Findlay234
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| posted on 2/12/09 at 02:09 PM |
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What should brake creep feel like?
I got into the car earlier and pressed the pedal slowely and it came to a point where if I applied more pressure it moved a little more, then a little
more and then all the force I could must wouldnt make it move any further....
So the brakes arent solid. they may be a little 'spongey' which could be a little air in the system but they dont go all the way to the
floor like they do when im pumping to bleed the lines. I pressed hard on the pedal for a good few seconds to see if they would creep lower and they
dont seem to...... So does this mean that the IVA tester was wrong? My brakes werent creeping? Im tempted to take it to an MOT centre and see what
they think. Can get them to set up the speedo needle as well!! What if the MOT centre agrees with me but the IVA tester still insists the pedal is
creeping??
Cheers
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blakep82
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| posted on 2/12/09 at 02:18 PM |
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could be it wouldn't go further because the master cylinder was at the end of its travel?
________________________
IVA manual link http://www.businesslink.gov.uk/bdotg/action/detail?type=RESOURCES&itemId=1081997083
don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
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Mr Whippy
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| posted on 2/12/09 at 02:34 PM |
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To check if its air, pump hard on the pedal about 10 times to heat up the air. Take you foot off and press again, at first the pedal will feel hard
but then with no more pressure added it will sink slowly down as the air cools.
Is the master cylinder new?
also is there any fizzing noises or groans as the pedals slowly pressed?
If however like you are describing you are just pressing the pedal and it slowly descends without prior pumping it suggests that the piston seals are
worn and weeping allowing fluid to return to the reservoir
[Edited on 2/12/09 by Mr Whippy]
Fame is when your old car is plastered all over the internet
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Bluemoon
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| posted on 2/12/09 at 02:38 PM |
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Mine was creeping to start with turned out this was a tiny leak at one of the fittings.. Only found it by pressing hard on the pedle for ages then
going round with a bit of tissue on each connector, found the leak that way.
Tightened up the fitting and now brakes don't creep at all...
Dan
[Edited on 2/12/09 by Bluemoon]
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wilkingj
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| posted on 2/12/09 at 02:42 PM |
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To me it would feel like "Shivers down my Spine"  
If the IVA man thinks there is a problem, I would NOT ignore it.
I would re-bleed, and check for leaks or any weeping. Not necessarily in that order!
Brakes are mission critical parts, and if the IVA man is not happy, I would not be happy either. Its not just your life, its any innocent passer by
that gets hit if the brakes are not right.
Basically dont take any chances.
1. The point of a journey is not to arrive.
2. Never take life seriously. Nobody gets out alive anyway.
Best Regards
Geoff
http://www.v8viento.co.uk
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Bluemoon
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| posted on 2/12/09 at 02:50 PM |
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You may find that the bulkhead flexes so the breaks might feel a little odd because of this, my Feista is like that always feels odd, but it's
fine.. Thing is as Wikingj says IVA man probably knows what feels correct from experience, this was my problem I don't know how it should feel.
The first bit of travel will feel slack until the master cylinder has moved pass the "fill" holes, then the slack in the system is taken
out i.e pads have to move a little until in disk contact, then it should go rock hard if the bulkhead is not flexing.. I had difficulty telling creep
from the flexing, but if you wait long-enough the peddle will slowly drop if you have a small leak (mine would have taken all week!)..
Dan
[Edited on 2/12/09 by Bluemoon]
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UncleFista
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| posted on 2/12/09 at 03:00 PM |
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When our master cylinder was on it's way out the symptoms were, if you put a fair bit of pressure on the pedal it was rock solid but it sank
slowly to the floor when there was only a bit of pressure on it.
What's it feel like with only a bit of pressure on the pedal ?
Tony Bond / UncleFista
Love is like a snowmobile, speeding across the frozen tundra.
Which suddenly flips, pinning you underneath.
At night the ice-weasels come...
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Findlay234
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| posted on 2/12/09 at 03:27 PM |
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With only a little pressure or a lot of pressure it doesnt sink to the bulkhead. It definately hasnt reached the master cylinder stops as the pedal
will reach the bulkhead when im bleeding the brakes.
At the moment applying pressure slowely the pedal head moves an inch or so then gets harder (guess this is the fill holes being covered as mentioned,
an inch movement in the pedal relates to a small movement of the mcyl piston) and then it will move half an inch or so before becoming solid and then
will stay there even with pressure on for 10 seconds or so...
Thats the thing.... it doesnt sink to the bulkhead as far as i can tell.
Anyone live in the farnborough area and has a free evening that they can come round and give and independant assessment??
cheers
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austin man
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| posted on 2/12/09 at 03:43 PM |
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sounds Like air or a sticking piston, do you have callipers on the rear ? these tend to get air trapped in them. We bled the brakes on an MK indy 3
times yet still had air in them. The calliper has to be tilted if I recall to get rid of the rest of the air
Life is like a bowl of fruit, funny how all the weird looking ones are left alone
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adithorp
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| posted on 2/12/09 at 03:50 PM |
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Whats usually described as brake creep is fluid seeping past one of the master cylinder seals, back to the resevior. You'll feel it if you put
SLIGHT pressure on the pedal and without the pressure increasing the pedal will go down. High presure and the seals usually get pressed out enough to
seal and you feel nothing.
Wouldn't go all the way down unless both seals are gone, just sink halfway normally.
adrian
[Edited on 2/12/09 by adithorp]
"A witty saying proves nothing" Voltaire
http://jpsc.org.uk/forum/
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britishtrident
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| posted on 2/12/09 at 04:29 PM |
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quote:
Originally posted by adithorp
Whats usually described as brake creep is fluid seeping past one of the master cylinder seals, back to the resevior. You'll feel it if you put
SLIGHT pressure on the pedal and without the pressure increasing the pedal will go down. High presure and the seals usually get pressed out enough to
seal and you feel nothing.
Wouldn't go all the way down unless both seals are gone, just sink halfway normally.
adrian
[Edited on 2/12/09 by adithorp]
Very good, clear explanation
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adithorp
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| posted on 2/12/09 at 04:37 PM |
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quote:
Originally posted by britishtrident
quote:
Originally posted by adithorp
Whats usually described as brake creep is fluid seeping past one of the master cylinder seals, back to the resevior. You'll feel it if you put
SLIGHT pressure on the pedal and without the pressure increasing the pedal will go down. High presure and the seals usually get pressed out enough to
seal and you feel nothing.
Wouldn't go all the way down unless both seals are gone, just sink halfway normally.
adrian
[Edited on 2/12/09 by adithorp]
Very good, clear explanation
...and for once I beat you to it! 
"A witty saying proves nothing" Voltaire
http://jpsc.org.uk/forum/
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russbost
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| posted on 2/12/09 at 07:15 PM |
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It sounds to me as tho' you have some air in the system - what you're describing is not brake creep.
If it is genuinely creeping then as you apply LIGHT pressure the pedal will give a little, back off the pressure (extra pressure will flare the seals
& stop the creep momentarily) then gently reapply, if it's creeping you can gradually continue like this & the pedal will sink lower
& lower until eventually it will hit the stop.
I would suspect you either have some trapped air (a decent pressure bleed should sort it) or a caliper or cylinder is drawing a tiny amount in as the
pressure comes off - I haven't thoroughly read the thread but you do have all your nipples at the top of the calipers?
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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Findlay234
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| posted on 3/12/09 at 09:43 AM |
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Checked (again) this morning and applied slight pressure, it would move and inch or two before becoming hard. Then backed off the pressure and
reapplied and it wouldnt move any further. While i was doing this i used a torch to watch the bias bar move and it never gets to a point where the bar
is jammed at an angle in the pivot, ie showing that one of the cylinders was creeping. The two sides balance and maintain pressure...
I will rebleed and see from there.... might get a good pressure bleed system instead of my bleed valve for pumping....
The valves on the front calipers are on the top but I have rear DRUMS and they are on the bottom, but still in line with the fluid inlet.
Cheers
(still holding out for someone who lives in/near farnborough who can lend an experienced hand)
[Edited on 3/12/09 by Findlay234]
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prawnabie
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| posted on 3/12/09 at 12:14 PM |
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If the back nipples are are on the bottom, you will get trapped air regardless of where the inlet is. There will be a void the size of the piston to
fill with fluid and all the air will be at the top of this void, and so should the bleed nipple.
I would think about swopping the calipers around if possible, or taking the calipers off the car and bleeding them upside down.
HTH Shaun
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Findlay234
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| posted on 3/12/09 at 05:12 PM |
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sorry I meant to say DRUM, not disk.... edited above.... brain out of auto mode.
I have rear drums and the inlet and bleed are at the bottom... i think the caliper is horizontal..
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Bluemoon
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| posted on 4/12/09 at 05:34 PM |
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I'd get a pressure bleeder or borrow one, form a completely empty system you might find it difficult with a one way valve.. Pressure bleeder
worked wonders for me, 10min and the system was full and bleed!
I would offer to come over and have a quick look but I only have the 7 this weekend!!
Dan
[Edited on 4/12/09 by Bluemoon]
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Findlay234
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| posted on 5/12/09 at 04:04 PM |
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Completely rebled the system... no difference....
Have done a bit of reading and thinking now that the extra movement on the front cylinder will be because its a 0.625 while the rear is a 0.70. Now
the 0.625 will provide mechanical advantage but will need to be moved further for that advantage...
If the fronts are creeping and its not just the fact they are a smaller cylinder will I be able to replace it with a 0.70? re setting the bias bar
should allow two cylinders of the same size.... surely?
cheers
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turboben
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| posted on 5/12/09 at 04:24 PM |
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I dont think the cylinder sizes will make any difference. If it really is creeping the way I would check is to jam a bit of wood between the steering
wheel and the brake pedal just tight enough so you cant push the car. Leave it for half an hour and see if its still locked in place. If its free by
then the fluids escaping somewhere.
Ben
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