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MG Midget and Sprite Technical - Brake Bleeding Problem

Just started to rebuild car and fitted new brake and clutch master cylinders to new brake pipes . Bled clutch with eezibleed ok but when i bled brakes pedal still spongy takes three pumps for brakes to work you can see the fluid level drop when you pump the 3 times but it rises again when you release the pedal.So ther must be air in the system somewhere bled a second time with eezibleed let 1/4 ltr fluid out of each nipple but still no joy am i missing somthing also previous owner who fit the brake pipes seems to have don them a different way to the book ie single cuircuit brakes with 2 outlet on master one gose to the back and the other feeds the front unlike book which one feeds left front and rear other just front right could this be my problem i cant see it making a difference myself.
mark (1977 1500 Midget) Preston Lancs

I should have said 2 outlets screwed in the back of the master ie one on a banjo fitting
mark (1977 1500 Midget) Preston Lancs

Have you fitted new disks / pads / drums / shoes / adjusters? If the answer to any of these is yes then there may be no air in there at all. I once spent ages trying to bleed a car having changed the fluid and fitted new rear shoes. The flex in the unbedded shoes felt like air and meant the pedal could be pushed to the floor. I wasn't happy, so took it to a garage and asked them to bleed it. Their verdict was "nothing wrong with it guv". Once the shoes were bedded in it all became firm.

Also, on older cars the brake pedal often becomes more firm on a 2nd or 3rd press. It's the way the master cylinder works to collect fluid from the reservoir. The first press pushes the pads and shoes into contact, and when released it collects a bit more fluid for the 2nd go. But if you drive it without pressing the pedal for a while then the shoes / pads fall back and push the fluid out again. More modern master cylinders, and vacuum assist, mean that you don't notice this as much on modern cars.

All thoughts and ramblings. My basic point is - there may be nothing wrong with it!

Ant
Ant Allen

Just a few thoughts:

are the rear shoes adjusted?

are the front calipers put on the right way? (bleeders at the top)

are all three of the flex hoses in really good condition?



Norm
Norm Kerr

all flex hoses new and rear brakes adjusted and front calipers have bleed nipple at the bottom?
mark (1977 1500 Midget) Preston Lancs

Bleeders need to be at the top to dispel all the air. Sounds like the callipers are switched, left for right etc.
Guy Weller

Right - since air bubbles rise, you want the bleeder at the top of the caliper. And obviously, the same goes for the clutch slave.

Best of luck, and keep us posted,

-:G:-
Gryf Ketcherside

will swap calipers round last owner fitted brakes i bought part done car
mark (1977 1500 Midget) Preston Lancs

calipers swapped over brakes sorted thanks all.
mark (1977 1500 Midget) Preston Lancs

where is this third flexi hose?
there are the two at the front disks but where are the other two?

and is it typical for the brakes to smell like burning electrical insulation when they are bedding in? mine do.
Seth Brecklin

Seth -

Third flexi is beside the transmission tunnel just infront of the rear axle

The smell shouldnt last long at all Seth - but then it depends on how you are bedding in your pads - i personally believe in the fast methods, in the same way i believe in the 20min run in for an engine and not 1000 miles of driving miss daisy.

As for having trouble bleeding brakes - Will and I will use an Eezi-Bleed kit, but whilst the bleed nipples are open tap every brake pipe quite keenly with a ring spanner - you will be amazed by the air that actually comes out when you do this yet happily gets stuck when bleeding.

PeterJMoore

Peter,
That tapping the brakes with a ring spanner sounds like a good tip. Never heard of that before.
I believe in driving a car to sort out problems - in the case of brakes I always bleed them, drive for a couple of days and then bleed again. Driving dislodges and coalesces any remaining air bubbles and then they bleed out at the second session. The tapping with a ring spanner sounds like a good short-cut method of achieving the same.

Guy
Guy Weller

This thread was discussed between 15/06/2010 and 17/06/2010

MG Midget and Sprite Technical index

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