Bleeding brakes

Started by Gaz mr-s, May 22, 2021, 20:53

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Gaz mr-s

I've been cleaning up the rear brakes.  All back together & bleeding them the old simple way, tube into a glass, but videoing the end of the tube looking for the bubbles to stop.
Did both sides & started the car to check the pedal. Lots of travel before resistance.

So I just repeated the process, with the same result...??  After the air in the hose is expunged, the 2nd time I'm not seeing any bubbles at all. (1st attempt took longer to get rid of air)

Do I need to do the fronts too, - or any other reason for the soft pedal?

jonbill

if the fluid ran out and the MC emptied, you'll need to bleed the front and the MC itsel

Gaz mr-s

No, the reservoir never went below minimum.

Dev

There are a few tricks I do when installing new calipers or master. I will tap lightly with a plastic mallet on the calipers after the first bleed or will gravity bleed again after driving. I usually always find a trapped bubble or three that tightens up the pedal. Sometimes the pedal will feel better after sitting overnight for unexplained reasons.

Joesson

All good advice above. In theory if you clamped off the rear hoses when working on the brakes, only  the rear should need bleeding. But how long has the fluid been in the fronts?. In my experience it's prudent to bleed all four brakes, starting with the most distant from the master cylinder (nearside rear) and ending with nearest (offside front). In that way you should be sure of having new bubble free fluid throughout the system.

Gaz mr-s

The brake lines were not disconnected from the caliper.  The front end is about to get work done, but I want to drive it for a few miles & don't want to touch the front yet.

JB21

Try bleeding the fronts, then the rears again. If that doesn't work, take the car out and activate the ABS on grass or loose gravel a few times and rebleed.

frogger

If you have disconnected the calipers and reconnected them, the copper crush washer may need replacing... or just tightening more!  Even the slightest smallest lack of sealing at the banjo bolt will give a soft as pedal... and it is common on 20yr old caliper bolt connections.

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