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DarinNDebra1961VW
Samba Member
Joined: October 12, 2006
Posts: 48
Location: Saraland Alabama
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 Posted: Sat Nov 01, 2008 2:26 pm Post subject: Updating early model car with late model master cylinder |
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| I am in the middle of restoring a 61 model beetle. This afternoon I was working on the car and looked at the master cylinder and thought to myself. This has to go...it needs to be updated with a two stage late model unit. Any of you guys got any ideas regarding the reseviour? I know the one that came on the car was trashed. So I purchased one from my local VW parts guy...but its garbage........is there anything "trick" out there that could be retrofitted that would work with the two stage cylinder (with two fluid supply line nipples?) or something that I could use and then put a t in the line between the reseviour and the cylinder? Im just trying to save myself some time by depending on the experience of you guys !!!! Looking forward to seeing the responses !! |
Hotrodvw
Samba Member
Joined: July 06, 2004
Posts: 6327
Location: Orygun
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| Posted: Sat Nov 01, 2008 4:21 pm Post subject: |
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Search for a '67 bug reservoir. It's adual circuit unit. A tee in the line for the single circuit res. isn't a good idea. It defeats the purpose of the dual circuit m/c.
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pupjoint
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Joined: May 23, 2007
Posts: 1140
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| Posted: Sat Apr 04, 2009 9:25 pm Post subject: |
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i plan to do this also to my 66.
i will be putting the volvo 240 reservoir on top of the MC.
what else i need to change? |
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rzepko6194
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Joined: January 30, 2005
Posts: 829
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| Posted: Sun Apr 05, 2009 8:55 am Post subject: |
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| Hotrodvw wrote: |
| Search for a '67 bug reservoir. It's adual circuit unit. A tee in the line for the single circuit res. isn't a good idea. It defeats the purpose of the dual circuit m/c. |
How so? Let's say there's a leak in the rear circuit which drains the reservoir. The front circuit should be unaffected since there's still fluid in the front part of the master cylinder. Am I missing something here? |
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vdub
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Joined: September 07, 2003
Posts: 442
Location: Valley Springs, Ca.
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| Posted: Sun Apr 05, 2009 9:44 am Post subject: |
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The purpose of a dual circuit master is it has 2 individual chambers for front and rear brakes.
It has nothing at all to do with the reservoir. I would just ad a Y to the hose coming out of your single reservoir. |
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ScrapJunkie
(O\U|U/O)
Joined: March 17, 2004
Posts: 3977
Location: Hutchinson, Kansas
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| Posted: Sun Apr 05, 2009 9:53 am Post subject: |
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| rzepko6194 wrote: |
| Hotrodvw wrote: |
| Search for a '67 bug reservoir. It's adual circuit unit. A tee in the line for the single circuit res. isn't a good idea. It defeats the purpose of the dual circuit m/c. |
How so? Let's say there's a leak in the rear circuit which drains the reservoir. The front circuit should be unaffected since there's still fluid in the front part of the master cylinder. Am I missing something here? |
The master cylinder has to push fluid to open up the wheel cylinders, causing the master to suck air from an empty reservoir, thus causing spongy brakes, or worse.
A dual circuit master cylinder is designed so that if one brake system fails (front or rear), then the other system is unaffected. That's why the reservoir is divided, with two hoses.
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Russ Wolfe
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Joined: October 08, 2004
Posts: 25187
Location: Central Iowa
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| Posted: Sun Apr 05, 2009 9:53 am Post subject: |
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But if one circuit leaks, and you have a single circuit reservoir, you will run out of fluid. Defeating the purpose of the master cylinder.
Also, putting the reservoir under the car puts it into the splash zone where water can get in through the vents in the cap.
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KTPhil 
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Joined: April 06, 2006
Posts: 34009
Location: Conejo Valley, CA
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| Posted: Sun Apr 05, 2009 9:59 am Post subject: |
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| It depends on the failure mode. A partial internal MC failure or wheel circuit failure would still leave the other side operational, even with a shared reservoir. But if the failure was a leaky hose or crack in the reservoir, the single-hose system would fail utterly, like a single system would. |
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vdub
Samba Member
Joined: September 07, 2003
Posts: 442
Location: Valley Springs, Ca.
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| Posted: Sun Apr 05, 2009 10:04 am Post subject: |
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You could remove the reservoir and still have working brakes.
The reservoir is used to replace fluid in the system. If you have no leaks anyware then the reservoir just stores fluid for when you do.
Also the fluid in the reservoir replaces the space used brake parts make.
My whole point is the reservoir is the least concerning part of the system. The single reservoir would work just fine. I have used them many time in dual conversions with no problems. |
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Zundfolge1432
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Joined: June 13, 2004
Posts: 12467
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| Posted: Mon Apr 06, 2009 10:13 am Post subject: |
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Do a search on this topic and you'll see its been beat to death.... I posted an detailed how-to a couple of years back.... Then someone fobbed parts off a volvo to accomplish the same task, however using the 67 VW setup retains the stock look and keeps the reservior protected..... The vulva er I mean volvo thing looked ok if you like custom one offs JMO it looked like a busy mass of shit to me..... Next we got hammered by people reading the Bentley and telling us never to adjust the M/C pushrod ...... Again a search will flood you with info..... Its time consuming doing it the 67 VW way but the end result will look like a factory job and you'll gain the saftey factor you are looking for.... 
Jim- |
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ScrapJunkie
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Joined: March 17, 2004
Posts: 3977
Location: Hutchinson, Kansas
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| Posted: Mon Apr 06, 2009 3:30 pm Post subject: |
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| Zundfolge1432 wrote: |
| Its time consuming doing it the 67 VW way but the end result will look like a factory job and you'll gain the saftey factor you are looking for.... |
It didn't take me long at all to do it to my old 65..
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petrol punk
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Joined: August 21, 2007
Posts: 975
Location: Las Vegas, NV
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| Posted: Mon Apr 06, 2009 3:40 pm Post subject: |
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| vdub wrote: |
The purpose of a dual circuit master is it has 2 individual chambers for front and rear brakes.
It has nothing at all to do with the reservoir. I would just ad a Y to the hose coming out of your single reservoir. |
Reservoirs on cars with dual circuit have 2 separate chambers for each braking circuit. Say your hose for your rear brakes becomes disconnected/gets cut/etc. all the brake fluid in that chamber is leaked out but the front brakes circuit still has a full chamber. I think you would be totally fine with Teeing the lines so long as the the volume of fluid between the tee and the master is greater than the volume of fluid displaced by the master cylinder as it is pushed in.
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vdub
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Joined: September 07, 2003
Posts: 442
Location: Valley Springs, Ca.
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| Posted: Mon Apr 06, 2009 3:48 pm Post subject: |
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| petrol punk wrote: |
| vdub wrote: |
The purpose of a dual circuit master is it has 2 individual chambers for front and rear brakes.
It has nothing at all to do with the reservoir. I would just ad a Y to the hose coming out of your single reservoir. |
Reservoirs on cars with dual circuit have 2 separate chambers for each braking circuit. Say your hose for your rear brakes becomes disconnected/gets cut/etc. all the brake fluid in that chamber is leaked out but the front brakes circuit still has a full chamber. I think you would be totally fine with Teeing the lines so long as the the volume of fluid between the tee and the master is greater than the volume of fluid displaced by the master cylinder as it is pushed in. |
There is no fluid from the reservoir displaced when you push the break pedal. The reservoir is extra fluid that is there to allow the breaking media to wear. When your pads where out the space is replaced with more fluid in the system. The only way fluid is used quickly is if you have a leak. Otherwise the amount of fluid displaced from the reservoir is very minute.
In fact if a hose broke from the reservoir to the master you would have working brakes for a while until the pad wear would allow air to be sucked in to the system. |
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KTPhil
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Joined: April 06, 2006
Posts: 34009
Location: Conejo Valley, CA
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| Posted: Mon Apr 06, 2009 4:09 pm Post subject: |
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| vdub wrote: |
| There is no fluid from the reservoir displaced when you push the break pedal. |
Doesn't the volume of fluid moved to the wheels have to be replenished from the lines/reservoir until the pedal is returned? The volume displaced is not large but if the incoming line were broken anywhere near the master I would expect air to be sucked in shortly. |
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vdub
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Joined: September 07, 2003
Posts: 442
Location: Valley Springs, Ca.
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| Posted: Mon Apr 06, 2009 5:11 pm Post subject: |
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| KTPhil wrote: |
| vdub wrote: |
| There is no fluid from the reservoir displaced when you push the break pedal. |
Doesn't the volume of fluid moved to the wheels have to be replenished from the lines/reservoir until the pedal is returned? The volume displaced is not large but if the incoming line were broken anywhere near the master I would expect air to be sucked in shortly. |
Think about it this way. When you push the pedal the plunger in the master moves the fluid to the wheel cylinders. The system is full of fluid there is nothing to replace. once the peddle is released the only fluid that enders the system is enough to compensate for pad ware. This you can imagine is very little. Now on the chance that you have a leaky house or cylinder this amount can be greater. Proper maintenance should take care of that. |
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Culito
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Joined: December 07, 2006
Posts: 5866
Location: Columbia Missourah
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| Posted: Wed Jun 03, 2009 10:23 pm Post subject: |
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Not to interrupt this fascinating reservoir debate, but I have a question.
I notice the '67 MC has 5 ports not including the reservoir holes at the top.
Which ports go to which wheels, and where do you put the brake light switch(es)?
-Thanks. And FWIW, I plan to use a dual chamber reservoir as the system was designed.
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'64 standard w/2.0L type 4
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Jeckler
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Joined: September 27, 2005
Posts: 2718
Location: Mesa, AZ
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| Posted: Wed Jun 03, 2009 10:37 pm Post subject: |
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Top hole goes to right front wheel. Of the two sticking straight out the side, the front goes to left front wheel, the back to the rear wheels. The two below those, pointing towards the ground are for the switches.
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'63 Bug rebuild here.
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Culito
11010101
Joined: December 07, 2006
Posts: 5866
Location: Columbia Missourah
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| Posted: Wed Jun 03, 2009 10:44 pm Post subject: |
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Cool, thanks a lot.
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Copyright CJ Industries, Inc.
'64 standard w/2.0L type 4
'62 bug
| johnnypan wrote: |
| ...dont pay no attention to Culito,he's a cornhole.. |
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flat4
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Joined: July 18, 2002
Posts: 141
Location: NoVA
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| Posted: Thu Jun 04, 2009 2:22 pm Post subject: |
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| I recently saw So Cal imports is selling a dual chamber resevoir ala the Volvo one that fits on top of the MC. Now, keeping the fluid monitored would be a tough task with it tucked behind a wheel but those interested in keeping things stock looking might look into feeding that Dual chamber resevoir with a stock single chamber one. That way, you monitor levels at a glance like before, but you don't risk running a single chamber dry when you have a leak. |
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just bugn
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Joined: April 15, 2008
Posts: 39
Location: Pendleton Indiana
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| Posted: Thu Jun 04, 2009 4:14 pm Post subject: |
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| I have also done this upgrade and used the volvo resevoir but im planing on using the cap from a rabbit with the level sensor the diameter of the hole is perfect for an extra gasket and one of the nipples that came with the master then running a line to the stock resevoir. Easy to check without loosing the benefits of the dual chamber reservoir.. Looks stock |
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