Physics of brake bleeding


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bohdan
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Physics of brake bleeding

Post by bohdan »



Gents, it seems like most of the time of brake bleeding, I get bubbles. Apparently, air goes past the threads of the bleeder valve. Let’s assume that is the only reason for the bubbles. If that was the case, would it be safe to assume that maybe I got air out of the system.? Cheers
.


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Re: Physics of brake bleeding

Post by dingdong »

You must be using a vacuum bleeder. Don't assume. Finish the bleeding process by hand pumping the brakes. No air to get past the threads. If you still have bubbles then you still have air in the lines.
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Swagonmaster
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Re: Physics of brake bleeding

Post by Swagonmaster »

The proof of the bleeding will be a firm pedal and front brake lever, if you have those then you have done the deed.
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Re: Physics of brake bleeding

Post by Snowmoer »

I get air bubbles from around the threads all the time when using a vac. Just make sure you tighten up the valve while you are still applying vacuum and you will be fine. My brakes are always firm after bleeding.
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Re: Physics of brake bleeding

Post by DenverWinger »

Unthread the bleeder valve and put a little grease around the threads, then thread it back in. This will help to stop pulling air thru the bleeder threads when using a vacuum bleeder.
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Swagonmaster
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Re: Physics of brake bleeding

Post by Swagonmaster »

The grease on the bleeder threads definately works but just be sure the grease that you use is silicone based so it won't have any possibility of contaminating the brake fluid and damaging the seals. Very low likelyhood of that happening but I don't recommend risking it.
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Re: Physics of brake bleeding

Post by vladimirch »

Hello,
I use Speed Bleeders on my 2nd Gold Wing. Break bleeding is for me easy and fast job now. Brakes are under pressure all the time and all visible air bubbles are 100% from brake fluid. You can select right type here - http://www.speedbleeder.com
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Re: Physics of brake bleeding

Post by Polkat53 »

Picked up a pneumatic brake bleeder, off Amazon. Makes bleeding my brakes a breeze. Your air compressor has to have 90 to 100 psi capabilities.
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Swagonmaster
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Re: Physics of brake bleeding

Post by Swagonmaster »

This type of bleeder isn't the cheepest and you do need the correct adaptor for your reservoir but it only needs 20psi that is hand pumped.

https://www.ebay.com/itm/Motive-Product ... ect=mobile
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Re: Physics of brake bleeding

Post by WingVetteGSXR »

Swagonmaster wrote: Wed Sep 01, 2021 9:58 am This type of bleeder isn't the cheepest and you do need the correct adaptor for your reservoir but it only needs 20psi that is hand pumped.

https://www.ebay.com/itm/Motive-Product ... ect=mobile
Where do you get the reservoir attachments for this pressure bleeder? I have the exact same one that I use for my Corvette, but would like reservoir attachments for my two bikes. Motive doesn't make reservoir attachments for all vehicles.
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Re: Physics of brake bleeding

Post by WingVetteGSXR »

DenverWinger wrote: Sat Aug 07, 2021 9:23 am Unthread the bleeder valve and put a little grease around the threads, then thread it back in. This will help to stop pulling air thru the bleeder threads when using a vacuum bleeder.
Teflon tape works well. Just be sure you wrap it around the threads in the correct direction. (So it doesn't start to unwrap when you tighten the bleeder. I use this method on my speed bleeders also.
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Re: Physics of brake bleeding

Post by Swagonmaster »

WingVetteGSXR wrote: Fri Sep 03, 2021 9:58 am
Swagonmaster wrote: Wed Sep 01, 2021 9:58 am This type of bleeder isn't the cheepest and you do need the correct adaptor for your reservoir but it only needs 20psi that is hand pumped.

https://www.ebay.com/itm/Motive-Product ... ect=mobile
Where do you get the reservoir attachments for this pressure bleeder? I have the exact same one that I use for my Corvette, but would like reservoir attachments for my two bikes. Motive doesn't make reservoir attachments for all vehicles.
One way would be to find a automobile that takes the same cap as the bike so you know what to order otherwise a universal cap would work if there is room for it. I'm afraid I am used to buying pro version caps since I worked in shops for 40 some years and some cost as much as this bleeder itself but this plastic stuff seems to work ok, especially if you don't use it every day.
One example of a universal cap type:
https://www.ebay.com/itm/402783017410
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Re: Physics of brake bleeding

Post by WingVetteGSXR »


One way would be to find a automobile that takes the same cap as the bike so you know what to order otherwise a universal cap would work if there is room for it. I'm afraid I am used to buying pro version caps since I worked in shops for 40 some years and some cost as much as this bleeder itself but this plastic stuff seems to work ok, especially if you don't use it every day.
One example of a universal cap type:
https://www.ebay.com/itm/402783017410
Wonder if this would work for a round Nissin reservoir?

https://www.motiveproducts.com/collecti ... -universal
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Re: Physics of brake bleeding

Post by Swagonmaster »

Quite possibly or you could do this:
https://www.toolsource.com/shopping_cart.html
See what I mean about price? Honestly I think a search of ebay or amazon would come up with the correct inexpensive adaptor for a car whereas it might be hard to specify a cap for a bike without having one to compare.
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Re: Physics of brake bleeding

Post by WingVetteGSXR »

Swagonmaster wrote: Fri Sep 03, 2021 6:34 pm Quite possibly or you could do this:
https://www.toolsource.com/shopping_cart.html
See what I mean about price? Honestly I think a search of ebay or amazon would come up with the correct inexpensive adaptor for a car whereas it might be hard to specify a cap for a bike without having one to compare.
Not sure what product on the page that your link takes me to you're referring to?
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Re: Physics of brake bleeding

Post by Swagonmaster »

For some reason these folks don't put prices on the adaptors, you have to put it in your cart to see a price but look at the Nissan adaptor listed.
https://www.toolsource.com/index.php?ma ... %20adapter
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Re: Physics of brake bleeding

Post by Solo So Long »

WingVetteGSXR wrote: Fri Sep 03, 2021 9:58 am Where do you get the reservoir attachments for this pressure bleeder? I have the exact same one that I use for my Corvette, but would like reservoir attachments for my two bikes. Motive doesn't make reservoir attachments for all vehicles.
Get another reservoir cap, drill a hole and attach the appropriate fitting.
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Re: Physics of brake bleeding

Post by Swagonmaster »

I have done the "hole in the stock cap" on two of mine, it is rather hard to make the fitting seal up under the pressure of the brake fluid but it does work.
Try to learn from the mistakes of others..... you won't live long enough to make them all yourself!
Solo So Long
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Kawasaki KZ900-PS (1977)
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Re: Physics of brake bleeding

Post by Solo So Long »

Swagonmaster wrote: Sun Sep 05, 2021 5:53 am I have done the "hole in the stock cap" on two of mine, it is rather hard to make the fitting seal up under the pressure of the brake fluid but it does work.
You don't need a lot of pressure. I've always been able to make a new gasket when I needed to.


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