[V8 Super Beetle]

I have a few questions about my brake system.

I have this dual master setup.




1) One master is .75 and the other .875. I'm going to use the .875 for the front and .75 for the rear. Does this sound right? The larger bore will apply more force?

2) Does brake line size matter? The factory setup has a 1/4" line to the rear brakes with a t fitting and the front lines are 3/16" with a tee fitting.

3) Fittings. I understand that the fitting to convert from the brake line to the master is tapered. Once I screw in the fitting by hand and it stops, how much should I torque it into the master cylinder?

4) Last, what's the best way to bleed this type of system / pedal configuration? I know you bleed the furthest points in each system first, but should I leave one master unhooked from the brake pedal, do one, and then hook up the other and do it? Or do I keep them both hooked up and bleed them at the same time? Should I not hook up the pedal and bleed each system push the pushrod?


Thanks for the help!

[V8 Super Beetle]

I noticed these fittings are flush with the master cylinder.




Do I just tighten until the master to brake line fittings are flush?

[aosborn]

Originally Posted by V8 Super Beetle

I have a few questions about my brake system.

I have this dual master setup.

1) One master is .75 and the other .875. I'm going to use the .875 for the front and .75 for the rear. Does this sound right? The larger bore will apply more force?

2) Does brake line size matter? The factory setup has a 1/4" line to the rear brakes with a t fitting and the front lines are 3/16" with a tee fitting.

3) Fittings. I understand that the fitting to convert from the brake line to the master is tapered. Once I screw in the fitting by hand and it stops, how much should I torque it into the master cylinder?

4) Last, what's the best way to bleed this type of system / pedal configuration? I know you bleed the furthest points in each system first, but should I leave one master unhooked from the brake pedal, do one, and then hook up the other and do it? Or do I keep them both hooked up and bleed them at the same time? Should I not hook up the pedal and bleed each system push the pushrod?


Thanks for the help!

1.The smaller bore will produce higher pressure with everything else being equal. Smaller area + same application pressure = more pressure per square inch. Disc brakes require more hydraulic pressure than drum brakes for similar clamping forces.

2.With a pressure hydraulic system, line size doesn't matter within reason. 3/16" line everywhere will be fine, but the 1/4" to the rear "T" won't hurt.

3.The fitting will need a sealing gasket and a machined surface to mate up to if it screws in flush to the master cylinder. If the threads are good, hand tight plus 1/8 turn or so should do it. With aluminum threads, be careful. Better a little loose to start with and then tighten more, than too tight and strip the threads.

4. Bench bleed both masters, connect both to the pedal and bleed as usual. Just make sure the balance bar is centered so you get full travel out of both master cylinders.

Andy

[V8 Super Beetle]

Thanks aosburn! I have the pedal mocked up and master mocked up, but when I press the pedal it pushes on one master more than the other. The bar is pretty even from what I can see. There is some play in the balance bar.

Should the play be reduced so I get even travel to both master? Can it be that the side that's getting more travel has the pushrod threaded in more? It's the side without the nut on it. Is it cause the nut needs to be tightened more?

I'm trying to figure out how to fine tune the pedal action so I can evenly bleed each system and them tune the brake how I want afterwards.

Thanks again!

[aosborn]

Here is a link to the Wilwood engineering page for that pedal assembly.

http://www.wilwood.com/Start/Product.../pedaltech.asp

This should be able to answer your questions.

Andy

Note: Until both the front and rear systems are bled, the balance bar will act strange. If the rears are bled, and the fronts aren't there is less pushrod resistance to the front master cylinder causing the balance bar to go offcenter. It will be fine once the whole system is bled.

[V8 Super Beetle]

Thanks again aosborn. I have the brakes all hooked and the pedal is nice and firm. The rear brakes are firmer (discs front, drums rear) but they seem to work really well. I have yet to actually put them to the test. I will on my first test drive next weekend, hopefully.

Thanks

[aosborn]

Good luck on your test drive. Post some photos!

Andy

[V8 Super Beetle]

Originally Posted by aosborn

Good luck on your test drive. Post some photos!

Andy

Definitely will! I normally post updates weekly on my project thread here.

V8 1973 VW Beetle Project - Help Needed!