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Rear master cylinder problems spada nt

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danmiluk View Drop Down
Falcone
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    Posted: 15 Jul 2018 at 21:56
My rear brake which are linked to the front are terrible. I've tried bleeding them which has not made any difference pads are fine and the pistons are moving freely when the the calipers are off. I was wondering if the master cylinder could be on the way out. I've had this off a stripped to clean it out, put it back together, there seems to be a lot of movement of the piston before any pressure is building looking for thoughts on this rebuild kit or new m/cylinder

Cheers 
Danny
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 16 Jul 2018 at 10:44
If you mean the pedal movement seems excessive and spongy, it is likely that there might still be some air in the system. They can be difficult to bleed properly.

You are not the first to have this problem, and in some cases it is due to a worn master cylinder.
Brian.

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danmiluk View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote danmiluk Quote  Post ReplyReply Direct Link To This Post Posted: 16 Jul 2018 at 15:27
I going to have another crack at bleeding them does anyone know the correct sequence in which to bleed them?
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theoneandonly View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote theoneandonly Quote  Post ReplyReply Direct Link To This Post Posted: 21 Jul 2018 at 16:04
rubber hoses ? clamp off front , bleed back , then clamp off back bleed front .

have front by h/bar when you bleed . 

redo once more to be sure. 

what brand of pads ? 

new pads will be soft. 
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Mike H View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mike H Quote  Post ReplyReply Direct Link To This Post Posted: 21 Jul 2018 at 20:35
Can we assume it basically works, just long travel of the pedal? Real master cylinder problems tend to make it impossible to get any pressure at all or bleed properly. 

I've probably said this a zillion times but mustn't forget every time caliper pistons are disturbed and especially if new pads put in as well, will take some time with use for them to bed in again until then the pedal / lever will always seem to be soft with too much travel. Don't forget also Spada has a proportioning valve which uses a bit of pedal travel too. 

Also the OEM Brembo pads were never very good, I eventually changed to Ferodo, was quite a revelation how different. Before I was chucking Brembo pads barely half worn yet because they'd "gone off". 

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TonyF View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote TonyF Quote  Post ReplyReply Direct Link To This Post Posted: 24 Jul 2018 at 10:18
Hi

It can be difficult to get all the air out of the lines for the linked brake. Have you tried using a vacuum bleeder? Start with the bleed valve on the proportioning valve. 

Is the piston in the proportioning valve moving freely?


Tony
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danmiluk View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote danmiluk Quote  Post ReplyReply Direct Link To This Post Posted: 20 Aug 2018 at 18:09
Vacuum bleed kit did the job although didn't realise how little brake fluid is used in the rear braking system. Thanks for all your advice. 
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