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Brake Headaches


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#1 Ratty89

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Posted 21 January 2018 - 03:26 PM

i have an '83 mini Mayfair, It was sat for quite some years before I acquired it, so I've replaced all brake cylinders, flexible hoses (now braided) and any suspect hard lines.

I bled the system, and the pedal will pump hard, but if I lift off for a few seconds, the pedal will go right to the floor. I suspected it was a master cylinder issue, so I replaced this. And the issue is still there.

One thing that strikes me as odd is that when the pedal goes to the floor, when I lift, there is a noise from in the engine bay, that sounds like a spring moving.

Could this be the proportioning valve moving? Does it normally make a noise?

Cheers

#2 nicklouse

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Posted 21 January 2018 - 04:30 PM

sounds like you still have air in the system.

 

yes there is a spring in it as it allows the piston to return to normal position after it has closed of the failed side.

 

remember pedal bleeding needs to be done with a very slow and steady motion.

 

i always found just opening up a bleed nipple at a time and letting gravity do it job was the best way after replacing any pipes.



#3 absx2

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Posted 21 January 2018 - 05:29 PM

Did you replace the master cylinder with a brand new item as the corrosion will be bad on even the shiniest used brake part. 

If the slow and steady bleed operation that nicklouse has suggested still leaves you with the issue turn your attention to the brake limiter valve.  

Those lovely valves on the bulkhead do not like to sit around unused so my bet is that it has failed. You can test the theory by removing it and fitting two METRIC sleeve nut connectors to temporarily bypass the valve before coughing up another £80 for a new one.

 

Don`t drive the car on the road without a limiter valve.  


Edited by absx2, 21 January 2018 - 05:30 PM.


#4 Ratty89

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Posted 21 January 2018 - 06:22 PM

Thanks for your replies,
It is a brand new yellow tag MC from minispares, I bled it before fitting too.

I've tried bleeding slowly, and with an ezbleed kit.

By the sounds of it, it may be the proportioning valve.
Makes sense, it's the only bit that isn't new.

#5 richmondclassicsnorthwales

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Posted 26 January 2018 - 08:15 PM

The PDWA valves are a nightmare, can't service or repair them, never know if they work either, **** design



#6 Spider

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Posted 26 January 2018 - 08:47 PM

The PDWA valves are a nightmare, can't service or repair them, never know if they work either, **** design

 

I agree they are not much good and that's always one of the first thing to go from my cars. I usually fit up the Inertia Valve, but even the older Pressure shut off valve is better.

 

The new type (4 / 5 port) Pressure shut off valves can be overhauled and I have done them, but they are still little more than junk.



#7 Sprocket

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Posted 26 January 2018 - 10:52 PM

The PDWA valves are a nightmare, can't service or repair them, never know if they work either, **** design

On an 83 plate, It's not a Pressure Differential Warning Aactuator. It's a brake limiter valve. A very different animal to the 'PDWA'.

It could well be a combination of air and incorrect adjustment of the rear brake shoes



#8 richmondclassicsnorthwales

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Posted 27 January 2018 - 10:37 AM

Still Crap



#9 cal844

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Posted 29 January 2018 - 10:40 AM

Nipples on the calipers at the top?

If they are I'd suggest to start rebleeding 😊

#10 Ratty89

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Posted 04 March 2018 - 04:28 PM

Ok, so I've replaced the magic limiter valve, bled the brakes quite thoroughly, and still no luck... 😭

The current thoughts are:
Seals on the front slaves are dry and not allowing the Pistons to move correctly/pulling the Piston back

Still a bubble in the system somewhere, maybe need to get the rear of the car in the air to see if it will encourage it to come out.

I'll give this a shot when I'm less cold and irritated 😔

#11 cian

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Posted 04 March 2018 - 04:41 PM

Did you adjust the front shoes correctly?

#12 cal844

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Posted 04 March 2018 - 06:20 PM

Ok, so I've replaced the magic limiter valve, bled the brakes quite thoroughly, and still no luck... 😭

The current thoughts are:
Seals on the front slaves are dry and not allowing the Pistons to move correctly/pulling the Piston back

Still a bubble in the system somewhere, maybe need to get the rear of the car in the air to see if it will encourage it to come out.

I'll give this a shot when I'm less cold and irritated 😔


You now want to crack each union and get fluid out of each, tighten up then move to the next

#13 Steve220

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Posted 04 March 2018 - 06:59 PM

Ok, so I've replaced the magic limiter valve, bled the brakes quite thoroughly, and still no luck...

The current thoughts are:
Seals on the front slaves are dry and not allowing the Pistons to move correctly/pulling the Piston back

Still a bubble in the system somewhere, maybe need to get the rear of the car in the air to see if it will encourage it to come out.

I'll give this a shot when I'm less cold and irritated

 

Definitely bleeding in the correct order?






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