bi22le
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| posted on 19/3/15 at 05:54 PM |
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Brake bleeding advice
Hi all,
I am trying to check \ bleed my brakes and am worried I have made things worse, just what I wanted to do 4 days before the 1st track day of the
year!!
As I brought and not built my car I have never bleed brakes, although I understand the method and been the pedal man before. I brought a vacuum one
man bleed system expecting it to be almost straight forward and easy as I am on my tod.
1) Connect up the system to a bleed nipple
2) Create a vacuum
3) take the lid off of the reservoir and keep it topped up, at all costs.
4) undo the nipple.
5) watch dirty old fluid pleasantly drain into my vacuum reservoir and tighten nipple once clean is coming through.
The problem - It starts to drain and then with time air bubbles appear more and more. It gets to a point where the fluid stops flowing completely and
I am just sucking air. The reservoir has gone down by approx the amount I have collected but then stops. The air is a massive concern. The brakes were
good anyway, just not had new fluid for many track days and 5 years so needed a flush. Due to this I know that this is not just masses of air in the
system. Its almost like the bleed nipple is letting air in through its external tread although I am only undoing it half a turn.
There are NO leaks in the system nipple to hand pump, if I keep the nipple closed or put my finger over the end it holds its pressure very well (very
small drop in pressure but its tiny)
I cant drive it yet, not road legal, so cant check what has changed or if they are spongy.
The questions,
1) When loosened does the bleed nipple allow air in or should I only get fluid out?
2) As it is a vacuum system pulling through air, as long as the reservoir has always got liquid in it, cant be introducing air into my brake system,
right?
3) How do I get a perfect seal around the brake nipple I have used both the 90deg connector supplied in the kit and RC car fuel hose?
4) Why does it start off ok and then just constantly pull air?
5) I try to keep the vacuum low so it does not expose any leaks is this sensible?
HELP AND ADVICE, PLEASE!!!!
Track days ARE the best thing since sliced bread, until I get a supercharger that is!
Please read my ring story:
http://www.locostbuilders.co.uk/forum/13/viewthread.php?tid=139152&page=1
Me doing a sub 56sec lap around Brands Indy. I need a geo set up! http://www.youtube.com/watch?v=EHksfvIGB3I
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mark chandler
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| posted on 19/3/15 at 06:26 PM |
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Pull the bleed nipple right out, coat the threads with copper ease then put back and try again, it sounds like you are drawing air in by the
threads.
I just get someone to push the pedal down, crack the bleed nipple and close before they lift these days, it may be the old way but works well.
And yes, keep the reservoir topped up at all times
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Dick
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| posted on 19/3/15 at 07:28 PM |
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Sounds to me like you may have a tandem master cylinder have you got the filter in it. if so remove the filter why they put one in when you are using
new fluid i cant get my head round. You may be looking at the level not seeing the other chamber going down.
If you have as Im thinking then start again fill it up to the top and start again just crack the bleed screw open you don't need to wind it out
half a turn sould be all that's needed. Then vacum keep the fluid up to the top .
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britishtrident
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| posted on 19/3/15 at 07:30 PM |
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Don't put any kind of mineral grease or oil near threads on brake hydraulics even a tiny amount of mineral oil in brake fluid will harden the
seals in a couple of years or so.
If you are unsure about manual bleeding pressure bleeding is the way to go.
Incidentally with any method of bleeding at some point the brake pedal must be pumped to clear the master cylinder of air.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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JAG
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| posted on 19/3/15 at 07:41 PM |
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You're sucking air in around the bleedscrew threads - you're NOT getting air into the brake system
However as "Britishtrident" says don't try to seal the bleedscrew with any kind of grease. It will eventually destroy your brake
system.
quote:
get someone to push the pedal down, crack the bleed nipple and close before they lift
DO THIS - IT'S A MUCH BETTER METHOD  
Justin
Who is this super hero? Sarge? ...No.
Rosemary, the telephone operator? ...No.
Penry, the mild-mannered janitor? ...Could be!
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bi22le
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| posted on 19/3/15 at 08:48 PM |
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Thanks for the responses.
I have a Wilwood master cylinder and its single, I have a balance bar to a separate circuit for the back end.
So how do I seal the bleed nipple thread if I cant use any grease?
I have pumped the pedal a few times to see how it felt, it did not change anything. I really don't have a person to help at the moment so need
to solve this with a one man system.
It seems to be a lot of air coming out, I am half convinced its not even from the threads but it is defiantly not from the system, the reservoir level
is just not dropping.
I have Wilwood 4-pot callipers in case that makes a difference and it happens on any of the 4 nipples. Only touched the front right brake, I dare go
any further!
Track days ARE the best thing since sliced bread, until I get a supercharger that is!
Please read my ring story:
http://www.locostbuilders.co.uk/forum/13/viewthread.php?tid=139152&page=1
Me doing a sub 56sec lap around Brands Indy. I need a geo set up! http://www.youtube.com/watch?v=EHksfvIGB3I
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Scuzzle
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| posted on 19/3/15 at 11:02 PM |
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I've seen a lot of cars that won't bleed properly with the press the pedal method but will with a pressurised bleeding kit like a
Gunson's Ezibleed whick uses the air from one of your tyres to pressure force brake fluid through your system. The pressurised kit often pushes
air out of the master cylinder and calipers that otherwise might not be budged. You just have to make sure the selection of screw fit caps you get
with the kit will fit your fluid reservoir.
[Edited on 19/3/15 by Scuzzle]
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rodgling
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| posted on 19/3/15 at 11:09 PM |
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You can use PTFE tape to seal the threads instead of grease, this works well and you can then vacuum bleed without problems. I'm not aware of
any issues using this on a brake system (I hope not as this is what I've done!).
Edit: just did some searching... not everyone agrees with using this. Do your own research...
[Edited on 19/3/15 by rodgling]
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Dingz
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| posted on 19/3/15 at 11:35 PM |
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Silicon grease will be fine with standard seals and fluid. I found when using a vacuum device that the air in the system tends to be big bubbles and
air bubbles sucked around the nipples are very small. Don't undo the nipples very far just crack them open.
Phoned the local ramblers club today, but the bloke who answered just
went on and on.
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Slimy38
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| posted on 20/3/15 at 08:50 AM |
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I'd just like to add another vote for an eezibleed. Instead of trying to pull the fluid out, you're pushing the liquid in. So issues like
gaps in the thread just means a bit of fluid leaking out rather than the distracting sight of bubbles.
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Charlie_Zetec
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| posted on 20/3/15 at 02:21 PM |
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quote:
Originally posted by JAG
You're sucking air in around the bleedscrew threads - you're NOT getting air into the brake system
However as "Britishtrident" says don't try to seal the bleedscrew with any kind of grease. It will eventually destroy your brake
system.
quote:
get someone to push the pedal down, crack the bleed nipple and close before they lift
DO THIS - IT'S A MUCH BETTER METHOD
I agree with 99% of the above, but I have used the smallest smear of red rubber grease on brake nipple threads before when bleeding if I encounter
problems you have mentioned. It's designed for rebuilding callipers etc. (used this on my Defender and CBR before now) to re-fit pistons, and
it's specifically designed not to contaminate/affect brake fluid.
Artificial intelligence is no match for natural stupidity!
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