Air in Right Hand front brake


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agedbikeman
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Motorcycle: 1995 GL1500 Aspencade with bolt on trike kit, made by Kit Trike Portugal.
2014 Can-Am Spyder RT(sold, glad to see the back of it)

Air in Right Hand front brake

Post by agedbikeman »



Hello
Anyone got ideas, I rebuilt both front calipers, new seals, pistons, everything, washed out calipers in my parts cleaner tank and dried thoroughly, then rinced with brake cleaner.

Left hand one perfect, but the right hand one seems to have air that won't go, I started with a vacuum bleeder, 'til no more bubbles, still a bit spongy, then went back to the old way, got a few more bubbles. Tied lever to handlebar overnight, bingo next morning lever solid, following day, spongy again. I can pump 3 or 4 time and it's harder, leave a few hours or overnight it's spongy again

Tie the lever down, next day ok, few hours later, spongy again, never had this problem before.

before I rebuilt caliper it was alway correct, but the pistons were stiff and wearing break pads unevenly.
After rebuild, this problem but only the right caliper, left is ok.

Any input appreciated
Alex


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ct1500
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Re: Air in Right Hand front brake

Post by ct1500 »

Air can be trapped in the master unless handlebars are turned fully left for hand brake bleeding. Try bleeding again with cover off looking for air bubbles in reservoir.
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offcenter
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Re: Air in Right Hand front brake

Post by offcenter »

Could it be that you have a porous casting or line?
A friend had that problem with an airplane he owned. Constant air in the brakes. Turned out to be a porous casting on the wheel cylinder.
George in Jersey.
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rider1939
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Re: Air in Right Hand front brake

Post by rider1939 »

What you are be doing is forcing the air into the fluid, this is normal when under pressure. Then when you release the lever the air slowly exits the fluid (degases).

What one needs to do is when you release the lever, bleed out the "old" oil and flush with fresh oil.

In deep ocean dive instruments (1000+ meters) the pressure does just that, forces any air into the oil, and when the instrument returns to the surface it degases and causes all sorts of issues, so the oil has to be degassed under very heavy vacuum prior to launching.

Hope this helps.
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agedbikeman
Posts: 270
Joined: Tue Jun 18, 2019 3:41 pm
Location: Bruay la Buissiere, France
Motorcycle: 1995 GL1500 Aspencade with bolt on trike kit, made by Kit Trike Portugal.
2014 Can-Am Spyder RT(sold, glad to see the back of it)

Re: Air in Right Hand front brake

Post by agedbikeman »

Thanks for yor reply, the fluid is only weeks old as I completely drained and flushed new fluid through, but am I to understand that air is trapped within the new fluid in the system.

The brakes worked perfectly before I rebuilt the caliper, I only rebuilt it because when changing the pads, the pistons were sticking.

I bled them manually again last night, did not see any air bubbles, but there is some improvement , I have ordered a new master cylinder kit which will be done next week, so I will be flushing all new fluid through again starting from a new sealed bottle of fluid.

Alex


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