I just finished installing a 19mm master cylinder on my 75, and bled the system twice. My brake pedal is firm, and brakes seem good. I also replaced the brake pads front and rear, and adjusted the vent space to 4mm.

Now my brake lights stay on, and the blinker on the dash won't stop blinking, no matter what. I'll take another look and bleed it again, but I am baffled.
I replaced the pads three weeks ago, but then realized the master cylinder was shot. I didn't have the problem until I changed the master cylinder yesterday.


Any tips?

Did you check the brake switch? That may need adjustment with all of the work that you did. When you push down on the brake pedal, it allows the switch to close. Rleeasing the brake opens the switch. Sounds like the switch may not be opening enough to turn the brake light off.

I believe you need to reset the pressure switch on the MC as well. That is where the blinking light gets its ground when you lose pressure.

The mechanical brake light switch needs some adjusting. If you wiggle in there after removing the floor board again you will see the little mechanical arm that moves against a disk shaped piece of metal and it can easily be out of adjustment after your work. There is a very small adjusting screw to move the arm in/out as needed.

Yep, what John said...plus ya gotta push dat button....

Thanks Guys....I'd be lost widout youse guys

If the light stops on the dash after you reset it but your brake lights stay on still it is possible you need to take a look at your peddle cluster... Brake lights lingering are a sign of peddle cluster wear... Often happens because of leaking master cylinders... Hmmm

You have the arm on the brake light switch (on the pedal cluster) on the wrong side of the washer on the brake pedal pushrod.

BTDT!! The switch works opposite to the most obvious way.

Move the arm to the other side of the washer and you should be set.

--DD

Thanks again....But I discovered while changing the MC that the actuating rod has a bend in it. ( I had trouble getting it to line up with the MC and had to remove it and line it up from the inside of the car)

I didn't it give a second thought until I thought about adjusting it. That bend shouldn't be there, because to adjust you have to loosen the locking nut and turn the rod....Am I right?

I believe that's correct.

Oh, the reset button on the MC (as was mentioned several times above) should turn off the blinkenlight on the dash (assuming the handbrake handle is down). Moving the switch to the other side of the washer should cure the "brake lights don't go off" part of the problem.

--DD