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matthew henricks
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Joined: January 02, 2002
Posts: 1219
Location: So. Cal
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 Posted: Mon Mar 18, 2019 5:38 pm Post subject: How many pumps? brakes |
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65 bus. New AC front disc kit. Stock rear brakes.
How many pumps of the peddle should it take to bleed the rear cylinders???
Background. Bus has sat for 3 years. Replaced MC back then with a 67 only unit but never finished. Now installed the MC with the disc kit. Have tried to bleed both rears now with well ever 100 pumps each and nothing. Not even a drop.
Both fronts bleed in about 10 pumps.
Whats wrong here as it seems the rear is not getting any pressure.
peddle has about 1mm clearance at full retract. |
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sub-hatchtim
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Joined: September 19, 2006
Posts: 2610
Location: Phoenix AZ
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| Posted: Mon Mar 18, 2019 6:11 pm Post subject: Re: How many pumps? brakes |
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How old are your rubber lines?
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busdaddy
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Location: Surrey B.C. Canada, but thinking of Ukraine
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| Posted: Mon Mar 18, 2019 6:26 pm Post subject: Re: How many pumps? brakes |
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Single circuit master cylinder?, or double?
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Bruce Amacker
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Joined: December 26, 2007
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aa390392
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Joined: March 28, 2007
Posts: 3602
Location: So.Cal
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| Posted: Mon Mar 18, 2019 8:20 pm Post subject: Re: How many pumps? brakes |
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?? Check valve?? Where is the check valve?
Finger bleed? Explain finger bleed..
These are all terms im not familiar with.
Thank
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matthew henricks
Samba Member
Joined: January 02, 2002
Posts: 1219
Location: So. Cal
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| Posted: Mon Mar 18, 2019 9:09 pm Post subject: Re: How many pumps? brakes |
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- New SS lines up front.
- Rubber lines in rear are old. Probably 5 years plus.
- Dual Circuit MC. Front brakes connected at end. Rear on side opposite the brake switch.
Will check the Check valve. Thanks |
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dms
Fred G. Sanford
Joined: August 05, 2007
Posts: 493
Location: At large. . .
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| Posted: Mon Mar 18, 2019 9:20 pm Post subject: Re: How many pumps? brakes |
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If the master cylinder has air lock and has not been bench bled and was empty new or has sat empty you could be pumping the air lock back and forth for a long time. If you have a short section of brake line, feed it around so that free end will be submerged in the fluid in the resevoir and pump it till it flows free without any air bubbles then unscrew it and screw the actual lines on.
Sometimes you can pump the pedel really fast and the airlock will backup through the resevoir.
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sub-hatchtim
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Joined: September 19, 2006
Posts: 2610
Location: Phoenix AZ
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| Posted: Mon Mar 18, 2019 11:09 pm Post subject: Re: How many pumps? brakes |
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The rear hoses could have swelled up so you may be getting little to no flow
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ToolBox
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Joined: January 27, 2004
Posts: 3439
Location: Detroit, where they don't jack parts off my ride in the parking lot of the 7-11
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| Posted: Tue Mar 19, 2019 9:48 am Post subject: Re: How many pumps? brakes |
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| If it has been sitting for 5 years with no fluid in it the master may be toast, the rubber will dry rot. |
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matthew henricks
Samba Member
Joined: January 02, 2002
Posts: 1219
Location: So. Cal
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| Posted: Tue Mar 19, 2019 10:11 am Post subject: Re: How many pumps? brakes |
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| ToolBox wrote: |
| If it has been sitting for 5 years with no fluid in it the master may be toast, the rubber will dry rot. |
Regarding the MC i replaced the one that had been sitting.
| sub-hatchtim wrote: |
| The rear hoses could have swelled up so you may be getting little to no flow. |
Quite possible. I will likely replace them while i am at it.
First i am going to check the new MC valve and get fluid through that area. |
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Eric&Barb
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Joined: September 19, 2004
Posts: 24764
Location: Olympia Wash Rinse & Repeat
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| Posted: Tue Mar 19, 2019 10:47 am Post subject: Re: How many pumps? brakes |
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| busdaddy wrote: |
| Single circuit master cylinder?, or double? |
Guessing dual circuit, but would be good to know for sure.
If dual, has the OP bled the front first, before the rears???
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matthew henricks
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Joined: January 02, 2002
Posts: 1219
Location: So. Cal
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| Posted: Tue Mar 19, 2019 11:45 am Post subject: Re: How many pumps? brakes |
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Dual.
I did bleed both fronts after the rears initially did nothing and was able to get fluid in about 5 pumps. I then went back to the rears and still nothing. |
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Bruce Amacker
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matthew henricks
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Joined: January 02, 2002
Posts: 1219
Location: So. Cal
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| Posted: Tue Mar 19, 2019 5:21 pm Post subject: Re: How many pumps? brakes |
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| yes. I did install the AC MC. dual circuit. I will test your solution. May find time tomorrow night to try it out. |
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Eric&Barb
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Joined: September 19, 2004
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Location: Olympia Wash Rinse & Repeat
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| Posted: Tue Mar 19, 2019 9:12 pm Post subject: Re: How many pumps? brakes |
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You have to get the fronts bled first.
Have you fully locked up the rear shoes with the brake adjusting stars??
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matthew henricks
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Joined: January 02, 2002
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Location: So. Cal
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| Posted: Tue Mar 19, 2019 9:51 pm Post subject: Re: How many pumps? brakes |
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Forgive my ignorance. Why the fronts first? Everything i have every heard including the AC directions say farthest from the MC to closest. What is different about this set up that you do the front first?
Thank you. |
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Eric&Barb
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Joined: September 19, 2004
Posts: 24764
Location: Olympia Wash Rinse & Repeat
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| Posted: Wed Mar 20, 2019 9:39 am Post subject: Re: How many pumps? brakes |
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| matthew henricks wrote: |
Forgive my ignorance. Why the fronts first? Everything i have every heard including the AC directions say farthest from the MC to closest. What is different about this set up that you do the front first?
Thank you. |
Which AC manuals that are dual MC specific are you seeing that in, please??
A dual MC is split up into two MCs in one. The circuit closest to the brake pedal rod is for the front brakes. So when you push down on the pedal the fronts are worked first. So if you try to pump up the rears first you are doing so thru the front circuit that is full of air. This is kind of like putting a very fluffy pillow over the brake pedal in a beetle that takes up the entire front seat area and you have to sit back in the rear seat to bleed the system. So you waste much of each stroke pressing the pedal squeezing pillow instead. Also of the two circuits in the dual MC the front circuit has less volume in the brake lines, so less air to bleed out from it.
From the hard to find Volkswagen Service Manual VW 1300 1500.
"Bentley 1966-69 type 1 "Volkswagen Official Service Manual".
Page 32, section 11.8
"Bentley 1970-79 type 1 "Volkswagen Official Service Manual"
Page 27, section 8.3
"Bentley 1970-79 type 1 "Volkswagen Official Service Manual"
Page 26, section 8.3
Same info in the original VW dealer workshop manuals:
1. Type 3 printed in 1961. Guess which model of VW got dual MC first...
2. Type 2 1963-67, in the dual MC 1967 section.
Another thread that is a must read on this:
https://www.thesamba.com/vw/forum/viewtopic.php?t=242594&highlight=type
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turbotype1
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| Posted: Wed Mar 20, 2019 10:13 am Post subject: Re: How many pumps? brakes |
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If it was a singe circuit MC than you would bleed them furthest first...
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matthew henricks
Samba Member
Joined: January 02, 2002
Posts: 1219
Location: So. Cal
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| Posted: Wed Mar 20, 2019 10:27 am Post subject: Re: How many pumps? brakes |
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Thank you. I learned something today.
I will re-check my instructions tonight. Maybe i misunderstood and maybe I was too quick to read but it what you posted sure makes sense.
Thanks. |
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Eric&Barb
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Joined: September 19, 2004
Posts: 24764
Location: Olympia Wash Rinse & Repeat
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| Posted: Wed Mar 20, 2019 10:49 am Post subject: Re: How many pumps? brakes |
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| matthew henricks wrote: |
Thank you. I learned something today.
I will re-check my instructions tonight. Maybe i misunderstood and maybe I was too quick to read but it what you posted sure makes sense.
Thanks. |
No problem! Personally still learning and sorting out info about these olde ACVWs.
Was not that long ago that we went from only using feeler gauge to set points. To now also using a dwell meter to set them much more accurately/correctly and there on at each tune up rechecking the points by the dwell meter only. Has made for a lot less physically fiddling with the points over many tune ups.
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