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Tips

T-Series Break Pressure Switch

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L

LLAngus

Jedi Knight
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Has anyone reset the pressure switch on a B GT? I have read about it but can't remember where. The pressure switch activated when only one of the lines was being used because I put the MC cup in backwards. I am having trouble getting the rear to bleed because the switch thinks only the front is operating. Any hints or solutions? In the morning I am going to try to bleed out the front. Hauled hay tonight (so much for a free day). /ubbthreads/images/graemlins/cowboy.gif
 
The pressure switch ahs nothing to do with the mechanics of braking. It measures the pressure between the front and the rear systems. If the differential is too great, it triggers a light on the dash. To reset it, just loosen it, press the pedal a couple of times and tighten it.

I suspect that your problem is either a bad master, or perhaps a crushed brake line. (The location of the line leads to it being crushed if a tow hook is hooked around the rear axle).
 
I have moved the cylinder in the pressure switch back to the center with a small pick (actually a Dental tool) and the rear brakes would bleed until the cylinder moved back over. I know I read an article or forum how to move the cylinder back to the center without having to disassemble the switch and if I'm not mistaken it also talked about how the switch helps stop excessive fluid until you could get home. /ubbthreads/images/graemlins/confused.gif
 
Well--I have just taken off the line going from the MC to the pressure switch (rear side) and have lots of flow and can bleed the fluid to that point. I am now going to try to bleed the front only to see if I can get the switch to reset.
 
LLAngus, if you are bleeding using the pump and hold, while an assistant bleeds the line method. i am afraid that the shuttle in the pressure switch is going to give you trouble over and over. it is best to use a mity vac to draw the fluid thru to all 4 wheels first. this will allow you to get fluid in system and keep equal pressure on both sides of the switch when you step on the pedal, barring any leaks of course.


mark
 
I have take the pressure switch off the car and cleared some gunk out of it. I guess I need to get a mity vac to bleed breaks as I'm looking at two more MGs to purchase. Will a pressure unit work or will that be the same problem as pump and hold?
 
/ubbthreads/images/graemlins/lol.gif I have found the article on bleeding out brakes and it does say the brake pedal must only be moved with gentle pressure and the pedal must never be "tried" until bleeding is complete. This is exactly what I was doing. Also, the instructions told me how to centralize the pressure failure switch shuttle. If anyone needs the instruction let me know and I'll type them out on the forum. This came from Autobooks MGB Owners Workshop Manual for the 69-73 MG, MGB, MGB GT. /ubbthreads/images/graemlins/driving.gif
 
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