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tree hugger Samba Member
Joined: April 28, 2006 Posts: 195
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Posted: Thu Jul 12, 2007 10:20 pm Post subject: Dual Circuit Master Cylinder conversion |
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Hi Guys
I want to convert our bus to dual circuit brakes. What I'm not sure of is what master cylinder I would need if I want to go 4 wheel disc later on. I'm definately going to convert the front to discs but will PROBABLY do the rear as well. Is there a cylinder I should use or more importantly is there one I shouldn't??? Any help would be great . Cheers.
Moderator Notes:
Along with the discussion in this thread, here are some external links as well:
http://www.aircooledtech.com/dual_MC_upgrade/
http://www.aircooledtech.com/dual_MC_upgrade/
If anyone wants to do a summary w/photos for this first post, PM EverettB. |
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67stang302 SBS Hit Squad
Joined: February 08, 2005 Posts: 1236
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Posted: Thu Jul 12, 2007 10:27 pm Post subject: |
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Split bus FAQ at the top of the page is a great place to spend some reading time.
http://type2.com/library/brakes/dualmas.htm _________________
EverettB wrote: |
Hondaz rulez my lifez |
SBSeven 1 YR and still going
59 Kombi laying beam
64 type 34 |
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67stang302 SBS Hit Squad
Joined: February 08, 2005 Posts: 1236
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tree hugger Samba Member
Joined: April 28, 2006 Posts: 195
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Posted: Thu Jul 12, 2007 10:35 pm Post subject: |
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Yeah thanks man, I've read the Type 2 article but I wasn't sure if that m/cylinder would be OK for 4 wheel discs. I remeber reading a post on a forum somewhere ..... might have been here?, explaining that there was one model that worked really well for 4 wheel discs. |
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67stang302 SBS Hit Squad
Joined: February 08, 2005 Posts: 1236
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Posted: Thu Jul 12, 2007 10:41 pm Post subject: |
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tree hugger wrote: |
Yeah thanks man, I've read the Type 2 article but I wasn't sure if that m/cylinder would be OK for 4 wheel discs. I remeber reading a post on a forum somewhere ..... might have been here?, explaining that there was one model that worked really well for 4 wheel discs. |
Sorry overlooked the 4 wheel disc part My Bad _________________
EverettB wrote: |
Hondaz rulez my lifez |
SBSeven 1 YR and still going
59 Kombi laying beam
64 type 34 |
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ZENAK Samba Member
Joined: May 15, 2007 Posts: 136 Location: Alaska
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Posted: Thu Jul 12, 2007 11:29 pm Post subject: |
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quote:
CAUTION: It is essential to use a master cylinder
designed for disc brakes.
WARNING: If you use the front disc brake system
with a drum brake master cylinder,
the built-in residual pressure
valve will cause a steady pressure at
the front wheel, causing them to
drag, overheat and become
damaged.
- Please note that all vehicles with drum
brakes at the front need to change the master
cylinder to a disc-brake type.
http://www.thesamba.com/vw/forum/viewtopic.php?t=219574&highlight=bay+breaks |
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ZENAK Samba Member
Joined: May 15, 2007 Posts: 136 Location: Alaska
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Posted: Thu Jul 12, 2007 11:38 pm Post subject: |
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is it pretty straightforward to fit bay disks on a split?...-not shur if i should start a new topic? |
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tree hugger Samba Member
Joined: April 28, 2006 Posts: 195
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Posted: Fri Jul 13, 2007 12:04 am Post subject: |
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No add it on to this post I don't mind I'd like to know |
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ZENAK Samba Member
Joined: May 15, 2007 Posts: 136 Location: Alaska
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Posted: Fri Jul 13, 2007 12:08 am Post subject: |
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iv done a search and found a LOT of info...but its a LOT of info..i think all you need is the breaks, the Bay proportioning valve (in/near the left front frame rail-dont know what it looks like) and the Vacuum Booster (what ever that is)? |
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krusher Samba Member
Joined: September 24, 2002 Posts: 7652 Location: europe
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Posted: Fri Jul 13, 2007 12:30 am Post subject: |
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Vacuum Booster = servo |
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ZENAK Samba Member
Joined: May 15, 2007 Posts: 136 Location: Alaska
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Posted: Fri Jul 13, 2007 12:33 am Post subject: |
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krusher wrote: |
Vacuum Booster = servo |
aahhh a servo----and this does? |
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Karl Samba Member
Joined: January 29, 2001 Posts: 6170 Location: Coos Bay, Oregon
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Posted: Fri Jul 13, 2007 7:26 am Post subject: |
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ZENAK wrote: |
krusher wrote: |
Vacuum Booster = servo |
aahhh a servo----and this does? |
Gives you power brakes.
# 68 here:
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abim Samba Member
Joined: October 23, 2003 Posts: 43
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Posted: Fri Aug 17, 2007 8:27 am Post subject: brake line position |
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read the tech articles about this dual MC conversion:
anyone have pics to display for reference especially to brake line position:
some people are using T fittings to plumb the front brakes into ONE port
some people are plumbing their front brake lines directly into the REAR ports of the master cylinder with no T fitting.
i plumbed my 61 lines right into the FRONT of mine and it works fine.
anybody know what is OK and what is NOT? What port is for WHAT and does it matter if you reverse front and rear?
THANX |
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Eric&Barb Samba Member
Joined: September 19, 2004 Posts: 24670 Location: Olympia Wash Rinse & Repeat
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Posted: Fri Aug 17, 2007 12:32 pm Post subject: Re: brake line position |
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abim wrote: |
anybody know what is OK and what is NOT? What port is for WHAT and does it matter if you reverse front and rear?
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VW designed and plumbed the dual MC in the post-1966 buses for a reason. Best to stick with that setup.
Check out the dual circuit brakes article we wrote up on type2.com website in the "Brakes" section. _________________ In Stereo, Where Available! |
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abim Samba Member
Joined: October 23, 2003 Posts: 43
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Posted: Sat Aug 18, 2007 11:59 pm Post subject: more plumbing |
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thanx for info. . .so all post 66 buses have their front brake lines T'ed together and enter one port of master cylinder? can one not plumb the front brakes into the MC separately? thanx. . . |
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vwluver74 Samba Member
Joined: February 29, 2004 Posts: 889 Location: at the buffet in the fetus room
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Posted: Sun Aug 19, 2007 12:14 am Post subject: |
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i have this conversion done on my 62 singlecab. i can post up pics of the conversion and all its parts if youd like. |
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Eric&Barb Samba Member
Joined: September 19, 2004 Posts: 24670 Location: Olympia Wash Rinse & Repeat
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Posted: Sun Aug 19, 2007 9:17 am Post subject: Re: more plumbing |
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abim wrote: |
thanx for info. . .so all post 66 buses have their front brake lines T'ed together and enter one port of master cylinder? can one not plumb the front brakes into the MC separately? thanx. . . |
Hi Abim,
Exactly. Plus all rear brakes only used one brake line that is "T" near the rear axle. So it does not seem to pose a problem. While you could run two lines into the front circuit (if you could find an adapter) of the MC that would require you to get rid of the front circuit brake sender. This would mean you would have no brake lights if the rear brake blew out. In turn this increases your chances of you getting rear ended when you have that circuit of brakes blow out or as you limp it to the repair shop or home.
If you check out the 1963-67 "Workshop Manual Volkswagen Transporter" Section "B-14", pages 1-6, you find a lot of good dual MC info. For instance the stroke of the 1967 dual MC was 32mm, but only 13 mm was for the rear brakes which only had one small slave cylinder per rear wheel. While the front circuit stroke was 19mm due to having two slave cylinder per front wheel needing that more fluid!
The 1972 (introduced in 1971 here in N. America and not in most of the reat of the world till 1972) thru 1979 dual MC used discs up front which needed even more fluid. Fortunately having more brake fluid to go to the front brakes when using drum type is not a problem.
Also the dual MCs do not engage both front and rear brakes at exactly same time! The rear brakes start to slow down the VW first and then the fronts start to engage as you further increase pushing down on the pedal. _________________ In Stereo, Where Available! |
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abim Samba Member
Joined: October 23, 2003 Posts: 43
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Posted: Sun Aug 19, 2007 6:50 pm Post subject: followup |
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thanx for the all the information!!
pics would be nice and i will post my pics also. . .
i have access to a 70 bus MC which i believe had drum brakes not disc in front, has anyone tried this one? |
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Eric&Barb Samba Member
Joined: September 19, 2004 Posts: 24670 Location: Olympia Wash Rinse & Repeat
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Posted: Sun Aug 19, 2007 7:17 pm Post subject: Re: followup |
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abim wrote: |
i have access to a 70 bus MC which i believe had drum brakes not disc in front, has anyone tried this one? |
Welcome! The problem with the 1968-71 MCs is the connections for the resevior are spaced differantly from the 1967 bus or later Rabbit resevior. So you will have to find a resevior that will not only fit on the 1968-70 MC, but also line up fill hole to the access plate in the bus floor, OR figure out how to plum the 1968-72 resevior into the earlier bus. _________________ In Stereo, Where Available! |
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'58 Single Cab Samba Member
Joined: December 06, 2004 Posts: 16
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