Author Topic: Spongy Rear Brake  (Read 1960 times)

Offline HONK

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Spongy Rear Brake
« on: November 05, 2015, 04:50:07 PM »
Well circumstances and changing responsibilities have decided for me that its time to part with the mighty 1300.
But I cant honestly hand it on to anyone else with an erratically spongy brake pedal. if I bleed the system the pedal feel will be ok for anything from a few months to a couple of days. Strange thing is if the front brake is activate the pedal is rock hard.
Does anyone have a clue as to the probable cause.my friends think my cologne is DOT4 I have used so much of the stuff.
I have used a vacuum kit in the correct order and also the one man bleeding aid that supercheep sell.
I have put new seels in the rear calliper and fitted a new master cylinder.
Could the problem be in the secondary master cylinder?
Cheers
Honk     
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Offline alans1100

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Re: Spongy Rear Brake
« Reply #1 on: November 05, 2015, 06:20:32 PM »
Not sure about the 1300 CBS system as it's a little different to the 1100 version.


The pressure control valve (PCV) needs bleeding where the 1100A doesn't and the secondary master needs to be in certain position when bleeding. It doesn't say in the manual to remount the LH front Calliper after bleeding the PCV but I would think that you need to before doing the rest of the bleeding.

1300 secondary master position when bleeding the PCV and I would suggest placing something in the calliper prevent the pistons from working.







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Offline HONK

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Re: Spongy Rear Brake
« Reply #2 on: November 05, 2015, 07:41:37 PM »
Done this so many times that I have a dedicated piece of pink string to tie up the front left calliper that is kept wrapped around the slab of plastic that I use to chock between the brake pads.
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Offline Gadget

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Re: Spongy Rear Brake
« Reply #3 on: November 05, 2015, 08:05:17 PM »
Have you put new seals in the front as well?
The combined braking system means some pressure is applied to the front cylinders. Maybe it is leaking air back in through the front seals.
Cheers,
Gary
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Offline tding

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Re: Spongy Rear Brake
« Reply #4 on: November 06, 2015, 07:34:49 AM »
check the secondary master cylinder
 

Offline HONK

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Re: Spongy Rear Brake
« Reply #5 on: November 06, 2015, 07:47:23 AM »
New SMC kit and calliper seals ordered so watch this space for next installment.
Better get some more Dot4.Does anyone have a use for 1 litre brake fluid tins I seem to have about 5 empties in the shed.
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Offline HONK

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Re: Spongy Rear Brake
« Reply #6 on: December 08, 2015, 08:59:32 PM »
New SMC Kit installed and all bleed points bled and bled some more. result=we have a win.
also found this thing/valve that doesn't get a mention in the manual or any parts list.
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Online Shiney

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Re: Spongy Rear Brake
« Reply #7 on: December 08, 2015, 09:50:13 PM »
Awesome news Honk :clap :clap :clap :thumbsup
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Offline Gadget

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Re: Spongy Rear Brake
« Reply #8 on: December 08, 2015, 10:14:37 PM »
Great news!
Cheers,
Gary
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Offline alans1100

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Re: Spongy Rear Brake
« Reply #9 on: December 08, 2015, 11:51:51 PM »
New SMC Kit installed and all bleed points bled and bled some more. result=we have a win.
also found this thing/valve that doesn't get a mention in the manual or any parts list.
Where on the bike is it located?
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Offline HONK

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Re: Spongy Rear Brake
« Reply #10 on: December 09, 2015, 06:03:49 AM »
Its on the inlet side of the SMC
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Offline Brian

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Re: Spongy Rear Brake
« Reply #11 on: December 09, 2015, 09:06:01 AM »
and now it goes on the market?
I jus wanna ride my bike

09 ST1300 Charcoal Metallic (Grey GhoST)
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Offline HONK

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Re: Spongy Rear Brake
« Reply #12 on: December 09, 2015, 09:38:03 AM »
Sadly yes
Couldn't load photos last night only 350 kb each so try again later.
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