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Abscate
Samba Member
Joined: October 05, 2014
Posts: 22670
Location: NYC/Upstate/ROW
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 Posted: Mon Mar 02, 2015 11:30 am Post subject: |
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| Luft kühl wrote: |
Wrong.
In a dual master cylinder the pistons for both hydraulic circuits share the same bore. When one circuit fails, the piston from the good circuit moves up against the failed one to maintain a connection to the pedal. As the piston moves, the additional space that is created needs a small amount of additional fluid in order to remain full. If the single reservoir is already empty, it will suck in air instead and cause the remaining circuit to fail as well. |
The residual brake fluid in the Tee-d off hose would be more than enough to provide fluid in this case.
I agree that if you can't determine you have half braking power after 20 pumps, then Darwin should claim you anyhow.
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57BLITZ
Samba Member
Joined: June 12, 2012
Posts: 2385
Location: DEEK - U.S.A.
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| Posted: Mon Mar 02, 2015 4:14 pm Post subject: |
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| mukluk wrote: |
| How old are your soft brake lines? They may have collapsed internally and are restricting fluid flow to and from the master and slave cylinders. |
Thanks for suggesting that!
I replaced my Ghia calipers and the M/C before I discovered the bad flex-hoses . . . The brake dragging problem was starting to drive me nuts!
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EA812
Samba Member
Joined: December 07, 2008
Posts: 1223
Location: North central, CT
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| Posted: Tue Mar 03, 2015 12:35 pm Post subject: |
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| Notablecarrot3 wrote: |
| mukluk wrote: |
| How old are your soft brake lines? They may have collapsed internally and are restricting fluid flow to and from the master and slave cylinders. |
Replaced in 2008...  |
Sounds like the MC but how old are the wheel cylinders? German or non? Leaking? What do them flex lines look like? Are any swollen? I've replaced two new ones because they reacted to grease that got on them from the axle. They were still working but swelled up from that grease.
Who did you get the master cylinder from? Maybe it went bad right away.
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Notablecarrot3
Samba Member
Joined: January 22, 2008
Posts: 461
Location: Sunny South Of France
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| Posted: Wed Mar 04, 2015 12:49 am Post subject: |
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| EA812 wrote: |
| Notablecarrot3 wrote: |
| mukluk wrote: |
| How old are your soft brake lines? They may have collapsed internally and are restricting fluid flow to and from the master and slave cylinders. |
Replaced in 2008... |
Sounds like the MC but how old are the wheel cylinders? German or non? Leaking? What do them flex lines look like? Are any swollen? I've replaced two new ones because they reacted to grease that got on them from the axle. They were still working but swelled up from that grease.
Who did you get the master cylinder from? Maybe it went bad right away. |
Flex lines are ok, wheel cylinders are all reasonably new, no signs of any leaking.
This is the 3rd master cylinder to go bad and I desperately need a car! Any ideas?
The piston gets stuck and takes ages to work it's was back up ( 10 minutes )
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Notablecarrot3
Samba Member
Joined: January 22, 2008
Posts: 461
Location: Sunny South Of France
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| Posted: Wed Mar 04, 2015 2:06 am Post subject: |
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My dad took the master cylinder to bits, is this the correct order for putting it back together?
IMG_4311 by Tom.Wheatley, on Flickr
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| EverettB wrote: |
| Your Donkey has a large head. I like your donkey. |
| EverettB wrote: |
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KTPhil 
Samba Member
Joined: April 06, 2006
Posts: 34018
Location: Conejo Valley, CA
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| Posted: Wed Mar 04, 2015 9:42 am Post subject: |
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| Is there a restriction in the connections and lines leading to the reservoir? That would slow down the pedal return. |
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pdowty68
Samba Member
Joined: April 07, 2014
Posts: 224
Location: Long Island, New York
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| Posted: Thu Mar 05, 2015 7:09 am Post subject: |
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| On my 73 super I had a bad problem with the brakes. There was no freeplay in the pedal and the brakes were constantly dragging, and they would get hot and the pedal would get rock hard, making the brakes pretty much useless. I adjusted the stop plate, and the problem was solved. But then the clutch pedal fell down and the cable slipped off the hook. After that I now know to tie the clutch pedal up when adjusting the stop plate. |
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lavo56
Samba Member
Joined: July 20, 2005
Posts: 52
Location: South West Wyoming
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| Posted: Sun Mar 08, 2015 9:07 am Post subject: |
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Notablecarrot3
To answer your original question. Yes you might have the wrong pushrod. When it was converted to dual cylinder, the person who did the conversion might not have realized a different pushrod was needed.
KTPhil and bill may have both stated that master cylinder brake pushrods are NOT all the same!!! They have to be matched to the master cylinder. My research shows 4 different pushrods for the bugs and at least 2 different ones for the Type III. Some look similar but are NOT the same
This subject is often overlooked and rarely mentioned when conversions are done.
Maybe someone with better writing skills and more knowledge than me could do a sticky on master cylinders and pushrods and how they need to be matched.
IMO I think this might be the cause of some brake bleeding problems also
Steve |
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Mayor Marion Berry
Samba Member
Joined: August 30, 2014
Posts: 119
Location: Fredericksbug VA
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| Posted: Mon Apr 27, 2015 9:59 am Post subject: |
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| Luft kühl wrote: |
| grandpa pete wrote: |
| the single fill reservoir does not affect the dual circuit master as long as it is " T'd " off so it can supply each side . |
Anyone who understands how a dual master cylinder works will know why this statement is not true. |
can folks shed some light on this for me? I am upgrading my 59 to a dual but im.using the original metal reservior, but T'd to feed each master cylinder. Should i not do this? |
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60ragtop
Bonneville Belt Bitch
Joined: March 13, 2006
Posts: 7800
Location: Big Wonderful WYO 82401
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| Posted: Mon Apr 27, 2015 10:03 am Post subject: |
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the proper dual circuit reservoir has 2 separate chambers in case one leaks all the fluid out, this way you still have some braking. with just a single chamber you are SOL if it leaks all the fluid
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Rick
Certified Mechanic by the State of Michigan in 1977
ASA certified in 1987
Certified Hunter Wheel Alignment Master Technician 1986
| tasb wrote: |
I've restored a large number too, but I don't toot my horn quite as loud.
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| sb001 wrote: |
maybe he just snapped cause his car sucked  |
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