rear brakes, #1
> and #2 can definitely cause the light to come on and #3 might cause it. 
>    But don't despair.  When you walk away from the project tonight it may
> be in complete frustration. When you return tomorrow, the bubble may have
> found its way out of its own accord. Doesn't seem reasonable, but has
> been known to happen.
>   BTDT on all the above.
> Bob
> On Sat, 31 Aug 2002 14:20:08 -0700 (PDT) Zach Dorsch
> <> writes:
>>Help, I am getting very frustrated with my car.  1973 MGB dual line, 
>>non-servo brakes.  I asked a few weeks ago about a replacement for a 
>>master cylinder, so I decided to order a new one from LBCarco.
>>To recap, front brake lines started leaking somewhere, checked 
>>connections, nothing, but the line was wet.  I replaced the front 
>>lines.  So far so, good, only when I hit the brakes gradually the 
>>pedal slowly goes to the floor without really stopping.  However if 
>>I stab the brakes the car squealed (sp) to a stop.  Okay figured 
>>master cylinder, so I replaced it today.
>>Went ahead and attempted to bleed the brakes with a friend that has 
>>helped me bleed the brakes before.
>>I first put the MC in without the lines connected and put in a 
>>little fluid and pumped until the fluid came out of the fittings (to 
>>prime the MC).  I then hooked up lines and proceeded to bleed like 
>>normal, only something was not quite right.  I had to depress the 
>>pedal about two inches to get it to brake.  I don't think this seems 
>>right but I tested it around our block.  I could lock up the brakes, 
>>but it took an incredible amount of pedal effort and that is when 
>>the brake warning light came on.  I figured that I had not bled them 
>>the right way, so I tried again.  
>>For some reason when bleeding back brakes the pressure goes down and 
>>does not return?  Could the rear brake adjuster affect this?  Any 
>>other ideas?
>>Thank you 
>>Zach Dorsch
>>(I have posted this to the bbs as well, so I apologize if you have 
>>already read my note)

Paul Root

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