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bleeding new master cylinder


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#1 Torryhead

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Posted 25 August 2010 - 12:35 PM

hey i have new brakes in my LH, front to back including new lines. i connected all the lines to the master cylinder etc etc and bled up the system. after about an hour i was free of bubbles and brakes were hard on the peddle. drove the car a bit and now half the time the peddle goes to the floor and i have no brakes. i have since read that i should have bench bled the master cylinder before install. well its all in now so what advice can you guys offer on how to bleed the system up properly???

#2 _robslxhatch_

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Posted 25 August 2010 - 01:40 PM

the alternative to bench bleeding is to undo and move the brake lines to the side , then fill the reservoir , have a mate push the pedal down (to the floor ) then put your fingers over the holes as the brake pedal is lifted up then off as pedal goes back down ect ect , it is effective, but care is required to make sure brake fluid does not get on the paintwork . strange that it only happens every now and then though..

Edited by robslxhatch, 25 August 2010 - 01:45 PM.


#3 76lxhatch

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Posted 25 August 2010 - 03:20 PM

If you got fluid to the wheel cylinders then the master will be fine, no need to bench bleed now. It does sound like you still have air somewhere further down the system though - especially if it took you an hour to bleed the first time! I'd be looking for leaks.

#4 _rorym_

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Posted 25 August 2010 - 09:17 PM

Something is loose/sucking air back in.
R

#5 Torryhead

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Posted 25 August 2010 - 09:59 PM

thanks for the replies guys. i have checked over the car. there are no leaks anywhere... when i say the brakes work half the time, i might be driving and push the foot down..... nothing then after a couple of pumps they come good again???? any ideas

i'm guessing i should bleed them again. Also the brake warning switch that is built into the master cylinder is not changing state when the system is bled up. that was leading me to think i had an air lock in the master cylinder still. does anyone know the internals/ switch or if i'm on the right track

#6 dattoman

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Posted 25 August 2010 - 11:05 PM

The Chinese master cylinder you bought might be faulty

#7 S pack

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Posted 25 August 2010 - 11:45 PM

thanks for the replies guys. i have checked over the car. there are no leaks anywhere... when i say the brakes work half the time, i might be driving and push the foot down..... nothing then after a couple of pumps they come good again???? any ideas

i'm guessing i should bleed them again. Also the brake warning switch that is built into the master cylinder is not changing state when the system is bled up. that was leading me to think i had an air lock in the master cylinder still. does anyone know the internals/ switch or if i'm on the right track


G/day Torryhead

Is the master cyl you have for disc/disc or is it for disc/drum?
Certainly sounds like you still have some air in the lines if you can pump the pedal up.
You might need to bleed the the master cyl at the brake line nuts as air will rise back up the lines to the master cyl.
Have an assistant pump the pedal and hold while you crack the brake line nuts connecting the pipes to the master cyl to release any air. Then assistant calls out when pedal is all the way down and you tighten the nut before assistant releases pedal. Do this for front and rear brakes lines a few times then bleed each caliper again and hopefully all the air will be gone.
Make sure you take appropriate measures to prevent brake fluid spills onto any paintwork.

If the brake warning switch doesn't reset automatically you might need to reset the switch by removing it from the master cylinder, pump the pedal once should be sufficient then refit the switch. Don't do this until you have finished bleeding the brakes. If this still doesn't resolve the switch issue then maybe there is a problem in the proportioning valve or the switch is faulty.

Hope this helps
Cheers
Dave

Edit: Have you installed all calipers correctly? ie: bleeder nipples at highest point.

Edited by S pack, 25 August 2010 - 11:51 PM.


#8 Torryhead

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Posted 26 August 2010 - 12:06 AM

The Chinese master cylinder you bought might be faulty



Ahahahahahaha funny one mate, the master cylinder is a 1" PBR out of commodore to suit 4 wheel disc with inbuilt proportioning valve P10037 if i'm not mistaken. i haven't spared a cent on this brake job, if i knew how to attach bloody pictures to this reply i would happily show you.

As for the other blokes, cheers, i will disconnect and bleed from the nuts on the master cylinder. i was hoping to avoid as i have a nice new gloss black engine bay. will have to be careful. the brake warning switch is located in the master so i will check that out also. being a first time doing brakes, i was hoping there may be something i had just overlooked.

Thanks again.

oh and yes mate i have located all the bleed nipples at the highest point and installed the calipers correctly. well i hope so ;)

when they work she stops on a dime :) helps when i need to pull up about 420HP in my little chev

Cheers

#9 ls2lxhatch

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Posted 26 August 2010 - 12:28 AM

This is one way to bench bleed the master on the car.

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#10 Mort

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Posted 27 August 2010 - 10:07 PM

Don't know if you have done this or how important it really is but i have always been told (and read) that you should bleed the furtherest brake from the master first.

Mort

#11 fuzzypumper

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Posted 28 August 2010 - 11:27 AM

What Dave(S pack ) said.

Sounds like you still have air in the lines.
If its a commodore 1" one I suspect its a DISC/DISC model which may be causing you
a problem with drum rears as the residual valve is missing.
Always bleed with the warning switch removed.
IS the Master cyl new, reco or secondhand untouched?

#12 S pack

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Posted 28 August 2010 - 04:04 PM

What Dave(S pack ) said.

Sounds like you still have air in the lines.
If its a commodore 1" one I suspect its a DISC/DISC model which may be causing you
a problem with drum rears as the residual valve is missing.
Always bleed with the warning switch removed.
IS the Master cyl new, reco or secondhand untouched?


Hey fuzzypumper

Disc/Disc master cyl is correct for his car as he has fitted disc brakes to the rear.

Cheers
Dave

#13 Torryhead

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Posted 28 August 2010 - 07:56 PM

Cheers Dave your right i do have 4 wheel disc brakes on the Torry. 330mm rotors up front with VE calipers and 300mm rotors with camaro calipers on rear. not sure how you knew but your right.

thanks for your info too fuzzypumper and to everyone else for giving me help and info. it sounds like i have air in the lines still (i hope) so i will bled up the system again. i have been using the self bleed kit working from the further most wheel to the closest etc.

So should i remove the brake warning switch before i bleed again????? i take it that is important. whats the go, should i just let fluid out into a container or just block off the hole?

Cheers boys

Torryhead

#14 S pack

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Posted 28 August 2010 - 09:46 PM

G/day Dan

Probably a good idea to remove the switch as fuzzypumper suggested, then fit it when bleeding operations are complete.
I think with the complete makeover you've done with your brakes you need some decent pressure in the system to get all the air out.
Forget the self bleeder, have an assistant pump the brakes for you while you get under the car and manually bleed each caliper.
That way you can see when no more air is coming out. Same sort of operation as I described for bleeding the master cyl.
Assistant pumps brake pedal (usually 4 or 5 pumps) and hold, you crack open the bleeder nipple to let out fluid/air, assistant calls out FLOOR when pedal hits the floor, you close bleeder nipple and call out OK or whatever you want and assistant lets pedal up.
Repeat operation as necessary until you are happy that all air is gone and check fluid level in master regularly.
Yes, start with the Left rear caliper first, then Right rear, then Left front then Right front.

I just use a small ring spanner fitted to bleeder nipple, a length of clear tube that fits snugly onto nipple and an old glass milk bottle to catch the fluid and of course rags to wipe hands etc.

I knew you had 4 wheel disc cause I'm psychic, lol.

Edit: No fluid should come out of the hole if you remove the switch but proceed with caution just in case until you are sure.

Happy bleeding
Cheers
Dave

Edited by S pack, 28 August 2010 - 09:51 PM.


#15 76lxhatch

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Posted 28 August 2010 - 10:34 PM

Forget the self bleeder, have an assistant pump the brakes for you while you get under the car and manually bleed each caliper.

Absolutely, this is a lot easier and more effective. Some of those big calipers can be a pain to bleed properly from dry too, keep at it.

#16 _Gunmetal LH_

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Posted 29 August 2010 - 06:35 AM

With a black engine bay you may not want to do this as it usually ends up with some sort of spillage- well, everywhere...

Also can make a hell of a mess under the car...



Might help flush through any bubbles?

Have a mate give you a hand, (someone who hopefully doesn't let the pedal down and up too fast) undo a bleed nipple and just lightly hold your finger over the hole.

Get a mate to pump the pedal slowly for 3 or 4 stokes and you'll be able to 'feel' any bubbles farting and spluttering out of the bleed nipple.

Top up the resivoir and repeat. You should be able to feel a nice spray coming out with no bubbles. Tighten the bleed nipple and move on to the next caliper.

If your good you can get the 'spray' aimed into an old tin or some sort of container. Otherwise use a bit of hose so you can get the end of it where your finger is into the container, if you do then you MUST use your other hand to hold the hose on the bleed nipple.


Then do the method of pumping up the pedal and holding it down while you crack it open etc. <-It works the best.

Give the area you got brake fluid on a good squirt with the garden hose ASAP and you shouldn't have any problems.


As far as the furthest caliper first, I've heard all sorts. I like to do the lot with just my finger over the hole twice, then do the lot again pumping it up. I start with whatever is most convenient?

#17 _robslxhatch_

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Posted 29 August 2010 - 08:36 AM

those vacuum type bleeders are only really good for changing fluid , and not to good for getting air bubbles out . does the pedal feel randomly poor without driving it?? or do you have to go down the road ?? because there could be an issue somewhere with the pads being pushed back into the calipers , if trying the above method gets you a solid pedal with no 'pedal creep' with the vehicle running in the garage (just make sure you wait a few seconds between pedal applications) then it should stay that way , if you drive it only to find the pedal starts to travel too far then look for things such as , run out in disc rotors , free play in wheel bearings, calipers not mounted squarely .i am suggesting you check this next because when you have air in the system the pedal will be doughy all the time , if you have a leak then you would have 'pedal creep' , if you have something not square or loose the pedal will feel great in the garage but when driving the pads retreat too far back in the caliper requiring you to 'pump' the pistons back out of the calipers.

#18 dattoman

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Posted 29 August 2010 - 10:43 PM

Clamp the back brakes off and test it
Then you will know if its the back or fronts that are the issue
Isolate it to find the problem end

Then adjust the rear calipers properly (now I know what they are)

#19 Struggler

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Posted 30 August 2010 - 07:52 AM

....there could be an issue somewhere with the pads being pushed back into the calipers...


That would be my suggestion.

I have a vacuum type bleeder and I love it. Works perfectly every time.

#20 Torryhead

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Posted 08 September 2010 - 06:56 PM

G'day fellas, just thought i should get back to you to let you know mt brakes are going strong. i had to remove the front calipers as i was having clearence issues (330mm UPC kit on front) of which i still am!!!! but when i put the calipers back on and bled the system up (front passengers took bloody ages to get air out) i have fully working brakes with no sponges or need to pump them up. must have had some air hiding in the line somewhere. the rear calipers arent perfect though as they dont sit dead square with the disc if you bolt them directly to the mounting plate. i had to space with shims etc. have you guys had this issue with the hoppers 300mm rear disc kit?

thanks again for all the help.

Torryhead

#21 Lima31

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Posted 22 April 2018 - 01:28 PM

Useful thread - issues are with an unusually soft pedal, fairly sure it is still the master but I'm still in the process of trying the above suggestions.

Attached Files



#22 cameron

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Posted 22 April 2018 - 10:07 PM

I have found reverse bleeding especially from empty gets the best results. Its just easier for trapped air to rise through the fluid.

reverse-bleeder-MaxProHD-1.jpg

 

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#23 Lima31

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Posted 23 April 2018 - 09:25 PM

Thanks for sharing, I wish I knew about those earlier !






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