im putting discs all around my bug what master should i use?

vw62rag · Post by **vw62rag** » Mon Feb 24, 2003 7:18 pm

im putting discs brakes all around my 62 bug and was looking for some advice on what master cylinder i should use? one place told me to use a early bus master,becuse its bigger and flows more. any info would be cool.
thanks

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Hoxviii · Post by **Hoxviii** » Mon Feb 24, 2003 7:36 pm

I'd just run a '67 on Bug master cylinder.

Justin

captCRUNCH · Post by **captCRUNCH** » Mon Feb 24, 2003 10:26 pm

hey justin, did you just bolt the master cylinder up? did you add any residual valves to it? how does your pedal feel? i'm curious cause i'm about to bolt up some front disc's and wondering if i need to add these or do any other mod's. by the way i'm doing this on a 72. thanks

Tom Perso · Post by **Tom Perso** » Tue Feb 25, 2003 4:24 am

Porsche 914 M/C.

It takes a little rigging to make the brake light switch work, but it's worth the effort. I have one in my Bug with 4-wheel discs and the pedal feel is awesome.

Later,
Tom

Thai_1_On · Post by **Thai_1_On** » Tue Feb 25, 2003 5:00 am

Hey Rag I have 4 wheel disc on my 65 with the stock single master cylinder and it works fine. The pedal feels good and firm just one word of caution. When you slam on the brakes be ready because my car stops like I threw a anchor out the back

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MANG 65 "street" Baja

vw62rag · Post by **vw62rag** » Wed Mar 05, 2003 10:35 pm

i jus talked to a guy in so cal (oldspeed), he told me to use a early bus master becuse they flow more,and if i use my stock bug master the pedal would go almost all the way to the floor.and if i wanted a duel circit master hed get me a modified rabbit M/C, cuz its the same size as the early bus one. im confused.

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Post by **Marc** » Thu Mar 06, 2003 6:03 am

<BLOCKQUOTE>quote:<HR>Originally posted by vw62rag:
i jus talked to a guy in so cal (oldspeed), he told me to use a early bus master...
<HR></BLOCKQUOTE>

As in single-circuit? That's insane.
The stock late master should be fine - if you like a firmer pedal than that gives, you can add residual pressure check valves.

Pillow · Post by **Pillow** » Thu Mar 06, 2003 6:32 am

Early 911 is what I like.

As for the Old Speed setup he (Russell) modifies the early bus MC and Rabbit MC. Definately not off the shelf units. The way it is described here is a little inaccurate.

Granted I think it is stupid to run a single circuit MC in anything at all. (yah I might get flamed for that)

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Adrian Pillow
'66 VW Westfalia
'79 Porsche 911 SC - FS
VolkSport Kafer Gruppe

chigger · Post by **chigger** » Thu Mar 06, 2003 6:38 am

The type of calipers determine the size of the MC. The bigger the pistons and if you have more of them requires more fluid. A floating caliper (piston on only one side)requires the most fluid to move it into position. Drum brakes require alot of movement and hence fluid also.
A large diameter MC pushes more fluid, but it has less mechanical advantage and so a harder petal. A smaller MC pushes less fluid at a greater mechanical advantage and has a longer easier stroke. If you have a small MC with large diameter pistons and a worn rotor the MC may run out of fluid before the pistons clamp the rotor.
Residual valves hold a certain amount of fluid in the piston to keep it from retracting completely. This improves the brake feel as the piston has less distance to go before engaging the rotor. The down side is the pads drag on the rotor very slightly. www.stockcarproducts.com recommend
2 lb valves on disks and 10 lb valves on drums. An all disk system would use 2 lb valves.
Contrary to popular belief the fluid in the brake system doesnot flow it just moves back and forth. Bleeding the air out is the most important thing especially with new parts. You won't get it all the first time.
I would try the dual circuit late model bug MC first and see how it works since it just bolts up. The bus MC or residual valves would be a valid alternative if you run out of petal. Hope it helps.

vw62rag · Post by **vw62rag** » Thu Mar 06, 2003 10:42 am

thanks for the help, i think im gona just use a late model bug MC. do i need to take out the residuel valve?

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Post by **Marc** » Thu Mar 06, 2003 12:47 pm

<BLOCKQUOTE>quote:<HR>Originally posted by Tom Notch:
Use one for a disc brake Ghia, what I used on my bug. Works fine.
<HR></BLOCKQUOTE>

That would be the 113 611 015BD again. It has no residual pressure check valves, just tiny drillings. If you came across an early diskbrake M/C that had a resid valve on the rear circuit it'd be fine for rear drums but not for 4-wheel disks (too much drag, pads'd last less than 20K).

vw62rag · Post by **vw62rag** » Thu Mar 06, 2003 1:00 pm

so should i use a later bug MC with no residuel vaves?

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Post by **Marc** » Thu Mar 06, 2003 2:05 pm

<BLOCKQUOTE>quote:<HR>Originally posted by vw62rag:
so should i use a later bug MC with no residuel vaves?
<HR></BLOCKQUOTE>

It's gotten 3 votes so far:

<BLOCKQUOTE>quote:<HR>Originally posted by Hoxviii:
I'd just run a '67 on Bug master cylinder.
<HR></BLOCKQUOTE>

<BLOCKQUOTE>quote:<HR>Originally posted by Marc:
...The stock late master should be fine - if you like a firmer pedal than that gives, you can add residual pressure check valves.<HR></BLOCKQUOTE>

<BLOCKQUOTE>quote:<HR>Originally posted by chigger:
...I would try the dual circuit late model bug MC first and see how it works since it just bolts up. The bus MC or residual valves would be a valid alternative if you run out of petal. <HR></BLOCKQUOTE>

...but it's not the only option, just the most prevalent. I've also heard that Audi M/Cs can be used.

volksmann · Post by **volksmann** » Thu Mar 06, 2003 5:14 pm

My 71 auto-cross bug has a stock duel master cylinder and disc brakes on all fours, works great but, when the course had some really rough section in it, the first time I stepped on the brakes the pedal would go to the floor, then the second time I stepped on the brake they were fine, after that I would tapped the padded first, before I had to use them. I used the same car at a rally-cross and it did the same thing. Residual valve would eliminate that problem.

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that's volksmann with 2 n's

Derrick from NC · Post by **Derrick from NC** » Thu Mar 06, 2003 5:28 pm

Do a search on the EuroLook forum. Several folks there are using the Porsche 944 m/c and it's suppose to be almost a bolt-on swap. I currently have ghia front and 914 rear disc brakes with the late bug m/c. I feel it has just a little too much pedal travel for my taste.
I will be converting to Porsche 996 front and 944T rear Brembo caliper/rotors which will require more juice to move than my current setup. I will install the 944 m/c at that time.