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#Post#: 102475--------------------------------------------------
Bleeding brakes
By: Namrac Date: August 27, 2017, 6:36 am
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Read subject line whichever way you like. Vehicle is a 1971 88
inch, which in the past had 11 inch brakes (109), instead of
usual 10 inch, fitted, no servo. Having had a serious lack of
brakes found that many of the cylinders had seized solid. I have
replaced them all plus the master cylinder with the correct spec
units for 11 inch brakes. However no matter how much bleeding I
do the first push on the pedal goes almost to the floor, the
second push goes solid and the brakes drums are solid. First
time they stayed on and I had to release a bit of pressure at
front LH nipple which freed brakes. but after several more
bleeding attempts still getting soft pedal on first push. All
brakes shoes are adjusted OK. I have been using a one-man bleed
unit which seems to work fine but think there must be some air
still in the system, but where? I have checked carefully and
there are no fluid leaks.
Any suggestions what I'm missing or do I need to keep on
bleeding to find any possible trapped air? Haynes manual says
start bleeding from front left, front right, rear right and
lastly rear left. This seems contrary to what I have always been
told ie start with the brake furthest away from the master
cylinder. What is best practice?
#Post#: 102477--------------------------------------------------
Re: Bleeding brakes
By: fuckwit Date: August 27, 2017, 11:56 am
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I'd be very surprised if the snails are good. It only takes one
go and one ham-fisted LRO reading moron with these and you'll
want a new set. Buy Bearmach, Shitpart versions are made of
cheese. Get your long-suffferin' on the pedal before you go near
any adjusters or **** the splines on the snails, and be ready to
spring for another set. And make sure shoes are on correctly -
so easy to ****-up on 109 rears... but 88 ain't much easier.
Leading edges are handed. And if you have shoes on wrong, or
adjusters spinning on nothing, they won't adjust anyway, and
you'll get exactly your symptoms.
[quote]This seems contrary to what I have always been told ie
start with the brake furthest away from the master cylinder.
What is best practice?[/quote]
It won't really matter a toss with a pressure-bleeder. Don't
mince about with it. I'm afraid steel-braid hoses and fresh
fluid flushed thru' and said pressure-bleeder, will be worth
every penny - will possibly save your neck. Even then it won't
stop. So upgrade to a servo. Remeber you schoolboy Physics,
friction is a factor of force, not area. So you can can have
shoes pads the size of a barn-door and whilst they'll get rid of
the heat better, all they'll really do is take longer to wear
out.
Discs is luvverly but I digress.
A fiver says the adjusters are rounded on the splines...
#Post#: 102480--------------------------------------------------
Re: Bleeding brakes
By: fuckwit Date: August 28, 2017, 4:41 am
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Oh yeah, and the TLS set-up can be a pig to bleed. A vacuum pump
is the quick and easy method. You'll fight all day with a
one-man bleeder.
#Post#: 102482--------------------------------------------------
Re: Bleeding brakes
By: Namrac Date: August 29, 2017, 4:19 am
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Thanks for suggestions. Will let you know what I find.
#Post#: 102495--------------------------------------------------
Re: Bleeding brakes
By: fuckwit Date: August 30, 2017, 6:07 pm
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When you KNOW your adjusters actaully adjust rather than
swinging in the breeze, put your foot on the pedal and gently
turn adjuster as far as they'll go, untill you can't turn your
wheel. Then back off one. Let them bind a little. Do NOT gorilla
the adjuster. Use your pedal to fight the springs. Do NOT try to
do this fighting the springs with your snail-splines, the
springs will win, the splines will lose.
You might get away with it once, twice even, but I doubt it.
Certainly, never for long.
#Post#: 102502--------------------------------------------------
Re: Bleeding brakes
By: NoelC Date: September 1, 2017, 9:35 am
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I've had series for 25+ years and never had issues with bleeding
the brakes until the last set of wheel cylinders went on the 2A
109. To cut a very long story short, after advice from Rog176
amongst others I bled using the G clamp method.
Put the vehicle on chassis stands and pull off all 4 road wheels
and brake drums. Remove the brake shoes or pull them aside off
the wheel cylinders. Using 4 G clamps clamp the wheel cylinder
pistons fully home on the front axle. Using 2 G clamps do the
same on the rear axle but ensure the twin pistons are central
and not biased more one way than the other or you'll block the
bleed nipple. Making sure the bleed nipples are still done up,
stamp on the brake pedal hard and sharply a good 20 or 30 times.
This breaks up any large air bubbles into much smaller ones. I
use an eezibleed to pressurise the system, crack off each bleed
nipple and bleed in turn. The fluid will probably look milky,
that's the tiny air bubbles in the fluid. Once it runs clear
with no air on each corner before removing the G clamps jump in
the cab and press the brake pedal. It should be rock solid and
not move at all. If this is the case you can be confident you're
air free. Press and hold the pedal down for a while, just to
check the master cylinder isn't allowing fluid past seals
internally. Assuming it stays rock solid you're good to
reassemble and adjust up.
I have to say since doing this to my 109 (non-servo) I'm yet to
experience a series with a better feeling brake pedal and it
stops really well. A servo does reduce pedal effort, however it
does not improve the performance of the brakes. Just means you
don't have to push as hard. My other 109 and 88 have servos,
can't say they're massively better TBH.
#Post#: 102508--------------------------------------------------
Re: Bleeding brakes
By: fuckwit Date: September 2, 2017, 6:24 pm
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Well, I've never heard of that method before and I suspect it
works too. Saves on pricey pressure-bleeders too. I'm curious to
give it a go.
[quote]A servo does reduce pedal effort, however it does not
improve the performance of the brakes. Just means you don't have
to push as hard. My other 109 and 88 have servos, can't say
they're massively better TBH.[/quote]
Er, but I'm afraid I have to put you task here, even in
contradiction of yourself. If, and I quote: 'A servo does reduce
pedal effort, however it does not improve the performance of the
brakes. Just means you don't have to push as hard.',
Ahem, so we push not so hard for the same braking effect? It
must lead us to ask... For the same pedal-effort where would the
force be off to then? Perchance, a day at the races?
To keep everybody sweet, we'll assume the force has gone racing,
and definitely didn't go into hydraulic pressure. Because it is
true, even if it did go into hydraulic pressure, which we've
already established it didn't, it could well NOT have been
converted into noticable reduction in stopping-distance. This
for any number of shortcomings in our braking system.
That won't be any fault of the servo? It upped the force, even
if it didn't result in a corresponding improvement in
stopping-distance. A servo is only part of the brakign system,
so sadly, a servo won't do it all, not on its own.
If you do fit one, make it a 10". Stock is 8" and not large
enough. See Mr Heystee if you're flush. If not a Debender can be
shoehorned in.
#Post#: 102509--------------------------------------------------
Re: Bleeding brakes
By: w3526602 Date: September 3, 2017, 3:14 am
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Hi,
The problem with 11" front brakes is that the bleed nipple is
halfway up the wheel cylinders. Any air above the bleed nipple
is trapped, so in theory is unbleedable. OK, sometimes it will
bleed.
The solution is to wind the adjusters right OFF. This allows the
shoe pull off springs to push the pistons deep into the wheel
cylinders, reducing the space available for trapped air to
virtually nothing. In theory, the springs should be strong
enough to hold the pistons in while you are bleeding, so there
should be no need for clamps. But as I said ... in theory.
I worked all this out by myself, about 20 years ago ... and
earlier this year, I noticed it was mentioned in the Green
Bible. Doh!
The Green Bible says to slacken the outlet pipe from the master,
bleed the master. I have met masters with there own bleed nipple
(possibly Bedford SL and RL, or maybe Austin Lodestars ... a
long time ago) and was taught to bleed the master first.
The Green Bible says that air can be trapped in CB masters (big
hexagon at the blunt end), so it may help to raise the front end
of the vehicle until the master is horizontal.
The Green Bible also says to start bleeding at wheel nearest the
master cylinder ... not what I was taught.
The Green Bible says that CV masters (same as the clutch master)
should be bled with one long stroke, followed by three short
rapid strokes, then let pedal return quickly. Repeat until no
air from each bleed nipple.
The Green Bible says the CB masters (big hexagon) the pedal
should be depressed slowly through full stroke, then allowed to
return slowly, then wait three or four seconds. Repeat until no
air from each bleed nipple.
I assume you are aware that it is crucial that the bottom of the
brake pedal is 6.25" above the floor, measured vertically. The
pedal must be free to swing and return easily (not seized pivot
pin) and there should be a smidgen of free play in the push rod.
I never had this PITA with any other car.
602
#Post#: 102517--------------------------------------------------
Re: Bleeding brakes
By: fuckwit Date: September 4, 2017, 10:24 pm
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I used to actaully remove the lot and tilt whilst bleeding as
the only way to bleed from empty, but not done it that way for
20 years. Went over to discs and vacuum-bleeders long since,
but yes I've never known another system with so many trip-ups
and assembly and bleed hurdles to deal with before you get them
right. And even then, they're not good.
Observe any modern vehicle of similar weight and see a 11-12
servo for a start, look at any modern van and you wil confirm
this. This serves as a good measure of the force required to get
decent brakes. Then of course there's how that force gets
deployed. For kick-off, many leafers came without servos, and
when they did, at 8" they were too 'kin small. So on the servo
issue:
[quote]My other 109 and 88 have servos, can't say they're
massively better TBH.[/quote]
Kinda bears this out. I've played for weeks getting my leafer to
stop to modern standards anf feel, and save for ABS, it now
does. Stock leafers never will truly stop, they can't.
Leafer brakes and brakes in general is a greatly misunderstood
subject, I did try to write a fully comprehensive thread on it
once, will try again soon. Last one got hijacked. To get them
to even work as stock can be awkward, to actaully make a leafer
'stop' starts with a decent servo and discs. Discs because they
are controllable, consistent, and do as they are told, and stay
controllable, consistent, and doing as they are told. But it's
just as easy to make a hash of discs.
And you can't jsut put a big servo on drums, because they'll
self-servo at inconsistent levels so all you'd have is an
overbraked undriveable mess. Which is why LR under-sized the
servo.
#Post#: 102518--------------------------------------------------
Re: Bleeding brakes
By: w3526602 Date: September 5, 2017, 3:01 am
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Hi,
Many yonks ago, I read in a Haynes manual ... I think for Morris
Marinas ... that cars with servos used different brake linings
from those without servos.
Hmmm! S3s were fitted with servos. S2s did not, normally, have
servos. But did the cars leaving the factory have different
brake linings? All you can buy nowadays is "one size fits all"
brake shoes. Not only that, HMG in their wisdom banned asbestos.
I read that modern cars wear their discs out, because asbestos
free-brake pads require greater pressure for the same stopping
power. Discuss.
Fitting bigger tyres will require greater braking force ...
Principal of Levers.
ALL my Series Land Rovers are fitted with 11" front brakes, OE
rear brakes (10" or 11") with 1" rear cylinders, and the 3/4"
master cylinder from S2 88". This will give you shorter pedal
travel, and nearly double the fluid pressure over a 1" master
from a 109".
602
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