Hasse
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| posted on 26/10/04 at 06:52 AM |
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Spongy brake pedal?
Hello,
Hope someone can help me with this:
Although mu car is beaking ok, the pedal feeling is very poor.
I have my one designed floor pedal box, with about 6:1 ratio on the brake pedal, and a single master cylinder (mk2) connected to the
"normal" cortina front discs and the mk2 rear axle with drums.
My flexible brake hoses dont seem to move/expand much at high pressures.
I have bled the system several times and also tried two different master cylinders but still have the spongy feel.
I friend was of the opinion that this can come from the the rear drums flexing at high brake pressure, or from the 6:1 ratio beeing to high and making
the forces in to the master cylinder "over strong".
Any experience from similar problems?
Thanks in advance.
/Hasse
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JAG
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| posted on 26/10/04 at 07:50 AM |
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I doubt your friends theory regarding the drumbrakes. I would re-engineer the brake pedal with a lower ratio first.
Can the car be brought to a stop without making your leg hurt?
is the pedal effort about right?
If so I would make a new pedal with about 4 or 5 to 1 pedal ratio and see how that feels.
Justin
Who is this super hero? Sarge? ...No.
Rosemary, the telephone operator? ...No.
Penry, the mild-mannered janitor? ...Could be!
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Surrey Dave
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| posted on 26/10/04 at 09:14 AM |
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I have had similar problems before.
I think the 6:1 ratio should be fine , you need to be sure that the self adjusters are working on the rear ,also if the drums are not new make sure
you remove the wear ridge around the inner edge, then you can adjust the rear by screwdriver and get them running close.
Also a complete change of fluid can help depending on how old it is and bearing in mind that brake fluid absorbs moisture (hydroscopic).
Did you rebuild the Escort master cylinder ?
I've just done mine and found that the seals nearest the pedal where quite worn ,and they related to the rear brakes again.
Another thing is to be sure that the handbrake cable is correctly adjusted, that may mean removing it from the rear brakes and adjusting them 1st and
then refit the cable.
These are all the things I have done and have improved things...................
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MikeP
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| posted on 26/10/04 at 02:11 PM |
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Another thing that you might double check is that the panel to which you've mounted the master cylinders isn't flexing under the load.
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Dale
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| posted on 26/10/04 at 10:51 PM |
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If your calipers are the moving kind make sure that they are both moving together. My wifes is continually having this issue -effing pontiac sunbird
piece of litteral crap- asside from my rant --one pad on the front applies more pressure on the disk and flexes and just does not feel right, also
wears one pad much faster.
Dale
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skinny
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| posted on 27/10/04 at 12:53 PM |
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this may be a stupid question but what brake fluid are you using? if it's a DOT 5 (silicone-based) fluid, even if bled properly, it will be more
spongy than a DOT 3, 4, 5.1 just due to the compressibility of the fluid.
if you don't fail, you aren't trying hard enough.
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Hasse
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| posted on 28/10/04 at 06:33 AM |
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Thanks for your input!
Pedal forces needed for good brakining is ok. They come into action with just a small pedal movement, but the feeling is spongy after this point.
Fluid is new DOT4.
Front calipers are bought remanefactured, rear cylinders are new, all flexi tubes are new.
Handbrake works fine and the master cylinder is not flexing at all. Same with pedal box.
My thinking now is that maybe I still have some air trapped somewhere in the system. I will try to bleed with the car jacked up in steep angels.
/Hasse
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skinny
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| posted on 28/10/04 at 08:50 AM |
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try a pressure bleeder?
if you don't fail, you aren't trying hard enough.
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