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Disc brake conversion, issues

The victim:

1967 beetle

The modifications: Type3 front disc, T3 rear drum brakes. (They are 4 lug, at least.) Lines: All new stainless, braided teflon Bupack(?) flex lines Master cylinder:

Ay, here's the rub. Read a lot of the ramva archives, and it seems evenly split as to "The original master cylinder should work fine", "You need to get some proportioning valve thingys", and "Use a Bus/Ghia/ master cylinder."

Last night, I removed the original master cylinder, and put in a Varga '67 bug standard dual circuit. Same symptoms as with the old master cylinder:

I've been playing with my rod (no, the brake pedal rod on my bug) and if I adjust it in, the brakes work nearly perfect. Then, after about 20-30 minutes of driving, all 4 wheels lock up. Oops, too tight.

I turn it out 1/2 of a turn (very very little), and then pretty much only the front brakes work, and are kinda hairy on wet pavement due to locking up. Two pumps of the brakes, and they seem to work nicely. (With the old master cylinder, would take me 3-4 pumps, so I guess that's an improvement...).

I've been thinking of replumbing for a T3 master cylinder ('68) (replumbing due to everything being on the incorrect side for a bug, we had a couple of them on the desk at the local FLAPS to compare), or possibly a Ghia '68 master cylinder.

Thoughts? Flames? Suggestions? Beer?

Reply to
ekoman
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I had the same experience once with another car. There where som kind of pressure valves insertet to the mastercylinder. These should be removed after converting to disk brakes from drumbrakes...... (It was a Rabbit/Golf 74 - the first models here in Denmark had drumbrakes in the front) Bye....MIC

Reply to
BS

I would try the T-3 MC, I was going to do it on my beetle, but I am curious if it will actually work or not, so try it and Let us know ;-). I would however, in either choice use a German MC. The Vargas are made in Brazil and last about 3 years, tops. Brazilian hydraulics suck major frog's ass. You should be able to use a Proportioning valve similar to the ones they use on sandrails. I know Jamar makes one that fits inline. Again I haven't tried this yet, but was planning on it, so don't shoot me.

Reply to
Zarana-X

Yup.. you need a metering valve (also called a hold-off valve) in the front circuit. It delays the onset of the discs until the shoes in the rear are in contact with the drums.

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Reply to
David Gravereaux

I have this setup:

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Fronts are ghia discs and rears are from a '71 squareback in my '73 super. The only complaint I have with all the valving is that you really do need to press the pedal more than before. The 2psi residual (i'm just using one btwn the MC and the metering valve) probably isn't needed.

I wonder how I could add a power booster? As it stands, it would hang below the car...

Reply to
David Gravereaux

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