Mk 1 Brake Master Cylinder Switches - Why are there 2?

[Garbon]

Why is there 2 brake switches on my master cylinder?

1 has 3 prongs (towards the front of the car) and the other has 2 (towards the rear)

Anyone know why the difference and what they do?

[GRN_VAGN]

just another reason for your brake lights to randomly not work...
I believe they both work on fluid pressure, both work together on both circuits to work properly. I had one burn out and my brake lights wouldnt come on intill i was half way on the stop pedal.

Gone a pedal switch now and havnt looked back

[Peter Jones]

In case one pressure circuit fails your brake lights will still work.

In some wiring scenarios a loss of pressure at one switch will also light the brake warning light on the dash.

[Garbon]

Hi Pete

My brake lights still work, which is great however the top dash brake light came on yesterday, I just pulled the passenger side wheel off and the disc is loose what do I need to tighten to get this snug again? I had a grinding noise yesterday on this wheel when driving the car.

[Garbon]

I think I worked it out, I tightened the centre nut which seemed to have fastened it again

[Garbon]

I think that I need to tighten the driveshaft nut some more as it is still grinding on the passenger front wheel? Is this correct?

I disconnected the battery for a few minutes and the top red brake light on the dash went off as well. I also adjusted the rear brake shoes and hand brake cables on the weekend, brakes feel a little better now but still a bit spongey

Time for a brake bleed...

[Golfer_76]

if your front center nut was loose you might need to fork out for a new wheel bearing. they dont like to be driven on when they're loose.
how tight did you do the front nut up out of curiousity?

Tim

[Preen59]

If your axle nut has come loose (and they shouldn't unless the bearing fails), your wheel bearing is now shot. Unfortunately you don't get a second chance with them..

[gldgti]

^^yup

needs to be VERY tight. What works for me is my weight (105kg) on my long breaker bar (500mm) with a decent bit of "bouncing" until its RFT.

And, it will certainly be failed now, you'll have to replace unfortunately.

[wai]

I think I worked it out, I tightened the centre nut which seemed to have fastened it again

More importantly you need to work out why it has come loose.

These nuts are either castelated or have some other locking mechanism to stop them coming loose. You could well have worn bearings or something else. My recommendation would be to have it checked out by a mechanic. Better to get it checked and fixed now rather than it suddenly breaking down.