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Lack of Brake pedal pressure


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Hi, I am at the end of my patience with this RHD Tii.

Tried to take it for a test drive tonight and still no brakes, no pressure on the pedal.

I've replaced;

Servo's (x2 RHD UK) refurbished by Past Parts and tested.

Service kit and renovated Brake Master Cylinder.

Brand new Tii rear wheel cylinders.

Brand new Turbo Front Callipers (Wallothnesch.com)

Brand new Flexible Brake hoses.

I have a pressure bleeder and pumped it to 1 Bar, then started with Servo's, then rear brakes and finally front callipers. I repeated the exercise, everything looks good and no leaks. But still virtually no pressure on the pedal.

I've had enough now and losing my patience. Sensible suggestions - anyone?

Chairman of the 02 Register BMW Car Club (GB) Ltd.

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try a "NEW" master cylinder

and sorry for the stupid questions:

the brake pedal goes to the floor?

did it do the same thing BEFORE your

list of repairs?

'86 R65 650cc #6128390 22,000m
'64 R27 250cc #383851 18,000m
'11 FORD Transit #T058971 28,000m "Truckette"
'13 500 ABARTH #DT600282 6,666m "TAZIO"

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My bet is on the master....... I agree with CD. Get a new one!

Bob

3410619 - 74 1802 Verona Touring

3460120 - 74 Verona Touring....... (Sold) sent off to LA.

2760306 - Ultimate driving machine Skidmark 204 car. 72 Inka (Sold)

Formerly the old and slow division of Skidmark Racing. 

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yeah, you might try loosening the lines into the servos (from the masters)

and bleed them until you get good flow. It's messier than hell, but

sometimes a master gets really stubborn about airlocking.

And sometimes they're just bad.

Is there a procedure for bleeding and testing those hydro servos?

I know we had a wretched time getting a friend's E- type to start

bleeding. Once we got fluid everywhere it was supposed to go, then

it started to obey logic. But it took FOREVER to get that system to

start behaving.

Again, loosening lines, while really messy, is also pretty effective.

Good luck- those things are a bear.

t

"I learn best through painful, expensive experience, so I feel like I've gotten my money's worth." MattL

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I had the same problem when I reworked my brake system, no pedal pressure. My problem was I bolted the front calipers on the wrong sides making the bleed nipples pointing down. Trapping air in the calipers.

11 year work in progress

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Ok RHD are a pain in the arse to bleed .The 2 vac units are some of the problem and the way it is all connected is interesting to say the least but...I would go for a new master as I have not had a lot of success with rebuild kits both in brake and clutch masters, I usually go 20 psi on my bleeder , crack the metal lines on the M/C and yes crack the lines to the vac units until clean flow then crack rear metal lines till clean flow. Then crack the front metal lines. Now back to the start and do the bleed nipples.Then do them again. It always seems to be like this for some reason.See how you go.

72/2002 Inca

72tii/2002 "Apple"

70/2002 "Five "

73/2002 "Freeda"

2007 Lotus 7 Replica

2011 Ford xr6 Ute

85 E30 325

70 1600-2 "Orange"

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Tim is familiar with the RHD systems and I am not, but on LHD systems i don't put that much pressure in the system when bleeding...15psi max. have seen the clutch master fill line blow out of the clutch master as it is not designed for the pressure...especially if it is old. I use 10-15psi to prevent air from coming into the system and pump the pedal to move the fluid.

just a thought. ymmv.

3xM3

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Silly question but are the drums assembled and adjusted properly?

Did you hone the MC bore before installing the new seals? Any visible marks?

Did you reassemble the MC properly? Every thing the right way around?

Do you get any brake action if you pump quickly or is it literally straight to the floor with no resistance?

rtheriaque wrote:

Carbs: They're necessary and barely controlled fuel leaks that sometimes match the air passing through them.

My build blog:http://www.bmw2002faq.com/blog/163-simeons-blog/

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Hi tried again tonight and still useless, however when pumping the pedal now I do get pressure for a short period.

The MC was supposed to have been refurbished as you can't get RHD ones anymore.

I bleed servos, then rear wheel cylinders, then fronts (as Haynes manual).

I even snapped a bleed nipple on the rear, but luckily I had a spare one so had to replace that.

I pressured to 1 bar as any higher the fluid pours out the cap on the reservoir.

I might try that MC cracking pipes at weekend.

Chairman of the 02 Register BMW Car Club (GB) Ltd.

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Hi tried again tonight and still useless, however when pumping the pedal now I do get pressure for a short period.

The MC was supposed to have been refurbished as you can't get RHD ones anymore.

I bleed servos, then rear wheel cylinders, then fronts (as Haynes manual).

I even snapped a bleed nipple on the rear, but luckily I had a spare one so had to replace that.

I pressured to 1 bar as any higher the fluid pours out the cap on the reservoir.

I might try that MC cracking pipes at weekend.

Chairman of the 02 Register BMW Car Club (GB) Ltd.

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if you start the motor,

and place your foot on the brake pedal

with moderate pressure,

does the pedal slowly fall to the floor after 5 - 10 - 15 sec. of pressure?

or does the pedal just hold and not fall - and just feel soft ?

if it 'holds position' and not fall to the floor then there's hope.

continue to bleed at 1bar(14psi) and keep going around all bleeders,

and quickly crack open then close

the pipes attached directly to the master cylinder - then all others

till your pedal returns to a up firm pedal.

IF YOUR REAR SHOES are not adjusted correctly,

and if you have NEW brake pads with OLD front disks,

you will never get a firm high brake pedal.

keep at it ...........

'86 R65 650cc #6128390 22,000m
'64 R27 250cc #383851 18,000m
'11 FORD Transit #T058971 28,000m "Truckette"
'13 500 ABARTH #DT600282 6,666m "TAZIO"

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Here is a picture of my pressure brake bleeder, just hook up the compressor , adjust the pressure on the regulator, I dont touch the pedal at all when I bleed the brakes. The air pressure seems to do it fine .BMW E12 master also works, slightly bigger piston size but more avail than 02 ones and is a direct fit.See how you go after cracking the MC steel lines , you should fairly quickly get clean fluid with no bubbles.

post-325-13667669886193_thumb.jpg

72/2002 Inca

72tii/2002 "Apple"

70/2002 "Five "

73/2002 "Freeda"

2007 Lotus 7 Replica

2011 Ford xr6 Ute

85 E30 325

70 1600-2 "Orange"

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I went round 10 times and was still getting air out all the brakes. I cracked the pipes on the MS first, then bled servos. I ran out of fluid. Started again today and still air coming out the callipers. If you pump the pedal several times it goes nice and hard. If I keep my foot on it it stays up and hard. But as soon as I remove my foot and press the pedal again it goes to the floor.

Front callipers are up the right way and the master cylinder was supposed to have been rebuild (by this cowboy). So I suspect I'll have to go down this route again. But waiting for a second opinion next week.

Chairman of the 02 Register BMW Car Club (GB) Ltd.

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