bleeding brakes

Technical MGB discussion
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Charles Farran
Posts: 303
Joined: Fri Oct 31, 2014 11:08 am
Forename: Charles
Surname: Farran
Location: Warwickshire

Re: bleeding brakes

Post by Charles Farran » Thu Oct 15, 2020 8:33 am

Hi Chris,

I am aware that some find the process helps if the front of the car is slightly higher than the rear .
Follow the notes in the extract from the repair manual that i sent you.
On my computer, when i click on the attachment,it corrects it's orientation & you can enlarge it which makes it easier to read.
Given my experience, check you can easily screw the pressure switch into it's position.(I didn't find it very easy to get started, so may be worth trying it before you put the new master cylinder in the car).
Your end objective is to ensure that the brake warning light stays off (with the ignition on & handbrake off) when either the brake pedal is pressed or not.If the light stays on, then it means the pressure switch plip must have been triggered by the differential bar moving to a point where the plip is released into one of the indents. (Hence the need to unscrew the switch when bleeding the brakes to enable the bar to move).

Good luck

1980 Roadster

Vic Butler
Posts: 565
Joined: Wed Dec 21, 2016 6:07 pm
Forename: Vic
Surname: Butler
Location: North West Hampshire

Re: bleeding brakes

Post by Vic Butler » Thu Oct 15, 2020 10:46 am

That's the sequence to bleed the brakes Not Anumber but don't forget the correct pedal action, a rapid push down, let it return unassisted and a short pause before another rapid push down until all the air bubbles are gone.
I agree with Charles about screwing in the pressure warning switch before fitting the master cylinder. It's very fiddly with the cylinder in place.
If the meter shows the switch is on then start all over again.
Best of luck.
1977 Stage 2 MGB GT
1975 SWB Series 3 Land Rover with a later 2.5 petrol engine

Posts: 60
Joined: Tue Sep 22, 2020 9:33 am
Forename: Chris
Surname: Silk

Re: bleeding brakes

Post by Not_Anumber » Fri Oct 23, 2020 3:15 pm

The new master cylinder has made all the difference in the world. Surprised to see how much old fluid was still lurking in the rear pipes and cylinders, all is now flushed through with fresh fluid and the air safely expelled.

Ian Fozzard
Posts: 517
Joined: Fri Mar 27, 2015 8:18 am
Forename: Ian
Surname: Fozzard

Re: bleeding brakes

Post by Ian Fozzard » Fri Oct 23, 2020 4:37 pm

That's pretty well what I experienced with my BGT brakes. I did suggest a new master cylinder in my initial reply, but I will try not to be too smug about it😇😬😇!

Ian F
1972 BGT, Blaze, Navy trim, recessed grill
1961 Midget, 948cc, Clipper Blue, Blue trim and weather gear

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