1982 900ss - Brembo PS15 Bubbles!

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robax
Cucciolo - the Lil Pup
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1982 900ss - Brembo PS15 Bubbles!

Post by robax » Mon Jul 06, 2015 11:39 pm

Hi all

My bike was restored over several years and then sat for 5 years after it was largely completed. As part of readying it for some road use, I have flushed fresh brake fluid through and bled the brakes front and rear.

Front worked fine, but the rear is a bit off. There is no air going through the system, but bubbles come up in the reservoir no matter what I do. They are coming out of the bottom of the two intakes in the cup. It's only a few tiny ones, but I can make it happen over and over again, no matter how much fluid is put through and no matter how I do the bleeding.

I'm aware that fluid can absorb water over time and I'm thinking this might have caused damage in the barrel.. perhaps the seal is not tight. During the initial flush and bleed, plenty of what I assume was assembly grease came up through the reservoir (showing as a cloudiness in the fluid). I flushed until it cleared and so now I've just got this bubble issue.

Has anyone had similar experience? Pics and video below.

This is the part
http://1drv.ms/1J1Tgox

These are the bubbles
http://1drv.ms/1J1Thcc

And here's me showing it happening on video
https://www.youtube.com/watch?v=LcgZrQIuMPw
Rob - NZ
-------------------------------------------------
1982 Ducati 900ss

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geodoc
750 GT
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Re: 1982 900ss - Brembo PS15 Bubbles!

Post by geodoc » Tue Jul 07, 2015 8:19 am

Something that might be worth a try - I've had a few bikes that were hell to get thoroughly bled no matter how much fluid was pumped through the system. A Ducati mechanic friend suggested a simple trick that has almost always worked.

With the reservoir cap off, use tie-wraps (in the case of the front brake) or by what ever means you can rig up to secure the lever / pedal at its furthest "brake applied" point. Just leave it in that position over night and it seems that the system will tend to self-bleed.

Caveat: I've only used this method on front brakes where the M/C is at the top of the system, but amazingly it always seems to work.

Easy to try and who knows?

GD

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BevHevSteve
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Re: 1982 900ss - Brembo PS15 Bubbles!

Post by BevHevSteve » Tue Jul 07, 2015 8:38 am

1: take caliper off hanger and sit on something lower down, put a piece of wood or alloy whatever between pads (so they stay apart like a rotor was in there) and set caliper so the hose never goes up then back down to the MC.
2: try it now
*************************
you might not have the piston in the MC installed all the way/correctly.

If the crush washer is not pressed down far enough, you will have problems like you describe.

Order of bits:
black rubber bumper>spring>piston>flat washer>seal>crush washer See image below.

Image
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Steve Allen (925)798-BEVL[2385] Ride'm, Don't Hide'm
Ducati/Euro Spares -> https://Store.BevelHeaven.com
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robax
Cucciolo - the Lil Pup
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Joined: Mon Jul 06, 2015 3:50 am

Re: 1982 900ss - Brembo PS15 Bubbles!

Post by robax » Tue Jul 07, 2015 8:06 pm

Thanks for the replies guys. Yes, I did the one where you leave it tied down over night as well. There's just no air in the pipe going to the calliper.

Looking at those parts and at an exploded diagram I've just found, I'm pretty convinced the entry point is there on the right of the piston where that seal sits between the washers. That's the only place where it could come in and get into the reservoir without going through to the calliper. It could be faulty seals, faulty assembly or even internal corrosion causing a bad seal.

Does that piston assembly just come right out or is that some sort of press fit that I might not be able to do without special tools?

And Steve, is that kit the exact one necessary for the 82 900ss - I think yes?
https://store.bevelheaven.com/Brake-Rel ... -rear-MCs/

I'd rather buy a rebuild kit in advance rather than pull it all to bits and then find I need it.
Regards
Rob
Rob - NZ
-------------------------------------------------
1982 Ducati 900ss

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BevHevSteve
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Re: 1982 900ss - Brembo PS15 Bubbles!

Post by BevHevSteve » Tue Jul 07, 2015 8:36 pm

Hi Rob, that is the right kit for your rear and for your front master cylinder.

Removal: lever off, banjo bolt out, insert long adrift into banjo hole and pound it out

Installation: use tool to seat the expando washer to hold everything in place.

You can buy the installtool when you buy the kit, choose "Kit & install tool" from the drop down when you place your order.

If the expando ring is not fully seated you will see bubbles etc

Also, in my "install guides" section I have a downloadable "how too" article fully explaining in detail this process.
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Steve Allen (925)798-BEVL[2385] Ride'm, Don't Hide'm
Ducati/Euro Spares -> https://Store.BevelHeaven.com
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