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 Posted: Sep 10, 2019 05:55PM
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my two cents
I believe that air trapped in the U shape above the MC's causes a great deal of bleeding problems and shows up as soft pedal. My son and I ran into this on his race car where the pipe was above the MC. A Tee with a plug was useful here so that simply bleeding from the Tee plug would allo9w air bubble to be expelled. But a classic mini has the U which ttraps air. Simply installing a Tee at the top of the U would solve the problem. However purists would frown on  this I'm sure. 
I recognized that air would be trapped in my Mk1 so I did the following.  With normal bleeding a helper would press,let off depress, hold while first person would bleed at the brake. and repeat several times until hard pedal. If there is an air pocket at the U it will never be expelled under normal bleeding. Installing the pipe on the MC I reasoned would result in an air bubble regardless of the care taken to fill the pipe and fill the MC plunger. I reasoned further that the air bubble must be driven out. since the RF bleed was the closest I chose to drive a volume of brake fluid thru the pipe and expell it into a waste bucket without drawing air into the MC. I then opened the bleed wide open an firmly, but not  too fast, pumped the pedal. I guessed that the bubble would get expelled before the resevoir emptied.
Result was well adjusted brakes.
Here's what I did with new pipes all around and a Single LE sytem that needed to be filled without air.  
Skim cut all drums to round them to make easier (and more precise) to adjust the adjuster nut.
Leak checked rear half of sytem with air at the fireall Tee. Held 80 psi for 10 minutes. Did the same for the front half. I was then assured that there were no leaks front to back. 
Filled the MC with brake fluid and allowed fluid to drain out thru the bleeds by gravity and fill wheel cylinders.
Pumped the pedal as above to drive out any air bubble.
Adjusted nut tight the backed off quarter turn.
Bled all four brakes with helper in normal fashion.
Brake operation was flawless.
my two cents

 Posted: Sep 10, 2019 07:03AM
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Bubbles do not always move.

They require a certain velocity of fluid flow to "break them loose" because of surface tension -induced clinging to the pipe wall, or even to other bubbles.

This is a fluid dynamics issue not just in brake fluid.  For example, and this is the way I learned about it, if you have enough flow while refilling a house hot -water radiator and pipe system, you can get the bubbles "blasted out" and not have much  (or any) air to relieve at the bleed screws 

Pretty esoteric stuff.
See //www.thermopedia.com/content/8/DOI:10.1615/AtoZ.b.bubble_flow

 Posted: Sep 10, 2019 06:17AM
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Quote:
Originally Posted by TK
I was told if you "un-adjust" (is that a word?) drum brakes, then bleed and re-adjust, you get a better pedal.
Probably makes sense. With the shoes pulled back, the wbeel cylinder pistons would move more and help shift bubbles.

.

"Hang on a minute lads....I've got a great idea."

 Posted: Sep 9, 2019 10:28PM
TK
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AU
I was told if you "un-adjust" (is that a word?) drum brakes, then bleed and re-adjust, you get a better pedal.

 Posted: Sep 2, 2019 02:04PM
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 After bleeding the server which doesn’t work and I bleed it a number k I have found that I don’t even need to raise the car to bleed the brakes, and it’s lowered, I just crawl under there and bleed it literally takes five minutes.   Since I’m using silicone for my brakes I have two eezi  bleeds One for silicone one for regular brake fluid. It has worked for me for a number of years maybe 10 or 12

 Posted: May 29, 2018 03:49AM
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Onetim: I had doubts/concerns about damage to hoses as a result of clamping. It just seems counter-intuitive to me. Fortunately I did not have to resort to clamping. Since my brakes needed a good flushing spillage was not a loss.

I was able to do a driveway brake test... WHOA!!!  Big improvement - nice firm pedal with better height and the Mini does a bit of a nose-dive compressing the front Smooth a Ride springs.

Thanks for all the guidance and encouragement guys!

.

"Hang on a minute lads....I've got a great idea."

 Posted: May 28, 2018 11:57AM
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Just a word on clamping off rubber brake hoses. We have a OEM brake line group at work, it’s their opinion you should never clamp off rubber brake lines. You will hear a crunching sound if you listen closely, that is the internal braided line snapping. Can lead to one way lines and or lines expanding under pressure, which will push more fluid than they allow to return. Brakes will drag, get hot, pull one direction.

 Posted: May 28, 2018 06:37AM
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Quote:
Originally Posted by malsal
Glad it is sorted Dan.
If the rear hoses were not blocked and as the bleeders were not bleeding what was blocked?
I haven't been able to figure that out.
Hard to blame it on Lucas, Prince of Darkness. Must be some other Mini diety/demon I upset.
I suspect there might have been some sludge in the bleeding orifices in the rear cylinders that eventually yielded. All I know is that it finally bled by gravity and the pedal feels more or less normal. I was too dirty to sit in the car and give it a proper foot test.

.

"Hang on a minute lads....I've got a great idea."

 Posted: May 27, 2018 07:17PM
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Glad it is sorted Dan.
If the rear hoses were not blocked and as the bleeders were not bleedingwhat was blocked?

If in doubt, flat out. Colin Mc Rae MBE 1968-2007.

Give a car more power and it goes faster on the straights,
make a car lighter and it's faster everywhere. Colin Chapman.

 Posted: May 27, 2018 09:17AM
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New rear hoses etc. arrived and were installed yesterday. My body is recovering today...
A few fine points discovered:
 - hose wrench size appears to be 11mm but nuts and hard line fittings seem to be 9/16 even though threads were correct.
 - hard pipes on suspension trailing arms are copper - upper ends released OK but fittings to rear brake cylinders were stuck to copper tubing and risked twisting off (could not separate them).
- keeper nuts for each end of hose are different depth - fitting on copper pipe is deeper than on steel pipe. This was learned the hard way after getting the right-side hose almost completely installed but could not tighten the fitting on the copper pipe. So I got to re-and re- 3 rear pipes!
 - car must be level to get every wheel to bleed: I had the car up on all 4 axle stands to do the front part and to bleed as far as the T- fitting at the rear subframe. When it came to replacing the rear hoses, I took the car down and turned it around to get the rear end close to the work bench. Since I "just needed to change the hoses", I lifted the rear end. I got the hoses fully installed but again was unable to get anything out of the rear bleeders. So, I lifted the front end to replace the broken bleeder while I thought about the problem. Then on each side, I loosened the fitting from the copper pipe to the hose and let fluid drain and observed some small bubbles escaping. That told me I had flow as far as the copper pipes. Back under the car, I tried opening the other ends of the copper pipes but stopped as noted above. In despair, I tried the bleeders once more, giving the brake pedal a few pumps. Lo and behold, when I looked at the bleeders, they were damp! At first, they would barely weep but the flow slowly increased to a proper gravity flow.

I think I have most of the air out but a road test is needed to verify pedal feel and stop-ability. I'll put the insurance on it tomorrow.

Once more thing... the rear hoses were not blocked at all.

.

"Hang on a minute lads....I've got a great idea."

 Posted: May 22, 2018 02:58PM
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I'm pleased and relieved to report that all four connections to the rear hoses loosened without injury to me or any parts. I have placed an order for standard hoses (they will probably outlast me), replacement bleeder for the right front caliper and a new set of rubber pedal pads... they'll certainly make it stop better!
Until the parts arrive, there are yard chores and the boat needs spring cleaning, waxing and polishing for the upcoming sailing season.

.

"Hang on a minute lads....I've got a great idea."

 Posted: May 21, 2018 08:17AM
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Quote:
Originally Posted by dklawson
Good point Malcolm.  

When I got my car as a project the rear hoses had collapsed inside.  They were working like check valves.  You'd come to a stop and the rears would stay "locked" when you went to move again.

FWIW, the braided hoses cost a bit more than stock rubber ones but have been good investments for me.
I like the braided hoses but the only negative i have come up with is the inability to clamp them off when working on the brake system.

Glad you are getting it sorted Dan i have run into collapsed hoses (and broken nipples for that matter) a number of times.

If in doubt, flat out. Colin Mc Rae MBE 1968-2007.

Give a car more power and it goes faster on the straights,
make a car lighter and it's faster everywhere. Colin Chapman.

 Posted: May 21, 2018 04:42AM
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Good one, Mark!

Kinda extra funny considering I had a mastectomy (took away one "fitting") and radiation which took away most of the hair on that side.

.

"Hang on a minute lads....I've got a great idea."

 Posted: May 20, 2018 03:33PM
 Edited:  May 20, 2018 03:34PM
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URL: [img]https://s5.postimg.cc/uzrlzxxzb/Dripping.jpg[/img]

Mark Looman, Ada Michigan 1967 Austin Cooper S
 Posted: May 20, 2018 02:00PM
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Quote:
Originally Posted by malsal
Check the rear flex hoses Dan they collapse internally and if they are blocked just replace all four as the rest if original are not far behind needing replacement.
You called it!
This afternoon I was able to disconnect the long rear line from the limiter valve and get gravity and pedal flow through it.
Next step was to disconnect one of the pipes at the T-fitting at the rear subframe. All three pipes must have been tightened by the same 600 lb gorilla, but one finally gave in and opened up. Good gravity and pedal flow to this point. Even with the joint opened up I was unable to get any flow from either rear adjuster.
Time for new flex hoses.
Side note: brake fluid will attack epoxy floor paint.

.

"Hang on a minute lads....I've got a great idea."

 Posted: May 20, 2018 09:11AM
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Some progress to report, and a small setback.
So far, I've flushed and bled the front system. Both front bleeders opened with little wrench effort and flowed freely, including under gravity alone. I will probably re-flush one I've got the rears flowing. Since the front circuit is short, I decided to try bleeding it first - if it bled OK, I didn't need to crack its joints individually.

On the right-side front caliper, I had trouble keeping a wring wrench firmly seated on the bleeder but it opened OK. Even though my clear-tubing bleed line was securely connected, and the bleeder was barely cracked open, there was some fluid dribbling down the caliper and tire onto the floor. Annoying bit not critical. As I rotated the bleeder, I noticed the bleeding tube seemed to not be in line with the axis of the bleeder, even though I reset it several times. Not being able to get my head in there for a good look, I cap-sealed the master cylinder and removed the bleeder completely. Once I got it out and cleaned, I could see the problem - see photo. Most likely the brakes were last done by a 600 lb gorilla. I put the bleeder back in and tightened it gently - I wouldn't want it to snap off in the caliper.

Time for lunch. This afternoon, I'm having a look at the rear system.

Since this is a long weekend in Canada, I won't be able to go shopping for bleeders until Tuesday.

.

"Hang on a minute lads....I've got a great idea."

 Posted: May 18, 2018 05:11PM
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Good point Malcolm.  

When I got my car as a project the rear hoses had collapsed inside.  They were working like check valves.  You'd come to a stop and the rears would stay "locked" when you went to move again.

FWIW, the braided hoses cost a bit more than stock rubber ones but have been good investments for me.

Doug L.
 Posted: May 18, 2018 06:37AM
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Check the rear flex hoses Dan they collapse internally and if they are blocked just replace all four as the rest if original are not far behind needing replacement.

If in doubt, flat out. Colin Mc Rae MBE 1968-2007.

Give a car more power and it goes faster on the straights,
make a car lighter and it's faster everywhere. Colin Chapman.

 Posted: May 18, 2018 04:53AM
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Dan if you can go borrow an easy bleed. That pump pump crack the valve never works for me. My assistant was either pumping too hard or I was letting air back in the system. The eezibleed puts constant pressure in the system. There's nothing more to do than crack the valves or do one go have lunch come back and finish where you left off. I've been so happy with the first one which I use with the dot 5 in the brakes that I bought a second one for the clutch.

 Posted: May 18, 2018 03:58AM
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Thanks, Doug. That's my plan of attack.

.

"Hang on a minute lads....I've got a great idea."

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