David Jenkins
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| posted on 19/6/04 at 09:04 PM |
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Brake feel
I have an interesting problem - I've just fitted some new flexible brake hoses and bled the whole system with an Eezy-bleed until all the
bubbles were gone (as in the instructions)
Trouble is, I can't remember the last time I drove a car without a servo (at least 30 years ago!) and can't remember how it should feel!
At the moment I can push the pedal and get a progressively stronger resistance - it's not immediately 'solid'. It's not
spongy, but I am able to push the pedal more than I expected. I can't 'pump it up' - it's the same feel every time I push.
I took it up the drive and whizzed back, stomping on the brakes, and locked everything up (FUN!  ) so they do seem to be working.
So... and clues, anyone? Or should I find someone with a Mk2 Escort and compare? 
David (aka Puzzled of Bentley)
BTW: The engine makes a lovely noise when I zoom up and down the drive!
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JoelP
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| posted on 19/6/04 at 09:14 PM |
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sounds right to me. Long drive, david?
Beware! Bourettes is binfectious.
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pbura
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| posted on 19/6/04 at 09:14 PM |
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Doesn't sound bad at all!
If you've got nylon/rubber hoses, they'll pump up a little bit. Perfectly normal.
That's one sharp car, btw, David! 
Pete
Pete
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mangogrooveworkshop
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| posted on 19/6/04 at 10:50 PM |
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get hold of an old beetle and that should show you how good your brakes really are. Very tidy book car by the way.
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Fozzie
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| posted on 19/6/04 at 11:35 PM |
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quote:
Originally posted by David Jenkins
I have an interesting problem - I've just fitted some new flexible brake hoses and bled the whole system with an Eezy-bleed until all the
bubbles were gone (as in the instructions)
Trouble is, I can't remember the last time I drove a car without a servo (at least 30 years ago!) and can't remember how it should feel!
At the moment I can push the pedal and get a progressively stronger resistance - it's not immediately 'solid'. It's not
spongy, but I am able to push the pedal more than I expected. I can't 'pump it up' - it's the same feel every time I push.
I took it up the drive and whizzed back, stomping on the brakes, and locked everything up (FUN! ) so they do seem to be working.
David,
Sounds right to me too!
Have fun!
ATB fozzie 
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David Jenkins
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| posted on 20/6/04 at 06:35 AM |
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quote:
Originally posted by JoelP
sounds right to me. Long drive, david?
Well, I did use a bit of the road...
25 yard journey, there and back - but I had to accelerate energetically to test the brakes properly, didn't I?
(Still feels weird, driving it around after all these years...)
David
[Edited on 20/6/04 by David Jenkins]
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David Jenkins
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| posted on 20/6/04 at 06:37 AM |
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quote:
Originally posted by pbura
Doesn't sound bad at all!
If you've got nylon/rubber hoses, they'll pump up a little bit. Perfectly normal.
They're teflon/stainless braided ones...
quote:
That's one sharp car, btw, David!
Thanks!
David
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britishtrident
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| posted on 20/6/04 at 07:05 AM |
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A car without a servo will have less pedal lost motion than one with a servo -- but drum brakes have more lost motion and are not anything like as
stiff as disc brakes.
Type of flexi hoses make very little difference to pedal feel on a car with drum brakes -- the ammount of lost motion and distortion within the drum
and shoes far exceeds the the elastic expansion of a fabric/rubber hose.
You need some play for the drums to work but causes of lost motion that you can do something about are
(1) Shoes and pads need to beded in.
(2) Self adjuster in rear drums need tweaking --- also check the handbrake cable isn't too tight.
(3) Pedal box flexing excessively ---- very common on kit cars gives a springy pedal
(4) Air -- the ezy bleed is a good tool but it is impossible to bleed brakes single handed even using an ezybleed as it won't get all the air
out of the master cylinder without depressing the pedal 3 or 4 times.
(5) One other cause is a stuck caliper piston or pad -- the car will initially stop normally but as the pads wear the pedal will become progressively
softer -- was commom on 70s Fords when new.
(6) similar to (5) on cars with rear disc brake conversions excessive pedal travel is often caused by the calipers not being in perfect alignment
with the disc, tweaking the brackets by very slight bending usually fixes this.
To trace excessive travel thought to one particular wheel it is useful to clamp the (fabric/rubber) flex hose to each wheel in turn.
[Edited on 20/6/04 by britishtrident]
[Edited on 20/6/04 by britishtrident]
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David Jenkins
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| posted on 21/6/04 at 08:36 AM |
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quote:
Originally posted by britishtrident
You need some play for the drums to work but causes of lost motion that you can do something about are
(1) Shoes and pads need to beded in.
Everything on mine is brand new so that certainly needs doing!
quote:
(2) Self adjuster in rear drums need tweaking --- also check the handbrake cable isn't too tight.
Too tight? or too slack? Mine was certainly slack, which means that the non-piston ends of the shoes were too far away from the drum (haven't
tried it since re-adjusting the handbrake).
quote:
(3) Pedal box flexing excessively ---- very common on kit cars gives a springy pedal
Something to check... although my pedal box is very solid!
quote:
(4) Air -- the ezy bleed is a good tool but it is impossible to bleed brakes single handed even using an ezybleed as it won't get all the air
out of the master cylinder without depressing the pedal 3 or 4 times.
Not 100% sure I've got the bleeding done properly, yet... Next weekend's job!
quote:
(5) One other cause is a stuck caliper piston or pad -- the car will initially stop normally but as the pads wear the pedal will become progressively
softer -- was commom on 70s Fords when new.
Think I'm all right here.
quote:
(6) similar to (5) on cars with rear disc brake conversions excessive pedal travel is often caused by the calipers not being in perfect alignment
with the disc, tweaking the brackets by very slight bending usually fixes this.
Again - think I'm OK here.
quote:
To trace excessive travel thought to one particular wheel it is useful to clamp the (fabric/rubber) flex hose to each wheel in turn.
Can't clamp these hoses! (but you did say rubber hoses).
Thanks BT - plenty to think about...
rgds,
David
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Peteff
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| posted on 21/6/04 at 10:34 AM |
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Pedal ratio.
The pedal ratio can make a lot of difference to the feel and the effort needed. You can get to a point where you are fully braked but can still exert
more pressure on the pedal but not achieve anything by doing it apart from flex the cylinder mounts.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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Rob Lane
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| posted on 21/6/04 at 10:51 AM |
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Concur with Pete. More than anything that affects the brakes (when working!) is the pedal ratio.
I made my original pedal box and always had solid brakes which took some effort to use. Then I modded pedal and increased ratio. Result, more travel
but easier action braking.
As now I have a floor mounted pedal box with bias bar. The brakes are OK but I would prefer them easier on the leg. However, lengthening the pedal
would necessitate lifting leg up under scuttle to apply brakes!! There's really no room for a mod.
Rob Lane
www.robs7.com
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David Jenkins
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| posted on 21/6/04 at 11:21 AM |
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I'm fairly confident that my pedal ratio is OK - I've used the original Escort pedals. I've also reproduced the layout of the
original pedal box, so the geometry should also be OK.
I'll try some of the other options discussed earlier before I worry about ratios, etc. 
cheers,
David
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Rob Lane
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| posted on 21/6/04 at 12:27 PM |
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Pedal ratio is OK then.
Unservoed brakes do get a bit of getting used to. Especially if you drive a servoed car in between.
I drive a Fiesta Diesel van daily and that has a lot of servo assistance so it tends to spoil me for first few miles when I get in Locost.
Pics of car look good! SVA soon?
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David Jenkins
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| posted on 22/6/04 at 03:05 PM |
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I think I may have identified my problem... in my wisdom, I used Automec DOT 5 silicone brake fluid instead of regular stuff. After doing a major web
search, it seems that a significant usability problem with this stuff is a spongy brake pedal. The main reason for this is that the fluid holds air
within its molecular structure far more than glycol fluids.
This can be largely avoided by (a) gently pouring the fluid into the master cylinder and letting it stand for 10 minutes before starting to bleed the
system, and (b) NOT using an Eezi-bleed, which has air at 20psi over the top of the fuid in the reservoir, and splashes the fluid when it tops up the
level!
Item (b) explains why my system felt more spongy after changing the flexible hoses - the first time I bled the brakes I used a 1-way valve bleed tool,
but the second time I used the eezi-bleed.
I still intend to use the DOT 5 fluid as it's benefits suit my use of the car (a couple of thousand miles/year doesn't keep glycol fluids
up to spec), but it looks like I need a different bleeding technique... (read those last few words in whichever way you like! )
Second attempt this coming weekend...
David
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timf
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| posted on 23/6/04 at 07:23 AM |
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quote:
Originally posted by David Jenkins
NOT using an Eezi-bleed, which has air at 20psi over the top of the fuid
my instructions for my old eezi bleed says use 2-3 psi not 20
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David Jenkins
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| posted on 23/6/04 at 07:33 AM |
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quote:
Originally posted by timf
my instructions for my old eezi bleed says use 2-3 psi not 20
Mine's fairly new, and the instructions say 15 - 20 psi (lower for Fiats, which have a weak master cylinder reservoir!)
David
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