Robert Noel Reddington
Post Number: 1076
|Posted on Monday, 01 August, 2016 - 03:42 am: |
This bit can be a bugge to bleed the method I use is as follows.
Depressurise the power system fully.
Retract the master cylinder Pistons either put in an old set of thin pads or a pair of screw drivers between disk and piston.
Pump the master cylinder Pistons out.
Whilst holding down the pedal open the nipple and fully retract the Pistons this will expel air from the caliper. Repeat. When this has been done then retract piston without nipple open do this twice. Then with nipple open again.
This is because the volume of fluid output from the master isn't enough to clear the air and air locks just travel back wards and forwards in the lines. The volume of the caliper with piston out is much larger. Retracting with nipple closed will push air back to reservoir. Remember that the feed pipe to master is only 3/16 bore ( 1/4 o/d ) and fluid must be given time to flow under gravity and atmos pressure to the master.
Setting the push rid length.
Lengthen the push rod until the rear brakes drag then back off until free.
Leave the rat trap cover off.
And in DRY weather drive the car for 5 miles applying the brakes once in a while.
If the rear brakes start to drag once the car is warm
Find level surface.
Turn engine off car not in park.
Back off master cylinder push rod until car rolls under human effort plus 1/4 turn to fully clear the inlet port in the master.
Then go home and put rat trap cover back.
A helper is handy for pushing the car a bit while one shortens the push rod. Plus a chock kicked under a wheel will stop the car rolling too much should the level surface not be as level as it appears.
Retracting Pistons to bleed works on lots of cars including clutch hydraulics and will also work on the power side of both the Shadow and the Spirit. If the nipple is closed its shows up restricted hoses as well. So all in all a good way of bleed awkward systems.
Retracting Pistons with nipple closed drives any nasties in the caliper back up the system. Which is not good and if the car has abs even worse. BMW open nipples before retraction because of this. So first always retract a couple of times with nipple open first then to save fluid close the nipple and retract as many times as necessary with nipple closed. Topping up after wards introduces a bit of nice new fluid into the system which is good. On YAK 363 add a spoonful of castor oil. I am on yak and I don't premix I just add the castor direct to the reservoir and allow the pumps to mix the the fluid it takes probably 1 minute to mix. That way my fluid stock can be used in any car. 5% yak.
On LHM systems retracting with nipple open will hopefully remove any water collected in the caliper ( lowest point of the system) once every 3 months is not over kill. Plus again a bit nice new LHM is good.
Post Number: 201
|Posted on Monday, 01 August, 2016 - 06:23 pm: |
Hi Bob,thanks for the advice, just to say I had major difficulties bleeding the master cylinder say 3 years ago.My only saving grace was to put put a bleed nipper to the end of the reconditioned master cylinder to ensure it was good and then replace pipe and bleed away. With this method I found the low pressure system relatively easy to bleed.
Post Number: 1335
|Posted on Tuesday, 02 August, 2016 - 12:02 am: |
Yes, a good method. Beats standing the car on it's front bumper.
I invested in a hand operated vacuum pump. I had no trouble bleeding the low pressure system with this tool. Bob's method is better, by 30 bucks.
Robert Noel Reddington
Post Number: 1078
|Posted on Tuesday, 02 August, 2016 - 04:33 am: |
I tried vacuum bleeding and the air got sucked in via the master cylinder seals.
I had a merc 207D van and fitted a new clutch slave cylinder all done and bleed out in about 5 mins by simply working the piston back and forth.
Moving caliper Pistons near full stroke a few times also ensures that the pistons are not sticky. All good stuff then.