I am trying to bleed the brakes on my new install and I am not having a lot of luck getting the pedal rock hard. I am using the Gunsons Eezi bleed pressure bleeder and have the standard Westfield master cylinder. I have tried tiliting the car forwards, backwards and sideways and must have put over 10 litres of brake fluid through the system and the pedal is nowhere near as firm as when under the pressure of the bleeder and I can pump the pedal and firm it up.
Should I have bench bled the master, is there some magic trick?
I can't see any fluid leaking anywhere
Brake Bleeding - any handy hints?
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seajayare
- Posts: 80
- Joined: Fri Mar 01, 2013 9:28 pm
- Location: Wiltshire, UK
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allymally
- Posts: 70
- Joined: Fri Jul 29, 2011 6:20 pm
Re: Brake Bleeding - any handy hints?
Hi, From an old head! This is how I bleed brakes. 
Buy yourself a good length of silicon tube which will fit tightly on to bleed nipples, the tube needs to be long enough to reach from the furthest bleed Nipple to your master cylinder reservoir, self explanatory no need to keep filling and you can do it yourself and its cheap
when pipe is in place crack open the bleed nipple and pump the pedal slowly you can watch the fluid and air as it comes through the pipe back to the cylinder, "Slowly" as you don't want to make fine bubbles which will negate the process! make sure you refill master cylinder to replace the fluid in the tube.
When the returning fluid is clear of bubbles tighten the BN back up, remove the tube carefully squeezing it to stop fluid from escaping, then go to the next furthest away bleed nipple and so forth. when you have finished and have a decent but perhaps not perfect pedal, its nice to get help to crack open the bleed nipples again in sequence, but this time when under a little pressure from the pedal, this is to force any air that may be trapped in a high spot, but this may not be necessary if the pedal is good which it should be.
Generally I have found that the pistons in new cylinders can stick in the forward position if you press the pedal to the floor! so take it easy when you start only press the pedal gently I would probably only press the pedal one third of its travel several times, slowly increasing the travel after, you should be able to feel as the piston as it engages through the pedal when depressed.
I hope this helps
All the very best Malc
Buy yourself a good length of silicon tube which will fit tightly on to bleed nipples, the tube needs to be long enough to reach from the furthest bleed Nipple to your master cylinder reservoir, self explanatory no need to keep filling and you can do it yourself and its cheap when pipe is in place crack open the bleed nipple and pump the pedal slowly you can watch the fluid and air as it comes through the pipe back to the cylinder, "Slowly" as you don't want to make fine bubbles which will negate the process! make sure you refill master cylinder to replace the fluid in the tube.
When the returning fluid is clear of bubbles tighten the BN back up, remove the tube carefully squeezing it to stop fluid from escaping, then go to the next furthest away bleed nipple and so forth. when you have finished and have a decent but perhaps not perfect pedal, its nice to get help to crack open the bleed nipples again in sequence, but this time when under a little pressure from the pedal, this is to force any air that may be trapped in a high spot, but this may not be necessary if the pedal is good which it should be.
Generally I have found that the pistons in new cylinders can stick in the forward position if you press the pedal to the floor! so take it easy when you start
only press the pedal gently I would probably only press the pedal one third of its travel several times, slowly increasing the travel after, you should be able to feel as the piston as it engages through the pedal when depressed.I hope this helps
All the very best Malc-
Westfield 129
- Posts: 867
- Joined: Sat Jun 04, 2011 4:20 am
Re: Brake Bleeding - any handy hints?
It takes two to bleed the brakes. One to pump, the other to crack the bleed screw, then tighten it when the pedal bottoms.
It all starts when the "volunteer" (wife, girlfriend, neighbor, Best Friend..whoever you can get) pumps the brake pedal.
Yes, the piston can stick, so don't pump too hard the first few times, until some brake fluid gets in there. Then pump to the floor.
Disconnect the hand brake rods at each rear brake. I suggest a spring pin through the clevis for quick removal so that this can be done quickly and easily for both brake bleeding and for rear drum brake adjustment.
Adjust the rear brakes FIRST. Remember that some of the adjusters have flats so you need to turn past the first or second tight spot when you are making the adjustment to ensure that the adjuster is on a flat, and not on a corner, which may slip and change the adjustment, the pedal feel and travel.
Then, you need a tube to attach to the nipple, and a jar to drain the fluid into as it squirts out. Throw away the fluid, and make sure that you keep the reservoir topped up during the bleed process. Lots of exercise, going back and forth...
Start with the brake farthest away from the master cylinder. That would be the left rear on your RHD car.
Have your helper pump the brakes until they can feel some resistance. Then call "Push", or "Down"... which means to hold pressure (full travel) on the brake pedal. Then crack open the bleed screw. allowing the fluid and air to escape. The brake pedal will go to the floor, where the volunteer will then shout "Down!", holding the pedal until the bleeder shouts "Pump!" or something to that effect. Repeat this as many times as it takes to get clear fluid, with no bobbles. Don't forget to check the reservoir and keep it filled.
Then, advance to the RR brake, then the Left Front, and RF.
It may take a couple of rounds... OR...
For about $50 US, you can order from a company called Motive Power, a pressure bleeder, which puts pressure into the reservoir using a hand pump and valve. Then, all you have to do is crack each bleed screw (checking the level of the fluid as you go). No need to pump the brakes until you are finished extracting all of the air. This makes bleeding very quick and easy, with only you as the mechanic.
There are also vacuum bleeders, that pull a vacuum at each bleed screw, pulling fresh fluid into the system, and eliminating the air. These also work quite well if you prefer to bleed your brakes in solitude.
I use both the vacuum and pressure bleeders on a routine basis with my 11 and other cars. I have not had anyone help me bleed brakes (or a clutch system) i a decade.
Now, one more observation or so...
You may NEVER get a "Rock Hard Pedal" from your current setup.
In my experience (and that of others), I have found that the tandem master cylinder of the RHD W11 is known for being "spongy", having a pedal that "is squishy, with hard bits, like stepping on a dead animal" to quote a brilliantly written review of the car from about 10 years ago (it echoed my own frustrating experience with my own car). Even under the best of circumstances, the supplied tandem cylinder is not precisely matched, and feels a bit soft. My solution would be a slightly larger tandem master cylinder, as available from Caterham, which appears to be a common change among some W11 (and even some Caterham) owners.
I installed a dual master cylinder (5/8") set up in my RHD car, as the bias bar was available from Westfield, and the pedal box was drilled for dual master cylinders. This resulted in a nice, firm pedal, with very precise braking control. Also, with my pressure bleeder, made for a quick (5 minute) bleed procedure, with remote reservoirs up on the firewall for easy inspection and filling.
Another reason for soft brake pedal, or a pedal that seems to become soft and not predictable over a few miles of driving is the due to the excessive run out from the front ball type wheel bearings (even new ones). Installing a proper Timken tapered set with the shims to set the spindle nut torque will usually give a very firm, predictable pedal. On two RHD W11s with the tandem master cylinder, I installed Timken wheel bearings, and greatly improved brake feel and modulation. Installing the twin master cylinders gave even more improvement.
I have a couple of standard W11 tandem master cylinders (unused from builds that I installed dual master cylinders) that I want to try on my LHD car (it's an early car with a single .75" Girling master cylinder), but the single cylinder pedal is firm, and the modulation is precise. Getting that performance took about 3 years of work... The key turned out to be the wheel bearings. Maybe I need to fabricate a new pedal quadrant for twin master cylinders. We shall see...
It all starts when the "volunteer" (wife, girlfriend, neighbor, Best Friend..whoever you can get) pumps the brake pedal.
Yes, the piston can stick, so don't pump too hard the first few times, until some brake fluid gets in there. Then pump to the floor.
Disconnect the hand brake rods at each rear brake. I suggest a spring pin through the clevis for quick removal so that this can be done quickly and easily for both brake bleeding and for rear drum brake adjustment.
Adjust the rear brakes FIRST. Remember that some of the adjusters have flats so you need to turn past the first or second tight spot when you are making the adjustment to ensure that the adjuster is on a flat, and not on a corner, which may slip and change the adjustment, the pedal feel and travel.
Then, you need a tube to attach to the nipple, and a jar to drain the fluid into as it squirts out. Throw away the fluid, and make sure that you keep the reservoir topped up during the bleed process. Lots of exercise, going back and forth...
Start with the brake farthest away from the master cylinder. That would be the left rear on your RHD car.
Have your helper pump the brakes until they can feel some resistance. Then call "Push", or "Down"... which means to hold pressure (full travel) on the brake pedal. Then crack open the bleed screw. allowing the fluid and air to escape. The brake pedal will go to the floor, where the volunteer will then shout "Down!", holding the pedal until the bleeder shouts "Pump!" or something to that effect. Repeat this as many times as it takes to get clear fluid, with no bobbles. Don't forget to check the reservoir and keep it filled.
Then, advance to the RR brake, then the Left Front, and RF.
It may take a couple of rounds... OR...
For about $50 US, you can order from a company called Motive Power, a pressure bleeder, which puts pressure into the reservoir using a hand pump and valve. Then, all you have to do is crack each bleed screw (checking the level of the fluid as you go). No need to pump the brakes until you are finished extracting all of the air. This makes bleeding very quick and easy, with only you as the mechanic.
There are also vacuum bleeders, that pull a vacuum at each bleed screw, pulling fresh fluid into the system, and eliminating the air. These also work quite well if you prefer to bleed your brakes in solitude.
I use both the vacuum and pressure bleeders on a routine basis with my 11 and other cars. I have not had anyone help me bleed brakes (or a clutch system) i a decade.
Now, one more observation or so...
You may NEVER get a "Rock Hard Pedal" from your current setup.
In my experience (and that of others), I have found that the tandem master cylinder of the RHD W11 is known for being "spongy", having a pedal that "is squishy, with hard bits, like stepping on a dead animal" to quote a brilliantly written review of the car from about 10 years ago (it echoed my own frustrating experience with my own car). Even under the best of circumstances, the supplied tandem cylinder is not precisely matched, and feels a bit soft. My solution would be a slightly larger tandem master cylinder, as available from Caterham, which appears to be a common change among some W11 (and even some Caterham) owners.
I installed a dual master cylinder (5/8") set up in my RHD car, as the bias bar was available from Westfield, and the pedal box was drilled for dual master cylinders. This resulted in a nice, firm pedal, with very precise braking control. Also, with my pressure bleeder, made for a quick (5 minute) bleed procedure, with remote reservoirs up on the firewall for easy inspection and filling.
Another reason for soft brake pedal, or a pedal that seems to become soft and not predictable over a few miles of driving is the due to the excessive run out from the front ball type wheel bearings (even new ones). Installing a proper Timken tapered set with the shims to set the spindle nut torque will usually give a very firm, predictable pedal. On two RHD W11s with the tandem master cylinder, I installed Timken wheel bearings, and greatly improved brake feel and modulation. Installing the twin master cylinders gave even more improvement.
I have a couple of standard W11 tandem master cylinders (unused from builds that I installed dual master cylinders) that I want to try on my LHD car (it's an early car with a single .75" Girling master cylinder), but the single cylinder pedal is firm, and the modulation is precise. Getting that performance took about 3 years of work... The key turned out to be the wheel bearings. Maybe I need to fabricate a new pedal quadrant for twin master cylinders. We shall see...